Solar Panel Electricity

How does solar power work?


Solar cells exploit the photovoltaic (PV) effect - the property of certain materials to transform light (sunlight in the case of solar cells) into electricity. Although much research is currently being conducted into using other organic and inorganic materials, commercial solar cells are currently almost exclusively made from silicon. Cells are typically made from monocrystalline or polycrystalline silicon ingots, measure 10cm x 10cm, and are capable of generating 0.5 to 0.6V. Individual cells are wired together in series to make solar panels; a typical panel contains 36 individual cells and can generate around 20V.

Amorphous cells are relatively new and consist of a thin film of silicon which is deposited onto a substrate of some other material. This is a lower-cost way of producing solar cells, but they are also less efficient at converting light to electricity, and are typically used for small applications like calculators or garden lamps.

Wikipedia provides the following simple explanation of the physics behind the technology:
  1. Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
  2. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction. Complementary positive charges, called holes, are also created and flow in the opposite direction to the electrons.
  3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.
(The same article also provides a much more detailed explanation, for those interested).

Solar power systems

Solar panels by themselves are of limited use since they can only be used when the sun is shining; a solar power installation normally comprises a few other components too:
  • Inverter - converts the DC electric current produced by the solar panel array into AC (the same as mains power) so it can be used with household appliances.
  • Battery - to store excess electricity for later use.
  • Meter - allows you to monitor your system's performance, and importantly makes it possible to sell excess power back to the grid.