The scientists at the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg have achieved an efficiency of 36.7 percent, thereby beating the previous record of the US company Semprius, by 1.2 percentage points. The so called “Flatcon” concentrator module used by the ISE researchers consists of 52 solar cells, each just seven square millimetres in size.
Fresnel lenses built into the module capture the sunlight and conduct it to the tiny cells at 230 times its original intensity. The cells themselves are also record-breakers: they convert 44.7 percent of the light into electrical energy. This is possible because the cells consist of four levels, each optimised to use different wavelengths of light. The ISE scientists developed the cells in collaboration with experts from the Helmholtz Centre in Berlin, the French research institute CEA-Leti and the company Soitec Solar. The new module should enter the market within the next two years.
However, the technology is unsuited for use in Germany: it works only in regions with direct insolation, such as southern Europe, North Africa and large parts of the USA. In such places, concentrator modules have two major advantages over traditional silicon modules: they are almost twice as efficient and less temperature-sensitive, which means that their efficiency does not decline to the same extent in hot conditions. ISE expert Andreas Bett estimates that the new modules can produce electricity for eight cents per kilowatt-hour, enabling the generation costs of solar electricity to compete with those of electricity from coal and nuclear power.