Photovoltaic cells (PV)
PV cells convert the sun's light energy into electricity in a process discovered by 19 year-old Edmund Becquerel in 1839. The name is made up of the word "photos" - the Greek term for light - and "volta" - named after Alessandro Volta, the founding father of the electrical age. Traditionally PV cells have been made of silicon, a semiconducting element found in sand. More recent PV cells use alternative materials that allow them to be thinner and more flexible. This enables them to be used in building facades rather than rigid panels on a roof. In parts of the world nearer the equator, hundreds of giant panels make up PV power plants that can generate tens or even hundreds of megawatts of power every hour.
Solar Thermal Panels
These panels absorb heat from the sun to heat water for use in kitchens and showers, or on a larger scale to heat swimming pools. They can use either 'flat plate' or 'evacuated tube' collectors.
The south-facing solar array at Beaufort Court innovatively combines both PV and solar thermal technologies. All of the 22 solar panels (170m2) generate hot water using flat plate collectors. The solar thermal array transfers heat from its collectors into copper water pipes. The heat can then be stored or used directly and the cooled water returned to the solar panel. The panel units are highly insulated with fibre glass, and encapsulated in a glass cover, enabling efficiencies of up to 70%. The flow temperature of the water can reach over 80°C in summer, and even in mid-winter as much as 35°C, warmer than a municipal swimming pool! The solar thermal array has a peak thermal output of approximately 100kW, and generates around 69MWh of heat every year.
7 panels (54m2) also generate electricity: they are hybrid PV Thermal (PVT) units, which were uniquely developed by ECN in the Netherlands and Zen Solar, incorporating Shell Solar PV polycrystalline silicon cells. The PVT array has an electrical capacity of 75W, with a peak output of 5.25kW. An optimal array of this capacity can generate more than 4.5MWh of electricity every year.