Solar air collector - covering window?
I built a collector that I am putting inside my very large window facing south-west. The room naturally warms up when it is sunny, so I wanted to capture that sun exposure and produce pure heat. I'm not heating the house during the day, so the temperature goes down to 15 degrees Celsius. The air coming out of my collector is about 24-25 degrees Celsius. It seems effective. However, I just stumbled across this site: https://rimstar.org/renewnrg/window_...er_furnace.htm and basically, according to the author, there would be a net zero benefit to capturing the sun's energy through a window.
I imagine that the benefits are much smaller because the double-pane glass prevents some of the sun rays from reaching inside the house. However, I would assume that the difference in temperature with the collector does somewhat prove it is effective. What do you guys think?
Thanks for the help!