Most efficient single-junction solar cell ever

England-based QuantaSol Ltd. says it’s developed what it likely the most efficient single-junction solar cell ever manufactured.

QuantaSol, established in June 2007 as a spin-out of Imperial College London, is an independent designer and manufacturer of strain-balanced quantum-well solar cells.

Developed in just two years, QuantaSol’s new single-junction device has been independently tested by Fraunhofer ISE as achieving 28.3-per cent efficiency at greater than 500 suns.

“Our technology is the industry’s best kept secret,” said Kevin Arthur, CEO of QuantaSol. “This is the first time that anyone has successfully combined high efficiency with ease of manufacture, historically a bug-bear of the solar cell industry. We’re now gearing up to provide multi-junction cells of even higher efficiencies as early as Q1 2010.”

QuantaSol’s approach combines several nanostructures of two or more different alloys to obtain synthetic crystals that overcome the problems associated with current solar cell designs. It also greatly enhances the photovoltaic conversion efficiency, according to the firm.

The company, which has a development laboratory in Kingston-upon-Thames, Surrey, last week completed a £2 million second round of funding. It now plans to concentrate on cutting the cost of ownership of solar energy by moving to multi-junction devices.

Solar cell manufacturers need to find a crystalline semiconductor material that exhibits the optimum light absorption range, is a good absorber of solar radiation (silicon, for instance, is weak), has essentially the same lattice spacing of commercially available substrates like gallium arsenide or germanium, and can be deposited seamlessly on those substrates to form a unique artificial crystal with no defects or unwanted impurities, using commercially viable crystal-growth technologies. None of the known semiconductor compounds or alloys can meet all these conditions at the same time.

QuantaSol’s approach aims to overcome the problems currently associated with today’s solar cell designs and also to enhance the photovoltaic conversion efficiency.