Generating electricity from sunlight while travelling is a tempting idea. However, to cover the energy requirements of an average yacht, a solar cell area of several square metres is required. This can hardly be achieved without an elaborate equipment rack at the stern, especially as conventional energy converters are sensitive to shading.
The French branch of UK Halsey Sails has now developed a system for integrating solar cells directly into the mainsail. Thin-film modules with an efficiency of 14 per cent are used. These are printed on a film just 65 micrometres thick and are designed to be so flexible that the sails can be rolled or folded as usual. To improve the durability of the cells, they are also only installed in the lower section of the mainsail. There is sufficient surface area available there, but the loads when tacking are comparatively low.
The solar cells themselves come from the USA and are designed to deliver a very high power yield even in indirect light, which is common in sails. The cells can either be integrated directly into the company's own titanium membrane sails or retrofitted to existing sails. Biminis or sprayhoods can also be retrofitted with the solar cells. In the case of membrane sails, the cabling takes place directly within the laminate. On retrofitted sails, the cables are protected by Dacron strips.
The system is currently being tested on a Dehler 39, among others. According to Alain Janet, head of UK Sails France, the technology should be ready for series production by the summer. It will be marketed under the name Solarcloth system marketed and should be UK Sails Lofts will be available. The surcharge for the solar equipment has not yet been determined, but is likely to be in the region of 4500 euros for retrofit systems with two square metres of cells, cabling and charge controller. Membrane sails with integrated cells are likely to be somewhat cheaper.
