How Solar Panels Work

Each solar cell is small, only a few millimetres square, so many solar cells are electrically connected together to form a module. The cells are connected in series so that the module will have a higher voltage output, typically in the range of 0.5 to 1.5 Volts. A solar panel is then made up of an array of modules, connected either in series or parallel to achieve the desired maximum voltage and current ratings. The typical size for solar panels used for a home is about 1 m2. Finally, multiple panels are tied together to generate the amount of power your home requires.

There are two things that affect how much electricity your solar panel generates. The first is obviously the amount of solar energy incident on the panel itself. This is why the same size solar panel in Madrid will create 30% more electricity than one in London; the sunlight you receive is both stronger and more plentiful the closer you are to the equator. This is also why your solar panel will generate more electricity at midday than in the morning or late afternoon. The second thing that affects the electricity production is the efficiency of the solar panel itself. Most solar panels achieve between 7-17% efficiency in the conversion of solar energy to electricity.

There are three types of solar cells available for home solar panel systems. The first is monocrystalline and polycrystalline panels, made from cut slices of silicone crystal. These types of panels have traditionally had higher efficiencies, from 12-15%, so less space was needed for panels to achieve the necessary power output. The second type of solar cell is thin cell, made from amorphous silicone. Thin cell panels have only 7% efficiency and so need more roof space, but they are better in low light conditions such as foggy days than crystalline panels. The third type is a hybrid panel made up of both crystalline and amorphous silicon. Hybrid cells have very high efficiency, up to 17%, whilst still retaining the low light benefits of thin cell panels.