HELSINKI (AP) — Michael Graetzel of Switzerland has won the euro800,000 ($960,000) international Millennium Technology Prize for inventing low-cost solar cells used in renewable energy, organizers said Wednesday.

The German-born chemist — director of the photonics and interfaces laboratory at Ecole Polytechnique de Lausanne, in Lausanne — was awarded the 2010 prize by the Technology Academy of Finland for his innovation, which led to the development of electricity-generating windows and mobile solar panels.

The academy described finding ways to replace the diminishing fossil fuel supply as one of mankind's greatest challenges, adding that the sun is "the most obvious energy source."

"The constraint of solar energy has traditionally been its price. Graetzel cells provide a more affordable way of harnessing solar energy," said Ainomaija Haarla, president of the academy. "Graetzel's innovation is likely to have an important role in low-cost, large-scale solutions for renewable energy."

It was the fourth time that Finland has awarded the biennial Millennium Technology Prize, which was launched by the government and industry in 2004. It is given for achievements in energy and the environment, communications and information, new materials and processes as well as health care and life sciences.

The previous winner, in 2008, was American Professor Robert Langer from MIT for developing bio-materials used in combatting cancer and heart disease.

Other winners include Japanese Professor Shuji Nakamura for inventions in laser technology and LED lighting, and Tim Berners-Lee, the MIT scientist credited with inventing the World Wide Web.