Cologne - Hail and lightning rain down, while temperatures up to 85 degrees Celsius prevail, as solar cells are tested at the world's largest and most modern facility in Cologne. Solar cells are big business across the world, but particularly in Germany and Japan. And here is where the world's top manufacturers come to have their products certified under the most extreme conditions.
"We are the leading force, and what we introduce in the way of safety ideas is often adopted by other countries," says Wilhelm Vaassen, head of the Testing Laboratory for Photo-Voltaics of the quasi-official German Technical Monitoring Association (TUEV).
There are only a handful of laboratories across the world that test solar modules - the others are in Japan, the United States, Italy and Spain.
"When it comes to solar cells, Germany is by far the largest market in the world," says Sebastian Fasbender of the industry's association in Berlin.
Japan is the next-largest market. Demand is growing strongly in both countries, with Japan now producing more solar modules than Germany.
Japanese companies like Sharp, Sanyo and Kyocera have become major players.
Around 70 per cent of all manufacturers have their solar modules tested for durability and efficiency in Cologne. The laboratory issues around 300 certificates a year, Vaassen says.
The modules are subjected to extreme conditions - heat, hail, extreme cold - with the tests extended over about six months.
"Around 30 per cent fail our laboratory tests," Vaassen says.
The TUEV group is expanding in Asia to maintain its position. "We go wherever the manufacturers are," he says.
The group has set up a facility in Yokohama in Japan and plans further sites in Shanghai in China, India and Taiwan next year.
"At least a third of the products in our laboratory here are solar modules from China," Vaassen says.
"Just like other beginners, the Chinese manufacturers have to do their homework, but they prove to be quick learners," he adds, noting that the demands on the European market are high.
Fasbender says the target markets for these products lie in Italy and Spain in Europe and increasingly in the United States.
The sector is experiencing boom conditions globally, with solar electricity and solar heating rising.
In Germany demand is set to grow from 4.8 billion euros (7.0 billion dollars)a year to around 8 billion euros in 2020.
Silicon solar cells currently dominate the market, although shortages mean that the sector is looking to alternatives such as so- called "thin film" cells based on cadmium and indium.
Fasbender believes that both will continue to exist side by side.
