Hi Dave
Keep us posted on your results.
What are you using for Glass?
I'm using 1/4" - 6mm plate. (I tried Lexin, "that sucked")
I'm going to try one with thermopane this year to find the better one.
Our bay window faces the winter sun. It is only thermopane (2 sealed panes "no" Agron gas). I paced a 6x6x1/4" 150x150x6mm plate of steel painted
flate black in the sunny window. I attached a thermo senser to the plate. house temp was 25c 75f the black plate reached a temp of 121 F / 40+c. out side temp
-20c "0" f... still lots of room to improvements. Solar has lots of protential, if the clouds stay away.
Also see, build it solar.com
Garry has lot of of test results and experments that have proven good