In the industry it is discussed whether concentrated solar energy solar mirrors made from tempered or annealed glass achieve a better overall performance.
According to calculations by DLR (German Aerospace Center) the increase in yield resulting from annealed parabolic mirrors over a period of 25 years amounts to more than seven million Euros. This is based on independent figures and on the company’s practical experience with more than seven million solar mirrors that have been installed in the field for 30 years already.
In the industry it is discussed whether concentrated solar energy solar mirrors made from tempered or annealed glass achieve a better overall performance. Manufacturers of tempered mirrors advertise lower costs for mirror replacement. This calculation fails to take account however of the higher plant yield that solar mirrors made of annealed glass achieve owing to their better precision collector interception.
The key parameters for the yield of a plant are the bending properties of the mirrors. The basis for assessing the bending properties of a solar mirror is the focus deviation (FDx). This measures the frequency distribution of the real focus deviation in transversal (x) direction of the reflected beam from the ideal focul line of the collector parabola. Consequently, the lower the FDx value, the higher the plant yield. According to the calculations of the DLR each millimetre of decreased scattering loss amounts to an additional plant yield of 11.25 million Euros