Photovoltaic Systems

Photovoltaic (PV) cells, often referred to simply as solar cells, directly convert light into electricity.  They do not, however, need direct sunlight to work - they can still generate electricity on a cloudy day.  A typical solar panel consists of an array of cells containing photovoltaic material.  Each cell is composed of thin semiconductor layers, such as silicon.  These layers are treated to form an electric field across the material - one side positive, the other negative.  Due to a process called the photoelectric effect, when photons strike the solar cells, electrons are knocked loose from their atoms.  By attaching electrical conductors to the positive and negative sides of the cells, an electric circuit is created which can then be utilised to power an appliance.  

After development, PV cells were most famously used to provide electricity for satellites but are now commonly used in many everyday applications such as: calculators, lights, pumping water, and recharging batteries.  These cells are available in a variety of shapes and colours, from the typical grey tiles most people are familiar with to transparent cells that may be used on conservatories and glass.  The unit of measurement used to represent the strength of a PV cell is known as a kilowatt peak (kWp) and is the amount of energy generated by the cell in full sunlight.  

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