The $120 DIY 12v Solar Power System




Here's my guide for a simple off-the-shelf and off-grid solar power system you can build yourself. I use this to power a Raspberry Pi that monitors my chicken coop, but you can use this in your RV, shed, garage, pool house, you name it.

What do you want to power? How many devices, how much current do they draw? The size of your solar panel and battery will determine that and can be upsized if needed. This guide will only cover what I need for my system.

Step 1: Parts

Here's my build list, straight from Amazon. Search for the names and you should come up the exact same items. I've seen lots of similar things from Harbor Freight and other places too.

  • instapark 30w solar panel with charge controller
  • DROK Parallel To Dual USB Adapter 12V to 5V/1A
  • 12v wire
  • 12v battery
  • (optional) 8 way terminal block
  • (optional) Insulated Car Battery Clips Alligator Clamps

There are many varieties of solar panels, make sure the model you purchase comes with the charge controller. The variety I selected comes with small alligator clips to connect to the battery. If your battery has flat terminals it'll work great, otherwise you may need to buy additional clips.

My goal was to run a computer off 5v USB power, so I chose a 12v->5v/1A transformer. If you need more or less power, select a different transformer. If you want to power 12v stuff YOU DON"T NEED THE TRANSFORMER.

Buy new wire if you don't have any, otherwise feel free to recycle what you have as long as it's rated for 12v. Color matters, it will help down the road if you use RED for + and BLACK for -. Think about what you want to power, where it will be installed, and choose length accordingly.

Any 12v battery will do, old, new, however IT MUST WORK and be able to HOLD A CHARGE. Get a new one for your car, and use the old one. I bought a new tractor battery because it had a smaller footprint and smaller terminals.

How many things do you want to power? If you have a bunch of stuff you want to power up you will need to use a terminal block to safely distribute power. I wanted 12v AND 5v power, so I used a terminal block to wire it up. I The model of transformer I chose specifically because comes with 2 USB connections for easy 5v computer connections.

Step 2: Wiring

The solar panel you bought came with something called Solar Charge Controller. It does all the heavy lifting and provides the hookups you need. Connect the battery to the controller, connect the positive and negative leads from the solar panel to the controller, then connect your transformer to the load terminals.

The solar panel charge controller will come with a build sheet that has a wiring diagram and installation details. Read and use them, my instructions are very generic and are good enough to get you started.

*Extra bonus* - if you plan on hooking up more than one or two items to the load terminals on the solar charge controller, use a terminal block to safely provide power. If you choose to go this route, you can connect multiple transformers to give 5v, 9v, or whatever voltage you need. Keep in mind that the more devices connected, the more power will be used. You may need to upsize the battery and solar panel if you go wild.

Step 3: Installation

Plan out your wiring diagram and decide where the components will be installed. Use additional wire to separate the components and put them where you want them to be.

Most electrical devices like to be dry, so make sure the solar charger and battery go in a dry place. An alternative would be to place them in a waterproof (but not airtight) container.

Naturally the solar panel needs to be installed on the roof in a sunny location.

Plug in your stuff and enjoy being off the grid. I built a Raspberry Pi with camera to tweet photos of my chickens, but that is another instructable.

Thanks and enjoy, follow me on Twitter @peterhagemeyer or my chickens @NJchickens



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    13 Discussions


    2 years ago

    Sorry to be pedantic, but a 'transformer' by definition converts AC volts to AC volts, when converting a DC voltage to another DC voltage you actually are using a 'DC voltage converter'. That's a neat converter you used, I might grab one to power a RiPi myself.


    3 years ago on Introduction

    Nice setup, I hope you added some fuses (simple car blade fuses will work up to 32Volt and are ideal to work with on 12V)

    6 replies

    hey Techie66, I'm building a similar system but I noticed that this instructable did not have fuses and I know that is a key safety feature. Do you have some insight on this? 12v car fuse between the battery and the charge controller? 12v car fuse between the battery and each switched light?

    Hi, I would at least add two fuses, one between te battery and the charge-controller. Even small batteries (like 20Ah) have very high maximum currents that will destroy your charge-controller, so if you have a 20A controller, use a 20 Amp fuse, this can be a (DC) circuit breaker or a regular blade-car fuse between the battery and the controller. On the output you can either use one fuse between you controller (or battery) for all the lights or multiple fuses for each light. One fuse is sufficient, but all the wiring needs to be able to accept the current rating of that of fuse. If you use more fuses you could use thinner cables, but more imporatant, you won't loose power everywhere if you blow just the one. A small schedule can be found here

    Thanks Techie66, I'm hoping to get this together this week. I'm trying to build the most basic but safe system I can come up with.

    Clearly you are knowledgeable on these things and I appreciate the help. I'm wondering if I could get your opinion on my wire attachment method? I'm stripping about 3/4" of the wire, twisting and then covering with heat shrink tubing. How many 12v wires do you think I could attach safely using this method? After reading this instructable I'm thinking I should have used a terminal block.



    To be honest I think you should re-connect all the twisted wires by using a terminal block. 12V is pretty safe when it comes to touching it, but the current is much higher on the same power, so sparks are much more intense and you loose more power on bad connections.


    4 years ago

    You mentioned to make sure that the wire us rated for 12V. That will be easy, as most wire is rated for higher voltages. However, the important thing is to be sure it is adequately rated for the Amperage!

    2 replies

    Look at the wire guage and check a table on the web. If you use metric, a guideline could be 10A per square millimeter, but that is the absolute max, better use 6A / sqmm


    4 years ago on Introduction

    I bet a motorcycle battery would work well in applications this size and smaller. Nice setup!


    4 years ago on Introduction

    Great instructable. having done a lot of off grid living I have found you usually need a lot less solar than most people think.