Flat solar heat collector - is transparent and incorporates selectively blackened fluid for heat transfer

摘要

The flat solar heat collector is transparent and incorporates selectively blackened heat-transfer fluid. The blackening system has two transmission windows, one passing orange-red light with a wavelength of roughly 455 A, and the other blue light or roughly 680 A, so that green plants behind the absorber receive enough light to excite their photosynthetic systems, without appreciable reduction in the heat absorption of the photo-thermal part of the collector.