Here are some pics of my solar DHW heater. My solar collector is based on the design by Gary Reysa http://builditsolar.com/ I made some things a little differently. I used 20G steel studs for the sides, I used .030 aluminum for the absorber plate, and I installed the absorber plate with the copper tubing facing out. I used special solar selective coating collector paint form Dampny Co http://www.dampney.com/Products/Products.asp?ProductID=28 Instead of silicone for bonding the absorber to the copper tubing I used Permatex® Copper Spray-A-Gasket® Hi-Temp Adhesive Sealant. http://www.permatex.com/products/Au...r_Spray-A-Gasket_Hi-Temp_Adhesive_Sealant.htm I chose the Permatex because my absorber plates fit the copper tubing very tightly, I figured the copper sealer would give a bit better heat transfer; I did not think I needed the gap filling ability of silicone. The absorber plates were formed on a bending break; I designed and built the dies myself. I used a sheet of 1” poly iso insulation and strips of ½” polyiso under the absorber and tubing. A few weeks ago I did some testing of the panel, I used an insulated cooler holding 12 gl, the pump is a computer cooling pump running about 1.50gl/min. I started at 9:30AM with 60* water and by 3:30PM the water in the cooler was up to 165*, it was a sunny day with a temps in the 70’s. I was quite happy with the initial results. Not bad for a $200 collector. There is still a lot more work to be done, I plan to build another collector, get a differential controller, mount the collectors on the roof and tie them into the heat exchanger tank I am using for the wood stove water heater.