Build a 12v solar charger system for camping, a caravan, or a shed

A solar charger is now even more cost effective to build as you may think. 6 years ago I looked into adding a solar charger for the 12v side of our old caravan but the panels were quite expensive back then, as was the equipment to set the system up. Thankfully solar has become even more popular now and prices have really come down, meaning that you can buy a 10 watt panel for under £20 and a charge control unit for less than £10.

Use your solar charger system in a camping, a caravan, or a shed

The great thing about 12v systems is that they’re really easy to set up with a little bit or research and these low voltage circuits can be used almost anywhere that you can’t find mains electricity.

I’ve seen them used in caravans, in the desert and in dense forest. You can plan the battery in a toolbox, the control unit on the site and the panel on the top. You can fit the panel to the top of an allotment shed, in a works trailer or as a back-up power supply in a camper. With the right batteries and a big enough solar panel you can also use a power inverter to convert 12 volt DC to 110/230 volt AC.

What you’ll need:

• Knowledge in wiring up 12v circuits and understanding of currents
• A 12v lead acid battery (deep cycle is better for this but a car battery will suffice)
• Some cable (13 amp will suffice unless you’re pulling high amperage)
• A solar panel (10w minimum)
• A charge controller unit (vital)
• Some fuse connectors (ignore if you already have fitted fuses) and electrical connectors
• Some battery terminal connectors
• Some hand tools including a Philips screwdriver, wire cutter and crimpers

Wiring the solar circuit

It’s vital that you use a solar charger controller in this system. If you don’t, you’re going to end up putting well over 14v into your battery at times which will eventually kill it. A charge controller regulates the amount of power going into the battery to prevent overcharging (I set mine at 13.6v). Do not skip this important bit of equipment,

The charge controller will require wiring in a specific way. This is usually (but not always) carried out by connecting the battery first, followed by the solar panel and then finally the accessory output of the controller (if used). Your controller will provided specific instructions on how to do this. Here’s the basic layout:

You’ll notice if you check the panel output with a voltmeter when not connected to the battery that the voltage will be over 17 volts. Don’t expect that to continue as the voltage will drop once you at the load (resistance) of the battery.

My video below explains how this is done in more detail. Note that I used a controller with 5v USB outputs for easy charging of my phone. This system could be made portable by placing the battery and controller in a waterproof box and then mounting the panel on top of the box. Ideal for wild camping where no source of mains electricity is available and all made for under £27.

What’s the best solar panel?

This is open to debate and the quality of panels varies. There are certainly a lot of cheap and nasty products out there but it’s a case of going for the largest wattage you can afford; the more watts produced the faster your battery will charge.

I recommend 10 watt minimum and if you can afford it an 80 watt panel. You can also add more batteries to increase capacity.