skip to Main Content
school bus build school bus interior school bus build school bus interior school bus build school bus interior school bus build school bus interior

400+ Watt Solar Panel Setup For A Van

This 400+ Watt solar panel setup for a van gives a baseline guide of everything necessary to build and connect a solar panel system. A 400-600 watt solar kit is enough electricity to power all necessary small electronics as well as full household items such as water pumps, 12V refrigerators, induction burners, diesel heaters and more.

Note that this system will not be large enough to power AC (most people find they need about 1000W for this to work). The 560 Watt panel combo listed below produces between 165-300Ah on a sunny day depending on exposure and charge controller efficiency.

This guide is suitable for a solar-only power system. When planning to pair it with shore power or a generator then additional equipment is needed to make sure the wiring is handled safely.

Need a different amount of solar? Check out our guides on 100 Watt solar system, and 200 Watt solar system.

400 Watt solar panel setup guide

Shopping list for a 400+ Watt solar system

Solar Panels (4 x 100 Watts)

Choose one of the following panel options. Any 12 or 24V panel will work and these can even be sometimes found used for a good price:

Mounting Hardware

Charge Controller

We recommend an MPPT charge controller for this amount of power because they are more efficient and can handle a 24V input. This allows for easier panel wiring.

Deep Cycle Battery

  • 12V 150Ah AGM Battery
    • (x2) Wire in parallel to create one 12V, 300Ah battery bank
  • 6V 300Ah AGM Deep Cycle RV Battery (alternative to 12V AGM battery)
    • (x2) Wire in series to create one 12V, 300Ah battery bank.
    • Wiring in series is better for the lifespan of the batteries because they can’t get out of balance.
  • 12V 150AH Lithium Battery
    • (x1) Lasts longer and can be fully discharged compared to lead based batteries

Inverter (12V DC to 110V AC)


Wiring is usually cheapest at automotive and hardware stores. We recommend keeping with red/black for safety and convenience when running wires. Some wire is sold in colored pairs as 14AWG, 12AWG, 10AWG, and 0AWG battery wires.  Make sure to purchase multi stranded wire so that it is easier to snake through your vehicle and more secure for connectors.

The wire sizes listed here are approximate and the length will depend on your setup. Using these exact wire sizes will work in most situations. If you need to run longer wires, such as 12ft. you should use a thicker AWG rating (lower number is a heavier wire) to reduce voltage loss. Remember, the longer and smaller your wire size, the less efficient your system will be.

  • 10AWG wire (to run from a Mc4 Y branch connector to the charge controller). We recommend this 10AWG in line fuse holder with a 20A fuse.
  • 8AWG wire (to run from the charge controller to the battery). Use an 8AWG in line fuse holder with a 35A fuse.
  • 5ft or less, 8AWG wire to run from the charge controller to the fuse block.
    • Use a 35A in-line fuse or a fuse the size of your charge controller rating for this line (whichever is smaller). Same fuse holder as above.
  • 0AWG wire (to run from the battery to the inverter)
    • A 1500W inverter (peak 3000 Watts) can draw up to 250 Amps. This wire must have a fuse in-line. We recommend this 300A circuit breaker. A 300A in-line fuse will work as well.
  • 0AWG wire connecting the batteries to each other. This wire needs to be large enough to handle max current between the batteries. It is also important for the (+) and (-) wires to be the same length for proper load balancing. It doesn’t hurt to put a fuse/breaker between batteries wired in parallel in case one has an internal short.

Wires running from the fuse block to the DC electrics will vary in size based on the Amps each electric device uses. Use one fuse size up from the amperage produced. For devices listed in watts, divide by system voltage (12V) to get Amps.

For example, a 75 Watt string of lights will draw up to 6.25 Amps (75Watts/12Volts). In this case, use a 7.5A fuse because it is the next fuse size above 6.25 Amps. Wires need to be able to handle the current. See the Fuse Block section below for device wire sizing.

Fuse Block

For safety purposes, all positive (red) wires should be fused. The primary purpose of a fuse is to protect your wiring if something happens to your electronic device or you have a short, such as a wire rubbing and touching the frame. For this reason, you should never use a higher amperage fuse than the wire can handle. The fuse should always be the weakest link in your power system!

The fuse block organizes power from your battery into separate power circuits for each electronic device you have. This way if there is an issue with one device or wire it doesn’t affect the other ones, and is easier to diagnose issues.

For this system, use the wire sizes below for the max fuse size that you can use for each amperage. You can always use a smaller fuse, but should never use a larger one. If your wire can handle 15 Amps but your electrical component can only handle 5 Amps, it is completely fine to put in a 5A fuse to protect the device.

  • 16AWG wire: 10 Amps
  • 14AWG wire: 15 Amps
  • 12AWG wire: 20 Amps
  • 10AWG wire: 30 Amps
  • 8AWG wire: 40 Amps

If your wire can handle 15 Amps but your electrical component can only handle 4 Amps, it is completely fine to put in a 5A fuse to protect the device.

  • Automotive blade fuses for your fuse block can be purchased at any auto store.

Connectors and Terminals

Most panels come with MC4 connectors. You can buy connectors on your own or a pair of extension cables with connectors attached.

If you’ve got four panels, we recommend that you wire two pairs of panels together in series to create two larger 200W, 24V units.  Then wire each of those sets in parallel to make a 400W, 24V input into the charge controller. If you’re using two larger panels, wire them in series to make 24V. This allows for smaller gauge wiring to the charge controller because twice the voltage means half the amperage. To wire panels in parallel, use a Y Branch connector like this:

For your wiring, your batteries will likely not come with terminal connectors. Connectors on the posts of your batteries allow you to attach wires to the batteries. You need a set for each battery.

To attach wires to the batteries, ring connectors are recommended for easier and safer assembly. Make sure to use a connector that is appropriate for the wire size. They are usually labeled. Spade connectors are used to connect wires to your fuse block. If you need both connector types, it is usually more economical to buy everything in one kit.

For the large 0AWG wires you need heavy duty connectors if the wires do not already have them.

Connectors can be used to connect the negative (black) wires from your DC electronic devices to metal on the vehicle frame. Then connect the negative post of your battery bank to the frame as well. This means that your entire vehicle frame is grounded. Do this only for your powered devices. Your inverter and charge controller negative wires should be connected directly to your battery bank.

Total Cost of a DIY 400 Watt Solar Panel Kit

If you buy just the basics, you are going to spend at minimum $1700 on a 400W kit including everything except the wires themselves (this can vary depending on how much wire and how many devices you’re using). If you upgrade your battery, controller, mounting hardware and inverter, you are looking at upwards of $3500 or more.

If you don’t feel comfortable piecing together your own parts, Renogy offers a partial solar kit with MPPT controller at about $780. Purchasing all of the pieces separately you will spend about $750 on similar equipment. Renogy pricing is usually quite good for the convenience that it offers if they have a kit that matches your needs.

You can also buy a Renogy solar suitcase with charge controller. This is portable and would not attach to the roof. With this suitcase you would need to purchase an inverter, fuse block and batteries.

Alternatively, you can purchase a full system Goal Zero Yeti kit for around $1750. This would be the equivalent of a 100Watt solar suitcase paired with a 100Ah AGM battery and 1200 Watt inverter. Our estimate that the DIY pieces separately for this would be around $600-$700.

Tools For Solar Installation

Aside from general wrenches and drills for mounting, some basic wiring specific tools that are necessary:

  • Digital Multi Meter (DMM). This is critical for anyone doing electrical work as well as troubleshooting many electrical issues. For basic wiring you don’t to spend more than $20 like this Craftsman DMM.
  • Wire stripper and crimper. You can spend a good amount on a separate stripper or crimper and they are definitely better tools, but if you’re just getting started a basic combo tool will get you by just fine.
  • Dielectric grease. This is used to keep bare metal connections from corroding. Vaseline works for this as well if you already have some.

Tips On Installing Your Solar Panel System

Wiring 12V systems is relatively safe. You can short wires or start a fire but you are not likely to shock yourself like you can with household electricity.

  • Wire connecting order:
    • When wiring solar panels, always connect the panels to the system at the very end and disconnect them first. You don’t want that voltage connected with nowhere to go.
    • After the above tip, it’s a good habit to disconnect the negative (black) battery terminal before working on electrical systems. The order of assembly should be: 1) Connect all system wires 2) Connect negative battery terminal. 3) Connect solar panels to charge controller. Disassembly is in reverse of this.
  • Here is a good video on how to crimp wires.
  • There are two schools of thought for ground wires. You can run a ground wire from each component back to a bus bar. This often is easier because you don’t have to find frame grounds. Or you can ground each component to the nearest bare metal. This uses less wire and is easy if you have a lot of exposed metal.
  • Avoid running wires in areas where they may rub or chafe and cause a short. Along a similar vein, it’s good to lay out your wiring so that you have access after the van is built in case you need to troubleshoot or add more components.
  • Shade is the enemy of PV solar panels. The cells are arranged in a way that if one cell is shaded, the whole row loses power. So make sure to mount your panels on the van in a way that they will not be shaded by other objects on the roof. In certain cases, if 10% of a panel is covered, 90% of it won’t be producing electricity.
  • When pairing batteries:
    • Batteries must be the same size and type, otherwise they will be out of balance and have a drastically shorter lifespan. Even two of the same batteries that are different ages can cause issues.
    • Two 6V batteries wired in series is better than two 12V batteries wired in parallel. This is due to the ability for the 12V batteries to discharge at slightly different rates, making them less balanced. Two batteries in series will discharge at the same rate.

Leave a Reply

Your email address will not be published. Required fields are marked *

Back To Top