I'm looking into the practicality of heating water with a flat plate solar collector. Money wise its the only RE project that is practical in my part of the country; the eastern extreme of Nebraska. At my parents house we've used recovered glass from doors to build solar air heating panels, but for this project I'm more keen on heating water. In my own personal location glass is not going to be practical due to the accessibility by the kids. Polycarbonate and acrylic materials both seem to offer a comparable solution.
From what I've read about polycarbonate materials it is not transparent to the infrared wavelengths. I have access to 16 ounce copper sheeting as a backplate, and infrared wavelengths are readily absorbed by copper. (Real world experience tells me its an excellent solar collector all by itself!) It sounds like blocking infrared wavelengths would thwart the use of copper in this respect, meaning it then would offer no benefit to me over a matte black aluminum backing. I am also concerned with the corrugated shape of affordable polycarbonate panels. Is it difficult to seal the innards off from outside air to keep them from getting dirty inside?
Acrylic on the other hand is transparent to infrared wavelengths of light. The price for .040 thickness sheets is very competitive with polycarbonate. From what I've heard online people seem to worry about the ability of acrylics to withstand the temperatures in a solar collector. The acrylic materials will handle plenty of heat (over 250ºF) before it begins to deform, so I'm not too concerned with that aspect of acrylic. I have no experience with manipulating acrylic material and was wondering how drillable and cuttable this material is, whereas I already know polycarbonate is very simple to work.
A copper backplate, while expensive, would appear to be ideal for flush mounting copper line with soft solder. I haven't read about anybody exceeding the melting point of 50/50 with their flat plate solar collectors. Is this going to be overkill over the simpler pex/aluminum fin arrangement?
With the lack of people using acrylics it makes me wonder if I'm missing something obvious with this material. Otherwise it looks like a pretty decent material that can be used around the kids.