I'm building a small, portable, modular solar panel array to charge 5V power banks, phones, etc.

I got most of the electronics down, the Step-Up converter, by-pass diodes, blocking diodes, as well as JST connectors are somewhat in place, but now I'm struggling a bit in building an enclosure for them.

The idea is, the cover or case should be made from soft material, I was thinking Dacron backing, and using either Nylon or Polyurethane fabric as cover. But the tricky bit seems to be the cover for the active surface, that gets exposed to light. The problem is, using a material that doesn't impede the functionality of the panel too much. It doesn't have to be soft, as the panels aren't bendy themselves. I was thinking perspex (Plexi-Glass), but I'm not sure if that will filter out the wavelengths important to the panel.

There are these waterproof bags for tablets and smartphones available, they have a translucent front, which is soft and glued/welded to the rest of the plastic container. Unfortunately, I wasn't able to find out what sort of material that is (otherwise I'd have ordered a sample of it from AliExpress or something).

So, what sort of plastic should I use to cover the panels with?

I don't wan't to use glass. It's supposed to be carried either in a pocket or a backpack, so something that can shatter like glass would be too dangerous, obviously.

  • \$\begingroup\$ I'm not sure that glass is "obviously" too dangerous. iPhones and iPads are carried in backpacks and pockets all the time and they're covered with glass. Maybe you could look into Corning's Gorilla Glass or something like that since it may attenuate much less than plastic (especially over time). \$\endgroup\$ – John D Feb 6 '16 at 22:59
  • \$\begingroup\$ @JohnD that's because the phones have much more rigidity and the glass is encased with the rest of the product quite firmly. Even if the glass of smartphones or tables does shatter (which happens quite often), it's usually contained with the case, and that's not what I'm exactly able to do. Also Gorilla Glass in a custom size and for four panels would be way too expensive. \$\endgroup\$ – polemon Feb 6 '16 at 23:03
  • \$\begingroup\$ OK, the design is up to you, I could envision making it work but if it's not compatible with what you want to do then plastic sounds like the way to go. \$\endgroup\$ – John D Feb 6 '16 at 23:05

Most of the sun's energy is in the visible band, so anything that looks good to the eye will perform well. clear PMMA (perspex) or polycarbonate (Lexan) seem like suitable sheet materials.

  • \$\begingroup\$ Lexan is still rigid, right? is clear soft PVC OK, too? \$\endgroup\$ – polemon Feb 7 '16 at 0:15
  • \$\begingroup\$ thin lexan is as flexible as thick paper, how flexible are your solar cells? \$\endgroup\$ – Jasen Feb 7 '16 at 0:25
  • \$\begingroup\$ They aren't. The soft PVC would just be easier for me to cut and either sew or glue to the rest of the case. The panels themselves are about as rigid as a PCB. \$\endgroup\$ – polemon Feb 7 '16 at 1:17

First, determine the PV's spectral response by studying the data sheet.

Second, Google "Plastic spectral response" and find a matching material with low attenuation in the PV passband(s), or something completely transparent to the sun.

  • \$\begingroup\$ Finding a datasheet for the panels I have (ebay.com/itm/171356195881) seems to be quite difficult. It is encased in Polyethylene epoxy, don't know if that is indicative of something. \$\endgroup\$ – polemon Feb 6 '16 at 23:10
  • 3
    \$\begingroup\$ @polemon: CYA: No data sheet, no sale... If you know what it's encased in, then just find something that'll pass whatever passes through what it's encased in, yes? \$\endgroup\$ – EM Fields Feb 6 '16 at 23:17

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