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Solar energy is light or heat that comes from the sun. Solar power is generated by collecting this energy and converting it into usable electricity. It is clean, pollution free and, in practical terms, inexhaustible.
There are various types of solar power systems for your home (often called PV or photovoltaic systems). They generally consist of solar panels, an inverter and a metering system. Solar power systems (photovoltaics) are often confused with solar thermal technology, which is usually used for water heating (solar hot water).
Most solar power systems use PV modules installed on a rooftop to create and collect energy from sunlight. An inverter converts the direct current (DC) generated by solar panels into alternating current (AC), the form of electricity conventionally used in homes and businesses.
The system is usually connected through a meter to the main electricity network, which allows the household to use traditional electricity when the sun isn’t shining and sell any excess power back to the grid when it is.
Solar panels:
Solar cells are produced from thin wafers of silicon. When light falls on the cells an electric current is produced. A collection of solar cells connected together forms a module.
Most homes or commercial buildings will need around 10 square metres of unshaded, north-facing roof space to mount the modules for a 1kW solar system. Ideally the modules should be tilted towards the sun at around 30 degrees to maximise the solar collection. If the roof’s slope is not at the right pitch, a good designer can create a special mounting frame for the modules.
Cloud cover and shading can dramatically reduce a solar power system’s output.
Inverters:
You will need an inverter to convert the direct current (DC) power collected by the solar panels into power for your home, or power to send back to the electricity grid. It can be placed inside or outside your home, but should be well ventilated and protected from the elements.
Meters and the grid:
You still need to be connected to the electricity grid to ensure that you have electricity at night-time when no solar energy is being collected. A meter may also enable you to sell back excess electricity.
For safety reasons, when your electricity supply from the grid is interrupted, your solar PV system must automatically and immediately turn off. It is possible to have a system that will provide emergency electricity when the grid goes down, with the use of a suitable inverter and battery bank, however this can be expensive.
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