In a few years windows in various office buildings will collect energy. The Danish company Photo Solar will start its production of  windows with built-in solar cells in 2010. This will allow to transform thousands of square meters of building surface across the country into power sources, writes Berlingske Tidende.

'The solar cells are laminated into the window. Our windows give a transparency of 50 per cent. In so doing, light will still be coming into the room," says development engineer at Photo Solar Søren Jensen.

A single copy of solar cell window can capture around 50 kW-hours of electricity per square meter in a year if it is located on a south faced front, explains Søren Jensen. In comparison, the market’s most common solar cells capture enough sunlight to produce approximately 100 kW-hours of electricity per square meter.

The price of Photo Solar’s new window will be about Eur 800 per square meter. The solar cells have an extraction effect of 5 per cent compared with the present best collectors that convert up to 20 per cent of the sunrays into electricity. But on the solar collectors it is not possible to create a transparent surface.