Scientists at Airlight Energy have joined IBM and the Swiss universities, ETH Zurich and Interstate University of Applied Sciences, to develop an affordable photovoltaic system that is capable of concentrating sunlight 2,000 times onto hundreds of one centimetre square PC cells – yielding high efficiency at low cost.
The system uses a large parabolic dish made from a multitude of mirror facets. The dish is attached to a tracking system that determines the best angle based on the position of the sun. Once aligned, the sun’s rays reflect off the mirror onto triple-junction PV chips. On average, each chip can produce 200 to 250 watts over a typical eight-hour day in a sunny region.
Each solar PV cell is cooled using technology developed by IBM for cooling supercomputers. Microchannels, only a few tens of micrometers in width, pipe coolant in and extract heat for heating buidings or other uses.
In the prototype system, water, heated to 90°C, will pass through a porous membrane distillation system where it will be vaporized and desalinated. The system could provide 30-40 litres of drinkable water per square metre. A large system could provide enough water for a small town.
The PV cells are about 30% efficient, while another 50% of the Sun's energy is captured as heat – making the entire system capable of using arond 80% of the solar energy falling on it.
The developers are targetting a cost of $250 per square metre – which is a third of the cost of comparable systems.