Photovoltaic solar panels convert solar radiation to electricity.

When the solar panels are exposed to sunlight, they convert 5-17% of solar energy into electricity. The exact percentage depends on the technology used. There are three solar panel cell technologies: monocrystalline, polycrystalline, and amorphous solar cells. The latter have lower performance but cost less. The choice of PV type is a function of power need, available space and budget. The photovoltaics can be placed on land, roofs (flat and sloping) or on buildings' facades.

A photovoltaic installation can be a standalone system that covers the entire energy needs of a building. For continuous service, the facility must include a storage unit (batteries) and an energy management unit.

Alternatively, PV installation can be used in conjunction with the grid network. All produced electricity is sent to the grid even if the installation is on a house's roof or facade. The house always gets its electricity from the grid.

In some cases, solar panels are used to provide reserve electricity (ie uninterrupted supply systems - UPS). In this case, the system is connected to the grid, but has also batteries (plus all the necessary electronics) to cover power needs in case of power cuts.

1 kilowatt (kW) of installed solar power produces an average of 1.200-1.500 kWh per year and saves on average 1450 kg of carbon dioxide emissions each year.

Photovoltaics guarantee:

• zero pollution
• quiet operation
• reliability and long life (of up to 30 years)
• independence from the supply of fuel to remote areas
• scalability as needed
• minimal maintenance

Sources: http://www.helapco.gr , http://www.greenpeace.org