The year 2009 saw several breakthroughs in solar-energy technology, among them:

• England’s QuantaSol Ltd. announced in June that it had developed what is likely the most efficient single-junction solar cell ever manufactured. The device was independently tested by Fraunhofer ISE as achieving 28.3-per cent efficiency at greater than 500 suns. The technology combines several nanostructures, of two or more different alloys, to create synthetic crystals that overcome the problems associated with current solar cell designs and enhances the photovoltaic conversion efficiency.
• In May, Switzerland-based Oerlikon Solar, a supplier of thin-film silicon photovoltaic (PV) production equipment, said it had achieved a new record efficiency level of 11 per cent initial power conversion for commercial thin-film silicon PV modules. “This achievement … is another key milestone on our path to grid parity,” said CEO Jeannine Sargent. The company also set a  production cost target of $0.70 (US) per watt peak, and said it was on track to achieve that goal by the end of 2010.
• Donald Sadoway, a materials chemistry researcher at the Massachusetts Institute of Technology created a prototype liquid battery that could eventually “store enough electricity to allow cities to run on solar power at night,” according to the university’s Technology Review 10, which named the battery one of 10 emerging technologies with the greatest potential for changing how we live.
• Arizona-based First Solar in February announced that it had broken the $1 (US) per watt price barrier for the cost of manufacturing solar modules, achieving a price of 98 cents per watt. “This achievement marks a milestone in the solar industry’s evolution toward providing truly sustainable energy solutions,” said Mike Ahearn, CEO of First Solar. He added that clean-energy efforts by governments in Germany and other countries helped make the breakthrough possible.
• Early this year, T-Solar, a photovoltaics company based in Spain, began volume production of what it says are the world’s largest solar panels. With an area of 5.7m², the panels are designed for large-scale solar farms and — compared to smaller panels — can reduce installation costs by 20 per cent, the company said.
• In January, German researchers announced they had broken a new record for solar energy efficiency, converting a full 41.1 per cent of the power of incoming rays into electricity. The system, developed at the Fraunhofer Institute for Solar Energy Systems, concentrates incoming sunlight by a factor of 454, then focuses the beams onto tiny — 5 millimetres square — solar cells made of gallium indium phosphide and gallium indium arsenide on a germanium substrate. The result is a solar cell whose electrically active regions are free of defects and capable of record-high efficiencies. The Fraunhofer team said it had begun working with two German companies — Azur Space and Concentrix Solar GmbH — to “make this technology competitive as soon as possible.”