SPACE AGE TECHNOLOGY - Solar cells, also known as Photo Voltaic Cells, were rapidly developed to provide electrical energy for space missions. The beauty of solar cells is that provided the Sun shines, they keep on producing free electricity. Well, sort of free. Solar panels are still expensive to manufacture. It is the high purchase price and installation cost that effectively limits their use.
There are many types of solar cell. Polycrystaline (more than one crystal), monocrystaline and thin film. Monocrystaline is presently the most efficient at converting light energy into electricity. Sometimes as high as 20% but more usually 15%. A monocrystaline cell is made from a thin slice cut from a single crystal of silicon. A grid of metal is then embedded over the wafer ending in the contacts and other layers added. Thin film cells are plated onto a plate of glass. They are much cheaper to produce, but only around 5% efficient and heavy. Vehicle designers will normally want to capture as much energy as possible for a given area and weight.