How To Build A Campervan Solar System (Ultimate DIY Guide)

last updated: Oct 9, 2024

Are you looking to convert a campervan that can take you off-grid on an adventurous road trip? Or are you looking to live full-time in a van, and need power for the essentials?

The key to getting off-grid and living in a van, is having the energy to power your electrics. 

Solar power! 

I will never forget my first month travelling in my first van conversion. I suddenly realised that with one large solar panel, I had all the electricity I needed! Having just escaped from the London rat-race, it was a great feeling to no longer have to pay an electricity bill—or that my gas bill for winter heating cost less than eating out, once.

Not only is solar energy good for the environment but it is also, essentially, free electricity (after the initial setup costs) that you can use to run your campervan electrical system. 

This campervan solar system guide aims to teach you everything there is to know about solar power, how to install your own solar system, and even demonstrate three separate examples of different vanlifers’ solar systems. 

Let’s get stuck in…

Part 1: Campervan Solar System Components

Before jumping into exactly how a campervan solar system works, here is a quick breakdown of all of the different components that go into a camper van solar unit.

Individual units may vary slightly. However, these components are generally what make up the solar system:

  • Solar Panels: Solar panels for campervans sit atop the van, and absorb energy from the sun and then convert it into usable electricity for your campervan. There are two different types of solar panels: monocrystalline and polycrystalline.
  • Wiring: The campervan solar panel wiring gets the electricity from your panels to your leisure battery. There are two different ways to wire your solar panels: parallel and series.
  • Solar Charge Controller: A solar charge controller is a piece of equipment that regulates the voltage of the electrical current that flows into your campervan’s battery.
  • Battery: This is where the power to run your various campervan power loads is stored. The van solar panels will recharge your battery.
  • Mounting kit: A solar panel mounting kit includes the hardware necessary to install your van’s solar panels.
Campervan Solar System Components
If you are going to live through winter in your van, your solar and battery charging systems need to be well calculated.

Part 2: How a Campervan Solar System Works

In a nutshell, a campervan solar system works by absorbing the power of the sun, and turning it into electricity that will charge your campervan’s leisure battery, thus powering all of the electronics in your campervan.

A campervan solar system can be broken down into four main parts: the solar panels, the wiring, the charge controller, and the wiring.

Each part is equally important and they must all work together to charge your van’s battery!

The Solar Panels

When the sun shines onto your solar panels, they absorb the sun’s energy through the PV cells in your solar panels. ‘PV’ is short for photovoltaic, which refers to the ability to turn sunlight into a usable form of energy. 

There are two different primary types of solar panels: Monocrystalline and Polycrystalline.

Monocrystalline: 

Also known as mono solar panels, the PV cells in monocrystalline solar panels are each made from one individual silicon crystal. Monocrystalline solar panels are black.

Pros of monocrystalline solar panels:

  • Monocrystalline panels are more efficient than polycrystalline panels.
  • Monocrystalline panels have a longer lifespan than polycrystalline panels.
  • Monocrystalline panels perform well in hot temperatures.

Cons of monocrystalline solar panels:

  • They are more expensive than polycrystalline panels.
  • They do not perform as well in cold weather.

Polycrystalline:

Also known as ‘poly’ solar panels, the PV cells in polycrystalline solar panels are made from multiple pieces of silicon crystals fused together rather than one individual silicon crystal, like in monocrystalline panels. Polycrystalline solar panels have a blue hue.

Pros of polycrystalline solar panels:

  • Polycrystalline panels are cheaper than monocrystalline panels.
  • Polycrystalline panels tend to function better in colder environments than monocrystalline panels.

Cons of polycrystalline solar panels:

  • Polycrystalline panels are less efficient than monocrystalline.
  • Because they are less efficient, more polycrystalline panels will be needed to generate the same amount of energy as monocrystalline panels. 

Once the sun’s radiation is turned into electricity, it flows into the wiring of your solar panels. From there, it flows to the charge controller.

What do I install? I almost always go with monocrystalline because they tend to be all black and look cooler. The difference in performance, in my opinion, is fairly negligible for the size of the array on a van, and the pricing has come down so much in recent years that this is less of an issue.

The Wiring

To create a flow of energy, the negative terminal of a solar panel must be wired to the positive terminal of another solar panel. 

If you have more than one solar panel there are two main ways to wire multiple solar panels together: Series and Parallel.

Series

Solar panels are wired in a series when the positive terminal of one panel is connected to the negative terminal of the next panel.

Series

When solar panels are wired in a series, the voltages are added together, the amps stays the same (meaning that you can use a lower-rated and cheaper solar charge controller).

Pros of wiring solar panels in a series:

  • It is easier to wire solar panels in a series.
  • If none of the panels are obscured, wiring in a series will have a higher overall efficiency than in parallel.
  • Can use a lower rated Solar Charge Controller

Cons of wiring solar panels in a series:

  • If one solar panel is shaded, the overall productivity of the solar system massively decreases.

Parallel

Solar panels are wired in parallel when the positive terminal of one solar panel is wired to the positive terminal in another solar panel, and when the negative terminal of one solar panel is wired to the negative terminal of another solar panel.

Parallel

The positive-to-positive and negative-to-negative connections are made with branch connectors. 

When solar panels are wired in parallel, the amps are added together.

Pros of wiring solar panels in parallel:

  • If one panel is damaged, or partially shaded, the overall system will still perform well.

Cons of wiring solar panels in parallel:

  • You will need a bigger Amp-rated Solar Charge Controller and, therefore, more expensive, solar charge controller.

Which method of solar panel wiring is best for you?

When deciding if you should wire your solar panels in series or parallel, there is no ‘one size fits all answer’. It depends on your overall electrical system. 

Keep in mind, wiring solar panels in series will increase the voltage but not the ampage. Solar Charge Controllers are rated in amps, so wiring your solar panels in series means you can use a lower-rated unit for more solar power. 

If you are wiring your solar panels in parallel, be sure to use the right size solar charge controller. If you have any doubts, consider using our Electrical Design Service—a qualified off-grid electrical engineer will help design a safe system that matches your needs.

The Solar Charge Controller

Once the solar panels are installed and solar panel wiring is completed, the panels will be producing electricity! The next step in the campervan solar setup is where the solar charge controller comes into play.

The Solar Charge Controller

A solar charge controller regulates the voltage that the solar panels create. 

Campervan leisure batteries need a specific voltage to charge, so it is very important that this current passes first through the solar charge controller before going to the battery.

There are two different types of solar charge controllers: pulse with modulation (PWM) and maximum power point tracking (MPPT).

Pulse with Modulation (PWM)

A PWM solar charger is the cheaper and less expensive of the two. Honestly, I wouldn’t bother. Just get an MPPT unless you have a very tight budget—or are using your van just for weekends.

Essentially, a Pulse Width Modulation solar charger works by lowering the voltage flowing from the solar panels to a voltage that can safely charge the campervan’s leisure battery.

Maximum Power Point Tracking (MPPT)

MPPT solar charge controllers are more expensive than PWM controllers but they are also more efficient. (Warning, you can buy super cheap (and light) ‘MPPT’ units, but they are just not what they say they are). Expect to pay $100/£80 and upward.

Rather than decrease the voltage like PWM controllers, Maximum Power Point Tracking solar controllers are able to operate at the solar panel’s maximum power point and regulate that current to charge the van’s leisure battery.

As a result, MPPT charge controllers can be 25% more efficient than PWM charge controllers!

Battery

Once the voltage has been regulated through the solar charge controller, the battery can now be recharged by the solar panels!

Then, that energy can be used to power all of your campervan electronics. 

Part 3: Campervan Solar System Considerations

Before jumping into the ins and outs of installing and choosing your campervan solar setup, there are a few important key factors to take into consideration regarding your solar system, and exactly how much solar power you need.

How to calculate how much solar power you need

To calculate the number of watts you need for your solar panels in a van conversion, you’ll need to estimate your total energy consumption and match it to the solar panel system’s capacity. Here’s a step-by-step process to help you figure it out:

How to calculate how much solar power you need
On my latest van I put two ‘short’ house panels (these are a bit shorter than standard size panels) which meant that they could fit width-ways giving 590W in total at a very reasonable price.

Step 1: List Your Electrical Devices

Start by listing all the electrical devices you plan to use in your van. This can include things like:

  • Lights (LED or other types)
  • Refrigerator
  • Laptops
  • Phones
  • Fans
  • Water pumps
  • Cooking appliances (e.g., induction cooktop)
  • Inverter

Step 2: Calculate Daily Energy Consumption

For each device, determine its power consumption in watts (W) and how long you’ll use it per day (hours). If you can’t find the power rating directly, you can often find it on the device or in the manual. Many devices will list power in watts (W) or voltage (V) and amperage (A).

  • Formula:
    If you know the device’s power rating in amps and volts, you can calculate watts using:
    Watts (W) = Volts (V) × Amps (A)

Once you have the wattage, multiply by the hours of usage per day to find the total watt-hours (Wh).

  • Formula for each device:
    Watt-hours (Wh) = Watts (W) × Hours per day

Step 3: Add Up Total Daily Consumption

Add up the watt-hours of all devices to get your total daily energy consumption. For example, if your lights use 20 watts and you run them for 5 hours a day:

  • 20 W × 5 hours = 100 Wh

Do this for each device and sum them to get your total daily watt-hour consumption.

Step 4: Account for Inefficiencies

Energy losses occur in various systems, especially in the inverter (if you’re using one to convert DC power to AC, e.g. for mains appliances). Inverters typically have around 85-90% efficiency. To account for this, divide your total consumption by the inverter efficiency.

  • Formula for inefficiency adjustment:
    Adjusted consumption = Total daily Wh ÷ Inverter efficiency

For example, if your total consumption is 1000 Wh and your inverter is 90% efficient:

  • Adjusted consumption = 1000 Wh ÷ 0.90 ≈ 1111 Wh

Step 5: Determine Sunlight Hours

The amount of energy your solar panels generate depends on how much sunlight your location gets. This is measured in peak sun hours, which vary by location and season. For example, most locations receive 3-6 peak sun hours per day.

You can look up the average peak sun hours for your location using online solar maps.

Step 6: Calculate Required Solar Panel Wattage

Now that you know your total daily energy needs and average sunlight hours, you can calculate the total solar panel wattage you’ll need.

  • Formula:
    Required solar panel wattage = Total daily Wh ÷ Peak sun hours

For example, if your total daily energy consumption is 1000 Wh and you get 4 peak sun hours per day:

  • 1000 Wh ÷ 4 hours = 250 W

Step 7: Account for Weather and Battery Storage

You’ll want to add a buffer for cloudy days or inefficiencies, typically 25-50%, depending on your location and how much backup battery storage you plan to have. Multiply your required wattage by 1.25 or 1.5 to get a more realistic figure.

  • Example:
    250 W × 1.5 (50% buffer) = 375 W

Step 8: Size Your Solar Panels

Now, choose solar panels that meet or exceed the total wattage you need. For instance, if you need 375 W of solar power, you could use:

  • 2 × 200 W solar panels (400 W total)
  • 3 × 150 W solar panels (450 W total)

Step 9: Check Your Battery Storage (Optional)

If you’re using batteries to store energy for night use, calculate the battery capacity in amp-hours (Ah) using:

  • Formula:
    Battery capacity (Ah) = Total daily Wh ÷ Battery voltage

For example, for a 12V battery and 1000 Wh of daily consumption:

  • 1000 Wh ÷ 12V = 83.3 Ah

Battery Type: If using Lead-Acid/Gel batteries (not Lithium) – to allow for a 50% discharge (to prevent battery damage), multiply by 2:

  • 83.3 Ah × 2 ≈ 167 Ah

You would need at least a 167 Ah battery to cover your daily needs if using Lead Acid/Gel Battery. You would need at least 83 Ah if using Lithium.

Summary

  • List devices and their power consumption.
  • Calculate daily watt-hours needed.
  • Adjust for inefficiencies (e.g., inverter loss).
  • Divide total energy needs by peak sun hours to size your solar panels.
  • Add a safety margin (25-50%) for cloudy days.
  • Choose solar panels that meet or exceed your calculated wattage needs.

Part 4: Different Types of Campervan Solar Systems

A Budget Campervan Solar System

If you’re looking to convert a van with a simple solar panel system on a budget, you can do so for roughly $240 (not including battery).

This system will need the following components:

This camper solar system is ideal for vanlifers who only run a handful of electrics, like lights, a few small fans, and need to charge their electronic devices. 

Additionally, this is a sufficient camper van solar power setup for those traveling in extremely sunny locations, so their solar panels receive ample sunlight to charge their batteries!

With this amount of solar, especially in sunny locations, you should have ample energy to recharge your batteries and even get off-grid for a few days.

However, if you’re looking to have a heavier power load in your campervan, you may want to read on for the mid-range campervan solar system. 

Full video → Ezra’s Van Conversion

The Mid-Range Campervan Solar System

If you’re looking to convert a van with a mid-range campervan solar system, you can do so for roughly $760. (Again battery excluded)

If you’re looking to run a slightly larger load and get off-grid for longer amounts of time, then this camper van solar system should be more than enough to satisfy your needs!

This system will need the following components:

With this solar setup, there is enough electricity in this van to stay off-grid, and run a small load of electrics like lights, a water pump, recharge all my electrics, power a (small) fridge, and more! If you are going to travel in winter—work remotely, or both—however, you will probably need a bigger system.

Full video → My First Van Conversion

The High-End Campervan Solar System

If you’re looking to convert a van with a high-end campervan solar system, you can do so for roughly $1,875. (Battery excluded)

This system will need the following components:

We know that’s a pretty hefty price tag. However, this is enough solar power to recharge 2×200 watt Lithium batteries that are capable of running:

  • A water pump
  • Lights
  • Fans
  • A fridge
  • A Nespresso machine
  • A milk steamer
  • A blender
  • A hair drier
  • A heater
  • All of the electronics for two full-time working digital nomads!

If the above items sound like electrics that you may want in your van conversion, this is potentially the type of van solar setup you should be budgeting for in your overall cost of the van conversion.

Full video → Incredible Luxury Van Conversion

Part 5: How to Install a Campervan Solar System

Now that you have a better idea of the different ranges of van solar systems, it is time to dive into the actual installation process! 

Step 1: Order ALL of your campervan solar system pieces

Before moving forward with the installation of your campervan solar system, it is a great idea to order and already have all of your system’s components in front of you. 

This way, you can start the installation process and not experience any holdups in the middle of installation due to a missing part. 

Step 2: Create a wiring diagram

Once you have all of your campervan solar setup parts in front of you, the next step is to create a wiring diagram. 

In this diagram, you’ll hash out exactly how you’ll wire your panels together, and through the charge controller and battery. 

Step 3: Mount your solar panels

After you’ve completed the wiring diagram, it’s time to mount your solar panels! 

When mounting your solar panels, you’ll want to be sure your van’s roof is totally clean, and mark everywhere you plan to cut and drill ahead of time to ensure accuracy.

Step 4: Complete wiring

Once you’ve mounted your panels, it’s time to go ahead and wire them together! 

Whether you’ve opted for series wiring, parallel wiring, or a combination of both, this is where you’ll put the whole system together so electricity can flow from your panels, to your charge controller, to your battery!

** To learn exactly how to install, mount, and wire your solar panels, I highly recommend checking out my ebook The Van Conversion Guide

The ebook includes the exact parts, tools, and steps you will need in order to not only mount and install your solar panels, but also your campervan electrical system, and entire van conversion!**

Step 5: Perform a safety check

Once your solar panels are mounted and the wiring is completed, it’s time to perform a safety check. 

A safety check will not only double-check that your system is running safely, but it will also ensure every part is functioning properly. 

This will protect your valuable campervan solar equipment, as well as protect yourself and your loved ones from the dangers of faulty electrical systems. It’s always a good idea to have a professional electrician look over your system for maximum safety. 

How to Install a Campervan Solar System
It can be intimidating to install your first electrical system, but it’s not as hard as it appears (I promise!)

Part 6: Maintenance

Just like your van’s engine needs servicing to continue running smoothly, you’ll want to perform some maintenance on your solar panels from time to time to keep them running smoothly. 

One of the key ways to maintain well-functioning solar panels is to clean them and remove debris. Dirty solar panels covered in leaves are going to perform far less efficiently than clean and unobstructed solar panels. 

If you frequently check on and clean your panels, you’ll not only be extending the lifespan of your panels, but you will also be allowing them to provide even more energy to your battery, allowing you to stay off-grid longer. 

Campervan Solar System, Final Thoughts

That’s a wrap on our campervan solar guide! 

I hope this guide has helped you understand how solar power works and has given you a good idea of what type of solar setup you want for your own van conversion! 

Whether you’re looking for a minimal solar setup, or need enough juice to power everything from your blender to your hair drier, I hope you’ve gained a little clarity on what your van solar system needs. 

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the van conversion guide

The Van Conversion Guide (14th Edition)

The guide anyone can use to convert a van into a camper! This best-selling guide, now in its 14th Edition, has been used by thousands of people to transform a van into a camper.

  • 150+ page eBook
  • Helps you convert any kind of van
  • Diagrams for all the main systems
  • FREE mini-course - 28 video tutorials