greateyes GmbH

“It was a healthy level of scientific naiveté,” laughs Martin Regehly, managing director of greateyes GmbH in Adlershof, when asked what moved him to doubt the prevailing doctrine and pursue the development of “LumiSolarCell” together with his colleagues and a team at the Humboldt-Universität zu Berlin. “LumiSolarCell” is a procedure that allows his company to test the quality of solar cells at a very early stage of production – a technique that was only possible in limited form until now. Indeed, the new High-Power LED-Based Photoluminescence Inspection Procedure for Solar Cells and Wafers was so groundbreaking that it earned greateyes GmbH the 2010 Berlin Brandenburg Innovation Award.

Camera Reveals Solar Cell Damage

Quality testing on solar cells and modules has changed gradually over the past several years. Initially, companies would measure how much electricity a finished solar module produced. Three or four years ago, they started using so-called electroluminescence to perform their testing. In this process, electricity causes the silicon solar cell or module to emit a weak level of radiation undetectable to the human eye. A highly sensitive CCD camera – the building of which is the actual focus of the work of greateyes GmbH – records the radiation. The images produced make it possible to identify whether a solar cell has, for example, tears or contaminated spots. greateyes was one of the first companies to offer a corresponding system for this procedure.

Detecting Flaws in the Early Stages of Production

As Martin Regehly notes, however, this system had a key disadvantage:  “Here, too, manufacturers and retailers could detect mistakes only after the solar cells were already produced, because only then was it possible to connect electricity to the cells.” And this is exactly why greateyes GmbH developed its new photo luminescence inspection system, which allows manufacturers to inspect the solar cells for damages in the early stages – and then to optimize production accordingly. This approach involves the use of an intensive light source that stimulates the matter, which in turn generates radiation, i.e. so-called “photo luminescence.”

Globally Unique Use of LED Light Sources

The internationally unique characteristic of the greateyes system is its use of a LED light source. Until now, lasers were used exclusively to measure photoluminescence. Indeed, common knowledge had it that it would only work with lasers. But greateyes managing director Martin Regehly saw it differently and decided to give high-power LEDs a try. They are cheaper and less dangerous to the eyes than lasers. Regehly presented his ideas to Professor Ralf Reulke at the Department of Computer Vision at Humboldt-Universität zu Berlin and convinced him to undertake a joint project. Professor Reulke and his team performed several trials with LEDs – and their experiments worked.