If you’re looking to install solar panels on your campervan but haven’t the first clue where to start, you’re in the right place. In this guide, I break the process down into 7 simple steps. So that by the end, even a beginner will feel confident in installing a motorhome solar system.
If you want your time on the road to be comfortable, the chances are you’re going to need an electrical setup in your campervan.
Having power means you can charge your gadgets, install some home-comfort appliances, and most importantly, keep your beers cold.
The cheapest way of generating power in your camper van is with solar panels.
Sure, there’s an upfront capital cost involved; however, with the advancement of technology and the increase in campervan conversions, solar systems are more affordable than ever.
Believe it or not, installing solar panels on your campervan is pretty straightforward. And this guide walks you through the entire process step by step.
So let’s get to it and show you how to install a solar system in your campervan or motorhome.
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How to Install Solar Panels on a Campervan or Motorhome
Disclosure: I am not a qualified auto-electrician, and my advice shouldn’t be taken as such. I wrote this article based on my own experience, but it shouldn’t replace the guidance of a licensed professional.
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Pros of having solar panels on your campervan
Let’s start with why you might want to consider having solar power in your campervan.
As I mentioned earlier, having solar panels is the most cost-effective way of generating electricity in your van.
While there is an upfront cost involved, your solar system pays for itself in no time at all. As it means you can spend more time off-grid and less time on campsites.
Campsites in Europe charge anywhere from £5-25 for electric hookups. So if you plan on living in your van or having extended trips away, you can see how that can soon add up.
Another pro of having solar power in your van is that it’s environmentally friendly. Unlike burning fossil fuels, solar energy is clean, renewable energy.
You could argue that van lifers and travellers leave a bigger carbon footprint than most since we use a lot of fuel getting from place to place.
However, we can help counteract that by installing solar panels and rest easy knowing that our energy is not harming the planet.
How do solar panels work?
Solar panels are a genius technological advancement. They allow us to take free, renewable energy from the sun and generate a clean source of electricity.
More and more people are making the transition to solar-powered energy. Not only in camper vans and RVs but in homes and businesses too.
But how do solar panels actually work? Here’s a straightforward explanation.
- Solar panels are made up of solar cells. Solar cells are made up of trillions and trillions of silicon atoms.
- Light from the sun is made up of tiny particles called photons.
- When sunlight hits the solar panel, it knocks electrons free of the silicon atoms within the solar cells.
- The way solar cells are made causes electrons to flow upwards, creating a DC electrical current.
- Conductors attached to each solar cell forms an electrical circuit.
- The current then flows to the edge of the panel and into the conductive wires.
- An inverter is used to convert the DC current to AC in houses and other domestic situations.
- However, since the leisure batteries we use in our campervan are 12v DC, we can take the current generated by the solar panels and use it to charge our batteries.
Campervan Solar System Shopping List
Solar Panels: We will discuss the different types of solar panels available further down the article.
Solar Panel Cables: For connecting your solar panels. A cable made specifically for solar panels will come with MC4 connectors attached.
Red & Black Cable: For connecting other elements of your solar system circuit. You’ll need to calculate what cable size you need.
Roof Grommet: A neat and waterproof method of feeding cables through your campervan roof.
PV DP Isolator Switch: This will enable you to shut off the power supply from your solar panels.
Solar Charge Controller: Regulates the current drawing from your solar panels and protects your batteries from overcharging.
Circuit Breaker: A mechanical switch that breaks the circuit when too much current is detected.
Leisure Batteries: To store the power generated from your solar panels.
Miscellaneous: Cable lugs, heat shrink tubing, crimping tool
Best Solar Panels for Campervans
There are several types of solar panels on the market today. However, the two most common types used in campervans are monocrystalline and polycrystalline.
Let’s look at the differences between the two and why you might consider them for your solar system.
Monocrystalline Solar Panels
Monocrystalline solar panels are also known as single-crystal panels. That’s because they are made from a single pure silicon crystal cut down into individual cells.
Monocrystalline panels are the most space and energy efficient out of the two. However, this comes at a cost as they tend to be a lot more expensive than polycrystalline panels.
Polycrystalline Solar Panels
On the other hand, polycrystalline panels are made from several silicon crystals that are melted together.
This process makes them less efficient than monocrystalline panels. But at the same time, much more affordable.
You can tell the difference between the two types of solar panels by their colour. Monocrystalline panels are a dark black colour, and polycrystalline panels are blue.
Rigid vs Flexible Solar Panels
Another thing to consider is whether you want rigid or flexible solar panels. As always, there are pros and cons to both.
Flexible solar panels are more convenient for motorhomes since they are lightweight and very simple to mount. The downside is that they can sometimes overheat, reducing their efficiency.
On the other hand, Rigid are easier on the budget and are likely to last longer due to their robust build.
Naturally, though, there’s a lot more involved with the mounting process, and they add a lot of weight to your van.
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Type of Solar Panel Conclusion
Deciding which type of solar panel to use on your van will ultimately come down to your budget.
If you can afford monocrystalline panels, these are undoubtedly the better option.
But if you’re like us, and you’re converting your camper on a budget, then polycrystalline will do the job just fine.
We opted for flexible solar panels since we didn’t want to take on any more work than was absolutely necessary. But again, it comes down to your personal preference.
Either way, you’ll need to ensure that you are thorough with your power consumption calculations to get the most out of your system. We will look at how to go about that next.
What size solar panels do I need?
Solar panels are sized in watts. The higher the watts, the higher the output capacity and consequently the efficiency.
To calculate what size solar panels you’ll need for your campervan, first, you’ll need to work out your average daily power consumption.
This can be a tedious task, but it’s necessary if you want to have a reliable system.
I have already covered how to calculate your power consumption in this beginner’s guide to campervan electrics. So you might want to give that a quick read first.
For the purpose of this article, I will do just a short recap.
Calculating power consumption
- Make a list of all the electrical devices and appliances you’ll want to power in your van. This is best done in a spreadsheet so you can make calculations.
- Work out the amp power each appliance uses. Some appliances may tell you in watts instead of amps, so use an online calculator like this one to convert it.
- Estimate how many hours you’ll need to power the appliance each day – always better to overestimate in this case.
- Multiply amps (step 2) by hours (step 3) to calculate how many amp-hours (Ah) the appliance will use each day.
- Repeat steps 2 to 4 for each appliance.
- Add together the result for each appliance to get the total amp-hours required.
- Add an extra 20% to allow for any fluctuations, and you’ll have a rough idea of the power you will use in your van each day.
Calculating Solar Panel Size
Once you have an idea of your average daily power consumption, you can calculate how much solar power is needed to keep your batteries topped up.
You can use a simple calculation, which I’ll bullet point below. However, keep in mind that several factors can influence the efficiency of your panels.
For example, a summer’s day in Italy will naturally generate a lot more power than a winter’s day in Scotland. So it’s best to calculate using a worst-case scenario.
- Take your daily amp-hour usage, say as an example, 100 Ah.
- Convert into watt-hours (Whr) = 1200 watt-hours.
- Divide that by the daily average of sunlight, say 4 hours = 300 watts.
- Allow 20% for any system losses = 360 watts.
Based on these calculations, you will need around 360 watts of solar to keep your batteries sufficiently charged.
So, what solar panels do I buy?
Solar panels for campervans come in various sizes, ranging from 100w to 200w and beyond. But it’s not a one size fits all.
You will need to measure the roof space of your van so you know what size and how many solar panels you can fit.
Most medium to large-sized vans could comfortably fit 360 watts worth of solar panels on their roof.
For example, we have 2 of these 160-watt solar panels on our roof and have plenty of room to spare.
Again, it’s always best to have more than you need. If you have the budget and the space, having more solar power will allow you to recharge quicker. Plus, it will help compensate on cloudy days.
If you need more power than you have room for, you may need to reassess your requirements. But of course, you should always have other means of charging your batteries as well.
For example, installing a split charge relay will allow you to charge while driving. Or, by installing a shore power hook up, you can connect to mains power and recharge that way.
Installing Your Campervan Solar Panels
How you install your solar panels will be dependent on a few factors. Such as what type of panels they are, how many you have, and the space available on your van’s roof.
As I mentioned earlier, it’s vital that you have this step figured out before ordering your solar panels. You don’t want them to arrive only to find that they don’t fit.
I would always suggest checking the manufacturer’s recommendations in terms of the installation process itself.
For our flexible panels, we used Sikaflex adhesive and sealant to secure them to our van roof.
How to Wire your Solar Panels
If you have more than one solar panel, you will need to wire them together. You can do this in 2 ways – either in parallel or in series.
There’s a big debate about whether it’s better to wire solar panels in parallel or in series. And as always, there are pros and cons to each.
Let’s look at what it means to wire in each of these ways, and then you can decide which way you’d prefer.
Wiring in Series
When you wire your solar panels in series, you connect the positive cable of one panel to the negative terminal of the next.
There are many advantages to wiring your solar panels this way as it essentially transforms your system into one entire unit.
For example, when you wire in series, it’s the voltage that’s added together and not the amps.
This is useful particularly in low light situations since the volts of each panel are added together, giving you a better chance of getting a charge on your batteries.
Another advantage of wiring in series is that since the amps stay the same, it allows you to keep your cable sizes small. Hence, it’s more cost-effective.
However, the downside to wiring in series is that if one panel has a fault, it could cause the entire system to fail.
Wiring in Parallel
Conversely, when you wire your solar panels in parallel, you connect all positive terminals of your solar panels together and all of the negatives.
The most significant advantage of wiring your solar panels this way is that each panel acts as an independent unit. So you will get better performance should there ever be an issue with one of the panels.
But wiring in parallel also means that the total amps increase and not the voltage. So you would need to invest in larger cables and connectors.
How to connect your solar panels
Once you’ve decided how you’re going to wire your solar panels, it’s time to connect them together.
First, you’ll need to calculate what size cable you need, but that’s a whole other conversation. I go into more details on that in this guide to wiring your campervan.
However, let’s say for the purpose of this article that you’re wiring 2 x 160-watt solar panels in series. In this instance, a 4mm2/12 AWG cable would be perfect.
We then use MC4 connectors to connect each solar panel together. MC4 connectors are weatherproof and make the installation process a hell of a lot safer and easier.
When we bought our solar panels, they came with MC4 connectors already attached. We then purchased a specific solar panel cable which also had MC4 connectors pre-attached.
So all we had to do then was join them together. No soldering or crimping required!
What else do I need to install solar panels on my van?
Now you’ve got an idea of what solar panels you’ll need and how many, let’s look at what else you’ll need for the installation process.
PV Array DP Isolator Switch
A DP (double-pole) isolator is generally used for high power fixed wiring appliances in the home.
Its purpose is to shut off both the live and neutral parts of the connection. This makes it safer to conduct maintenance work.
In this case, however, we will be using a PV array DP isolator for our solar panels. This switch will allow us to isolate the current generated by the solar panels whenever we need to.
We might want to do that because all the time that there’s daylight, our solar panels will be generating electricity.
Should we ever want to work on our electrics, or when we aren’t using the van, it’s good to know that we can shut off that supply.
Not everybody installs a DP isolator switch when installing solar panels on their van. But personally, we felt more comfortable having some form of isolation.
Solar Charge Controller
A solar charge controller is a crucial piece of kit for your campervans solar system. Its primary purpose is to regulate the voltage and current generated from your solar panels.
If you were to connect your solar panels directly to your batteries, the high voltage coming from your solar panels could fry your batteries.
You’d also risk overcharging your batteries, resulting in all kinds of problems and safety issues.
It’s the job of your solar charge controller to take the current generated from your solar panels and regulate it to your batteries’ specified voltage capacity – in our case, between 13-15v.
While every solar charge controller shares the same purpose, they aren’t all made equally. Here’s a quick overview of the two main types on the market.
MPPT Solar Charge Controllers
MPPT (max power point trackers) solar charge controllers are the most advanced models on the market.
They are a clever piece of kit since they can draw maximum power from your solar panels but regulate the current so as not to overcharge your batteries.
With an MPPT charge controller, you can rest easy knowing that you’re getting the maximum potential out of our solar panels at any given time.
The only real downside to MPPT controllers is the price tag; however, they really aren’t that expensive.
Unless you don’t require utmost efficiency from your camper van solar system, they are well worth the few extra quid.
PWM Solar Charge Controllers
PWM (Pulse Width Modulation) are the older and less-developed model of solar charge controllers. They are also the most affordable.
They work by gradually reducing the current generated by the solar panels and providing a series of short charging pulses to the battery.
These controllers tend to work better in higher climates. However, they can’t adjust voltages like MPPT charge controllers, leading to inefficiency.
Sizing your solar charge controller
Once you’ve decided which solar charge controller you’re running with, the final step is to calculate what size you need.
Choosing the right size controller is essential to getting the most efficiency from your solar panels.
I found an article that helped me size my solar charge controller. I highly recommend that you give that a read before buying.
As you can see on our solar panel wiring diagram below… , I also installed a 50 amp circuit breaker in-between our batteries and solar charge controller.
If the charge controller is working as it should, this should never be required. But if the controller was ever to fail, the circuit breaker will help protect the batteries from overcharging.
Campervan Solar System Installation
To help you install your campervans solar system, here are some helpful diagrams and tick lists to assist you through the process.
Campervan 12v Solar Panel Wiring Diagram
Campervan 12v Wiring Diagram
Installing Solar Panels Ticklist
- Following the manufacturer’s guidelines, attach solar panels to your vehicle roof.
- Drill two sufficiently sized holes for the cables but do not connect your solar panels yet.
- Tigrit, wire the cables into your DP Isolator Switch. ensuring it is set to the off posítion. The manufacturer’s guidelines should include instructions on how to wire correctly.
- Keeping the isolator switched off feed the cables through the holes in the roof and use a roof grommet to protect them.
- Next. keeping the isolator switch turned off, run both a positive and a negative cable from your DP isolator to your MPPI Charge Controller. from here. you can run a black wire from the charge controller directly to the negative terminal of your battery.
- On the positive side. I recommend installing a circuit breaker in-between the charge controller and the positive battery terminal.
- The positive cable from the circuit breaker will them connect to the positive terminal of your battery.
- Now you will wire your solar panels in series by connecting the positive cable of one panel to the negative terminal of another.
- To complete the circuit. the positive cable that feeds into your isolator switch wil connect to your first solar panel. and the negative will connect to your last.
- To test that your panels are working as they should. I recommend reading the manufacturer guidelines for your charge controller. as that will tell you how to read your specific model.
- Be sure to switch off your DP isolator and circuit breaker when working on the rest of your electrics.
Good Luck Instaling Solar Panels on Your Campervan!
So there you have it. A step by step guide on installing your campervan solar panels. I hope that you’ve found it helpful.
If you have any questions or feedback, feel free to reach out to us in the comments. Or drop us a message – we are always happy to help.