I've got a 5v Peltier chip. What kind of and how many solar cells 4.5v 18mA do I need per 1 chip? I found these cells online on dealextreme, but there are also other different types. I'm lacking a basic knowledge in electronics, so I'd like to get an advise on how you make that math. Also if you can point to some quick online learning tutorial on that issue, it would be great. Thank you.

Update. Ok, I found online two links, the video is not very helpful because there is no explanation about what kind of solar cells and controller etc are needed, and the second one where the guy doesn't describe much about the 'solar' part of his hardware.

But please - if you are reading this - please add your valuable input!

Edit: The cooler is a 12 Vdc heater / cooler assembly utilizes a Peltier device to create heat on one side and cold on the other. Driven by a 40 mm square Peltier thermoelectric heat pump, it operates on 13 Vdc @ 5 Amps. Operating at 13 Vdc, we measured the hot side at 190 Deg. F and the cold side at 55 Deg F.

  • 2
    A single chip to build a refrigerator? Are you sure you're not better off buying some energy-efficient refrigerator and adding some solar panels to your roof? Why do you need a portable fridge? How portable really is a fridge anyway?
    – Earthliŋ
    Jun 8, 2013 at 17:07
  • Absolutely sure. A tiny refrigerator, like the commercial ones which can cool a small drink can. Sure it's only for studying purposes. Once I can make it, I guess there will no problem to extend it, right? Example: dx.com/p/usb-mini-cooling-fridge-7340
    – valk
    Jun 8, 2013 at 18:18
  • 3
    See What's needed to set up a personal solar power system? and Estimating the cost of solar panels and return time?. Once you've digested those, please update your question with something more specific, to enable us to get you the awesomest answer possible.
    – 410 gone
    Jun 8, 2013 at 21:11
  • To answer the question we'd need to know the exact part you have, and the exact panels.
    – Móż
    Aug 11, 2013 at 22:39
  • To clarify: you say you have a 5V peltier chip, but you link to a 13V one. If you have the chip out of one of those little USB can-coolers obviously it'll use less power (probably the 500mA USB limit @ 5V = 2.5W). Please edit to make it clear what you have. A part number off the cooler would be ideal.
    – Móż
    Aug 12, 2013 at 23:31

3 Answers 3


If I remember my high school tuition correctly, you need to put 4.5 volts through the chip and measure the current. 5 volts would be better if you can get panels that provide it, as the chip will likely function more efficiently at its designed voltage.

Essentially what you are measuring is the resistance of the chip. This could be done with a multimeter, but I'm not going to assume that the resistance of such a chip is independent of voltage, so therefore I'm suggesting you're better to measure the current at 4.5 volts. Rigging up 3 fresh AA sized batteries could be an option?

Once you know the current that flows through the chip at 4.5 volts, then you need to divide that value by 18mA if that's what your solar cells provide. Of course, when light on the cells is non-optimal (or when the cells have heated in the sun, which reduces their efficiency), the cells will give less than the desired current, so you may want to compensate for that with extra cells.

I'm no expert though, so you may like to double check this on electronics.stackexchange.com


Peltier coolers typically use quite a lot of power, and their performance is poor when underpowered (they often don't work at all, or act as heaters). Your second link above is to a cooler that uses 13 Vdc @ 5 Amps = 65Watts.

Your 4.5v 18mA cells put out 4.5 * 0.018 = 0.081 Watts each. In theory, if the panels were running at 100% of rated capacity and could be arranged to power that cooler directly, you'd need about 800 of them (65W/0.018W=802). More realistically, assume 80% efficiency in the electronics (PV controller, voltage converter) and cell output of 75% (typical peak performance) you'd need 802 panels / 0.8 / 0.75 = 1337 cells.

If instead you bought a single conventional 100W 12V panel you could use a simple linear regulator to run the peltier cooler. You'd be paying someone else to assemble and test the panel, but IMO that would be sensible - the chances of you successfully assembling 1300 components onto a sheet of glass are low.


I believe they are called zeerpots. terracotta "or other porous ceramic" pot with another identical but smaller pot inside, fill gap between pots with sand pour just enough water into sand to dampen it and throw damp towel over top inside cools quite nicely. With that in mind there is many ways of taking the idea and modding it to better suit your specific need

  • This is without electricity?
    – Earthliŋ
    May 17, 2016 at 14:10

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