Might I say that my design needs some refinement.
It's detailed in there fairly well, though the page needs an update. I'm at college, and only have second-hand reports of my second prototype back home - the "future revision" I spoke of.
The second revision ditched the wooden dowels in favor of aluminum ones. I also used Devcon Metal Welder epoxy, which is supposed to stick to aluminum and polycarbonte very well. My design's weakness is the corners. I would have liked a single piece to go over each corner, but I couldn't find anything suitable. My "solution" was 3 separate pieces over each corner, and covered it with Goop contact cement. It held up ok in the summer heat (yeah, this thing was put outside some time ago) as well as a few stays in a freezer, without breaking a seal.
But, after maybe a few weeks outside, something broke, and it started getting condensation. I know there are some people here using ventilated panels, but that still makes me wary. The professional panels appear to go to great lengths to seal their panels. So there must be good reason for that. Sealing something from nature is quite diffcult - nature is pretty harsh. Temperatures below 0F one part of the year (lower air pressure inside the panel) to 100F in the summer, and even hotter inside the panels, which makes them want to burst. Add in the effects of ultraviolet radiation, rain, snow, hail, and wind....weathering is pretty harsh.
And I know, from both reading and from experience, that solar cells do not like moisture. The silkscreen lines on the front will start to peel away, which will reduce output.
When I get home for Thanksgiving, I'll have a look at my solar panel and see what went wrong.
Ideally, and I just thought of this, the corners would have their reinforcement done from the inside as well as the outside. This would protect against bursting pressure in high heat, and from crushing pressure in cold weather. The pressure inside got very high in summer sunlight, with the inside of the panel well over 140 degrees Fahrenheit. The polycarbonate front bulged out considerably, and was not easily pressed back down.
Bear in mind too, this was only a small prototype panel. Constructing a full-size panel would be somewhat expensive, (though cheaper than a professional panel) assuming new material was used - aluminum backing and UV-resistant polycarbonate front - and it would be fairly difficult to assemble it quickly and accurately, before the epoxy set.
Why all the effort to make such a robust panel? First, quick explanations - I chose aluminum because it resists weathering naturally. Polycarbonate is impact resistant, quite transparent, and can be treated to withstand UV radiation. I wanted it durable, because what's the point of saving 50% on the cost of a professional panel, when the homemade panel might only last a year, whereas the professional panels have 10-year warranties on parts (and 25-year warranties on output)?
I'd love to give my panel one last prototype, but that's going to be quite some time off. It looks like I'll be in college about 3.5 years yet, so that's where all my time and money's going to have to go.
