Cool Earth Solar secures $21m backing for solar "balloons" technology

Cool Earth Solar has announced that it has bagged $21 million of Series A funding to support its solar concentrator photovoltaic concept.

The Livermore, California-based company has developed a series of inflatable balloons designed to reflect and concentrate solar rays in a process that it says will drastically reduce the cost of solar energy. The balloons, measuring 2 metres across and designed to be strung across wide areas between poles, use a thin plastic mirrored film to reflect rays into a solar concentrator.

The mirrored film, which maintains its shape thanks to the curve of the inflated balloon, is 400 times cheaper than traditional aluminium mirrors, the company said, adding that the energy produced can be 25 times cheaper than that created by traditional solar arrays.

Another advantage of the balloons is that because they are strung high in the air, they only shade 10 per cent of the ground beneath, making it suitable for use in farming or ranching environments.

Cool Earth Solar, which develops its own power plants rather than selling the balloons to third parties, has said that it could achieve power costs of 29c per watt in 2009.

Cool Earth Solar is not the only company trying to concentrate solar energy to increase efficiency. SolFocus, which uses mirrors to focus the sun's rays onto a high-efficiency solar cell, completed funding rounds totalling $63.6m last year. Meanwhile, Santa Clara-based SV Solar, which secured $10.2 m in funding last summer, says that its first module will collect the same power with half the material of a conventional solar cell. Fremont, California-based Solaria also received $50m in series C funding last year.