How can I run the Pi on Solar Power?

Question

Has anyone successfully set up their Pi to run on solar power? If so, what would be the cheapest way to sensibly and reliably achieve this, using a combination of solar cells / batteries / voltage regulators?

Is it a case of just building panels that give the required current, regulating the voltage and supplying a battery backup, or is there something else I should be aware of?

Answer 1

There are a few things you need to be aware of if you want to build your own solar power supply.

The main thing is that the voltage output of solar cells can vary wildly based on the incident sunlight.

Simple unregulated solar panels sold as 'battery chargers' are often designed for deep-cycle 12v 'leisure' batteries, but can be measured at 18v open circuit in bright sunlight (even in the UK *8'). The internal resistance of the battery keeps that voltage down to the battery level, but without one the higher than nominal voltage could do damage to directly connected electronics if it isn't regulated.

As such, you should be looking at either regulating the solar panel or moderating it's output with a battery and ideally both. Using a battery also allows you to accumulate excess energy production and supply power when power from the solar panel dips, which means that you may be able to get away with a solar panel sized for your average power needs, not you maximum power needs.

If you want to keep the size of solar panel and battery to a minimum, you may want to calculate the total expected power load, average power generation throughout the year and battery capacity to get you through the nights and the winter months.

There is some excellent advice about solar charging in answers to my question over on electronics stack exchange, including information on how to calculate whether sunshine in your area is sufficient for your application for a given solar panel and battery combination, using location specific information from gaisma.

Answer 2

It might be worth looking into the iGo Solar Chargers, which have built in solar panels, voltage regulators, and battery backup. They will also most likely have the proper power connection for the Raspberry Pi.

Answer 3

You should not for example expose Raspberry Pi directly to sun as you can expect issues. UV radiation is not beneficial to electronics. Apart from that, I think you should be fine if you have battery backup and a quality regulator.

(I'm very sorry for editing this answer like this but I can't write a normal comment. I was just going to add that you can easily shield your electronics from UV radiation by putting it in an opaque container, a simple cardboard box would do, you could wrap it in construction paper, even transparent glass or plastic would filter out most UV light. You could then run the wiring from the solar panel to the Pi through a hole in your case. Please rewrite this in more acceptable manner, again, I'm sorry)

Answer 4

For a low cost solution take a look at http://www.cottonpickersplace.com/ and have a look at the Raspberry Pi thread where there is a working solar powered charger for sale from under £20

Answer 5

You might try a Joos Orange. It works well, but cannot power a Raspberry Pi continuously.