Please head over to our updated Solar for Arduino guide for more information. 

Solar for Arduino Guide

We get a lot of questions about how to run an Arduino off of solar panels. We decided to do a bit of testing and came up with three pretty simple ways to run an Arduino even if you aren’t near your computer or an AC plug.

Direct to a Solar Panel – We plugged our 2 Watt, 6Volt panel into the Arduino’s 5.5mm x 2.1mm DC Jack via our 1 panel circuit box (don’t be mislead by the 18V in the title of the circuit box, if you connect a 6V panel, it is going to output 6V). On a hazy day and through a screen, it lowered the basic blink application. Of course, this will only work when there is sunlight and your application can work with extended downtime. The circuit box set has two outs so you can send power to another part of your application if needed. The panel is also available from Adafruit.

A 5Volt Battery with a USB Port – There are a number of battery packs out there with an integrated USB port. Our 3,000mAh V15 USB Battery Pack connects to the Arduino via a USB A/B Cable. It is also included with many of our portable solar chargers. The major downside is that there is a one hour shut-off in our battery if the load is drawing less than 50mA. This is great for preserving battery life in the pack but not great if you need to run the Arduino for over an hour. You can restart the battery by pressing the Power Button.

Solar & Battery Hybrid – We were pointed towards these Tenergy Lithium-Ion Cells (3.7V 2600mAh) and this smart battery case (puts two Li-Ion 3.7V cells in series) by office neighbors Breakfast NY. We connected three of our 10Volt panels in Parallel with our Generator circuit box (As an alternative, you could wire two of our 2.0 Watt, 6Volt panels in series to charge this configuration), connected the circuit box to the Arduino’s DC Jack, then connected the second out from the circuit box to the 2 Li-Ion cells.

The circuit box has a blocking diode which prevents power from draining from the batteries into the panel. When the sun goes down or is obscured by clouds, the batteries will kick in and provide power to the Arduino. When the sun is up, excess power goes into the batteries for later. Both the batteries and the battery case have built-in protections against overcharge and short circuit which simplifies the amount of supporting circuitry you need to do.