A TRACKING SOLAR CONCENTRATOR
Each of the 116 12" x 12" mirrors will be cemented into a spring clip which is in turn attached to the studs protruding from the array frame. Spring clips may be made from a number materials, each with its own advantages. In selecting your material, consider cost, weight, strength, springiness and maintenance. We chose to use .040" hard aluminum. It is light, has suitable mechanical characteristics and most important, it requires no painting. Periodic cleaning and painting of these would be a miserable chore that we can do without. The mirrors are simply mirror tiles available at most "home supply" stores. They are a very popular item for interior dec- orating. We use them without treatment, simply cementing them into the spring clips with a bead of silicon sealer. At this time, we'll also mount the outriggers that were built earlier.
Failure of the mirrors brought about the final shutdown after seven years of service. The reflective (silver) backing peeled off, starting at the mirrors edge. A few that failed early were replaced with a bead of silicon sealer added all the way around the edge and this did seem to extend the life.
The mirrors weigh about 145 pounds, the aluminum clips about 28 pounds, and the outriggers another 35 pounds. Consider this, if you have elected to not mount the array on the hub yet.
MIRROR INSTALLATION - MAJOR MATERIAL LIST
- mirror tiles, 12" x 12" x 3/32" 116 each (601)
- spring clips, drilled & bent per figure 23. 116 each (602)
- silicon sealer, 2 caulk gun size tubes
MIRROR INSTALLATION- ASSEMBLY
Refer to figure 7 and mount the outriggers (003) & (009) that you previously assembled. Weld them in place.
Drill a 1/4" hole through the center of the 116 4" x 15" pieces of sheet metal (602). Stack up a number of them and drill all at once so that only the top and bottom ones will need to be de-burred. Bend according to figure 23 . If you're using the hard aluminum make a gentle radius bend to avoid cracking it. It doesn't take much to hold the mirrors so don't overdo it. Before you mount the clips, I recommend taking a few 1/4" bolts and nuts and destroying them in the course of learning.
Mount a bolt in your vise and turn a nut right on up to the shank with a torque wrench. It strips the threads real easy, doesn't it?. Try a couple more noting the torque limits. Now assemble another bolt & nut but don't ruin it. Stack up the washers and clip, holding the first nut