Absorber Surface Durability Standard Testing

Solar absorbers, as a key component in solar thermal collectors, are in the focus of this paper. A well introduced durability testing method for the solar absorber is the testing procedure described in ISO 22975-3 [1]. This standard testing procedure is applicable to the determination of the long term behavior and service life of selective solar absorbers for use in vented flat plate solar collectors. Different samples of solar absorbers on aluminum and copper substrates are characterized before, during and after the accelerated ageing tests and outdoor exposure with various methods, including FT-IR spectroscopy and microscopic technologies like AFM microscopy to measure the degradation on different scales. It turned out, that the corresponding testing time of the procedure for high temperature test was less than in the standard ISO 22975-3. Therefore, the standard testing procedure is testing at higher thermal loads then the extreme test sites with high absorber temperature in constant stagnation mode.