Qualification of Collectors and Components by Exposure To Extreme Climatic Conditions
Abstract
Solar thermal collectors and the used materials have to withstand outdoor weathering for very long periods of time; usually more than 20 years are expected. How do they cope with snow, salty ambience, desert climate, sea climate or tropical humidity? The Fraunhofer-ISE has access to 5 outdoor exposure sites where samples have to stand extreme climates: high temperatures with high daily differences in the Negev desert at Israel, snow, wind, extreme UV-irradiation and frost in the German Alps, high humidity at warm temperatures at Indonesia and high temperatures, wind and salt at Gran Canaria. The test sites are presently used for the exposure of PV-modules and will be extended for the testing of solar collectors and samples of collector components like absorbers, glazing and reflectors. The main aim is not only to collect data about the stresses on the samples, but the detection of reliability problems caused by salty atmosphere, high humidity, high wind loads and high temperature cycling, too. These activities are carried out in the next years within the German project SPEEDCOLL in a cooperation of Fraunhofer ISE with ITW (University of Stuttgart) and a number of quality-conscious companies (see list in the acknowledgements). UV- and solar-irradiation, ambient- and sample-temperature, ambient humidity and wind speed is measured and collected at a central server in Germany. Results of the first 24 months are compared. This data is the base for the calculation of integral loads for the comparison of different climatic regions and for the development of test procedures. The load differences for the different sites and the resulting test conditions for solar collectors and their impact on accelerated service life testing are discussed. This is important because regions close to the sea are usually highly populated and therefore have high potentials for solar thermal installations and CO2 reductions.