Passive Dehydration System Mail

Aluminum Back Figure B

available at lumber yards has many brand names, such as Tuff R and Thermax. Both of these brand names are fiberglass reinforced polyisocyanurate with an R value of 7.2 per inch, but the Tuff R doesn't retard flame spread as well as the Thermax. This material can usually be identified in new construction by the silver aluminum covering on both sides of the 4x8 sheets. It comes in common thickness of 3/4 and 1 inch, but the lumber yard might have sheets 4 inches thick that were used for protection during shipping. Just ask! A major problem with polyisocyanurate is that it degrades from ultra violet rays from the sun. It has to be protected, usually by enclosing it inside the aluminum frame of the panel.

If you're going to use batts of fiberglass insulation, be sure to use low-binder fiberglass, such as used in ovens, so it will not outgas or deteriorate with the heat. See Figure E. Fiberglass doesn't keep the wind from penetrating the interior of the solar panel as well as the rigid insulation described above, nor does it offer the Rvalue.

Glazing

Glazing of a greenhouse or solar panel refers to the clear covering on the front of the panel. For an excellent article on glazing, see HP#30, page 28. In the case of a solar panel, if the collector plate is constructed of the best materials, (i.e., copper with black chrome selective surface) only a single layer, or lite, is required because an increase of R value is not beneficial. A few companies did use double insulated glass because of the heat loss — heat radiated off the selective black chrome surface through just one lite. But the amount of sunlight that got through the two layers of glass was less than with one lite.

Collector Plate

This is one part of the solar panel that is the easiest for the DIY person to become totally frustrated with! If you are constructing an air panel, construction of the plate involves building an air chamber that is airtight. This can be done with nothing more than a rivet gun or screws and an excellent grade of pure silicon caulk. Just remember the temperature inside can vary from 20°F below to 300°F above zero. See Figures C and D on right.

Construction of a liquid plate requires soldering and brazing of copper pipe and physically bonding the copper pipes to the copper sheet. The more physical contact between the sheet and the pipes, the more heat transfer to the fluid moving through the pipes. See Figure E bottom right. The other frustration is that normal black paint will outgas, or boil, off the metal under the extreme heat. Also, under normal cases,

Back view—Air Solar Collector Panel

6 inch hole

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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