This is a free wiring diagram for a 540 Watt solar system with DC-DC Charging (alternator charging).
What can this system do?
Expect up to 230Ah 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 travelers – Traveling remote workers – Boondockers
540 Watts with DC-DC charging is usually sufficient for 2 people.
How much does it cost?
Without batteries, this system cost about $1,600
Before we begin, let’s get an overview of what we’re building. To simplify the process, it’s best to think of a solar system as being 3 separate parts. We will build each of these sections separately. You can build them in any order you like, just be sure to only connect them together when once the entire system is built.
The Solar Array in this system is built using 3 x 180 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 at least 300Ah of lithium or 600Ah of traditional lead-acid batteries.
Here is a list of everything needed to build this project.
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- 180 Watt Solar Panels
- 50 Amp MPPT Solar Charge Controller
- 40 Amp DC-DC Charger from Renogy
- 2000 Watt Pure Sine Wave Inverter
We recommend at least 300Ah of LiFePo4 Batteries or 600Ah of AGM Batteries.
- (Best Option) 270Ah LiFePo4 from Battleborn
- (Budget Option) 200Ah LiFePo4 from Ampere Time
- (Cheapest Option) 200Ah AGM Battery from Renogy
Wiring and Terminals
Double-check wire length and terminal size prior to ordering premade cables.
The Solar Array
The solar array is built using 3 x 180 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, the voltage is high enough to be considered 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.
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.
The Component Board
For a Campervan solar system, I recommend building a “component 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. Ideally, you are able to mount everything except for the inverter.
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.
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The Battery Bank
For a system this size we recommend installing a large battery bank. At least 300Ah of Lithium, or 600Ah of AGM. But honestly the more, the better.
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. Just be sure to search for deep-cycle batteries, you don’t want to use car batteries. For solar systems, AGM batteries are a great option.
- (Cheapest Option) 200Ah AGM Battery from Renogy
A 540 Watt Solar System is powerful enough for 2 people to go off-grid for extended periods of time. Coupled together with a large battery bank and DC-DC Charging, you’ll have a reliable system that can support Boondocking and remote work quite well.
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