When you mention the words “solar panel” many people think of the rigid glass covered panels that you usually see mounted on the roof. That sort of panel, usually just over two feet wide and four or five feet long, is the main type that is used for current solar power installations.
Not so many people know about the flexible options for generating solar power. Firstly, for the home solar power system, you can buy solar shingles, which replace ordinary roofing shingles. These come rolled up, and unroll to about seven feet long. They can be nailed in place, and the wiring is passed through holes in the roof. They are made using a thin layer of amorphous silicon – that is a flexible form of silicon, unlike the crystal silicon used in the rigid panels. Because of their form, they are about half as efficient as regular panels in converting sunlight to electricity, so twice the roof area is required for a particular output.
A more common form of flexible solar panel is used in a unit to charge battery powered devices, such as cellphones and PDAs. This type of panel can be folded or rolled up for travel, then unrolled and used as needed. A thin film of silicon is deposited on a flexible plastic, which forms the active solar energy converter, and this is then wired to serve whatever function is required. The connections may include special plugs for cellphones, or a battery box for charging AA batteries. There are varieties of flexible solar panels to suit most battery powered applications, including MP3 and DVD players.
Finally, there’s been extensive research and experimentation in the production of solar cells from different materials in recent years, partly because there is a world shortage of silicon, the main constituent of conventional photovoltaic cells, which is predicted to last until 2010.
Researchers in New Jersey are developing an “organic” coating that may be painted or printed on to flexible plastic sheets or other surfaces. Organic means that it is carbon based (just as people and animals, organic beings, are carbon based). It is hoped that the technology will lead to a cost reduction for solar cells. A similar idea is being pursued in Wales, where a firm called G24i has developed a dye-sensitized solar cell, which is produced on a large roll of foil, and is providing it for mobile phones in the developing world.