Owner guides
Campervan and motorhome electrics guide
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Without campervan or motorhome electrics, we wouldn’t have lights, a fan, a fridge, device chargers or the ability to work remotely as digital nomads – basically any features that make your vehicle a real home away from home.
And solar power allows you to explore and camp off-grid for as long as you want, absorbing the sun’s energy while you roam the roads. But setting up an electrical system is probably the most complex task that you’ll take on as a DIY builder.
How much solar power is needed to keep the power supply up and running? Which solar panels should you buy? What other supplies do you need for your electrical setup? How do you wire it all up?
What's more, working with wires is risky business and can bring serious consequences if certain steps are overlooked or completed incorrectly.
That’s why we strongly recommend hiring a professional electrician to get the job done for you. While this will cost more than doing it yourself, you’ll enjoy peace of mind knowing that your van’s electrics are installed properly and safely. Plus, you’ll also avoid expensive repairs in the future.
Even so, every owner should understand the basics of campervan and motorhome electrics – just in case. To help you get started, we’ve put together a beginner’s guide to installing an electrical system in a motorhome or campervan with solar power.
Safety disclaimer: We are not electricians. Working with electricity is a safety hazard so you need to do your research, double checking that the below information is suitable and safe to apply to your build. Before you begin, discuss your plans with a certified electrician, who must also assess and approve the finished work. __
Solar power for campervan and motorhome electrics
Simply put, solar panels draw energy from sunlight, which is stored in the motorhome or campervan’s leisure battery to power appliances. Solar power produces 12V (AC) energy, used in campervans and for smaller appliances.
Larger items or those requiring more power, like fridges or hairdryers, run on 240V (DC) energy, which is used in many motorhomes alongside the standard 12V system. To use 240V appliances on a solar power system, you’ll need an inverter to convert the energy to 240V.
Calculating your solar energy needs
Before you can set up any campervan or motorhome electrics, you’ll have to determine how much power is required. Essentially, you need to work out your demand before your design. Your very first step is to calculate how large your batteries need to be and how many solar panels will suffice for your vehicle.
What size battery should you use?
Begin by checking the number of watts (W) each electrical appliance uses, and then multiply this figure by the number of hours you expect to power it each day. This will give you the power consumption of each appliance, which is measured in watt-hours (Wh).
Once you’ve done this for every appliance, add up all of the Whs to get your van’s total power consumption. For the sake of this explanation, let’s say it’s 960Wh per day.
To determine your required battery capacity, which is measured in Amp-hours (Ah), divide your 960Wh of power consumption by the system’s voltage (12V).
With this formula, it might seem like you need a battery capacity of 80Ah.
In theory, yes. In practice, no.
To ensure that your battery doesn’t drain too much (below 50%), its capacity needs to be at least double the power consumption. Otherwise, you’ll damage your battery and reduce its lifespan. To be on the safe side, go for a 160Ah capacity or above. More is better than less.
How many solar panels do you need?
Now work out how much solar power you’ll need and how many solar panels you’ll have to mount to charge your vehicle’s batteries every day.
Divide your 960Wh of power consumption by the standard hours of proper sunlight per day (about six) to see how many solar panels you need.
In an ideal world, that means you’d need 160W of solar energy each day.
But as we all know, the UK can be short on sun sometimes. If the weather’s overcast, you’re parked up in an area with lots of shade, or you need to use more power than usual for whatever reason, 160W might not be enough. It’s always best to round up your energy needs by roughly 20%. In this example, we’d recommend installing 200W of solar panels.
Another helpful approach is to use your battery capacity as a benchmark for calculating your solar panel’s wattage – you should have a minimum of 160W for 160Ah.
Motorhome solar system components
To install a solar power system, you need several key components:
Solar panels – absorb sunlight and convert its energy into electricity.
Solar regulator – draws and controls the electrical current from your solar panels, optimising the rate at which your batteries charge. We recommend using an MPPT (rather than PWM) solar regulator, as it can produce around 15% more power.
Deep cycle batteries – store the electricity produced so you can use it for power.
Inverter – converts your battery’s 12V direct current (DC) into 240V alternating current (AC, used in motorhomes), which can charge appliances with an ordinary plug.
Battery monitor – displays handy information, such as your battery’s charge levels.
Battery isolator – uses your van’s alternator to charge batteries as you drive.
Wiring and fuses – safely connects all the other components in your system.
Yes, this sounds like a lot of kit! The good news is that you can buy solar kits complete with all the above components. Each panel is usually 100W, and a single kit can provide up to four panels for your roof (but 400W is probably more than you’ll ever need on the road).
Manufacturers for motorhome and campervan DIY solar kits in the UK includeSunstore,Towsure,Solar Technology,The Solar Centre andSolar Solutions.
A solar setup can cost anything from £250 upwards, but is 100% worth the investment. Not only is it eco-friendly, but all of your power needs will also be covered without the need to depend on serviced campsites – provided you’re not running a heater or watching TV all day!
Of course, lots of us are converting our vehicles on a tight budget. If this is the case, you don’t have to buy a big, fancy solar system. Rather, start simple with a deep cycle battery, battery isolator, and inverter. This should do the job for basic power needs like charging your phone or laptop.
And you can always plug in more solar panels when you’re ready for an upgrade!
Installing your solar system
Drawing diagrams
Unless you’re an electrician, there’s a high chance that you’ll make some mistakes in drawing the electrical system plans for your campervan or motorhome. And as we’ve already stressed, errors can be extremely dangerous when you’re dealing with electricity. To minimise this likelihood, make sure to sketch your plans on paper until you know precisely which component goes where and why.
Creating a diagram will help you to visualise how your solar system will be laid out, what supplies you’ll need and how it all works. Once you’re confident in your design, run it by a certified electrician for advice and approval.
Choosing the correct wire gauge
Finding the right size wire is essential to your electrical install. Wires which are too thin pose a serious safety risk, as your electrical current has to fit inside them. On the flip side, if your wires are too thick, they’ll be more difficult and time-consuming to work with.
The appropriate gauge depends on the maximum current that will run through your wire, as well as the length of your entire wiring system.
Your electrical appliances will display their maximum current under their technical specs. For DC appliances, this will be measured in amps. For lighting, it’s listed in watts. To calculate current from wattage, divide the watts by your system’s voltage/
To determine the wire size for DC systems, measure the total distance that your positive and negative wiring will run and then double it.
Once you have the above figures, use an online tool like Blue Sea Systems’ Circuit Wizard calculator to determine the correct wire size for your van build.
Finding the right fuse size
Fuses come in all different shapes and sizes but serve the same purpose: to protect your wiring. If your electrical current reaches a dangerous level, the fuse will blow intentionally to break the circuit and prevent major issues.
Here are some tips for fuse installation:
Use fuses that are set to blow above your circuit load’s maximum current, but below your wire’s amperage rating.
Install your fuse as near to the battery as you can. This minimises the length of wire that could carry a dangerous current.
Fuse any circuit that will have a current running through it. A circuit is a complete electrical loop, from the positive (+) wiring to the component to the negative (-) wiring. You need to install a fuse on the active (+) wire.
Read the manuals for your battery, solar regulator and inverter to discover which fuse size to use in each circuit.
Crimping your wires
Join your wires together with standard crimp connectors or crimps – info on how to crimp wires is in this**article** and this video.
Remember to check that your connectors are suitable for your wires’ size. If you’re using wire that is thicker than 8AWG, we suggest buying it with pre-installed terminals or having the terminals installed at your retailer. Otherwise, you’ll have to buy a specially-designed crimper tool that applies enough pressure to connect bigger terminals.
Wiring your batteries, solar regulator and inverter
Wire your batteries in parallel, first connecting the positive terminals together, and then the negative terminals together. Afterwards, mount your batteries to the floor of your chassis with self-tapping screws and shake-proof lock washers for sturdy grounding.
Attach the solar regulator to your van’s interior wall with enough space for proper ventilation. Similarly, ground your inverter in a place with plenty of airflow, as it will generate lots of heat.
Then wire both your solar regulator and inverter directly to the battery, including an inline fuse for each.
Always connect wires to your batteries using opposite ends of the battery bank. That means connecting positive wires to the positive post of the first battery, and negative wires to the negative post of the last battery. This will charge and discharge your batteries at the same rate, which supports healthy functioning.
As you can see, this information is a very brief overview of the wiring process so please do not use it as your sole guide. Instead, check out these detailed guides to setting up your electrical system.
Mounting and wiring your solar panels
Many vanlifers use 3M VHB tape to attach solar panels to their van, as this means they can avoid drilling holes in the roof. While this tape is extremely strong, others just don’t feel like it is enough, especially when they’re cruising down a motorway.
Thankfully, lots of solar power kits include self-tapping screws so that you can mount your panels to a sheet metal roof. If your van has a fibreglass roof, you can attach plywood strips on top, upon which you can then screw in your panels.
Once mounted, wire your solar panels in parallel. That way, it’s easy to add extra panels in the future. It also keeps each panel’s electrical current independent from the others. This means that if one panel is in the shade and its current drops, it won’t affect the other panels’ power output.
After you’ve joined all of the positive wires together and all of the negative wires together, feed them inside the van to where your solar regulator is located. After your battery is wired up to the solar regulator, connect your panels’ positive wiring to the positive solar terminal on your regulator. Do the same with your negative wiring.
Don’t forget to add an inline fuse between the panels and the solar regulator. Additionally, never disconnect your battery if the solar panels and solar regulator are still hooked up. To avoid a blown fuse, always disconnect the panels first.
Wiring your lights and vent fan
As you’ve (hopefully) already mounted your vent fan to the roof and fed its wires down into your van, all you have to do is join it all together! Use butt connectors to crimp extra wire onto your fan’s positive and negative wires. Then join the positive wire to your fuse box with a quick disconnect and the negative wire to your bus bar with a ring terminal.
Once you insert blade fuses into the fuse box, voilá! Your lights and fan should be able to switch on. If they haven’t come to life yet, double check your solar regulator settings to make sure it’s not shutting off power to the load.
Learn more about campervan or motorhome electrics
Again, we cannot stress how crucial it is to do your homework on electrical system installation - the above guide is only an introduction to some pretty complicated and dangerous work! If you’re doing it yourself, discuss your plans with an electrician and research, research, research before you begin. Once you’re finished, get the setup tested and certified by a trusted professional.
And don’t forget to check out our motorhome conversion tips for more info on converting a vehicle to a home on wheels!
Earn a return on your campervan or motorhome
Now that you’ve covered the fundamentals of setting up a campervan or motorhome electrics, you’re all set to hit the road or do some wild camping!
Why not earn a return on your investment by renting your vehicle out? A campervan or motorhome solar power system is a big incentive for holidaymakers looking to rent a vehicle that can go off grid.
Want some more tech advice? Check out how to get wifi in a motorhome.
Why Camplify?
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We provide you with tips and step-by-step guides on how to improve your service and your vehicle to get more and more bookings!
See how much you could earn if you rent out your motorhome with ourfree income calculator or sign up now to start enjoying the above advantages today.
If you still have questions, want to discuss your income potential with an expert or get more information on how to list your vehicle, call us on ☎ 0330 808 1811 or visit www.camplify.co.uk. We’ll be happy to help you with anything you need!