solar sails sailboat

Yachting Monthly

• Digital edition

Sailing with solar power: A practical guide

• Duncan Kent
• November 13, 2020

The latest solar technology makes self-sufficient cruising much more achievable. Duncan Kent gives the lowdown on everything you need to get your boat sorted

SOLAR POWER ON BOARD

Solar power is fast becoming the most popular and economic method of keeping the batteries charged on a boat.

Particularly now that the efficiency of photovoltaic (PV) panels, charge controllers and batteries is improving every day.

Furthermore, the latest technology in regulators and charge controllers has brought about a noticeable increase in useable power output, so the problems of shading and non-alignment can be compensated for more easily.

Not only has PV equipment become more efficient and cost-effective, but many of the modern devices we want to use on a boat have become less power hungry.

This means it is now far easier to provide your entire yacht’s electrical needs, both 220Vac and 12/24Vdc, from natural energy resources – particularly solar power, even if you are planning on a fully electric boat .

Thinking carefully about how much power you need and how much your boat can accommodate is key to planning a solar array. Credit: Graham Snook

WHAT DO YOU NEED?

For instance, a boat with two new, good quality, deep-cycle house batteries of 100Ah each would supply 100Ah of energy to consume between charges, if you only use the recommended 50% of available charge between each charge cycle to protect the batteries.

From this you could run:

• a modern 12Vdc fridge (approx. 1.5Ah, or 36Ah over 24hrs),
• all LED lighting (say 20Ah per day),
• various small device chargers (20Ah)
• and a number of other items such as water pumps, TVs and stereos (25Ah/day)
• Totalling around 100Ah.
• For this you’d need 400W of solar capacity.

Of course, if you like to run a lot of AC devices off-grid such as hair dryers, microwaves, toasters and the like, then you’re going to need a DC/ AC inverter, which will take you to another level in power consumption terms.

But even then, with careful planning, solar could provide a large portion of the power you need before resorting to engine charging or a generator.

THE AVAILABLE SPACE

In practical terms, a modern 40ft monohull would have the space for around 1,200W of PV panels (cockpit arch, sprayhood top, deck), maybe 1,500W with the addition of a few portable panels for use at anchor.

The 1,200W of fixed position solar array could produce around 360Ah on a sunny summer’s day (zero shading) or more likely 250Ah on the average UK summer’s day.

So that’s enough for your 100Ah general DC consumption plus another 150Ah of AC consumption via the inverter.

Of course, to do this you’ll most likely need to increase your battery capacity to around 400-500Ah for maximum flexibility (you’ll need to store as much as possible during daylight hours), a typical figure for a 40-50ft offshore cruising yacht these days.

Get your solar charging right and you may never need to hook up to shore power

Typical daily inverter loads for a cruising yacht off grid might be:

• induction cooking plate (20min) 60Ah
• microwave (15min) 30Ah
• coffee maker (20mins) 25Ah
• hair dryer (5min) 15Ah
• laptop charger (2h) 10Ah
• or around 140Ah in total.

The trick is to monitor the batteries’ state of charge (SOC) at all times and vary your use of the inverter to suit.

For example, you might want to cook supper mid-afternoon, when solar is in abundance, and then reheat it in the evening when you want to eat it.

In some cases, when you’re cruising in warm climates such as the Med, you might end up with excess charge from your solar panels .

In this situation, many long-term cruisers devise a method of ‘dumping’ the extra energy by heating water for showers.

Do bear in mind if you’re planning to live aboard full time , then it’ll be a whole different story on cloudy days and during the winter, when inverter use might need to be knocked on the head entirely.

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POWER DISCREPANCIES

There’s often confusion as to how much power you can harvest from a solar installation.

A PV panel is nearly always advertised stating its theoretical peak output power (Pw).

But in reality, on a yacht where there are limited areas in which to mount them, they will more likely produce a maximum of 60% of their peak output if mounted horizontally, increasing to 80% if tilted towards the sun and regularly adjusted.

The latter is rarely achievable on a boat, however, as even at anchor it can swing through an arc of 180° in wind or tidal shifts .

Flexible panels can be mounted on sprayhoods or awnings to add power when it’s needed at anchor or in harbour

INSTALLATION

Having trawled through hundreds of ‘deals’ to get the best price on the most efficient panels you can afford you now need to know how to install them to best fulfill your energy generation needs.

The output, even from the highest quality photo-voltaic array, will only be as good as the installation itself.

So following our guidelines should ensure you extract every last drop of energy from your investment.

PANEL MOUNTING

Sailing boats are not the ideal structure on which to mount wide, flat PV panels.

So before you go ahead and purchase what looks like the biggest and best, take a few minutes to decide on exactly where you can mount them, as this will affect what size and type of panels you should buy.

In many cases the first choice would be on an arch, davits or gantry aft, especially if you already have, or plan to fit one.

Dinghy davits, particularly on multihulls, can support a huge solar capacity

These allow a solid metal framework to be constructed that will be strong enough to take the heavier, more productive rigid PV panels.

You can also build in some form of adjuster to the framework that will allow the panels to be orientated towards the sun for the best performance.

With luck (or careful planning) a gantry will also keep them aft of the boom, thereby eliminating loss of output caused by boom shading.

The next most popular position for mounting the panels is on a cockpit sprayhood or bimini, although this will often mean using the flexible or semi-flexible panels, which are generally less efficient than the rigid ones for the same area.

ELEVATED MOUNTING

Alternatively, there are kits available for mounting panels onto lifelines, which can allow their elevation to be manually adjusted to a certain degree.

Pole-mounted panels can be used for maximum adjustability

Finally, panels can be fitted directly onto the deck by either gluing them down using mastic or attaching them onto a rigid support frame.

Once again you will probably need to use semi-flexible panels – especially if the deck surface is curved.

Rigid, glass-coated panels will obviously not be suitable for deck mounting in an area that is frequently walked over.

Don’t be tempted to drill through the panels, even along the edges, as this will invalidate the warranty and possibly damage the panel.

With solid panels, the ability to adjust the angle can add significantly to output

It might seem obvious, but the key to an efficient system is to avoid shading wherever possible.

It’s no good fitting expensive, high-efficiency PVs right under the boom as they’ll perform little better than the cheaper types.

Saying that, in good quality panels each cell will be isolated from the next by a series of diodes (one-way electrical valves), so that if one cell is shaded at least it won’t drag down the other cells within the same panel.

Older panels often didn’t have these, so the slightest partial shading caused the output of the entire panel to cease.

OVERHEATING

Another important factor that is often ignored when installing the panels is that of overheating.

If a PV panel gets too hot, which is quite likely if mounted directly onto a flat surface without an air gap behind, its output will drop quite noticeably.

To allow for some air circulation behind the panels it’s best to apply mastic adhesive in numerous large dabs.

This is best achieved by placing wooden spacer strips between the dabs until the mastic has completely cured, after which the spacers can be removed.

You might need some form of trim around one or more of the outside edges, though, if they are positioned where sheets and other lines might get caught under them.

Raising the panels up will also help water to drain off and thereby helping to avoid possible delamination from sitting in water for too long.

CHARGE CONTROL

A PV module cannot supply an electrical device directly due to the changeability of the sunlight, which in turns varies the current it can produce.

Therefore, it has to be connected to a battery, which stores and smooths its output.

Whatever the size of your solar array you will need to fit a regulator, or charge controller as they are now more commonly known, to the system in order to control the output and to help extract as much power from the panels as possible.

There are two types of PV charge controller.

The older designs, called Pulse Width Modulation (PWM) types, were fairly basic voltage regulators and simply output volts at just above battery level.

The latest controllers use Multi Power Point Tracking (MPPT) technology and can accept much higher input voltages (up to 240Vdc).

MPPT controllers can be up to 30% more efficient as they use the peak output of the panels to charge the batteries, even compensating for partial shading.

BEWARE FAKE GEAR

If you buy online do be careful to ensure you’re getting what you pay for.

There are a huge number of fake MPPTs out there, which are simply the much cheaper PWM dressed up with fake labels.

It’s hard to tell which is which, but the old adage of ‘if it looks too good to be true, it usually is’ makes good sense.

MPPT controllers are usually bigger and heavier than PWMs, but if in doubt call or email the supplier to discuss the pros and cons of their kit before buying.

If they’re not happy to chat and advise you then I would steer clear of their gear.

Some good MPPTs are made in China, but unless they have a UK supplier, I wouldn’t bother with them as you’ll have no follow-up advice.

To calculate what size controller you need simply divide the panel’s peak power in Watts (Wp) by the battery voltage, which will give you the maximum current (Amps) they could theoretically supply.

For example 240W/12V = 20A. Although it’s unlikely you’ll ever get near the peak output from any PV panel, it’s best to go for the maximum possible.

Induction cooking is now a reality on board, even without shore power

PV panels come with a short length of cable, usually around 1m long.

Some are supplied with MC4 connectors already attached but most only provide bare wires.

The latter can be easily extended using proper waterproof connections but thought must be given as to the current rating and voltage drop (usually max 3%) for the size of cable you intend to use.

If in doubt, bigger is better!

Panels can sometimes be ordered with the wiring on the back so that the cable can go straight below deck through a hole under the panel.

You may need to fit extra battery capacity if you want to run an inverter from solar charging

SERIES OR PARALLEL?

A commonly asked question is ‘should I wire my PV panels in series or in parallel?’

The simple answer is, if there’s any danger of frequent shading to one or more of the panels then install them in parallel.

If wired in series the shading of a single panel will drag down the output from all of the others in the same series.

PARALLEL IS PREFERRED

Most commonly, multiple panels are wired together in parallel to a single charge controller, with diodes protecting each panel from discharging the others should one become partially shaded.

With the advent of MPPT controllers, however, there can sometimes be a benefit to wiring two or more identical panels into a series bank, thereby presenting a higher voltage to the controller.

It’s worth noting that, like batteries, wiring PV panels in series increases the voltage only – the current capacity of the array remains the same as for a single panel.

‘Where’s the benefit of wiring them in series then?’ you might ask.

Well, the higher the voltage fed into the MPPT, the more consistent it will be with its output, which could, in some cases, prove more efficient than a parallel installation with PWM controllers.

It’s also likely to be necessary if you have a 24V domestic system.

SERIES WIRING

Series wiring is usually only done when the cable runs are long, as it helps negate the voltage drop caused by the resistance of the cable.

While a decent controller will have no problem handling the output from four or even five panels wired in series, it is often inappropriate for sailing yachts as shading just one of the panels will reduce the output of the entire series array.

If you need to do so in order to reduce cable runs then it’s best to split the panels between each side of the boat – a series bank on each side.

If you do this, then you would ideally fit a separate controller to each series PV bank and then connect their outputs together in parallel to the battery bank.

Note, however, that panels wired in series must all be the same types with an equal number of cells per panel.

Furthermore, the charge controller needs to be sized for the total of all panel voltages added together and the current rating of one individual panel.

Differently rated panels can be connected together in parallel but only if each panel has its own controller.

The outputs of the individual controllers can then be joined together to go to the battery bank.

BATTERY BANK QUESTION

Another frequently asked question is ‘Can I connect another charging source to the battery bank while the solar array is charging?’

The answer is yes.

Any decent PV controller will be protected against feedback from other charging sources.

Think carefully about where shade from mast, boom and rigging will fall. Credit: Graham Snook Photography

CABLE SIZE AND CONNECTORS

A frequent cause of reduced output from PV arrays is wiring that is too small.

The resistance of a wire conductor increases in direct proportion to its cross-sectional area, so go as big as is practicable for the least cable loss.

Each panel should be supplied with the correctly sized cables for its own maximum output.

But if you’re combining panels, either in parallel or in series, you will clearly need to rate the single feed cable to suit the maximum current available at theoretical peak solar output and to minimise voltage drop.

Likewise, the cable from the controller to the batteries should be sized to suit the controller’s maximum output current and protected with a fuse.

For outside it’s important to use exterior grade cable, which is double- insulated and UV-proof.

WEATHERPROOF CONNECTORS

And wherever possible use compatible weatherproof connectors (usually MC4) to those found on the panels rather than cutting off the plugs and hard-wiring them.

Field- assembly MC4 plugs are available, so you don’t have to drill large holes in the decks or bulkheads when feeding the cables through.

When joining more than one panel together try to use the approved multiway connectors; not only do they keep the wiring neat and tidy, but they also offer a greater contact area than budget terminal blocks.

If you have to use screw-type connectors make sure to fit proper ferrules to the wire first to avoid any stray wires in the multistrand shorting across the terminals.

When feeding a cable from above to below deck, try to go through an upright bulkhead where possible to minimise ‘pooling’ of water around the access hole.

Also, use a proper watertight deck seal that matches the cable you’re using.

If drilling through a cored deck you need to drill a larger hole first, fill it with epoxy resin and then drill the required size hole through the epoxy to ensure no water gets into the deck core.

Ideally, the charge controller should be mounted no further than 2m from the battery bank.

If you need to go further, you’ll require larger cabling to reduce the voltage drop.

A generous solar array will keep you self- sufficient indefinitely. Credit: Graham Snook Photography

CONTROLLER LOAD TERMINALS

There is often confusion over the ‘load’ output of a charge controller (often depicted by a light bulb) and what can safely be connected to these terminals.

Rarely explained in the manual, the load terminals should be pretty much ignored in a marine installation as the output on these terminals is usually very limited (10A max).

Some attach an LED light to them to indicate the controller is operating, but all your usual electrical loads should remain connected to the batteries with the battery terminals on the controller connected directly to that battery bank via a fuse.

It is possible, though, to control a high-current switching relay in certain conditions.

Parallel installation is more resilient to shading, but a series installation will increase peak charging outputs. A combination of the two offers some of the benefit of both

CIRCUIT MONITORING

Unlike most cheap PWMs, the majority of good quality MPPT charge controllers come with an alphanumeric LCD screen to let you know what is going on.

This can either be a remote display or simply one on the front of the box.

It’s obviously a lot better to have a proper numerical display than to rely on a few flashing LEDs to tell you when something’s not right.

So if your chosen controller doesn’t have one be sure to fit a battery monitor (the shunt type) into your solar circuit between the controller and the batteries.

It doesn’t have to be a very ‘smart’ monitor, just one that can display the voltage and current being supplied by the panels.

For smartphone addicts there are several wifi apps that will do the job remotely on your phone or tablet.

DEVICE PROTECTION

All good quality PV panels feature built-in diode protection between each cell to prevent a shaded cell from dragging down the productive ones.

In addition, there will be internal blocking diodes on the final output to protect the panel from polarity reversal and to ensure that the batteries can’t discharge back into the panel during the night.

The latter can be added externally, the former can’t, so check before you buy.

A fuse, rated just above the maximum current available, should be fitted between each panel and the charge controller.

Another fuse should then be installed between the charge controller’s output and the batteries.

In the case of multiple arrays, this second fuse will be rated higher than the individual panel fuses and should match the maximum current rating of the cable.

With this protection installed other charging devices can be connected in parallel at the battery, meaning the solar can be left connected even when you are hooked up to shore power and the battery charger is operating.

In some circumstances, however, this arrangement can affect the sensing of the battery by the charger, causing it to fall back into float mode.

If this becomes apparent it can be overcome by installing a manual/auto switch to disconnect the solar array when on shore power.

Check the flex of the solar panel is sufficient for your deck

EXCESS POWER DUMPING

A solar charge controller works by disconnecting the supply from the PV panels when the batteries are fully charged.

But for some full-time liveaboards in sunny climates that can be considered a waste, when the excess power could be put to good use – heating water, say.

This is commonly done using an inverter to supply AC power to the heating element.

Alternatively, you can now buy a 12Vdc element for your calorifier (hot water tank) and supply this directly from your battery bank.

Both of these methods would require a voltage sensitive relay (VSR) to disconnect the element should the battery voltage drop below a pre-set level.

Don’t expect boiling hot water, as there will probably only be enough spare power to take the chill off it before your battery bank reaches its lower threshold voltage.

A 600W/12V element will draw some 50A, from the batteries, whereas a 1kW AC element run through an inverter will need close to 100A.

A small, semi-flexible panel will be sufficient for keeping batteries trickle charged, but not for heavy use

RIGID, FLEXIBLE, OR SEMI FLEXIBLE?

Despite massive recent improvements in semi-flexible panels in recent years, the solid glass panels still offer a higher power density.

That said, they are heavier, more awkward to mount and can’t be walked on, so unless you have a dedicated gantry aft, you’re better off choosing the more rugged semi-flexibles.

Modules incorporating monocrystalline cells also have a better output than those with polycrystalline cells (that’s cells made from a single slice of silicon as opposed to layers of smaller pieces).

Output voltage also depends on the number of cells on the panel.

In the past this has commonly been 32, but now some 36 and even 40 cell panels are available.

That said, they’re larger, of course, so an array of interconnected smaller panels might be a better solution.

Module efficiency is now more often around the 20% mark, as opposed to 12-15% for older models and semi- flexible (up to 20° bend) are usually better than flexible (up to 180° bend).

A rigid panel is more efficient, but less robust

There are a huge number of panels on the market, but many use the same cells.

Sunpower Maxeon cells are exceptionally good, as are the Panasonic HIT range and LG, but they are pricey.

If the maker is offering a 25-year guarantee instead of a 3-5 year one, you can be pretty confident they’re good.

When it comes to charge controllers it’s definitely worth paying a little more for a decent MPPT.

A cheap PWM might be okay just to keep a small starter battery charged with a 30W panel, but the MPPT will give you much more when it comes to heavy service.

Victron are probably top of the range, while cheaper brands like MakeSkyBlue and EPever are also good value – but treat imports of unclear origin with care.

ABOUT THE AUTHOR

Duncan Kent has been evaluating and reviewing yachts and marine equipment for the past 30 years

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This yacht sets sail with solar

The 60 square meters of solar panels produces 30-50 kWh of energy per day, enough to power all of the onboard electronic equipment for around seven hours.

• Commercial & Industrial PV

Solar-powered Baltic yacht.

Image: Solbian Solar

Baltic Yachts began delivery in July of its Baltic 146 Path, which includes an 8,714 watt solar rooftop and energy storage system designed by Solbian Solar using the company’s walkable solar modules.

Recently, some of the yacht’s technical work has been shared online. Built from 1,742 monocrystalline solar cells, many of the 86 solar panels were custom cut to fit the deck’s shape by the Solibian team in Italy. The units were based on the company’s Super Rugged (SR) Series .

The SR series has solar cell busbar technology developed by Merlin Solar. In one video, the Merlin team drives over the solar panel, throws bags of cement on it, and even shoots it with a bow and arrow in an effort to prove the product’s resilience. The company said its busbar technology makes this kind of abuse possible.

The 60 square meters of solar panels produces 30-50 kWh of energy per day. The company said that’s enough to power all of the onboard electronic equipment–including navigation, autopilot, lighting, and entertainment–for around seven hours.

Once the sun goes down, a Mastervolt MLI 44kWh LiFePO4 battery pack allows the diesel generator mostly to stay off, providing generally silent operation for 14-18 hours.

Baltic Yacht’s solar system is roughly half the size of the Silent 60’s 16.8 kWdc solar plus storage system. The Silent 60 is a solar-propelled yacht less than half the lengthBaltic yacht and price, which reaches 6-8 knots on solar power alone. The Path does not feature electric propulsion and therefore relies on diesel engines when the wind dies down.

Since the Path uses a sail for propulsion, the team installed 154 bypass diodes and 12 solar panel strings and trackers – Mastervolt SCM-60 MPPTS – in an effort to maximize power output and minimize the effect of the sail’s shadows on the panels. The entire solar system, including wiring, controllers and small parts, weighs less than 300kg, the company said

The 146 Path has an overall length of 146 feet. The yacht can accommodate eight in addition to the ship’s owner, as well as eight crew members. Path carries two tenders, an 8hp Torqeedo electric outboard-powered RIB, and a 6.5m twin-engined RibEye. There are also two ultra-lightweight Reverso Match sailing dinghies.

When the front tender is deployed, its storage container can be turned into a pool.

The ship’s main diesel engine is a 405kW (550hp), six-cylinder Scania. The specific model isn’t listed, however the “ DI13 092M IMO Tier III, EU Stage IIIA ” lines up with all of the stats and looks like the unit in a video of the engine being installed.

The owner’s suite includes a sleeping cabin, and an en suite lounge with a glass divider doubling as a movie, tv, and sailing information screen. An upper lounge features a 2.7m-long video wall.

This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com .

John Fitzgerald Weaver

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Since it is E propulsion all they have to do to change while sailing is use the motor in regen it’ll generate power back into the pack at much larger amounts. And a small RE fueled generator just in case. As a sailor who does solar, not a chance it’ll get that much from the solar from all the shading from the rigging. More likely 10-30kwh/day. On mine, I made the sails small with 2 masts so I can lower them to not shade the panels.

Any photos of your boat you can share?

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What is solar sailing?

Solar sailing is a revolutionary way of propelling a spacecraft through space.

A solar sail spacecraft has large reflective sails that capture the momentum of light from the Sun and use that momentum to push the spacecraft forward. The Planetary Society’s LightSail 2 mission is one example of this technology in action.

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A new way to travel space - with Bill Nye Did you know there's a way for spacecraft to travel farther, faster, and maybe one day reach other stars? Bill Nye is here to teach you about the game-changing technology called solar sailing.

How does solar sailing work?

Light is made up of particles called photons. Photons don’t have any mass, but as they travel through space they do have momentum. When light hits a solar sail — which has a bright, mirror-like surface — the photons in that light bounce off the sail (i.e. they reflect off it, just like a mirror). As the photons hit the sail their momentum is transferred to it, giving it a small push. As they bounce off the sail, the photons give it another small push. Both pushes are very slight, but in the vacuum of space where there is nothing to slow down the sail, each push changes the sail’s speed.

How does a solar sail control its direction?

When a solar sail faces the Sun directly, photons push the spacecraft forward, away from the Sun. But a solar sail can move in other directions by tacking like a sailboat, changing the angle of the sail relative the Sun. It’s even possible to shift the spacecraft's orbit around the Sun, by angling the sail so that solar photons push against the direction it is traveling. Solar sails can also control their direction in other ways, such as changing their center of mass or using tip vanes.

What is the advantage of solar sailing?

Spacecraft gain most of their momentum when they are launched from Earth, and then most increase their speed or change course using chemical rockets that burn fuel that the spacecraft carries on board. But more rocket fuel means more weight, which limits how much can be carried. Most spacecraft reach their maximum speed and then coast through space or rely on gravity assists from other planets to reach their destinations.

With solar sails, a spacecraft can continue accelerating as long as there is light pushing on it. Within a solar system, sunlight can continuously push on the sail, accelerating the spacecraft throughout its entire voyage. This means that solar sail-propelled spacecraft can reach speeds that would be practically impossible for chemical rockets to achieve.

Solar sailing spacecraft are also advantageous because they can be placed in orbits that would otherwise be unstable by using the sail acceleration as a balancing force.  As an example, this could enable solar monitoring missions to sit between the Earth and Sun at a closer distance than otherwise possible to provide more warning of solar storms.

What is a solar sail made of?

Current solar sails are made of lightweight materials such as Mylar or polyimide coated with a metallic reflective coating. LightSail 2 uses 4 triangular Mylar sails that are just 4.5 microns (1/5000th of an inch) thick. They unfold using 4 cobalt alloy booms that unwind like tape measures. The sails have a combined area of 32 square meters (344 square feet), about the size of a boxing ring.

How big does a solar sail have to be?

There is theoretically no minimum size for a solar sail, but for the same mass spacecraft, bigger sails will capture more sunlight and accelerate the spacecraft more quickly. A NASA team in the 1970s, headed by Planetary Society co-founder Louis Friedman, proposed a solar sail with a surface area of 600,000 square meters (6.5 million square feet), that would be used to send a spacecraft to rendezvous with Halley’s comet . This is equivalent to a square of 800 meters (half-mile) by 800 meters – the size of 10 square blocks in New York City! Of course, the practicality of building and deploying such an enormous sail is questionable. But if such a sail could be successfully developed, amazing destinations could be reached.

How fast can a solar sail go?

A solar sail’s speed depends on its size and its mass. A bigger sail captures more sunlight, gaining more momentum and accelerating more quickly for the same mass. For a given sail size, a lower mass spacecraft will have a higher acceleration.  The acceleration also depends on its distance from a light source and strength of the light source. As a solar sail spacecraft gets farther away from the Sun, the amount of sunlight available to it decreases, meaning that it accelerates less quickly. Theoretically, powerful lasers could be aimed at a distant solar sail, providing some extra acceleration as the spacecraft gets further from the Sun.

To give a specific example of solar sail speed, LightSail 2’s 32-square-meter sails accelerate it at just 0.058 mm/s². In one month of constant sunlight, the spacecraft’s speed would increase by a total of 549 kilometers per hour, roughly the speed of a jet airliner at cruising speed.

Larger sails, or small sails accelerated by lasers, could theoretically go much faster. In 2016, the group Breakthrough Initiatives announced a plan to send a fleet of tiny, laser-powered solar sails to our nearest star, Alpha Centauri. The spacecraft would be targeted in space by Earth-based lasers, and accelerate to 20 percent the speed of light.

How expensive is solar sailing?

Building a solar sail, especially a very large one, is a feat that still needs development. And that research and development can be expensive. But once solar sails are better tested and understood, they could be a relatively inexpensive means of propulsion. Sunlight is free and unlimited, meaning that a solar sail-propelled spacecraft could travel greater distances without having to increase the amount of fuel it carries on board, and could potentially use smaller, cheaper launch rockets for the same trip. So to travel at great speeds to distant destinations, or to provide long term stability in an otherwise unstable orbit, solar sailing could be an affordable option.

The Planetary Society’s LightSail spacecraft were funded entirely by Society members, private donors, and backers of a crowdfunding campaign through Kickstarter . Together, these tens of thousands of people pooled their resources to build and launch solar sailing spacecraft. This is a historic demonstration of what is possible when people unite in support of space exploration.

Why do we want solar sails? Where will solar sails take us?

The most exciting thing about solar sails is that they could open up new avenues for space science and exploration. A solar sail-propelled spacecraft could reach distant planets and star systems much more quickly than a rocket-propelled spacecraft because of the continual acceleration that solar sailing provides. The technology for interplanetary or interstellar solar sailing is still far from being developed, however.

In the near-term, solar sailing can also be used effectively for other classes of missions including solar monitoring, multi-object flybys, and “pole-sitting” spacecraft for continuous observations of Earth’s or another object’s polar regions.

Solar sails can also provide propulsion for CubeSats—small, inexpensive satellites that are increasingly being used by emerging spacefaring nations, small companies, and even school groups—allowing them to maneuver in space without relying on rocket fuel. The Planetary Society’s LightSail mission is demonstrating the potential use of solar sails for CubeSats .

When was the solar sail invented?

Solar sailing is a concept with a long history , dating all the way back to an idea Johannes Kepler shared with his friend Galileo Galilei in 1608.

The Planetary Society is one of the pioneers of solar sailing technology. In the early 2000s, we built the Cosmos 1 solar sail spacecraft. On June 21, 2005, Cosmos 1 launched from the submarine Borisoglebsk in the Barents Sea. However, a rocket failure prevented the spacecraft from reaching orbit. Had the mission been successful, it would have been the first ever use of a solar sail spacecraft, as well as the first space mission by a space advocacy group.

Who has built solar sails? What solar sailing missions exist?

Since the failed Cosmos 1 mission, solar sails have been successfully built and launched by the Japanese Aerospace Exploration Agency (JAXA) with their IKAROS spacecraft that first demonstrated controlled solar sailing, by NASA with their NanoSail-D spacecraft, and by The Planetary Society with our LightSail 1 spacecraft.

Many more solar sailing missions are in development, including The Planetary Society’s LightSail 2 mission and NASA’s NEA Scout mission to a near-Earth asteroid. NASA’s Advanced Composite Solar Sail System , or ACS3, launching in 2022 will test out a larger sail in Earth orbit than previous missions. NASA’s  Solar Cruiser mission launching in 2025 will test an even larger solar sail the size of over six tennis courts.

What is the biggest solar sail?

The biggest solar sail built to date is the IKAROS spacecraft developed by JAXA. IKAROS’s sail’s size is 196 square meters, about half the size of a basketball court. This was the first interplanetary solar sailing mission, traveling to Venus and onward on a trajectory to the far side of the Sun.

But size isn’t everything. Even with a smaller sail (32 square meters), LightSail 2's acceleration will be about ten times that of IKAROS. This is because LightSail 2’s spacecraft body is much smaller and lighter than that of IKAROS, so the sail has less mass to propel.

Does a solar sail fly on the solar wind?

No. Solar sails fly on photons, whereas the solar wind is made up of different ionized particles ejected by the Sun. These particles move slower than light and create a force that is less than one percent as strong as light pressure.

Can I be a part of solar sailing?

The public is invited to witness the launch of The Planetary Society’s LightSail 2 spacecraft from Cape Canaveral, FL aboard a SpaceX Falcon Heavy rocket. The launch is scheduled to take place in June 2019.

You also might be able to see the LightSail 2 spacecraft with the naked eye or with telescopes throughout the duration of its mission, which will last for about a year. You can find more information about that at sail.planetary.org .

And to be a part of groundbreaking missions like this in the future, you can become a member of The Planetary Society .

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Solar Sailing

  August 18, 2016    | By: Oceana

The wind is solar-powered. Quite literally, wind is convection currents created by sun heating the earth. Now 21 st century solar technology allows sailors to harness the sun, as well as the wind, to move us through the ocean. The J-88 day sailor is a leading example of a growing trend in integrating alternative energy technology into boatbuilding. We recently had the pleasure of test-driving the J-88 in Miami. 

Driving the OceanVolt Electric Drive

Imagine having a quiet conversation on board when powering to the marina after a relaxing day sail, instead of revving up the internal combustion engine. No more choking on diesel exhaust going downwind, no more gasoline fumes in the bilge, no more fuel dock runs. The J-88’s solar package, built around an OceanVolt SD6 6kW 48vdc propulsion system and UK Sailmakers SolarClothSystem® solar panels on the mainsail and bimini, opened our eyes to those possibilities. With these innovations, fossil fuel propulsion may soon be a relic for “classic boat” aficionados.

The OceanVolt drive is indeed quiet. While not Hunt for Red October silent, the electric drive is a huge improvement over the diesel experience.  When motoring at five knots, we had to ask whether the electric drive was on. Down below one can hear the drive humming when engaged, and there is of course the mechanical churning of the prop thru the water, but the contrast with diesel systems was striking. Perhaps the most surprising aspect of the electric drive was the brawny torque and “bite” on the water when accelerating or shifting into reverse. The electric drive ramps seamlessly from a standstill to full power like a Tesla Model S, noticeably more smoothly than a mechanical drive system.

Photo: J-Boats

Minimizing our Environmental Impact

Sailing is already relatively clean, but the solar sailing package reduces the remaining environmental footprint dramatically.  As stewards of the ocean, solar sailing is an inspiring opportunity to eliminate fumes from getting in the way of enjoying nature, make fuel spills a vestige of the past, and banish greenhouse gases that worsen climate change and ocean acidification.

Solar Panels in Sails

The electric drive is powered by an integrated system of Valence U24 lithium phosphate batteries and 600W solar panels. The solar panels are laminated right into the mylar sailcloth mainsail, allowing the batteries to charges while sailing, and another array of panels are sewn into the bimini for charging while at anchor or dockside. In the J-88 configuration that we sailed, the mainsail had 9 solar panels on each side, and the bimini has a zip-in 6-panel layout.  The thin-film solar panels are as flexible as the sail itself, shape smoothly when hoisted and flake easily over the boom (see photo). The panels can be placed in the lower third of the main for racing configuration, or in the mid-third for a cruising main to allow for reefing while keeping the panels in the sun. Thin wires run down the luff along the mast into battery bank, similar to wiring from wind instrumentation.

More ways to Power Up

Of course, the battery system can also be charged conventionally with shore power with a 5-6 hour recharge time from empty. But apart from the solar charging, the electric drive can actually power itself – if you have enough wind to cruise at 6-7 knots under sail, the prop will spin backwards to charge the batteries, serving as an underwater generator. 

Practical Sailing

Previously, the challenge of solar-electric propulsion has been range, but this new technology is a breakthrough. On a full-charge there is enough battery power to motor up to 20 nautical miles with no sail or with solar power support depending on wind and sea state. In theory, on a sunny day, with the solar panels charging and 4 knots of wind for the sails, the J-88 can motor-sail at a cruising speed of 5 knots all day long!  This estimate is based on perfect conditions, but considering even gas or diesel runs out eventually, the range is pretty impressive. We motored in Miami harbor for almost an hour and the battery charge scantly dropped from 93% charge to 86% with no solar charging.  In any event, most recreational sailing is coastal and easily within the electric drive’s range. J-Boats and other manufacturers are also looking at adapting highly efficient and clean fuel cell technology (which generates electricity from propane or natural gas) for sailors who need blue water cruising range.

The electric propulsion system is fully integrated with high-tech power draw monitoring and other data systems to allow the crew to manage charging and propulsion options.

The solar sailing package, being innovative technology, does cost more than a conventional diesel engine, adding 10 to 15% to the purchase price for a full solar sailing package.  But the cost is coming down rapidly and there are savings that one would not think of at first, such as not needing a muffler or fossil fuel storage system, and of course the savings (both financial and convenience) from not needing to purchase fuel.

The J-88 itself is a sporty day sailor with a nice mix of ease of sailing and race-ready performance — but others will write about that.  What gets us excited as a Sailors for Sea board member and cruising sailors is J-Boat’s integration of several cutting-edge products creating a green and clean energy package.  For more information, visit http://www.jboats.com/j88-oceanvolt

Check out Sailors for the Sea’s Green Boating Guide for more information on how to go green on your boat. Download your free copy by clicking here.

Max Williamson serves on the Board of Directors of Sailors for the Sea and boats on the Potomac River and coastal Maine with spouse Leslie and dog Talisker.

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The ZEN50 is a game changer. World’s first series production catamaran equipped with a wingsail, it defines a new distinctive class of its own, where genuine zero-emission meets high comfort and performance, limitlessly. 

Designed from scratch for ZEN Yachts by award-winning naval architect Julien Mélot , this full carbon catamaran is the ultimate essence of technology driven, high performance and luxurious, eco-friendly leisure yachting. 

The blue water capable ZEN50 lightweight racing carbon hulls are combined with a huge solar roof for an unrivaled solar power vs. displacement ratio above 1:1 (18 kW / 17 tonnes), making this yacht completely energy self-sufficient. A revolutionary, fully automated, wingsail - by Ayro© - can be added as a range and speed extender. The yacht’s high capacity battery bank powers a powerful silent electric propulsion, allowing the ZEN50 to achieve 14 knots and maintain high continuous speeds in unrivaled safety and comfort, indefinitely… 

The ZEN50 is offered with or without wingsail and comes in 3 main different versions: Racer, Cruiser and Explorer, each dedicated to a different usage and owner profile. We use these versions as a basis to define a final, bespoke specification for each of our valued clients and ZEN Community Members. Scroll down for more details, specifications and prices.

1st WINGSAIL series production yacht in the world!

The OceanWings32 - by Ayro© - was initially developed for Team Oracle, for the America’s Cup 2010 in Valencia. Over years, it has further been developed and automated by VPLP and was installed on Energy Observer in 2019. Two years of field feedback have allowed the Ayro team to fine tune the algorithm commanding the wingsail. The ZEN50 is the first series production leisure craft to be equipped with this fully automated wingsail. It is controlled at the touch of a finger on screens, is automatically adjusted and has several safety modes and features. The two parts of the wingsail can be hoisted and lowered independently and with the simple touch of a button. The wingsail OceanWings32 is the ideal complement for the solar roof for those wishing to cruise long distances off-shore with zero-emissions.

Greatest ratio SOLAR POWER / weight on the market

At 17 tonnes lightweight and 18,000 W of peak solar power, the ratio of the ZEN50 is at over 1 kW per displaced tonne of water or beyond 1:1 which is far beyond any other blue water CE Cat A yacht in this size range. Lots of solar power for little water to displace is the strong and healthy foundation the energy self-sufficient ZEN50 is built upon.

Performance CARBON sandwich hulls

The hulls of the ZEN50 have been designed from a blank screen for ultimate efficiency - understand minimum drag or minimal energy consumption for a range of speeds from 6 to 10 knots. Their shape is aggressive, sharp and slender. Their reverse bows cut through water like a sword cuts through butter and their curvature is reminiscent of graceful dolphin bodies. These hulls are undoubtedly of the performance type and are built with the best available composites: Carbon fibre and Corecell™. The combination of high strength, low weight and performance design allow the ZEN50 to reach speeds of up to 14 knots.

INFINITE range at high CONTINUOUS speeds

With maximized solar and wind power and minimized energy consumption… the ZEN50 can sail continuously at speeds varying between 6 and 10 knots. Thorough simulations in various sea states and weather system have consistently shown the ZEN50 will be able to achieve performance catamaran speeds continuously without using a genset. With the ZEN50, the world is your oyster and the wildest destinations are within your reach with this self-reliant vessel!

True ZERO-EMISSION operation

The first ZEN50 unit, whose construction started in March 2023, will not be equipped with a genset at all and will not have any fossil fuels onboard. The ZEN50 energy system with its very large capacity 160 kWh battery bank, has been designed to function for days in complete safety with minimal solar energy harvest and no wind. It is perfectly safe with no backup genset and operates 24/7 without any polluting emissions.

NO FUEL , no costs

Naturally, requiring no fuel to operate day in day out is great news for the environment, it is also fantastic news when sailing into remote areas where fuel bunkering might be near impossible or where the fuel quality might be an issue. Finally, it also makes a massive difference in this yacht’s costs of operation. Imagine the hundreds of liters of diesel saved over just a week, the obsolete engine maintenance schedules, the clogged filters and dirty tanks from another age… Welcome to a new burden-free, energy self-sufficient era, welcome to clean and graceful eco-yachting, welcome to ZEN Yachts.

Highest SAFETY & reliability

At ZEN Yachts, we have made some design choices to attain energy self-reliance with the ZEN50 that reduces the habitable volume in the hulls, similar to performance catamarans. Where we have not and will never compromise is on safety. Our main voltage system is 48V making it perfectly safe to work on. The level of redundancy of the batteries and solar panels is 10! The main electrical architecture is split in 2 so that should anything happen on 1 hull, the entire vessel can still operate normally. There are 2 independent helm stations and the ZEN50 is packed with special safety features, nonsubmersible compartments and we can even offer an in-depth practical course on safety equipment usage and management. Sailing with the ZEN50 is not only exhilarating and clean, it is ultra safe!

Unrivaled space & COMFORT

The ZEN50 offers the speeds of a performance catamaran, the comfort of a large motor yacht and the simplicity of an electric car. No less than 2 large day beds, 3 dining areas for over 10 people, 1 professional galley and 2 wet kitchens, 5 heads, up to 4 double ensuite cabins, 1 bunk double and 1 single together with both saloon and dining areas converting into extra sleeping areas, this is simply unrivaled on a 50 ft. catamaran. Add an electric tender, dive compressor, satellite internet, 2 helm stations (cockpit and flybridge), a solar roof that converts into a gigantic upper deck to enjoy the most epic sunrises and sunsets, welcome onboard the ZEN50!

SPECIFICATIONS

Main particulars.

• Length Over All: 15.7m

• Beam: 8.4m

• Depth Molded: 2.7m at midship

• Displacement (light) : 17 T

• Draft (design): 1.3m (4.3ft) incl. keel

• Passenger Capacity: 12

• Berths: 12 (4 x double + 2 x single + saloon)

• Building Material: Carbon Fiber - Corecell™ composite

• Certification: CE Cat A - Unrestricted with 12 persons

Note: Some of the above figures may vary between versions

PROPULSION & ENERGY

• Propulsion: 2 x 50 kW brushless DC motors

• Main Battery Pack Capacity: 160 kWh Lithium

• Solar Roof Peak Power: 18 kWp

• Wingsail: Oceanwings® OWS 3.2 by Ayro©

• Backup Battery Pack Capacity (Nav/Com/Wing): 5 kWh Lithium

• Main System Voltage: 48V - Low voltage for total human safety

• Accommodation Voltage: 110V or 220V

SPEED & RANGE

• Max. Speed on e-motor only: 10 kn

• Max. Speed on e-motor & Wingsail: 14 kn

• Cruising Speed for continuous operation - solar only: 4.5 - 5 kn

• Cruising Speed for continuous operation - solar and wing: 6 - 10 kn

• Cruising Speed day time: 8 - 10 kn

• Range Over 24 h: 180+ nm

Note: These values may vary between versions and sea / weather conditions

EQUIPMENT INCLUDED - RACER VERSION

• Integrated power management system

• Solar power & energy storage system

• Electric propulsion system

• By-wire steering system

• Helm stations at cockpit & flybridge

• Galley counters, storage, sink, oven, stove, fridge, freezer

• 4 en suite heads with enclosed shower, toilet, sink & faucet (in each head)

• All cabin furniture (as shown in layouts)

• Aft deck fixed dining table and aft sofa with collapsible back rest (as shown in layouts)

• Fore deck day bed and lateral seats (as shown in layouts)

• Outdoor marine cork decking / indoor saloon natural bamboo decking

• All cushions In/Outdoor upholstered with Sunbrella® fabric

• 6 deck hatches

• 2 x 500 liter (2 x 132 gal) fresh water tanks

• 2 x 100 liter approx. (2 x 26 gal) fresh water tanks + 1 fresh water pump

• 2 x 350+ liter approx. (2 x 92 gal) holding tanks

• Railings, cleats and fore deck trampolines

• Mooring equipment: 33 kg Rocna® stainless steel anchor + 50 m stainless steel chain 10 mm + 150 m nylon rope + e-windlass

• Regulatory navigation equipment including navigation lights & mast

• 2 x chart plotter 16”; 2 x VHF with DSC button

• Regulatory Life Saving Appliances

• Critical spare parts kit

Note: The above equipment is for the Racer version. Cruiser & Explorer versions carry additional equipment

ZEN50 Solar Wingsail Electric Catamaran - Solar Roof Layout

ZEN50 Solar Wingsail Electric Catamaran - Flybridge Layout

ZEN50 Solar Wingsail Electric Catamaran - Main Deck Layout - Asymmetric D (subject to changes)

ZEN50 Solar Wingsail Electric Catamaran - Cabin Layout - Asymmetric D (subject to changes)

ZEN50 Solar Wingsail Electric Catamaran - Cabin Layout - Asymmetric E (subject to changes)

SOLAR & WINGSAIL

OCEAN RACER

Solar power & Wing, basic configuration, navigation, safety, fridge, etc.

EUR 2 150 000

WORLD CRUISER

Solar power & Wing, well equipped with A/C and water maker

EUR 2 400 000

ARCTIC EXPLORER

Solar power & Wing ultimate configuration with all available options

EUR 2 650 000

Solar power, basic configuration, navigation, safety, fridge, etc.

EUR 1 700 000

CONTINENTAL CRUISER

Solar power, well equipped configuration with A/C and water maker

EUR 1 900 000

TROPICAL EXPLORER

Solar power ultimate configuration with all available options

EUR 2 100 000

Ready to reserve your ZEN50?

Want more information .

Boat Sailor

Solar sail: navigating the cosmos on sunbeams.

Greetings, fellow space enthusiasts! Join me as we embark on an exciting journey through the revolutionary realm of solar sail. These marvels of engineering and science are poised to redefine the way we explore the cosmos, harnessing the power of sunlight to propel us towards new horizons. So, strap in and let’s delve into the mesmerizing world of solar sails and their endless possibilities.

How Solar Sails Work

Imagine a sailboat in the vastness of space, its sail not catching wind, but sunlight. Solar sails operate on a simple yet profound principle: they use the pressure of sunlight to generate thrust. Photons from the Sun’s rays transfer momentum when they bounce off the reflective surface of the sail. Over time, this continuous push can propel spacecraft to remarkable speeds, unlocking unprecedented travel possibilities.

Advantages of Solar Sails

Harnessing solar radiation.

One of the most captivating aspects of solar sails is their reliance on a renewable resource: sunlight. Unlike conventional rockets that carry fuel, solar sails are fueled by the very photons streaming from the Sun. This sustainable propulsion method offers the potential for extended missions, as long as the Sun continues to shine.

Propelling Spacecraft

Solar sails offer a gentle but constant acceleration, enabling spacecraft to reach high velocities over time. This gradual acceleration can lead to remarkable speeds and efficient travel across vast cosmic distances, which is particularly crucial for interstellar journeys.

Applications of Solar Sails

Interstellar travel.

Yes, you read that right—interstellar travel! Solar sails hold the promise of enabling humanity to send spacecraft to other star systems within our lifetime. By gradually reaching a substantial fraction of the speed of light, we could envision missions to nearby stars like Proxima Centauri, opening the door to the exploration of potentially habitable exoplanets.

Deep Space Exploration

Solar sails also shine in deep space exploration. They can provide a constant and gentle thrust, allowing us to maneuver with precision around celestial bodies, study asteroids, comets, and even position ourselves for breathtaking observations of distant galaxies.

Orbital Maneuvers

Even closer to home, solar sails have the potential to revolutionize satellite operations. By utilizing the pressure of sunlight, satellites could adjust their orbits, extend their missions, and contribute to reducing space debris.

Challenges and Limitations

While solar sails present remarkable opportunities, they also face certain challenges. In areas with low solar flux, such as outer regions of the solar system, thrust becomes limited. Additionally, the durability of sail materials in the harsh space environment is a concern that requires innovative solutions.

Design and Materials

Solar sail design is a delicate art. Thin-film technology and reflective layers play a crucial role in optimizing the sail’s performance. Reflective materials are chosen to maximize photon absorption and momentum transfer, while maintaining structural integrity.

Future Innovations in Solar Sails

The future of solar sails holds exciting innovations. Advanced propulsion techniques like combining laser propulsion with solar sails could accelerate spacecraft even further. Hybrid systems integrating traditional propulsion methods with solar sails might offer versatility for various mission profiles.

Building and Launching Solar Sail Spacecraft

The deployment of solar sails is an intricate process. Folding mechanisms are crucial for compact storage during launch. Launch strategies involve deploying the sail in stages to avoid damaging the delicate structures.

Recent Missions and Successes

The LightSail project, initiated by The Planetary Society, successfully demonstrated solar sail propulsion in 2019. The IKAROS mission by JAXA in 2010 showcased the viability of solar sail technology, further inspiring future endeavors.

Practical Tips for Solar Sail Enthusiasts

Staying updated on developments in solar sail technology and collaborating with space agencies can provide insight and avenues for participation. The journey towards widespread solar sail adoption is a collective effort.

Exploring the Environmental Impact

As we venture beyond our planet, sustainability becomes crucial. Solar sails offer a promising solution by utilizing renewable energy and potentially reducing the need for traditional rocket fuel, thus minimizing the environmental impact of space travel.

Influence on Space Travel Paradigm

The emergence of solar sails could redefine space travel. They expand the boundaries of what we thought possible, offering a new outlook on exploration, resource utilization, and humanity’s place in the cosmos.

Dreams of Exploring Other Star Systems

The dream of sending spacecraft to other star systems is within reach. Concepts for missions to Proxima Centauri using solar sails are gaining traction, hinting at a future where we can directly explore our stellar neighbors.

The Collaborative Future of Space Exploration

The journey of solar sails is a collaborative endeavor. International cooperation and public engagement will be crucial in realizing the full potential of these revolutionary propulsion systems.

As we conclude our voyage through the boundless expanse of solar sail technology, one thing becomes abundantly clear: the future of space exploration is vibrant and full of promise. Solar sails, driven by the gentle push of sunlight, offer us the chance to reach the stars and unveil the mysteries that await us. So, keep your eyes on the skies, for the age of solar-powered cosmic exploration is upon us.

Can solar sails work beyond our solar system?

Indeed! Solar sails have the potential to propel spacecraft to other star systems, enabling interstellar exploration.

How fast can a spacecraft powered by solar sails go?

While speeds vary, solar sails can theoretically achieve a substantial fraction of the speed of light over time.

Are solar sails affected by space debris?

Yes, space debris poses a challenge. Careful mission planning and innovative sail materials can help mitigate this risk.

How long do solar sails last?

Solar sails can have long operational lifetimes, as they rely on sunlight for propulsion rather than finite onboard fuel.

How can I get involved in solar sail projekts?

Staying informed about developments, collaborating with space agencies, and supporting organizations focused on space exploration are great ways to get involved.

Michael Thompson

Embarking on a lifelong love affair with the sea, I found solace and exhilaration in the art of sailing. From navigating treacherous waters to harnessing the wind's untamed power, my passion has evolved into a mission to inspire others. Join me on a voyage of discovery as we explore the vast horizons of sailing's timeless allure.

More to Explore

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Harnessing Helios: The Science Behind NASA’s Solar Sail Breakthrough

By Wayne Smith, Marshall Space Flight Center March 3, 2024

NASA is developing solar sail technology for deep space exploration. This innovative propulsion system, powered by sunlight reflecting off its surface, has recently achieved a new readiness level, making it suitable for future science missions. Solar sails offer a fuel-free, environmentally friendly method of propulsion, capable of propelling low-mass missions to novel orbits and distant planets. Credit: NASA

NASA is pioneering solar sail technology for space exploration, offering an eco-friendly propulsion system that harnesses sunlight. This advancement enables potential missions to study space weather, explore the Sun’s poles, and venture closer to Venus and Mercury.

In his youth, NASA technologist Les Johnson was riveted by the 1974 novel “The Mote in God’s Eye,” by Jerry Pournelle and Larry Niven, in which an alien spacecraft propelled by solar sails visits humanity. Today, Johnson and a NASA team are preparing to test a similar technology.

NASA continues to unfurl plans for solar sail technology as a promising method of deep space transportation. The agency cleared a key technology milestone in January with the successful deployment of one of four identical solar sail quadrants. The deployment was showcased on January 30 at Redwire Corp.’s new facility in Longmont, Colorado.

NASA’s Marshall Space Flight Center in Huntsville, Alabama, leads the solar sail team, comprised of prime contractor Redwire, which developed the deployment mechanisms and the nearly 100-foot-long booms, and subcontractor NeXolve, of Huntsville, which provided the sail membrane. In addition to leading the project, Marshall developed the algorithms needed to control and navigate with the sail when it flies in space.

NASA and industry partners used two 100-foot lightweight composite booms to unfurl the 4,300-square-foot sail quadrant for the first time on October 13, 2022, at Marshall Space Flight Center, making it the largest solar sail quadrant ever deployed at the time. On January 30, 2024, NASA cleared a key technology milestone at Redwire’s new facility in Longmont, Colorado, with the successful deployment of one of four identical solar sail quadrants. Credit: NASA

Solar Sail Technology and Its Advancements

The concept behind the solar sail is simple yet revolutionary. It operates by harnessing sunlight reflection for propulsion, similar to how wind propels a sailboat. While just one-quarter of the sail was unfurled in the deployment at Redwire, the complete sail will measure 17,780 square feet when fully deployed, with a thickness of less than a human hair at 2 and a half microns. The sail is made of a polymer material coated with aluminum.

NASA’s Science Mission Directorate recently funded the solar sail technology to reach a new technology readiness level, or TRL 6, which means it’s ready for proposals to be flown on science missions.

“This was a major last step on the ground before it’s ready to be proposed for space missions,” Johnson, who has been involved with sail technology at Marshall for about 25 years, said. “What’s next is for scientists to propose the use of solar sails in their missions. We’ve met our goal and demonstrated that we’re ready to be flown.”

A solar sail traveling through deep space provides many potential benefits to missions using the technology because it doesn’t require any fuel, allowing very high propulsive performance with very little mass. This in-space propulsion system is well-suited for low-mass missions in novel orbits.

“Once you get away from Earth’s gravity and into space, what is important is efficiency and enough thrust to travel from one position to another,” Johnson said.

“A solar sail achieves that by reflecting sunlight – the greater the size of the sail, the greater thrust it can provide.” — Les Johnson, NASA technologist

Future Applications and Environmental Benefits

Some of the missions of interest using solar sail technology include studying space weather and its effects on the Earth, or for advanced studies of the north and south poles of the Sun. The latter has been limited because the propulsion required to get a spacecraft into a polar orbit around the sun is very high and simply not feasible using most of the propulsion systems available today. Solar sail propulsion is also possible for enhancing future missions to Venus or Mercury, given their closeness to the Sun and the enhanced thrust a solar sail would achieve in the more intense sunlight there.

NASA Marshall Space Flight Center technologists Les Johnson and Leslie McNutt at Redwire Space on January 30, 2024, following a successful solar sail deployment test. NASA cleared a key technology milestone at Redwire’s new facility in Longmont, Colorado, with the successful deployment of one of four identical solar sail quadrants. Credit: Redwire Space

Moreover, it’s the ultimate green propulsion system, Johnson said – as long as the Sun is shining, the sail will have propulsion. Where the sunlight is less, he envisions a future where lasers could be used to accelerate the solar sails to high speeds, pushing them outside the solar system and beyond, perhaps even to another star. “In the future, we might place big lasers in space that shine their beams on the sails as they depart the solar system, accelerating them to higher and higher speeds, until eventually they are going fast enough to reach another star in a reasonable amount of time.”

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6 Awesome Solar Boats for Eco Sailing in 2024 (Guide)

Liza pivoted from environmental consulting and doing impact assessments to writing about her two most counter-intuitive but passionate interests: sustainability and the importance of living an eco-conscious life; and marketing, martech, and AI. When she’s not writing, you can find her living a zero-waste-adjacent life in South Africa, falling down research rabbit holes on the internet, or out hiking with her dogs.

Introduction

Liza Shuttleworth pivoted from a career in environmental impact assessment and consulting to becoming a full-time writer, focusing on her most passionate (and diverse) interests: ecological conservation, sustainability, waste management and marketing, mar-tech, and AI.

Her professional portfolio reflects a diverse array of writing and consultancy roles spanning environmental science, marketing, and technology.

She has written for prestigious online and print publications on topics that include sustainability, climate change advocacy, waste management, and marine conservation, as well as marketing strategy, mar-tech, and the proliferation of AI tools for marketing.

Liza has an extensive professional background, having held management and consultancy positions within the environmental science, waste management, technology, and marketing sectors.

Her writing and editorial positions for both print and online publications have shaped content in ways that educate and inspire readers about sustainable living, climate change, and the power of innovative technology to overcome challenges in any setting.

Liza's academic background is rooted in a Bachelor of Social Science, focusing on Media and English. Beyond this, she has pursued tertiary qualifications in geography, psychology, and marketing, further enriching her knowledge base and contributing to her multi-faceted approach to writing and advocacy.

Solar boats are becoming a hugely popular choice for eco-friendly sailing. They’re quiet, can sail great distances without needing to stop for fuel, produce no carbon emissions, and do not rely on fossil fuels.

The popularity of solar-powered boats represents an evolution in marine transportation in favor of renewable energy and sustainability. Solar-powered boats provide a window into a future where clean, emission-free transport is not only possible but also preferred, due to developments in solar technology and design.

Solar boats are the ultimate of innovation and environmental responsibility, whether they are being used for peaceful journeys along beautiful canals or for bold ocean expeditions.

We reduce our dependency on scarce fossil fuels and lessen the ecological effect of traditional boating techniques by using the sun’s power to move us over the sea. Solar boats have the potential to completely transform the maritime sector and open the door to a more environmentally conscious and sustainable future for all, especially as the demand for eco-friendly alternatives keeps rising.

So, how do solar boats work? What are the benefits? And what are the best solar boats on the market? 

In this guide, we explain how solar boats function, the advantages of using them, and six impressive solar boats you can purchase in 2024.

Let’s dive right in!

Table of Contents

How Do Solar Boats Work?

In recent years, solar panel and rechargeable battery technology have improved dramatically. Panels are lighter, stronger, and more efficient.

Batteries are more compact, more efficient, and weigh considerably less than they did in the past. Both batteries and panels now last longer and cost less than they used to.

These advances in technology and a growing interest in eco-friendly sailing have shifted the development of solar yachts from idealists’ dreams to the mainstream.

So, how exactly do solar boats work? 

Solar boats use solar energy to power their motors, navigation systems, and onboard electronics, and appliances.

The solar system works much the same as a solar system on a house or RV , with some structural differences to meet the unique demands and challenges of a marine environment.

Solar panels mounted on the boat harvest solar power from the sun and send it to a charge controller , which controls the flow of electricity to a bank of rechargeable (usually lithium-ion) batteries.

From the batteries, power is sent to the electric motors, navigation systems and appliances via an inverter, which converts direct current (DC) to alternating current (AC). Most appliances like kettles, microwaves, and hair dryers use AC.

A solar system can be added to any boat, making it a hybrid or even just to supplement a little power using a renewable resource.

S olar is a great way to reduce your carbon emissions, reduce your fuel costs and increase the distance you can sail without stopping to refuel .

However, if you’re looking to buy a solar boat that is designed and built specifically for solar sailing, there are some really great options to consider.

What are the Benefits of Using a Solar Powered Boat?

When it comes to solar boats, there are some great benefits and they’re not limited to renewable energy and fewer carbon emissions:

• No reliance on fuel – diesel generators can be used as an emergency back up but they’re not needed for everyday sailing or electricity generation.
• Unlimited range: when batteries are constantly recharged by the sun, there is no need to stop to refuel and you can keep going indefinitely.
• No noise and no fumes: as there is no engine, there is no noise and no diesel fumes. This makes the experience of sailing a solar boat much more peaceful.
• No pollution: on a solar boat, there is no engine producing noise pollution, no carbon or greenhouse gas emissions , and no risk of fuel or oil spills.
• More space: the absence of engines frees up a lot of space. Electric motors and batteries can be housed anywhere on the boat and do not take up as much space as engines and machinery, which means room for more storage compartments to keep your gear or equipment.
• Lower running costs: beyond the initial investment and occasional maintenance, solar is completely free. This cuts out fuel costs and ongoing engine maintenance costs.
• Less maintenance: solar panels need to be cleaned regularly to be most effective but that is the only ongoing maintenance needed. Once a good solar system is installed, it generally needs very little maintenance.
• No limitations on electrical use: with solar, the supply is free and if you’re not pushing the motors to travel at speed you will often have more electricity than you need. This means you don’t need to watch your power consumption and you can run your air conditioning as much as you want!
• Options to sell power back to shore stations: if you regularly generate more power than you need from your solar, you can share it with others or sell it back to the grid at some shore stations.

The benefits you will enjoy from a solar boat vary, depending on your location and the specifications of the boat you choose. There are also some downsides, for example, solar boats are generally slower and the initial investment is quite high.

That said, solar boats are well worth the investment!

So, let’s look at some of the awesome solar boats available on the market in 2024:

6 Awesome Solar Boats

There are many great solar-powered boats to choose from and we have selected six of the best to feature here. We have chosen a range of sizes, styles, and price points so there should be something for everyone on this list!

1. Silent Yachts – Silent 55

The Silent 55 by Silent Yachts is one of their smaller solar yachts and can be handled by two people, with or without any additional crew.

It is spacious, and beautifully designed to be as economical as possible without losing any of the luxuries of their larger boats. With three to six cabins and all the amenities you can imagine, it offers everything you need to live on board permanently.

Check out this video by Kara and Nate to see their experience of the Silent 55 and meet the couple behind the iconic Silent Yachts company:

[embedyt] https://www.youtube.com/watch?v=iIte4FNI0U0[/embedyt]

Where to Buy: Silent Yachts

Price: From €1.97 Mio.

2. Serenity Yachts – Serenity 64

The Serenity 64 is a solar-powered hybrid yacht with a diesel engine. It can run on either, giving it a combination of unlimited range using solar or faster cruising using diesel.

It is a spacious and luxurious yacht, with plenty of living space and four cabins with en suite bathrooms.  The Serenity is the smaller of the two solar-powered boats offered by Serenity. The Serenity 74 is bigger and more luxurious, with an interior designed by Neiman Marcus Fashion Director Ken Downing.

Take a look at this video by Serenity Yachts to see more of the Serenity 64:

[embedyt] https://www.youtube.com/watch?v=ltyu-KPesg0[/embedyt]

Where to Buy: Serenity Yachts

Price: From $3.3 million

3. Sunreef Yachts – Eco 80 Sail Catamaran

Sunreef Yachts Eco sail catamarans take eco-friendly sailing to new heights. Their luxury solar yachts use a special ‘solar skin’ that covers any composite structure on the yacht to provide solar power from every angle.

They also use hydro and wind power to supplement the solar and have a sail. The green power generated on their innovative solar boats is enough to propel the boat, run all the onboard appliances and charge the electric water toys.

Taking their commitment to the environment up a notch, they use recycled and reclaimed materials, non-toxic paints, and natural fibers.

Check out the video below by SUNREEF YACHTS OFFICIAL on a day aboard the Sunreef 80 Eco Catamaran:

[embedyt] https://www.youtube.com/watch?v=hXFg1R1qcgI[/embedyt]

Where to Buy: Sunreef Yachts Eco

Price: Price on Request (depends on the custom specifications)

4. Soel Yachts – Soel Senses 48

The Soel Senses 48 is a 48ft solar electric catamaran. It was designed to be solar-powered and is slender and lightweight to make it more economical.

There are two sleeping berths for two people each, and another four people can sleep in the salon. The interior and the exterior are both sleek and modern.

Everything on the Soel Senses 48 has been designed thoughtfully to make it as comfortable and functional as possible. It is faster than other solar yachts, due to its smaller size and innovative design.

Check out this video by Jim Waltz to see a little more of the Soel Senses 48:

[embedyt] https://www.youtube.com/watch?v=t5IOCWPwGXY[/embedyt]

Where to Buy: Soel Yachts

5. Azura Marine – Aquanima 40

The Aquanima by Azura Marine is powered entirely solar and features some innovative adaptations that make it even more economical and eco-friendly. For example, rainwater collection from the solar panels on the roof and the fact that excess solar can be sold back to shore stations.

The Aquanima is beautifully designed and the interior is clean and modern. It has two double guest cabins and two single crew cabins. It is one of the most cost-effective options if you’re looking for a purely solar-powered boat.

Take a look at this video by Azura Marine to see the Aquanima in action:

[embedyt] https://www.youtube.com/watch?v=X25IRdHoHqI[/embedyt]

Where to Buy: Azura Marine

Price: From €523,000

6. Silent Yachts – Silent 80 Tri-Deck Solar Catamaran

The Silent 80 Tri-Deck Solar Catamaran is a superyacht that is completely customizable. It offers huge amounts of space, with three decks that can be customized to suit the owner’s needs.

The top deck can be open or enclosed and can be used as additional living space or a luxury master suite, opening onto a private outdoor space. Both open and closed versions include four to six customizable cabins.

As a solar-powered yacht, it has more space where the engines would normally be and that storage space can be used to house water toys and additional recreational equipment.

Check out this video by Yachts For Sale to see more on the Silent 80 Tri-Deck Catamaran, how it is built and what sets it apart:

[embedyt] https://www.youtube.com/watch?v=KCZMzE5Q8lc[/embedyt]

Price: From €5.51 Mio.

Final Thoughts on Solar Boats

As solar and battery technology has improved, and boat owners have become more conscious of their environmental impact, solar boats have become both more viable and more desirable.

Modern solar boats, from small solar-powered yachts to solar superyachts, are equipped with state-of-the-art technology to make them economical, easy to maintain, and a pleasure to use.

They’re also becoming increasingly affordable, and we hope, will be a mainstream option available to every eco-conscious sailor soon!

Electrek: I Drove A Rare Solar-Electric Yacht to Test Clean-Sea Propulsion, Here’s How It Went

Environmental Protection: The Environmental Impacts of Boating

Custom Marine Products: A Cruiser’s Guide to Selecting and Sizing a Solar Charging System

Forbes: Solar-Powered Yachting: A Look Inside ‘The Tesla of Yachts’

Knysna Yacht Company: Top Things to Know About Yacht Solar Power

Robb Report: How Zero-Emission, Solar-Powered Yachts Entered Boating’s Mainstream

Robb Report: Solar-Powered Yachts Are Taking Over. Here’s Why That’s a Good Thing

The Land Between: Recreational Boating and the Environment – Tips and Tricks for Environmentally Conscious Boating

Yachting Monthly: Sailing with Solar Power: A Practical Guide

Frequently Asked Questions

How does a solar boat work.

Solar boats use renewable energy from the sun to run their motors, electrical systems, and onboard appliances. They do not use petrol/diesel generators or engines and meet all their power needs using solar panels and batteries. Read the full guide for more details on how a solar boat works.

What are solar boats used for?

Solar boats are used for any boating purpose but they’re most frequently used for recreational sailing, such as yachts and catamarans, as ferries and tour boats, or as houseboats. Solar boats are generally slower and less powerful than fuel-powered boats. In situations where speed is needed, solar is usually supplemented with wind-sail or fuel-driven motors. Read the full guide for more on solar boats.

What is a solar yacht?

A solar yacht is a yacht that uses solar energy to power its electric motors and all the electronic equipment on board. Solar yachts do not rely on diesel or petrol engines and run solely on solar power. They do sometimes have other power sources, like backup diesel generators or engines. Read the full guide for more on solar yachts.

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Sailboat Cruising and Lifestyle Magazine.

Sailboat Solar Systems and How-To

Solar on a sailboat goes together like hands and gloves, but sailboat solar systems can be installed in a variety of ways. The solar components themselves create an infinite combination of possibilities for off-grid sailing. Victron Energy chargers, Renogy Panels, Sunpower Yachts, BlueSea Systems, and many more brands have entered the marketplace, and that’s not including the lithium battery companies.

To simplify things, we’ve compiled three sailboat solar systems videos to give you an overview of what’s possible. And to help you decide on your own simple solar panel setup for sailing.

How-To Install Solar Panels on Your Sailboat

This system from Zingaro shows flexible panels summing 300w of power on a 38′ catamaran.

300W Solar System:

• Three 100w solar flexible panels
• 1 MPPT Solar charger controller

View on Amazon >>

100W HQST Flexible Solar Panels $100-$200

20amp Solar Charge Controller by Victron Energy $150-$200

Simple Sunpower Solar System

This simple solar system from The Fosters shows a quick and easy setup with limited space on top of a bimini.

Sunpower Solar Panels are considered by most in the industry as the gold standard. They use the highest-efficiency solar cells and have top-notch build quality. In this simple installation, three 50w panels are just enough to get you started. Plus, it’s the most affordable installation!

150w Starter Solar System

• Three 50w Flexible Solar Panels
• A Single 15amp solar charge controller

50W Sunpower Solar Panels $150-$200

75v/15amp Solar Charge Controller by Victron Energy $100-$124

Off-Grid on a DIY Solar Powered Sailboat

Here’s a special installation that turned a derelict sailboat into an off-grid sailing machine!

Simon has transformed this derelict sailboat into an epic off-grid solar-powered and fossil-fuel-free cruising catamaran. He’s been living aboard and renovating the boat for the past 3.5 years We’re excited to show you the transformation as well as how he plans to propel the boat without the use of diesel or fossil fuels!

5280w Solar System for Electric Powered Catamaran

• 16 Rigid solar panels (330w each)
• 20kwh of Lithium Batteries

240W Rigid Solar Panels $250-$300

200AH Lithium 4d Battery $1200-$1200

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Adding Solar Power to a Sailboat

• By Emily Fagan
• Updated: October 18, 2019

During our nearly four-year cruise of Mexico, my husband, Mark, and I lived almost exclusively on 555 watts of solar power charging a 640-amp-hour house battery bank. We anchored out virtually every night aboard our 2008 Hunter 44DS, Groovy , and relied on the sun for power. During one 10-week stretch, while we waited for a replacement engine alternator to arrive, our boat’s solar panels were our sole source of power. We had no backup charging system to turn to, and yet we lived and sailed comfortably the entire time. Mounting solar panels on a sailboat was not difficult, but a few key decisions made a huge difference in how effective our panels were.

A solar-power installation on a sailboat is made up of two independent systems: one system to charge the batteries, and another system to provide 120-volt AC power for household appliances. In the charging system, the solar panels convert sunlight into electrical current and deliver it to the batteries via a solar charge controller. Similar to a voltage regulator, the charge controller acts as a gatekeeper to protect the batteries from receiving more current than they need as they are being charged. In the AC power system, an inverter or inverter/charger converts the 12-volt DC power in the battery into 120 volts AC whenever it is turned on.

Panel Positioning and Wiring Considerations

One of the biggest challenges for sailors installing solar power on a sailboat is finding a place on the boat where the panels will be shaded as little as possible. Just a few square inches of shade on one panel can render that panel all but inoperable. Unfortunately, between the mast, radome, spreaders and boom, shadows cross the deck all day long, especially as the boat swings back and forth at anchor.

What’s worse, if the panels are wired in series rather than in parallel, this little bit of shade can shut down the entire solar-panel array. When we installed solar power on Groovy , we had already lived exclusively on solar power in an RV for over two years. Our RV solar panels had been wired in series, and we had witnessed the array shutting down current production when just half of one panel was shaded.

Choosing whether to wire the panels in series or parallel on a boat affects the wire gauge required, which is why many solar-power installers lean toward wiring the panels in series. Panels wired in series can be wired all the way to the solar charge controller with a thinner-gauge wire than those wired in parallel. This is because the voltage of panels wired in series is additive, while the current remains constant, so the current flowing is just that of a single panel. In contrast, the current flowing from panels that are wired in parallel is additive, while the voltage across them is not. This means that in a parallel installation, the current going to the charge controller is several times higher and requires much thicker cable to avoid any voltage loss over the length of the wire.

Not only is thinner-gauge wire less expensive, but it is also more supple and easier to work with, making the job of snaking it in and around various crevices in the boat and connecting it to the solar charge controller much less of a struggle. Thus the choice between series and parallel wiring boils down to a trade-off between system performance, expense and ease of solar system installation.

Luckily, the size of the wire can be reduced if higher-­voltage solar panels are chosen. Since watts are determined by multiplying volts by amps, a higher-voltage panel that generates the same watts as a lower-voltage panel will produce less current. Therefore, selecting nominal 24-volt panels instead of 12-volt panels allows for the use of thinner wire sizes no matter how they are wired.

Our Marine Solar Panel Design Choices

In our installation, we decided to mount three 185-watt, 24-volt (nominal) Kyocera solar panels high above the cockpit, well aft of the boom, as far away as possible from potential shade. Our Hunter came with a big, solid stainless-steel arch, and we turned to Alejandro Ulloa, a brilliant metal fabricator at Baja Naval Boatyard in Ensenada, Mexico, to build a polished stainless-steel solar-panel arch extension onto the existing structure. He designed the arch extension with integrated telescoping davits to hoist our dinghy as well as support the solar panels. These davits were strong enough — and the lines and blocks had enough purchase — that either of us could lift our light Porta-Bote dinghy with its 6-horsepower outboard without a winch.

We spaced the panels about a half-inch apart and wired them in parallel. Using two twin-lead wires, we snaked the three positive leads and one common ground down through the inside of the arch tubes so they wouldn’t be visible, and placed wire loom over the exposed wires under the panels.

The junction points for the three parallel panels were on positive and negative bus bars inside a combiner box, all mounted in a cockpit lazarette. Inside the combiner box, we installed three breakers, one for each panel. This gave us the ability to shut off any or all of the panels if we needed to (we never did).

We mounted a Xantrex solar charge controller (model XW MPPT 60-150) in a hanging locker, as close to the batteries as possible, in a spot where it was easy to monitor and program. We ran twin-lead wire from the combiner box to the charge controller and from there to the batteries.

Our boat came with three new 12-volt Mastervolt 4D AGM house batteries, all wired in parallel, for a total of 480 amp-hours of capacity. We wanted a bigger house battery bank, and because it is best for the age, type and size of the batteries to be matched, we added a fourth new Mastervolt 4D AGM house battery, which brought our total to 640 amp-hours. Our batteries were installed at the lowest point in the hull, below the floorboards, and they ran the length of the saloon, from just forward of the companionway stairs to just aft of the V-berth stateroom door.

The best way to charge a bank of batteries that are wired in parallel is to span the entire battery bank with the leads coming from the charge controller. We did this by connecting the positive lead from the charge controller to the positive terminal of the first battery in the bank, and the negative lead from the charge controller to the negative terminal of the last battery. By spanning the entire bank, the batteries were charged equally rather than having the charging current focused on just the first battery in the bank.

We feel that AGM batteries are superior to wet cell (flooded) batteries because they can be installed in any orientation, don’t require maintenance, can’t spill (even in a capsize), and charge more quickly. Our Mastervolt batteries, like almost all AGM batteries on the market, are dual-purpose, combining the very different characteristics of both deep-cycle and start batteries. Our batteries work well, but if we were doing an installation from scratch today, we would consider the new Trojan Reliant AGM batteries. These batteries are engineered strictly for deep-cycle use and have been optimized to provide consistent current and maximize battery life.

Our boat came with a Xantrex Freedom 2,500-watt inverter/charger wired into the boat’s AC wiring system with a transfer switch. The inverter/charger performed two functions. While the boat was disconnected from shore power, it converted the batteries’ 12-volt DC power into 120-volt AC power, allowing us to operate 120-volt appliances, like our microwave. When the boat was connected to shore power, it charged the batteries.

Because this inverter/charger was a modified-sine-wave inverter, mimicking AC ­current with a stair-stepped square wave, we also had a 600-watt pure-sine-wave inverter to power our potentially more sensitive electronic devices. We chose Exeltech because its inverters produce an electrical signal that is clean enough to power medical equipment, and they are NASA’s choice for both the Russian and American sides of the International Space Station. For simplicity, rather than wiring the inverter into the cabin’s AC wiring, we plugged ordinary household power strips into the AC outlets on the inverter and plugged our appliances into the power strips. Like the charge controller, the inverter must be located as close to the batteries as possible. Ours was under a settee.

Shade’s Impact on Sailboat Solar Panels

Once our solar installation was completed on our sailboat, we closely observed the effects of shade on our solar-panel array. We were often anchored in an orientation that put the panels in full sun. Just as often, however, we were angled in such a way that shade from the mast and boom covered portions of our panels. It was fascinating to monitor the solar charge controller’s LCD display whenever the sun was forward of the beam — the current from the panels to the batteries fluctuated up and down as we swung at anchor.

Taking notes one morning, we noticed that the charging current was repeatedly creeping up and down between 9.5 and 24.5 amps as the boat moved to and fro. When the entire solar-panel array was in full sun, it generated 24.5 amps of current. When we moved so the mast shaded a portion of one panel, the array generated 15 amps. When it shaded portions of two panels and only one was in full sun, the array produced just 9.5 amps. Of course, it would have been preferable to see a steady 24.5 amps all morning, but this sure beat watching the current drop to zero whenever a shadow crossed a panel.

We discovered that shade makes a huge impact while sailing, too. Surprisingly, it is far worse to have the panels shaded by the sails than to have the panels in full sun but tilted away from its direct rays. One afternoon, we noticed that while we were on a tack that tilted the panels away from the sun, they generated 24.5 amps of current, whereas on a tack where the panels were tilted toward the sun but two of the three were partially shaded by the sails, the current dropped to a mere 10 amps.

Reflections On Our Solar Panel Installation

A wonderful and surprising side benefit of our large solar panels and arch system was that the setup created fabulous shade over the jumpseats at the stern end of the cockpit. Our metal fabricator, Alejandro, placed a support strut at hand-holding height, and sitting in those seats feels secure and comfortable while sailing, no matter the conditions.

After living on solar power for eight years of cruising and land-yacht travel, we’ve learned that you can never have too much solar power. Groovy’s 555 watts was enough to run all our household appliances as needed, including our nearly 4-cubic-foot DC refrigerator, two laptops, a TV/DVD player, and lights at night. However, it was not quite enough power to run all that plus our stand-alone 2.5-cubic-foot DC freezer during the short days and low sun angles of the winter months without supplemental charging from the engine alternator every few days. For the 10 weeks that we did not have a functioning alternator, our solution was to turn off the freezer, which enabled our batteries to reach full charge every afternoon.

Solar power made a world of difference in our cruise. Not only did it allow us to live comfortably and with ample electricity for weeks on end when our engine alternator went on the blink, but as a “set-it-and-forget-it” system, it also gave us the freedom to anchor out for as long as we wished without worrying about the batteries. In our eyes, the solar-panel arch enhanced the beauty and lines of our boat, giving her a sleek and clean appearance. It was true icing on the cake to discover that the panels and arch system also provided much-needed shade over the cockpit and helm from the hot tropical sunshine. If you are preparing for a cruise, consider turning to the sun for electricity and outfitting your sailboat with solar power.

The Installation:

Emily and Mark Fagan offer cruising tips and share their stories and photos on their website, roadslesstraveled.us . They are currently enjoying a land cruise across America aboard an RV.

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If there's life on Europa, solar sails could help us find it

"As humanity continues to expand space exploration, chemical propulsion will hit its limit."

Solar sails, which harness sunlight as sailboats harness the wind, could be affordable probes in the search for alien life on at least two icy moons in our solar system — Jupiter's Europa and Saturn's Enceladus, a new study suggests.

Unlike conventional rockets , which require lots of fuel to generate thrust, solar sails leverage the subtle push of sunlight to cruise through space. They are propelled when photons, or particles of light, strike them and impart their momentum. This way, "the light itself functions like the wind," Manasvi Lingam, an astrobiologist at the Florida Institute of Technology and the lead author of the new paper, told Space.com.  

The push given by light particles is slight but continuous, meaning they can eventually accelerate a solar-sailing probe to speeds unattainable with conventional rockets, which are heavier thanks to the propellant they carry — a problem that increases with the size of the spacecraft. Solar sails, however, gain momentum from the sunlight they capture, so "they don't have to carry their fuel onboard," said Lingam.

Related: What is a solar sail?

Given sails' reliance on sunlight, their use could be ultimately limited to the inner solar system, where sunlight is abundant. However, at least in theory, a network of tiny lasers here on Earth or placed in orbit at one of the Lagrange points could add further momentum and eventually propel solar sails to the outer solar system, said Lingam. 

For instance, in the new study, his team estimates that a 220-pound (100 kilograms) solar sail could reach Jupiter's moon Europa in just one to four years and Saturn's moon Enceladus in three to six years. 

Both worlds are thought to harbor a global salty ocean underneath their ice-covered surfaces, making them tantalizing targets in the search for alien life in our solar system. Enceladus is known to blast watery geysers from its south polar region, and hints of plumes have been spotted at Europa as well.

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Sampling such plumes, which may host intriguing biomolecules like amino acids, would allow scientists to study the makeup of the moons' oceans without needing to land a spacecraft and drill through thick ice.  

When performing flybys through these plumes, high spacecraft speeds would lead to the particles striking a probe relatively hard, meaning "the molecules can be destroyed, and that, in turn, can destroy any signs of putative life," said Lingam. To avoid that, a solar sailing mission should be capable of reducing its speed to the minimum encounter velocity of about 6 kilometers per second (about 3.7 miles per second), Lingam and his team report in their new paper , published Feb. 28 in the journal Acta Astronautica.

— Watch NASA unfurl basketball-court-sized solar sail for deep space propulsion (video)

— Solar-sailing probes may soon get their moment in the sun

— Watch this Jupiter moon lander handle harsh terrain it may face on Europa (video)

This particular space technology is not unheard of. For example, LightSail 2, a crowdfunded, shoebox-sized spacecraft operated by the nonprofit Planetary Society, launched to Earth orbit in 2019. By November 2022, LightSail 2 had achieved 18,000 orbits and traveled roughly 5 million miles (8 million kilometers) during its three years in orbit — three times longer than its original design lifetime. 

Solar sails have worked farther from home, too: Japan's Ikaros spacecraft demonstrated solar-sailing technology in deep space back in 2010.

Some scientists think solar sails could even propel humanity's first interstellar missions. For instance, the $100 million Breakthrough Starshot Initiative , announced in 2016, aims to build a swarm of lightweight microchip-sized spacecraft and send them to Alpha Centauri, the nearest star system to Earth. Propelled by lasers at 20% the speed of light, these light sails could reach Alpha Centauri in just 20 years—within our lifetimes.

After 65 years of exploring our solar system with conventional rocket technology, "at some point, we're going to encounter the limits of what can be explored with chemical propulsion," said Lingam. Solar sail technology could very well herald a new era of space exploration, he added, especially if it's going to be well-suited to search for signs of life in places "considered among the most promising habitats for life."

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Sharmila Kuthunur is a Seattle-based science journalist covering astronomy, astrophysics and space exploration. Follow her on X @skuthunur.

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• Sailboat Guide

Expo 14 (Solar Sailer)

Expo 14 (Solar Sailer) is a 13 ′ 5 ″ / 4.1 m monohull sailboat designed by Ted Hood and Gary Hoyt and built by TPI Composites starting in 1993.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

Equiped with motorcraft MInn Kota Endura30 electric motor built into the hull. A solar panel charges the included battery pack.

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Silent Yachts

Creators of the world’s first series produced, solar-powered electric yachts.

Unlimited Range

Noiseless cruising, zero emission, minimal maintenance, pioneering solar powered yachting since 2009.

The Original Solar Yacht

As the original inventors of series produced solar-electric yachts, we pioneered this innovative approach. Our first model, the Silent 64, was launched to the market in 2016, several years before any other shipyard considered the possibility of going electric.

Leading Technology

Our founders began to research alternative energy sources to power yachts during the mid 1990s. Today, the technology of our in-house developed solar-electric drivetrain has been perfected and is multiple generations ahead in terms of reliability, performance and efficiency.

Historical Track-Record

In 2009, the Solarwave 46 was launched as our first prototype of a fully solar-electric, self-sufficient ocean-going catamaran. Since then, our electric yachts have cruised many 10.000s of nautical miles, performing flawlessly during a variety of weather conditions.

Enabling Self-Sufficiency

What differentiates a Silent is the unprecedented level of autonomy provided by our yachts. Being able to produce your own energy enables a fully self-sufficient lifestyle on board. Travel the oceans sustainably while making them your infinite playground.

The award-winning entry to solar-electric yachts.

Timeless design meets state-of-the-art technology.

120 Explorer

The boldest expression of solar powered yachting yet.

What Makes Us Unique

The tranquility on board of our yachts is unique. A lack of noise, fumes and vibrations create a deep connection with the sea. Luxury and sustainability finally merged into a holistic experience, working hand in hand with nature by minimizing the impact on the marine environment without compromising comfort.

For optimal performance and efficiency, our solar-electric drivetrain integrates seamlessly with all onboard systems. Compared to fossil fuelled powertrains of motoryachts, electric powertrains have very few moving parts, resulting in minimal maintenance, maximum reliability and significantly lower running costs.

The ability to recharge your own batteries with the sun marks a new era of freedom. Depending on cruising speeds and weather conditions, a Silent has virtually unlimited range, enabling you to live a fully self-sufficient lifestyle on board. Unbound by the limitations of fossil fuels, you are free to explore the horizons.

The technology powering our yachts today has been pioneered by our founders almost three decades ago. Continuous upgrading and steady optimization of the entire system are some of the key reasons our in-house developed solar-electric drivetrain offers a comprehensive portfolio of assurances and warranties.

Powered by an advanced jet propulsion system, the fully electric Tender Series perfectly complements the experience on board of our catamarans. Following the same philosophy as our electric yachts, it was developed with a strong focus on being spacious, lightweight and efficient.

As a new breed of Silent, the Speed 28 combines futuristic design with blistering pace. Her high-performance drivetrain is supported by triple foils and embedded solar cells on the hardtop. Advanced hydrodynamics and latest AI management make for a stable ride which always remains comfortable.

Why Silent Yachts

A sensible approach to yachting which works in self-sufficient harmony with nature and creates a completely new experience on board.

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“The Tesla of the seas! An amazing founding couple, a highly innovative product as well as a really cool story behind it. Furthermore, a lot of love and attention has been invested into every single detail – truly impressive!” Frank Thelen / TV Personality, Founder, Angel Investor & Disruption Expert

While the present has brought us the dawn of smart cars, I strongly believe the future will bring us solar powered smart boats – and I definitely want to be at the frontline of that journey. Michael Jost / Former Head of Group Strategy of Volkswagen Group

The idea of sailing while charging your own battery is super powerful to me – solar powered sailing is the perfect love story! Jochen Rudat / Former Tesla Central Europa Director, Advisory Board Silent Group

Elon Musk single handedly forced an entire industry to go electric, as a matter of fact if they don’t all go electric now they will soon die. I would like to see the same thing happening for boating. You are not just selling boats – you are the actual leading edge of a crucial and much overdue revolution to sustainable transport!” Klaus Obermeyer / Emmy Award Winner

I am completely excited about solar catamarans. I knew before they are great but now I truly believe this is the future. After so many boats I’ve seen in over 18 years with Boote Exclusiv, this yacht truly blew my mind. Such a silent and peaceful cruising experience – just the way it should be. Martin Hager / Editor in Chief for Boote Exclusiv - Yachts

Recommended water toys, accessories and products to enhance every Silent voyage:

Top 3 Best Solar Panels For Sailboats

Last Updated by

Daniel Wade

June 15, 2022

Choosing whether or not to install solar panels on your sailboat is a big decision. They are not exactly cheap, though they can start to pay themselves off pretty quickly.

This article is going to cover not only why you might want to use solar panels but all the benefits they provide. You will also find a helpful guide on which solar panels would be best for you and your budget. Hopefully, by the end, you will feel confident in your decision to install solar panels on your sailboat and even have an idea of which ones you might like.

Table of contents

Are solar panels on sailboats necessary?

Whether or not you should be installing solar panels on your boat is a matter of choice, not out of necessity. Sailboats get their power from the wind, by harnassing it in their sail. So if you plan to be sailing for the afternoon you probably don’t need solar panels.

You could charge a battery pack from the marina and that will probably see you through several trips. The problems only really start to arise if you are planning to be on your sailboat for longer periods, or even permanently. If you plan to live on your sailboat year-round, even if you spend 80% of it in a marina, you would be better off with some solar panels. Even if it is just as a backup source of power.

Are solar panels on boats safe?

Solar panels are generally pretty safe. They have no moving parts and typically have a very strong protective cover over them so you never come in contact with the electrics themself. So, as a source of power, they are generally pretty safe. The only time they may become unsafe is if they are badly damaged.

Solar panels are often covered by glass plating that keeps them safe. It also helps them absorb sunlight and warmth. This is great, except when the glass breaks. If the glass protective cover on your solar panels should crack and splinter you are at risk of serious injury from sharp shards of glass. Not only is the glass itself dangerous at this point, so are the electronic components inside. They have powerful currents running through them, and if you come in contact with them you may be in for a shock.

Furthermore, if these electronics get wet they can become deadly. Electricity and water do not mix well at all. Being as you are on a sailboat, at sea, the chances of them getting wet is very high. Luckily, the chances of them breaking in the first place are slim to none. The only real way they would break, besides vandalism, is by debris hitting them during a bad storm. There is not often debris at sea, so this shouldn’t be too much of a problem.

What are the benefits of having solar panels on a sailboat?

There are so many great benefits of having solar panels on a sailboat. They can be a lifesaver if you find yourself at sea for a long time. There benefits range from trivial comforts to being the difference between life and death. Here are some of the benefits you might not have considered about having solar panels installed on your sailboat.

Money-saving

Solar panels are not cheap, it is far cheaper to just run a generator or charge your batteries from the marina the whole time. At least, it is in the short term. Over time, it can start to become very expensive. With solar panels, you are looking at a big initial cost (the solar panels themself) and then it’s smooth sailing. You don’t need to pay for power again. Solar panels last for about 40 years before they start to become too inefficient at producing power. The cost of a few solar panels upfront compared to 40 years of marina fees and gasoline for a generator is the financially savvy move.

Emergency power

If you find yourself at sea, the wind dies down (or becomes too strong), and you find yourself stuck bobbing around waiting for more favorable conditions you may run into trouble. Depending on how long you are out there, you may find yourself with dead electronics. Be it a satellite phone, radio, or secondary engine (depending on the boat). Having a set of solar panels and a power bank can be a genuine lifesaver in these situations.

Comfort amenities

Whether you are day sailing or making a week-long voyage, having access to the comforts in life can make the whole journey so much more enjoyable. The amenities may not be available to you without having a constant source of power at sea. Having access to a kettle, tv, videogame system, radio or microwave oven may be the only thing keeping you going at rougher times. As exciting as sailing can be, when you aren’t sailing and are just bobbing around it can be quite dull. The sea is beautiful, but there is only so much time you can spend looking at the water before you miss the comforts of land. With solar panels, you can bring those comforts with you.

Eco-friendly

There are only two alternatives to solar panels. A gasoline generator, and taking power from the grid. Neither of these is good for the environment. Luckily, solar panels are a great third option. Solar panels are completely eco-friendly and are great for the environment. This is not just great for the earth, and your conscience, but for the journey itself. If you are running a gasoline generator at sea you are going to be listening to it thrumming away and smell the burning gasoline. Wouldnt you prefer silence and nothing but the smell of the sea breeze?

How much do solar panels cost?

How much solar panels cost is almost entirely tied into both their voltage/wattage and whether or not they are portable panels. Portable solar panels are great for people who don’t spend a lot of time on their boat or are happy enough living off the marina’s power grid. Permanent solar panels, the kind that may need to professionally installed, can end up costing far more. They are also likely to be far superior and you can pretty much forget about them once they are installed.

Portable solar panels will cost just a few hundred dollars each. You will need a few to be sustainable, but that’s not going to be much of a problem. These portable solar panels can just be rolled out on the deck of your boat, weighed down, and then hooked up to a battery pack. The battery itself here is going to be the most expensive part of the whole set up. A decent-sized battery could set you back a $1000. But, when charged fully it will last days. Even with constant use.

Permanently installed solar panels can cost one or two thousand dollars in some cases. The advantage here though is once they are installed that’s it, you can forget about them. You don’t have to put them up, take them down, and find somewhere to stow them every time they need using. They too will need to be hooked up to a battery, the battery is still only going to cost you $1000. If you are installing permanent solar panels because you plan to be making long voyages, it is ideal to have two or perhaps even three large batteries hooked up to your boat. One to run off, one or two for emergencies.

How do I maintain my solar panels?

Solar panels, unlike gasoline generators, are generally pretty easy to maintain. They have no moving parts and are thus pretty self-sufficient. They don’t need taking apart and they last as long as 40 years. That being said, if they do break they need repairing as soon as possible. The exposed electrics can be deadly when water is thrown into the mix. Which, on a boat, is almost always. The glass cover will need replacing and the electronics inside may need repairing, though not always. Don’t ever attempt to do this yourself unless you are experienced at making these repairs. The cost of hiring someone to do it for you is preferable to being dead. Solar panels have very powerful electric currents, that when in contact with water and yourself can be fatal. As mentioned above, these panels rarely break so you will likely not ever run into this problem. If you do, hire a contractor.

Do my solar panels need cleaning?

Solar panels work by converting the light and heat of the sun into useable power. The process itself is rather complicated but the results are simple to understand. That being said, there are some reasons that your solar panels will stop working as effectively. They all revolve around a lack of sunlight. It could be because it is night time. It could be because it is very cloudy. Or, it could be because they are dirty. If solar panels become too dusty, dirty, and become too covered in grime they stop operating at maximum efficiency. This is not as much of a problem at sea, the sea spray stops dust settling. The biggest thing you will need to clean off your solar panels is salt build-up and slime. This is easy enough to do with some warm soapy water. Freshwater, not seawater. You want to be removing as much salt as possible. Salt is corrosive to electronics, so removing it is important. Never clean your solar panels using pressure washers as they can crack the glass.

Which are the best solar panels for sailing?

There are so many options on the market at various price points. Here are three very different options that will all make good choices, depending on your needs. It is important to consider not just price but power output. Spending a lot of money on solar panels now might not feel ideal, but it is the most cost-effective decision.

1. Renogy Starter Kit

This starter kit is going to be perfect for installing on almost any sized boat. There are four solar panels, each can be fitted permanently to the boat. They can be mounted (and unmounted) easily, for your convenience. They do require a flat surface, but they are small enough that that likely won’t be too much of a problem. This starter kit is very middle of the pack price-wise but should provide enough power for a small to medium-sized vessel easily. It is also possible to buy extra panels individually should you need them.

Wattage: 400/4 (100 per panel)

2. Nature Power Rigid

The nature power rigid is a large, powerful, single solar panel. If you are looking for the right panels to power your entire boat comfortably, these are the ones for you. They are very large so they will need a large flat surface area. alternatively, they can be hung vertically from rails. This is an inefficient way of using them, so you would need to buy more this way. Nature power makes various solar panels so you could find some smaller ones of the same brand to supplement it. This one is not so easy to install, you might need to hire someone to install it for you.

Wattage: 165

3. Nature Power Monocrystalline

Nature power makes a portable solar panel that fits inside a special briefcase. It is perfect for stowing away easily and only taking it out when it is needed. It is decently powerful considering its portable, but there is the inconvenience factor of having to set it up each time. If you planned to buy the nature power rigid, buying one of these portable panels might be ideal for supplementing your power supply when it is especially sunny. Though, it may be cheaper for you to just fit more of the Nature Power Rigids.

Wattage: 120

Hopefully, you now have a good idea about whether solar panels would be right for you and your sailboat. Sailing is great, but the lack of power at sea can be dreadfully boring. Luckily, there are so many great options available on the market. Not just the ones mentioned above. Buying a solar panel is an investment, the initial cost is minor compared to the steady return from all the savings you will make.

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I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

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• Sailboat Reviews

EXPO Solar Sailer

Designed as a sail trainer, this dinghy with an electric motor and solar panel makes a fun family boat..

Put Gary Hoyt, Ted Hood and Everett Pearson in a canoe and you have the marine industry’s maximum tripartite brain power. The cerebral sparks from these three New England dynamos produced the EXPO Solar Sailer.

Introduced at Sail Expo ’93 in Atlantic City, the EXPO Solar Sailer is a brilliant, purposeful little boat. The object is to “solo” a rank beginner in an hour.

Despite its utility as an educational tool, the 13-1/ 2-foot boat was dubbed by Naval Architect Bob Perry as “an ideal daysailer for a sailor with a relaxed attitude.”

In short, it’s a fun boat-at the other end of the scale from, for instance, a sailboard, which is guaranteed to make anyone look foolish for a couple of weekends.

Design and Construction

The EXPO was conceived by Hoyt (who has a long list of conceptions to his credit), designed by Hood (who needs no introduction) and built by TPI (at present, or one time or another, the builder of J Boats, Aldens, Jeanneau catamarans and Freedoms).

“It takes both the mystery and the fear out of learning to sail,” said Hoyt, who, beginning with the Freedom 40, has spent 20 years trying to take the mystery out of learning to sail. He can talk for hours about how fast, tippy boats intimidate beginners, and that if the sailing industry is serious about attracting newcomers, it must first provide a simple, safe boat that won’t scare off those on the edge of jumping in. That’s the premise of the EXPO Solar Sailer.

Hood calls the EXPO a “cruising Finn dinghy” because the shape of the hull, although beamier, is like the Olympic-class Finn. Pearson is proud of the EXPO’s sturdiness.

The hulls are “Infused Resin Molded” using a vacuum-bagged, injected resin system that creates a powerful, high strength-to-weight composite that should defy decades of hard usage.

She’s a fat little rascal, very stable. Hoyt said that of the 70 built and in use as of late 1994, mostly in educational programs and rental businesses, he knows of only one capsize (by a very hefty gentleman beginner who, in a stiff breeze, jibed and didn’t move until he was in the water).

The white-painted aluminum boom, independent of the rotating mast, arches up and over the cockpit. You’d have to stand up to get clouted. Hoyt has applied for a patent on the free-standing boom.

The 14-pound, tapered carbon fiber mast rotates on a Harken base. The 105-square-foot, loose-footed sail furls on the mast, very easily controlled by a continuous line that serves also as an outhaul. The outhaul and rotating mast also provides reefing, in seconds, with little effort.

On the non-skid deck just forward of the cockpit is a permanently-mounted windvane with color-coded sectors. To trim the sail, the beginner merely matches the color-sector indicated by the vane to the color-coded mainsheet, held in a Harken cam cleat pedestal mounted in the cockpit.

The kick-up rudder is mounted inboard, not only to make it very accessible to the skipper but to give the EXPO a proper yachty look. The daggerboard is easy to operate and has a stopper hole and pin to secure it in the withdrawn position. With the board up and the rudder taking care of itself, the EXPO can simply be winched up on a dock or trailer.

It has a two-way Henderson pump, one channel to pump the hull, the other for the cockpit, which is not self-draining because Hoyt wanted to keep the floor low for adequate leg room. A commodious bow compartment with a well-fitted door provides stowage for a cooler, lunch, foul weather gear and an anchor and rode (in case you want to stop to fish or swim).

The EXPO displaces 350 pounds. It carries up to six persons, but Hoyt conceded that with that load she’d be crowded and sluggish.

To get away from the dock and motor about, it has an electric engine powered by two securely-anchored gelcell batteries (with an in-line regulator and battery meter) charged by a flexible Unisolar solar panel mounted neatly on the deck aft of the cockpit.

There’s also a built-in 110-volt charging unit. The simple engine switch handle provides three forward speeds and two in reverse. The little prop is protected by a skeg. In flat water, the boat will motor at close to 3 knots (full power) for three hours, five hours at half-speed. Hoyt warned that, under power, it will not work against much of a chop.

Aboard the EXPO, you can shove off and be sailing in five minutes. The EXPO has a hull speed of 4.7 knots, which it should reach in a moderate breeze, even while dragging the little prop on the Minnkoto engine.

The Sail Trainer Test

To try out the EXPO, we dragooned two lads—a 14-year-old experienced Laser racer (he happens to be our son, Kyle Nouse), and Kyle’s 14-year-old buddy, Joe Costa, who knew absolutely nothing about sailing. In fact, he never before had been aboard a sailboat of any kind.

At Newport’s Ida Lewis Yacht Club, the day was hot, with a moderate breeze, with some slightly heavy gusts.

We elected to conduct the test as though we had bought the EXPO for use on an inland lake or bay, taken it out of the crate, assembled it, and said, “It’s all yours, boys.”

Our experienced lad looked over the boat for no more than 10 minutes, tried the furling and the engine controls, pushed the daggerboard down, straightened up the mainsheet, cast off and in less than three minutes was sailing back and forth. Our neophyte, Joe Costa, watched carefully from the dock.

As instructed, Kyle furled the sail and motored back to the dock, with little ado. All he said was, “Awesome.” but he says that often.

With Kyle as a passenger (under orders to not provide even a speck of help or advice), Joe Costa stepped aboard, a bit timorously, settled himself in the starboard aft corner of the cockpit and cast off. He motored away from the dock, hooked the boat into the wind, unfurled the sail, checked the color-coded wind vane and sheet and shouted, “Hey, I’m sailing!”

There was one glitch. Because Joe had an overwhelming tendency to jibe to starboard, round and round and round and round, he skinned too close to shore and ran aground. Kyle quickly furled the sail, put the engine in reverse, pulled up the daggerboard (she draws 2′ 6″ with the board down), backed into deeper water and had Joe sailing again in two or three minutes.

After coming into the dock to collect Joe’s wits and add a little advice about going to weather and the need to shift his butt to the windward side, off the boys went again, this time for a half-hour sail, during which Kyle quickly refined Joe’s skill at tacking, jibing and, most of all, going straight.

Kyle said the most difficult part for Joe was going to weather, keeping the boat moving in a straight line, and then tacking.

It all took about an hour and a half, at the end of which Kyle and Joe were zipping around the harbor, changing helmsmen frequently. When hailed, they responded:

“Do we have to come in now?”

When they did, they were making plans to go out in a Laser, at which time Joe’s learning curve will take a steep upward turn.

What do we think of the EXPO?

It’s a marvelous design, beautifully built with a great rig. With a sail area/displacement ratio of 37 and a displacement/length ratio of 76, it moves very well in most any kind of air. Reefed down a bit, it can handle some fairly heavy going.

However, as a dinghy, the EXPO wouldn’t do. It’s too heavy to tow or lift aboard. It might make a tender or harbor sailor for a big boat that can hoist her aboard, but unshipping the mast would be difficult.

As a teaching tool for both youngsters and adults, this little boat is peerless, squarely meeting its designed intent better than any boat we’ve ever seen. For both commercial usage and for junior programs at yacht clubs and sailing associations, it’s ideal.

We also see the EXPO as simply a very safe, comfortable, inland lake or bay boat that would be a joy to own.

The 1994 price, $6,415, which includes everything, reflects the high quality present in every detail. The price is difficult to compare with other daysailers. Lined up against engineless boats like a Laser ($3,200) or a Sunfish ($2,200), she’s expensive.

However, compared with a 15’ West Wight Potter at $5,995, a Peep Hen 14 with a 4-hp. outboard at $7,245, or an American 14.6 (a Carolina version with an outboard and trailer) at $4,250, the EXPO seems reasonably priced.

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Simple efficient solar solutions

FLIN solar GmbH develops and distributes solar modules and innovative solar systems for boats and yachts. Become independent through solar energy.

FLIN provides the optimal solution.

Are you looking for the right solar system for your boat? Whether you need a small solar panel for maintaining charge or a powerful solar system for large electrical loads - FLIN has the solution tailored for you.

The FLINrail + can be easily hooked into the railing and tilted depending on the position of the sun.

If required, the FLINsail can be pulled into the mast instead of the mainsail and aligned to the sun.

The FLINkite + is hoisted on any halyard and can be oriented towards the sun.

The FLINpole + is a solar panel that is mounted on the pushpit by means of an aluminum rod. It can be oriented in all directions.

Our FLINstripes are attached to the tree tarpaulin using Velcro strips.

The FLINflex series offers solar modules of any size with different mounting systems.

FLINfix is a solar module for fixed mounting on deck. It is attached by means of an adhesive film on the back.

Why do systems from FLIN deliver such good yields?

Decisive for the performance of a solar module is its alignment at the perfect angle. For maximum energy gain from solar radiation, the solar modules in the FLIN systems can be aligned to the sun. This enables maximum solar energy gain even in the evening hours when the sun is low in the sky.

FLIN-Videos

Discover more about FLIN solar GmbH: FLIN's YouTube channel contains many exciting videos about our products as well as customer interviews and test results of various Torqeedo electric motors.

FLINrail - The simplest and most efficient solar module for the railing on board

How does the FLINrail + work? Simply hook it into the railing, point it towards the sun and harvest solar energy. Find out more in our product video about the FLINrail + !

How to install the FLINsail solar system on your sailing yacht

It's very simple: In this video we show you step by step how to set up the FLINsail solar system on your sailing yacht.

FLIN for maritime e-mobility

We want to make existing energy usable. Our goal is to generate solar energy simply and highly efficiently on the water. In this way, we would like to contribute to advancing maritime e-mobility. In addition to reliable functionality, we place great emphasis on user-friendliness and sleek design.

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Our solar modules and solar systems are interesting products for your customers and you would like to become a sales partner? Please feel free to contact us. Are you interested in a cooperation or are you looking for an innovative solar solution for your project? Please feel free to contact us.

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Exploring the Dynamic Progress in Space Exploration – The Buzz at The Marshall Star on March 20, 2024

By Jessica Barnett

Visitors at the U.S. Space & Rocket Center were recently privy to an exciting exhibit featuring Les Johnson of NASA’s Marshall Space Flight Center. The focus was none other than the burgeoning field of solar sail technology, which Johnson, a noted technologist, elaborated upon through presentations and individual interactions.

Johnson detailed the workings of solar sail technology, included a demonstrative video of a solar sail quadrant being tested, and conveyed the revolutionary impact this technology may have on space travel. His optimism was palpable as he remarked, “This type of propulsion is free, doesn’t run out of fuel, and can accomplish amazing things in the future.” He imagines tremendous sails, amped by lasers, pushing the boundaries of space exploration to unprecedented limits.

The advancement of solar sail technology continues to be a priority for NASA, with a major milestone being achieved this January. The successful deployment of one of the solar sail’s quadrants, which will collectively form a massive 17,800-square-foot sail, is pivotal for the agency. Led by Marshall, with the support of the Florida-based Redwire Corporation and Huntsville’s NeXolve, the project is moving steadfastly forward.

Barnett, an integral team member at Marshall’s Office of Communications, provides media support through Media Fusion.

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Robert Champion’s ascent to manager of the SLS Exploration Upper Stage Office at NASA’s Marshall Space Flight Center is slated for March 24th. His purview includes the development of the exploration upper stage for the SLS Block 1B rocket, pivotal in the Artemis IV mission. With a commendable track record and numerous accolades, Champion is poised to take Marshall’s SLS Program to new heights.

June Malone is ready to step into her new role as director of the Office of Center Operations at Marshall on the same day. With a vast reservoir of experience across various roles within NASA, Malone looks set to adeptly manage a significant annual budget, overseeing services that play a crucial role in the smooth functioning of the center.

Rick Smith echoes the sentiments of excitement with his account of a groundbreaking test involving NASA’s LN-1 autonomous navigation system. Part of the CLPS initiative, this beacon in lunar orbit demonstrates a significant leap toward a safe and sustainable human presence on the Moon. The success of LN-1 is just a precursor to a future where real-time navigation and communication are seamlessly enhanced by such technology, barreling toward the ambitions of the Artemis campaign and the Moon to Mars exploration.

The trial launch of SpaceX’s Super Heavy booster with Starship signifies another leap towards the much-anticipated Artemis III and IV missions. With SpaceX’s third integrated test, numerous objectives related to the Starship HLS have been met, inching us closer to the vision of returning to the Moon’s South Pole.

The introduction of the universal stage adapter test article at Marshall heralds an exciting phase for the SLS Block 1B rocket. With testing in the offing at Building 4619, the readiness of the upgraded in-space propulsion stage, which will fuse with Orion spacecraft, is critical for future lunar missions.

The transformative DART mission’s impact on asteroid Dimorphos not only demonstrated its defensive potential against cosmic threats but also revealed new insights into the asteroid’s post-impact dynamics. This finding from NASA’s study is a testament to DART’s dual achievement in defense and discovery.

Onboard the International Space Station, a whirlwind of activity continues with equipment installations, health examinations, and preparations for upcoming crew arrivals and cargo. The HOSC at Marshall remains an instrumental force, ensuring mission success by providing year-round engineering and operational support for the station’s research endeavors.

Meanwhile, the assembly and preparation of Europa Clipper’s solar arrays press ahead at Kennedy Space Center, earmarking an exhilarating journey to Jupiter’s moon Europa. Managed by multiple NASA centers, the mission embodies the collaborative spirit driving extraordinary off-world explorations.

FAQ Section

What is the purpose of the solar sail technology being developed by nasa.

The solar sail technology being developed aims to create a novel form of propulsion for spacecraft, which, unlike conventional ones, requires no fuel and relies on the momentum of photons from sunlight or lasers to navigate through space.

What are the roles of Redwire Corporation and NeXolve in the solar sail project?

Redwire Corporation is the prime contractor, and NeXolve is the subcontractor, contributing to the solar sail project led by NASA’s Marshall Space Flight Center.

Who is Robert Champion and what will be his new position?

Robert Champion, with a 37-year tenure at NASA, has been named the new manager of the SLS Exploration Upper Stage Office at NASA’s Marshall Space Flight Center, responsible for the development of the exploration upper stage for the next-generation SLS Block 1B rocket.

What is significant about SpaceX’s recent test flight for the Super Heavy booster and Starship?

The test flight is a critical milestone in developing SpaceX’s Starship human landing system for future Artemis lunar landing missions, showcasing key capabilities in propellant transfer and stability during orbit, among other advancements.

What was the outcome of the DART mission’s impact on the asteroid Dimorphos?

The DART mission successfully altered the orbit and shape of Dimorphos, reducing its orbital period and generating new knowledge about the nature of such asteroids, while also proving the capability of kinetic impact to potentially safeguard Earth from cosmic threats.

How does the Europa Clipper mission relate to other activities at the Marshall Space Flight Center?

The Planetary Missions Program Office at NASA’s Marshall Space Flight Center is responsible for the program management of the Europa Clipper mission, which aligns with the center’s commitment to deep space exploration and scientific research.

The latest edition of The Marshall Star spotlights the unmatched strides made in space exploration and technology. From the promising developments in solar sail propulsion, the SLS program’s progress, to the sophisticated onboard navigation systems like LN-1, each innovation marks a significant step towards a sustainable and secure future in space travel. As Marshall Space Flight Center continues to spearhead these initiatives, the anticipation of upcoming Artemis missions with commercial partners like SpaceX, and the unfolding of cosmic mysteries through missions like the Europa Clipper, the pursuits of space exploration have never been more vibrant and enthusiastic.

Our endeavors in space are not merely about reaching new frontiers; they are about creating the technologies and capabilities that will allow humanity to thrive beyond our home planet. The dedication and collaborative efforts of all involved at NASA ensure that as we chart this extraordinary course, the possibilities remain as boundless as the universe itself.

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Best Solar Panels For Sailboats of 2024

Sailing uses the power of the wind to move, so why not use the power of the sun to charge your batteries? Solar panels offer the best way to charge boat batteries. This method can also save the engine from being used just for charging. Getting the best solar panels for sailboats means choosing the right size and power for your boat.

But, how much power will you need? Will your panels be able to keep up even on cloudy days? Do you plan to sail in cold water or deep in the tropics? Do you need the panels to sit on a curved surface? There’s a surprising amount of factors to consider when purchasing sailboat solar panels.

Whether you’re replacing old panels or buying for the first time, let us do the hard work of comparing the best solar panels for your boat.

For more of our top sailing gear recommendations, check out the Best Wind Generators for Sailboats . 

QUICK ANSWER – THE BEST SOLAR PANELS FOR SAILBOATS 

• Nature Power Monocrystalline
• Nature Power Rigid
• Renogy Starter Kit (4 panels)
• Newpowa Poly Solar Panel
• Acopower Polycrystalline
• Nature Power 90W Rigid
• Newpowa 150W
• Suaoki SunPower
• Eco-Worthy Semi-Flexible

SAILBOAT SOLAR PANEL REVIEWS

Nature power monocrystalline.

Check out the latest price on: Amazon  | West Marine

BEST FOR: Efficient high-power use

WEIGHT: Unspecified

WATTS/AMPS: 120W/6.6A

SIZE: 45.1” x 33.6” x 3”

PROS: Foldable for easy storage and portability, pop-out legs that allow it to easily sit at an angle, sturdy design

CONS: On the upper end of the price spectrum, short warranty

NATURE POWER RIGID

BEST FOR: Energy-hungry boats

WATTS/AMPS: 165W/9.4A

SIZE: 57.8” x 26.3” x 1.4”

PROS: Powerful and efficient, scratch resistant and anti-reflective coating, well-built aluminum frame, easy-to-use connections

CONS: Powerful but expensive, only suitable for larger boats with a big flat space to set it up on

RENOGY STARTER KIT (PACK OF 4 PANELS)

Check out the latest price on: Amazon

BEST FOR: Large boats needing lots of power

WEIGHT: 18.0lbs

WATTS/AMPS: 400W/22A

SIZE: 4 x 47.0” x 21.3” x 2.0”

PROS: Includes x4 100W panels along with a charge controller and everything else needed to set up, ideal for sailors looking for a lot of power, easy mounting system, great price for a comprehensive kit

CONS: Rigid solar panels can only be on flat surfaces or mounted on rails, included charge controller might not be the charge controller for your needs

NEWPOWA POLY SOLAR PANEL

BEST FOR: Keeping small battery banks topped up

WEIGHT: 6.3lbs

WATTS/AMPS: 30W/1.7A

SIZE: 27.0” x 14.3” x 1.9”

PROS: Sturdy design, small and slim making it ideal for stern rail, wattage should be enough to trickle-charge medium battery banks, very affordable

CONS: Rigid design means placement is limited, heavy for a small panel

ACOPOWER POLYCRYSTALLINE

BEST FOR: Larger sailboat trickle-charging

WEIGHT: 6.9lbs

WATTS/AMPS: 35W/2A

SIZE: 29.9” x 16.1” x 1.7”

PROS: Looks neat with silver aluminum frame, should be able to easily keep batteries topped up and contribute to energy requirements when boat is in use, very affordable and slim, other wattages available

CONS: Weighty, aluminum frames can have sharp corners

NATURE POWER 90W RIGID

Check out the latest price on: West Marine

BEST FOR: Permanent mounting

WEIGHT: 15.2lbs

WATTS/AMPS: 90W/4.9A

SIZE: 33.7” x 26.5” x 1.0”

PROS: Sturdy frame can be mounted on gantry rails permanently, good power output and small enough to be mounted alongside an identical panel for double power, long warranty, reputable brand

CONS: Awkward to move about the deck so not ideal for portable panel, fairly heavy

NEWPOWA 150W

BEST FOR: Medium to large sailboats

WEIGHT: 24.4lbs

WATTS/AMPS: 150W/8.3A

SIZE: 58.4” x 26.6” x 1.2”

PROS: Great for permanent mounting, powerful and well-built,

CONS: Very heavy, only comes with 3ft of cable which may well be too short and require extension

SUAOKI SUNPOWER

BEST FOR: Smaller, lightweight sailboats

WEIGHT: 4.8lbs

WATTS/AMPS: 100W/5.6A

SIZE: 43.3” x 22.4” x 0.1”

PROS: 30-degree curve possible making this ideal for boat coach roofs, very thin makes for less dirt buildup and less wind resistance, good price for a powerful panel

CONS: Cable connections are on the top of the panel which may encourage corrosion and UV damage

ECO-WORTHY SEMI-FLEXIBLE

BEST FOR: Coach roofs and curved deck areas

WATTS/AMPS: 100W/5.5A

SIZE: 47.4” x 21.6” x 0.1”

PROS: Capable of a 30-degree curve making it suitable for coach roofs and curved decks, thin and durable construction

CONS: Connector on top allowing salt build-up and accidental damage

COMPARISON TABLE – THE BEST SOLAR PANELS FOR SAILBOATS 

How to choose the best solar panels for sailboats, 1. required energy.

Buying solar panels for your sailboat involves more than going over a few models at random. You need to know how much power you’ll need daily. Also, you need to determine whether you will rely solely on solar power or use the engine as well.

SOLAR AND ENGINE

Will you use solar power most of or all the time? If yes, then you will need higher power, larger or more solar panels. If you plan to use the engine more, then you won’t need as much solar power.

Your sailing goals come into play in this decision. If you want to cruise the intercoastal waterways, chances are you’ll be using your engine a lot. If you plan on cruising the Caribbean, you can often rely on good winds for sailing.

Once you’ve worked out how you plan on powering your sailboat – solar and engine, or just solar – you’ll need to work out your daily amp draw . If you’ll be running a fridge, freezer, water maker, VHF and SAT NAV all day long, you’re definitely going to need a lot of power!

It can be difficult to determine how many amps your sailboat will need, especially if you still don’t have all the electronics you plan to bring on board. Some products will give you an idea of their power draw in their technical specifications. For others that don’t provide that information, you may have to settle for an estimate.

Once you have an idea of your daily amp draw, then you can work out the solar output required to keep up with that power draw. But there are other considerations too, namely, actual output vs maximum output.

ACTUAL OUTPUT VS MAXIMUM OUTPUT

While a 90W solar panel might sound like it’ll give out 90W, remember that this is its maximum output. That is, it refers to a clean panel in full sunshine. It won’t be giving anywhere near that output on cloudy days. In the case of a fixed panel, ask yourself if the sail will be casting a shadow over it on one tack.

Unless you plan on running the engine to top up the batteries on cloudy days, you will find yourself needing enough solar panel output for these times. Make sure to also consider the times when your panels aren’t giving out their optimum performance.

TEMPERATURE CHANGES

If you’re starting in Nova Scotia, your fridge won’t take much power to keep it at a cool temperature. But, what happens when you sail south to go diving in Mexico ? Suddenly, the water temperature is higher and the fridge would have to work twice as hard to stay cool. While good insulation is a bonus on a sailboat, it’s important to remember that atmospheric changes like temperature may mean an increase (or decrease) in your power requirement.

ARE WE TALKING AMPS OR WATTS?

While you need to know how many amps your sailboat will draw on a daily basis, solar panels are sold by watts. There’s no need for that to be confusing though, as we’ve also provided the amps in the chart. You can read more about watts and amps to get a better understanding.

2. HOW MANY SOLAR PANELS DO YOU NEED?

Many sailboats have more than one solar panel. This means you won’t need to move the panels to follow the sun or as the boat shifts at anchor. Having multiple solar panels also allows you to have smaller panels, which tend to get in the way less. Your required power output can be divided among them as well.

If you need 200W a day, then you could have three 90W solar panels on different parts of the boat and be covered power-wise, even on different tacks.

How much space do you have on deck? Where you place your solar panels is very boat and sailor dependent. Day-sailing in hot places? Solar panels on the bimini rack are an easy solution. Long-distance cruising? You’ll need solar panels that are efficient yet out of the way to improve windward performance.

If you spend a large amount of time on board, your energy consumption will be higher. You’ll need your solar panels to be as efficient as possible. Many cruisers have panels on top of gantries on the stern to keep them in sunshine all the time. This is terrible for sailing performance, so you have to think about where you want to compromise. Don’t forget to consider the other on-deck items, such as your paddle board , as well.

Solar panels generally come in two types: mono- and multicrystalline and amorphous thin film silicone. However, all solar panels listed in this article will be mono- or multicrystalline as they are the most effective.

MONO- AND MULTI-CRYSTALLINE

Efficient and sturdy, these panels will probably make up your core solar panel collection. For everything on board like lights, fridge, radio and navigation electrics, mono-and multicrystalline are your best bets. They aren’t forgiving on cloudy days though, and even a shadow over the corner of a panel will pull down the output by a lot.

AMORPHOUS THIN FILM SILICONE

Not as efficient as crystalline panels, amorphous panels are cheaper and flexible. They’re good for trickle-charging batteries while the boat is left unattended.

Solar panels are expensive, but their prices have been dropping over the years. If you only use your sailboat for summer weekends, chances are you won’t need pricey, hyper-efficient panels. You just need enough to keep up with your power consumption for two days a week and let the trickle-charge solar panel do the rest.

Take your solar panel budget and split it between the number of solar panels you think you’ll need. Keep in mind though that you’ll most likely need to buy a charge controller as well.

For more of our top sailing gear recommendations, check out these popular buyer's guides:

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