Economy Solar To Go

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PANEL DISCUSSION

In order to keep maintenance to a minimum, we elected to build our collector panels using commercially made aluminum frame sections, available from Solar Components Corporation, P.O. Box 237, Manchester, NH 03105. Each 13' 4" extrusion costs about $40, and it takes four to make the two 4' X 8' boxes used in this project. The EPDM rubber channel gaskets and the Kallwall Sun-Lite HP .040" polymer glazing we used are from the same source. The 1/8" hardboard backing, the 3/4" foil-faced isocyanurate insulation board, the 1/2" Celotex Tuff-R, and the high-temperature flat black paint, silicone sealant, and fastening hardware can be purchased locally.

The design of the absorber surfaces is critical to the success of the collectors. MOTHER research staffer Clarence Goosen carried out an extended test program to analyze airflow characteristics in a controlled chamber environment (see News from Mother for details). The partition arrangement used in the panels shown here netted a laudable 68% efficiency level, which can be explained by the fact that it creates a symmetrical turbulence throughout the chamber area.

To prevent rainwater from leaking into the storage area beneath the collector panels, we fastened an 8-1/2' section of flashing beneath a horizontal siding joint on the house and formed it over the upper edge of the collector frames. Weather stripping between the collector wall framing and the house siding discourages leaks at those junctures too.

Wiring between the limit switch, the blower motor, the junction box, and the thermostat (see the schematic) complete the collector project. The thermostat works just like a standard furnace unit, except that the collectormounted limit switch won't let it turn on the blower unless the air in the panel chambers is at 110°F or greater. At night, the return air register can be closed to prevent drafts . . . but this should never be done when the blower is operating, since such a restriction could overload the motor.

In the summer, when the collector is stagnant, greenhouse shade netting or some other type of cover should be placed over the panels to protect the glazing and absorbers from overheating. But in the winter, let the sun shine in . . . your $575 investment will return about 10,000 Btu per hour, under ideal conditions. And that will put a crimp in any greedy furnace's lifestyle.

Illustrations:

Collector Panels
Collector Framework Plan View
Collector Framework and Floor
Wiring Schematic & Window Plenum

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