US and Europe go head-to-head with solar efficiency records

Two teams of researchers on opposite sides of the Atlantic have this week staked claims for solar cell efficiency world records, each boasting they have recorded conversion efficiencies of over 23 per cent.

Earlier this week, Silicon Valley solar cell manufacturer SunPower claimed that it had broken the world record for a large area solar cell with a new 5in prototype cell, boasting a conversion efficiency of 23.4 per cent.

SunPower chief executive Tom Werner said that the improvement represented a "step function increase" compared to its current 22 per cent efficiency cells.

Bill Mulligan, vice president of technology and development at the company, predicted that the new cells would be commercially available in around two years, adding that the improvement represented a "key component of our plan to reduce system cost by 50 per cent by the year 2012".

The announcement was followed yesterday by claims from a team of European scientists from the Eindhoven University of Technology in the Netherlands and Germany's Fraunhofer Institute. They say that they have broken the efficiency record for crystalline silicon solar cells.

The scientists said that they had developed a technique of adding an ultra-thin aluminium oxide layer at the front of a crystalline silicon solar cell, resulting in an increase in conversion efficiency from 21.9 per cent to 23.2 per cent.

Although this may appear modest, the scientists claimed it can enable solar cell manufacturers to "greatly increase" the performance of their products because the costs of applying the thin layer of aluminium oxide are relatively low.

They added that a number of solar cell manufacturers have already shown interest in the approach, which works because the layer has an unprecedented level of built-in negative charges, through which the normally significant energy losses at the surface are almost entirely eliminated.

"Within 10 to 15 years the price of electricity generated by solar cells is expected to be comparable to that of 'conventional' electricity from fossil fuels," the researchers stated. "This technology breakthrough now brings the industrial application of this type of high-efficiency solar cell closer."

A spokesman for the university said that there were currently 30 different types of solar cells and the world record claim was made for just one type, meaning there was no contradiction between the scientists' world record claims and those of SunPower.

A version of this story first appeared at vnunet.com