A collector field for drinking water heating is in the glare of the solar simulator. Picture: University of Stuttgart
Read aloud Stuttgart researchers put the largest solar simulator in Europe into operation. At the touch of a button, 14 powerful halogen lamps illuminate the interior of a slightly oversized garage. With the artificial sun, the engineers from the Institute of Thermodynamics and Heat Engineering at the University of Stuttgart want to test and further develop complete solar collector systems, regardless of external weather conditions. With the solar simulator, we want to extend the international lead of German research in regenerative energies, explains Institute Director Hans Müller-Steinhagen. For the products, on the other hand, things do not look quite so rosy: While German research is at its peak, the collectors for the house roof are mostly from the Far East. With the new solar simulator, companies can have their systems tested faster and more comprehensively, test new ideas and shorten product cycles. So far, the gloomy winter season limited the testing capacity in this country, says Müller-Steinhagen. Also, the engineers no longer have to wait for certain weather periods for exams in the outdoor test.

The 14 metal halide lamps emit a radiant power of up to 1500 watts per square meter (square meter). This is a bit more than the maximum solar radiation on the earth's surface of around 1000 watts / sqm. The light spectrum of the lamps comes very close to the sun, explains Harald Drück, head of the test center. Special filters additionally adjust the lamp emissions to the solar spectrum.

Since the headlamps produce a lot of heat, the researchers place a double-pane system in the beam path: Cold air flows through the gap between the glass panes and cools the radiant heat of the lamps away. The researchers therefore speak of examination conditions under a "cold sky".

The radiant power of the lamps can be controlled computer-controlled. "We can use it to simulate real weather conditions like clouds, " explains Müller-Steinhagen. The test field is slightly larger than ten square meters. This allows researchers to investigate entire collector systems with several collector modules, the associated control technology and the heat storage. The solar simulator costs about 1.2 million euros. The majority of the sum was contributed by the Federal Environment Ministry. display

Further information: Institute of Thermodynamics and Thermal Engineering Martin Schäfer (supported by the Competence Network Optical Technologies in Baden-Württemberg, Photonics BW)

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