Everything you need to know about yacht solar power

Marine solar panels are becoming more efficient and eco-friendly. Dennis O’Neill reports on the latest design advances

Keeping your batteries topped up without having to run the engine is a continuous challenge for cruising sailors, especially those who are highly conscious of their carbon footprint or just wanting to cruise ‘off grid’.

Solar panels have been a good option for sustainable sailing in sunny conditions for some time, being almost maintenance-free and, unlike wind generators, silent. However, maritime conditions are a harsh test for even the best of them due to the incessant exposure they face from saltwater spray and, ironically, ultraviolet (UV) energy.

Now, though, new solar panel technology coming over the horizon promises further improvements in both their efficiency and ease of use.

Silicon cells

Most solar panels use silicon-based photovoltaic cells, with the most efficient type within this class being monocrystalline cells, made from a single pure ingot of silicon. Polycrystalline silicon cells, made from multiple silicon crystals bonded together, perform almost as efficiently as monocrystalline cells but are less expensive to produce.

Ordinary photovoltaic cells, meanwhile, which are the most commonly used, are much cheaper, lighter, and easier to mount where structural flexibility is needed.

The downside, though, is that their intrinsic chemical materials tend to be more environmentally hazardous and difficult to recycle at their end-of-life.

Perovskite revolution

The new buzz of excitement in the solar panel sector is coming from the development of perovskite solar cells, which promise 50% more efficiency than conventional photovoltaic solar cells in converting sunlight into electricity. They also have the extraordinary potential of being used in a liquid form, such as paint, and even being printed onto compatible surfaces.

Researchers are now reported to be trialling spray-on perovskite solar cells that could be applied as a tint for windows. The production of perovskite solar cells is also less energy-intensive than conventional solar cells and can be achieved at room temperature using relatively abundant and cost-effective base materials.

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Rigid Solar panels

Rigid solar panels currently on the market remain the most efficient and well-suited for mounting on larger boats with flatter surfaces. However, they are heavier, more awkward to mount, and can’t be walked on, so unless you have a hard top or dedicated gantry aft, you’re better off choosing a more resilient semi-flexible option.

Rigid solar panels are covered with impact-resistant glass in a metal frame, and often require hardware to install. Over time, the hardware and frame can corrode in unforgiving marine conditions, so it’s important to choose one with added weather protection.

Flexible Solar panels

Flexible solar panels, meanwhile, have become increasingly popular with yacht owners due to their versatility and adaptability. While not yet as efficient as rigid panels, they do offer a more eco-friendly and cost-effective option as well as being thin, light, bendable, and easy to install or mounted on almost any surface. You can, for instance, attach flexible solar panels easily to soft biminis and even sails.

However, attaching them to flexing surfaces may cause physical strain on the internal cells, causing damage in the long run. They also tend to have efficiency levels below 20% (compared to just above 20% for rigid solar panels), so they require more physical space to produce similar amounts of output.

They are usually encased in plastic coverings to make them more impact-resistant, but the plastic can degrade due to salt and UV.

Semi-flexible Solar panels

These are ideal for curved boat surfaces. The plastic covering on semi-flexible panels makes them highly resistant to impact and weight, in case you accidentally step on them while moving around a swaying boat.

Kite concept

Sailing enthusiasts working at the German engineering firm FLIN, based in Kiel, have developed a new broad range of versatile marine solar panel systems.

Products within the range include: the FLINrail, a rigid solar panel that can be used while sailing by being hooked onto a boat’s guardrails; the FLINstripe, designed to be mounted along a boom’s lazy bag using Velcro strips; and the FLINkite, a thin lightweight design comprised of up to six square panels that can be hoisted on a halyard and then tilted towards the sun using simple guide lines.

One owner who cruises a 40ft Fountaine Pajot Lavezzi catamaran in European waters has found that his FLIN installations have benefitted his cruising enormously.

‘We have four FLINflex panels mounted permanently on our built-in bimini, which produces around 450 watts while we’re sailing,’ he explains. ‘Then, when we’re at anchor or in port we can also set our FLINkite, which has six panels, each of which can produce up to around 50 watts.

We have a solar controller for each of the two systems and I’m able to monitor how well the systems are generating power using an app on my smartphone. Overall, the FLIN panels cover all of our electricity requirements, including our fridge and electric windlass. We’ve even now treated ourselves to an electric kettle!’

Origami Inspiration

Another exciting and innovative concept comes from two highly experienced sailors, Kim-Joar Myklebust and Sara Plaga, based in Milan, Italy. Together, they have designed and begun producing an origami-style marine solar panel made of recycled carbon fibre.

‘The idea came out of frustration,’ explains Kim-Joar. ‘We had regular power shortages on our sailing trips, even after we’d installed a large and bulky solar system which couldn’t keep our boat’s batteries charged.

‘As a motorsport design engineer I saw how space satellites used large solar panels that folded outwards to increase the area exposed to the sun, so I started cutting and folding a piece of paper until I found a shape
I felt could work as a compact, fold-out solar panel on a boat.’

The couple’s firm, Levante, tested the effectiveness of their origami panels extensively aboard a 36ft cruising yacht, finding that their new product was 20% lighter than other foldable solar panels and 40% more compact, whilst producing only half of the CO2 footprint.

‘We’re determined to revolutionise the entire concept of marine solar panels,’ adds Sara. ‘You can use our origami solar panels in many different ways – just fold them up and use them on your boat, or at home, or anywhere you like.’

Solar panel maintenance

Solar panel efficiency is compromised by both salt water and long-term exposure to UV and high temperatures. Industry experts advise that good regular maintenance will improve a solar panel’s performance by around 15%.

You should clean solar panels early in the morning, while they are at their coolest, as cleaning them when they are warm or exposed to direct sunlight can cause internal thermal stresses. Always use distilled or de-ionized water to avoid the formation of mineral stains or deposits on the surface of the panels, and avoid using harsh chemicals or abrasive solvents that could scratch the photovoltaic cells.

Let the panels air dry or use soft cloths, and make sure no water residue is left. You should also check regularly for cracks, breaks or loose connections.

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