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How to Build an 800-Watt Solar System (For Campervans)


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In this article we’re building an 800 Watt campervan solar system.

Amps per day

Expect up to 350Ah per day in Summer (without DC-DC Charging).


Actual performance varies greatly based on location and weather conditions. Your results may be far better or worse.

Who is this system for?

Full-time Vanlife – Full-time Travelers

How much does it cost?

Without batteries, this system cost about $2,000

Project Overview

An 800 Watt Solar system combined with DC-DC (alternator) charging is a massive system that will create alot of power. A system this size is about the largest you can squeeze on a normal van, but it still will be a bit challenging.

Before we begin, let’s take a look at this solar system’s 3 separate sections. Each section is built independently, in any order you like, just be sure to only connect them at the end of the project.

The Solar Array in this system is built using 4 x 200 Watt solar panels wired in series.

The Component Board is the “power distribution section” of your system. This is mounted to a board to make assembly easy.

The Battery Bank is your energy storage section. We recommend a minimum of 400Ah of lithium or 800Ah of traditional lead-acid batteries.

Here is a list of everything needed to build this project.
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Components Needed

Large Components

Battery Options

We recommend at least 400Ah of LiFePo4 Batteries or 800Ah of AGM Batteries.

Wiring and Terminals

Double-check wire length and terminal size prior to ordering premade cables.

The Solar Array

The solar array is built using 4 x 200 Watt solar panels wired together in series. This means you’ll connect the positive from one panel to the negative of the next panel, forming one single string of solar panels.

Since they’re wired in series, their voltages add together. In this case more than 120V in cold and sunny conditions. That’s high enough to be considered very dangerous. Make sure to take all necessary safety precautions or hire a professional.

You’ll need 6mm² (10 AWG) Solar Cables to go from the solar array to the solar charge controller. Install a PV Circuit Breaker on this cable in an easy-to-access location.

6mm² is the smallest cable you should use with this system. The charge controller recommended in this article can handle up to 35mm², that is however overkill for this PV array configuration.

The PV Circuit Breaker is used as a disconnect switch in this system, it is not used as circuit protection. Since there is only one series string in this solar array, additional fusing is not necessary.

Mounting the Solar Panels

The best method for mounting solar panels to a vehicle is by mounting them to a roof rack. This prevents you from have to screw in through sheet metal damaging paint, and risking leakage.

Here are some roof rack options for popular vans.

Another option for mounting solar panels is to use a Panel Mounting Z Bracket Kit. Like mentioned above, you’ll have to go through metal and paint, opening up the risk of rust and leakage. But this option is still secure.

Our least favorite method is using glue-on brackets like these here. Many people use them, we’ve even used them ourselves with no problems. You just have to be aware of the strength of the substrate you glue them on.

ie: If you glue these mounts to a painted vehicle roof and the paint flakes off, the solar panels will fly off!

Many factory vehicle paint jobs are poor in quality, especially on the roof of cargo vans.

The Component Board

For a Campervan solar system, I recommend mounting your smaller components to a board. This allows you to comfortably do most of your wiring at home, and when you’re ready you can bring the entire assembly to the van.

Try to mount as many components as you safely can to the board.

Be sure to pay attention to where fuses are to be located.

Mount your component board securely to the van, in an easy-to-access location since the majority of your fuses are located here. It must also be located near the Battery Bank and the Power Inverter should also be close by.

The Solar Charge Controller and DC-DC Charger will generate heat so be sure to provide adequate ventilation.

The Solar Charge Controller

This design uses a Victron 150|60 MPPT charge controller, meaning it has an maximum array voltage of 150V, and will charge your battery bank with a maximum of 60A.

This controller in combination with a 800 Watt solar array will produce about 56A during optimal weather conditions.

It’s important to program your charge controller for the type of battery you decide to use, this is to prevent damaging the batteries. Whether LiFePo4, Gel, AGM, or any other battery type, you can program the charge controller by following the steps in its user manual.

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The Battery Bank

For a system this size we recommend installing a very large battery bank. At least 400Ah of Lithium, or 800Ah of AGM. I personally would go with a 1000Ah of LiFePo4.

This system will produce a lot of energy in summer, and the DC-DC Charger will add to that every time you’re driving.

You’ll need to buy 12 Volt batteries and they must be wired together in parallel. That means connecting all the + terminals together, and all the – terminals together, forming one large battery bank.

LiFePo4 batteries are what we recommend for campervan installs. They’re half the weight and twice the usable capacity of traditional lead-acid batteries. Plus they have a much longer lifespan, so in the long run, they end up being cheaper.

Here are a couple of LiFePo4 options.

Traditional lead acid batteries can be used if you’re on a budget. For solar systems, AGM batteries are a great option with a lifespan of 3 to 6 years

Most popular Battery Monitoring Shunt

Installing a Battery Monitor

Every solar system should have a way to monitor the state of charge of the battery bank. Without this, you run the risk of over-discharging your batteries which will lower their capacity over time.

The easiest way to monitor state of charge is by using a Battery Monitoring Shunt.

This simple device is installed on the negative cable of your battery bank, so that all current must flow through it. This enables it to track how much current goes in and out of your battery bank over time.

Most of these units come with either a physical display which you can mount on a wall. Some however have bluetooth funtionalilty, enabling you to monitor battery health on your phone.

Summary

800 Watts is about the largest system that you can squeeze on a van roof without some serious modifications. When you couple this together with a large battery bank and DC-DC Charging, you’ll have a reliable system that can support Boondocking, remote work, and full-time travel without giving up that many comforts.


Download the free wiring diagram above to view the system layout with wire sizes included.


Use this list which includes everything you’ll need to build this solar system.

Other Useful Resources

Guide to Wire Size Selection Learn to size your wires the uncomplicated way. Learn more…
Guide to Fuse Size Selection Fuses protect your investment. Learn how to size them quickly and easily. Learn more…
The Basics of Solar Energy The bare minimum knowledge, in less than 10 minutes. Coming Soon…

Browse our other 12-Volt Systems

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