DIY Electrical System in your Campervan - Moving Oasis

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Three Easy Steps to Size your DIY Van Electrical System

Solar Panels on a van have become essential for van life, not to mention that the power source, aka the sun, is a renewable resource, and it’s FREE! Installing solar panels means more freedom to park your home in incredibly beautiful and remote places without worrying about plugging in at overcrowded campgrounds.

Disclaimer: Working with electrical components and wires can be dangerous. Be sure to consult a licensed electrician when installing these into your van.

Overall, the best way to have an off-grid electrical system in your van is to have solar panels on the roof that is hooked up to a battery bank that will power all your appliances. So how do you know how much power you need? Well, let’s get into it. We first need to calculate how big or small your system needs to be based on the appliances you want in your van. So here are three easy steps to do that:

  1. Calculate the electricity you need in Watt-hours (Wh).
  • List all the appliances, devices, and the number of watts they draw.
  • How many hours do you plan to use for each? (for ex: a fridge will be on 24/7, but a blender might be a few times a week for up to a minute).
  • Watts x Hours = Wh
    1. Note: If you can only find electrical consumption in amps, use the formula Watts = Amps x Volts to convert to Watts.
  1. Once you’ve determined the energy you need, you’ll need to determine how much battery power to install.
  • Battery capacity is measured in amp-hours (ah); convert Wh of power consumption in ah by dividing by your system voltage (12v or 24v).
  • Wh / 12v = ah —> the amount of battery power you will need.
  1. Finally, determine how many solar panels you need to fully charge your home batteries.
  • Solar panels are measured in watts, so divide the total Wh of power consumption by the average amount of full sunlight per day (say 5 hours).
  • Wh / 5 hours = x watts

Let’s run through an example. Here is the list of components I have installed in our van:

Step 1: Electrical Usage Calculation

12v DC Appliances

Lights 12.24W x 4 hours = 48.96 Wh

Propane Solenoid Valve 14.4W x 2 hours = 28.8 Wh

MaxxAir Fan 3.6W x 20 hours = 72 Wh

Dometic 12v Fridge 45.6W x 24 hours = 1094.4 Wh

Phone 1 12W x 2 hours = 24 Wh

Phone 2 12W x 2 hours = 24 Wh

Water Pump 72W x .2 hours = 14.4 Wh

120v AC Appliances

Laptop 1 45W x 1.5hours = 67.5 Wh

Laptop 2 45W x 1.5hours = 67.5 Wh

Stovetop Ignition 1750W x .2hours = 350 Wh

Total 1791.2Wh

Step 2: Battery Capacity

Now take the total energy usage and divide it by your system voltage

1791.2 Wh / 12v = 149 ah

Step 3: Solar Panels

Take the total energy usage again and divide by the average amount of full sunlight 5 hours on a good day

1791.2 Wh/ 5 hours = 358 watts

Based on these calculations, if we installed 358 watts of solar panels, it would charge a 149ah battery in 5 hours. However, 1) batteries and solar panels come in standard sizes, and 2) we also need to think about rainy days, clouds, and shade; therefore, it’s always best to install more power than your typical energy consumption.

We installed a 200ah lithium-ion battery and (4) 100-watt solar panels. And within those three easy steps, you can now understand how to size your DIY electrical system. If you have any questions, let us know, and we would be happy to help you!


Nat & Lil