Solar photovoltaic (PV), or solar electric, panels generate electricity using the light energy from the sun.
PV panels produce energy from daylight, not direct sunlight, so they still produce electricity on cloudy or overcast days. The electrical energy produced is either used directly in the building, or exported to the electricity grid. When the PV system is not generating enough electricity – like at night time, electricity is drawn from the grid as normal.
Solar PV systems consist of two main components:
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PV panels - also known as modules, these contain a series of PV cells which convert light electriicty. To give a desired electrical output (measured in Watts) a number of panels are connected together to form a PV array.
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DC/AC Inverter - this converts the direct current (DC) electricity generated by the panels into alternating current (AC) electricity which matches the building's mains electrical grid supply. If the building is not connected to the national grid the inverter is usually replaced with a battery bank to store the electricity generated.
The "photovoltaic effect" is the basic physical process through which a PV cell converts sunlight into electricity. Sunlight is composed of photons, or particles of solar energy. When a photon is absorbed by a PV cell the energy of the photon is transferred to an electron in an atom of the cell (a semi conductor). With its newfound energy the electron is able to escape from its normal position associated with that atom to become part of the current in an electrical circuit.
PV systems are unique in that they can be mounted on buildings to produce electricity at the point of demand without any adverse environmental effects - no noise, no moving parts, no exhaust gases and no dangerous by-products.
Apart from reducing carbon emissions and electricity costs, our experience shows that installing a PV system has a wider effect on electricity usage in the building. As occupants are able to monitor what their solar electric systems produce, they normally find they start using less electricity because of their new awareness of the resources that they are using.
