Solar fabric to produce electricity

The expert: Alain Janet, President of Argo Navis Finance and Solar Cloth System, which produces thin solar film, and owner of UK Sailmakers France.

What changes will these “solar fabrics” bring?
Alain Janet: They’re a revolution! Silicon technology has progressed photovoltaics a great deal but is now reaching its limits. It can’t go much further in terms of performance. Currently, with our encapsulation technique, we have thinned our films down to 0.5 to 0.75 mm, with a mass of 210 grams per square metre. A traditional solar panel weighs 12 kilograms per square metre. What we have achieved is a kind of “rollable solar panel”. This is completely new. It will enable solar energy to be brought into places never envisaged before.
Further reading: Storing solar energy is easy!

16 flexible solar panels have been integrated into the main sail of the Arcona 380Z, which has an electric, reversible motor system: under sail, the movement of the boat turns the propeller, which powers a generator. © Jukka Pakarinen
Why start with sails?
Firstly, because sailing is our industry. Our expertise lies in encapsulated fibre technology. We have developed a patented technique for encapsulating solar film to harness energy, plus two other techniques. One contains prisms (and the other OLEDs, but that’s another story … ). They enable us to recover the light that falls on the fabric at a shallower angle and to refract it onto the sensitive surface. So the panel works in a vertical position. And a sail is a pretty tough testing ground! On the Route du rhum race, the boat encountered extremely difficult conditions – wind, rain, storms, etc. The sail was rolled up, unfurled, scraped against the deck … But the 16 panels (5 square metres in total) held firm. It was a perfect demonstration.Also, sailing is an excellent field of application. We’re working with a yacht maker that has a fully electric model, and our panels are a worthy addition to this. When the boat is under sail, the propeller powers a generator which also produces a current (and this only slows the boat down by 0.1 knots, or 0.2 kilometres per hour).
How does that work?These PV cells are known as CIGS because their semi-conductor material is composed of copper, indium, gallium and selenide. They are used in thin layers – thin enough to be mounted on a flexible base. Before preparation, the film weighs 125 grams per square metre. To create these patches, which can be applied to or integrated into sails (under the brand name PowerSail), the technique used is encapsulation, which is common in polyester sail making. The film can therefore also be embedded into fabric to create a “solar fabric” with multiple applications. With an output of 12 to 14 per cent, the power currently available is around 100 watts per square metre. The addition of a layer containing prisms enables output to be maintained when the sensors are not perpendicular to the sun’s rays. One such sail was originally fitted to the Swedish Arcona 380Z yacht, which has an electric motor system.

What applications do you anticipate for this “rollable solar panel”?There are many. The power is relatively low (although our sail does generate 1 kilowatt) but it is very well suited to anything itinerant and to isolated installations. It would work on any surface that protects against rain or sun – a swimming pool cover for instance. Drinking water reservoirs are another application – to prevent evaporation. These kinds of fabrics cost less than PV panels, and could easily be used in isolated villages if needed. In urban areas, flexible and even vertical surfaces such as supermarket roofs or shelters for pedestrians, bikes or cars could become electricity generators.It could also be used by walkers, and for any outdoor activities. We’re currently studying these types of applications. There is genuine demand, particularly for extending smartphone battery life.

A PowerSail with flexible panels being finished in the workshop. © Alain Janet
You talked about OLEDs. Why would you want to integrate these diodes into fabrics?This is one possibility we’re exploring. OLEDs (organic LEDs, that are much more efficient) can be attached to flexible surfaces. They could go on luminous fabrics and even large-scale displays. And you could even put advertising on scaffolding covers. This is just the beginning when it comes to solar films. The price keeps on falling and this will open up new applications…
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