In the simplest of terms, solar panels work by converting sunlight into electrical energy. The basic element of a solar panel consists of a bonded pair of silicon wafers on a conductive backing, one called the ‘P’ layer and the other the ‘N’ layer. The photons of light interact with this PN substrate and a potential difference of approximately 0.6V is generated.
A typical solar panel comprises of 32 to 36 such elements electrically connected in series thereby producing a panel with an open circuit voltage of 18V to 22V. The silicon material used in the panel comes in three basic forms, monocrystalline silicon, polycrystalline silicon and amorphous silicon.
Mono-crystalline silicone is grown as one large crystal and subsequently cut into thin slices to form the individual cells. Panels made this way are a little more efficient, around 14-16%, but are also more expensive to produce. These panels usually comprise 34 to 36 elements producing 20V to 22V open circuit.
Polycrystalline silicon is cast in blocks and the final cut slices consists of many smaller crystals. Manufacturing costs are lower, therefore these panels are little cheaper to purchase. While the efficiency is a little lower, around 12-14%, the low angle light output can be higher, but they generally do not perform quite as well as monocrystalline types at higher panel temperatures.
Amorphous silicon panels are produced by a completely different and cheaper process by depositing a vaporised silicon directly on to a backing material. This results in a cheaper panel but the efficiency is half that of mono or polycrystalline types, around 6%. This means you need twice the panel surface area to achieve the same output. They do have one advantage however, the amorphous silicon can be applied to a flexible backing such as plastic or thin stainless steel to result in a flexible panel with the ability to be laid on a curved surface. However, these flexible panels usually have a poor Watt to Dollar ratio.