We discovered that we had done a little of the math incorrectly. Elliot has now re-cut the ribs using the CNC laser cutter. (Yay for easy technology!)
I originally asserted that bare aluminum was specular enough for building a concentrating collector. I now think that is only partially true. Investigation with a laser pointer suggests that the "brush marks" on the surface as it came to us allow an estimated 50% of the energy to be perfectly reflected.
I have therefore been polishing our panels. This produces a mirror-like surface, but with "swirls". I've worked about an hour on each of three panels (about 2 square feet to a panel) and not started the fourth. I think with additional labor, or better equipment, such as a car buffer, a truly mirror-like surface can be achieved. (I'm just using a drill right now.)
Hopefully this weekend Elliot and I will get to do a true test.
