Solar Energy Transmission Through Two Transparent Covers
ABSTRACT WE present a method to calculate the solar trans-mittance of solar collector cover systems that employ one or two covers. This method is based on theoretical optics of partially transparent materials. Comparison with experimental results shows the method to be accurate for most materials, including a corrugated glazing. The solar transmittance of nonhomogeneous, translucent materials is usually lower than predicted by this theoretical procedure. Since transparent materials transmit diffuse and direct sunlight at different rates, a method is included to calculate the direct and diffuse radiation on a surface of any orientation given hourly total horizontal insolation. We also include experimental measurements of the effect of a significant dust ac-cumulation on the transmittance of one and two sheets of Dupont Tedlar.