A TRACKING SOLAR CONCENTRATOR
With the edge welding complete, the stay bolts & nuts can be welded for a water tight seal. This will warp the faces somewhat, but they can't go very far. Pressure test it with about 30 pounds of air, about all you want to pump on a simple hand tire pump, under water for leaks.
- WARNING! Don't use a compressor- You're likely to have a very deadly or maiming rupture
Weld on four mounting ears, made from scrap strap or angle stock as shown in the figure 28. Make sure they line up with the holes in the collector frame (011) figure 10.
Clean and paint your collector with the high temperature silicone base paint that we used on the test collector earlier. This paint reduces reflection and increases the energy absorption while protecting the collector from rust. It should survive until you accidently run the collector dry. When this happens, you'll have to wire brush the white residue off and repaint it. We have not found a readily available dull black coating that will survive the high temperatures of a dry run. Even acetylene smoke sluffed off.
Fabricate a 20" x 20" box 5" deep (705), of light gauge sheet metal, clearly visible in the cover photo, to mount the collector in. Its sole purpose is to protect the one inch layer of fiberglass insulation from wind and storm. Aluminum will survive because it is not broadside to the concentrated sunlight as the collector is. Line the box with one inch duct insulation- if you can't find it, use scraps of fiberglass backed/vinyl skinned ceiling tile. Mount the collector, box and insulation with 1/4" threaded rods or spacers so that the insulation is not compressed.
An area you may find interesting to explore is the addition of glazing over the collector. We made some tests and gained about 15% recovery, up to about 23,000 total Btu/hr. The glass, spaced one inch from the collector and being of no special quality shattered as we went for higher fluid temperatures. It may be very difficult to find material that will survive a dry run. Such materials certainly do not meet the criteria for this "common material" project, and further research was abandoned.
