Third generation photovoltaic solar cells are the way that are lighter in more ways than one.

Apart from being more efficient in translating sunlight into electricity, the German start-up company Heliatek (www.heliatek.com) says its photovoltaic modules, built into a film substrate, will weigh 500 grammes per square metre, compared to the present 20 kilogrammes per square metre.

The company, formed two years ago as a spin-out from the universities of Dresden and Ulm, has just raised Euro 18 million with which it plans to build a pilot production plant in Dresden in the east of Germany. The backers include Bosch and RWE Innogy Ventures

Alexander Flaig, Vice President of Corporate Research at Robert Bosch, said the technology has made progress since the formation of the company and the time had come to show just how cost-efficiently the cells can be manufactured under industrial conditions.