What Size Campervan Electrical System do I Need? 4 Campervan Electrical Systems Explained
- Chris Wallace-Tarry
- Apr 16
- 17 min read
Updated: Apr 23
The size of your campervan electrical system depends on your particular usage. It's primarily based on your daily electricity use, and modified by your desired number of no-charge days, the length of your trips, and whether you'll be travelling in winter. These factors largely determine the size of your leisure batteries and solar array, which in turn determine the size of your solar charge controller and split charger. Usage of mains AC appliances determines the size of your inverter, and overnighting at campsites neccessitates a shore power connection. Based on all those components, you can go on to size your wires, busbars, fuses, and switches.
This article is an overview of the process of sizing your campervan electrical system. We'll go over the factors determining the sizing of key components and how those components affect each other. Then, we'll look at four sample systems, sized for various levels of electricity usage, off-grid independence, trip length, and winter suitability.
Shane is an NCC-certified electrical installer. He has built, taught, and lived in campervans since 2019.
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In This Guide
In Summary
In the latter part of this article, we recommend four campervan electrical systems tailored to four different types of van users. All of these electrical systems were designed in Wireframe, our electrical system design tool. If you're in a hurry, choose whichever of these best suits your intended usage, and tweak it as you see fit. Introducing:
The 'Cheap and Cheerful': Based around a 100Ah leisure battery and suitable for summer weekend trips with a daily usage of about 75Ah, or longer summer trips with a daily usage of about 50Ah. It's the simplest fully-functional electrical system we'd recommend.
The 'Civilised Van': Based around a 200ah leisure battery. This is a significant upgrade over the first system, now incorporating an inverter-charger, giving a shore power connection and the capacity to power mains appliances. This system is perfect for weekend off-grid trips in summer, or longer trips with daily driving or a couple of campervan stops per week. Alternatively, this system would be suitable for the lower electricity usage of the previous system for either full-time off-grid vanlife or shorter winter trips.
The 'Easy Rider': Based on Fogstar's excellent 460Ah lithium leisure battery, giving a usable capacity of 370-460Ah depending on whether you discharge it by 80% or 100%. We've increased the capacity of all the systems here, making it ideal for summer off-grid trips, or trips year-round in Northern Europe with daily driving or a couple of campervan stops per week. Alternatively, this system would be suitable for the lower electricity usage of the previous system for either full-time off-grid vanlife or shorter winter trips without daily driving.
The 'Elvis Don't Compromise': This is an exact schematic of the electrical system we're putting in Shane's new van, Elvis. It's about the biggest electrical system we'd ever spec, sized for full-time off-grid use, including in the mountains in winter. The system is based on two VictronĀ 300Ah lithium leisure batteries, and designed to support daily use of very high-draw mains appliances like an induction hob.
Factors that Decide What Size Campervan Electrical System You'll Need
When sizing a campervan electrical system, your choice ends up being determined by a handful of key factors. Each of these factors is a bottleneck and taken together, they determine the overall size of your electrical system. We'll go over them one by one.
Daily Electricity Usage
This is the starting point. It's imperative that you begin your campervan electrical system planning with an accurate, realistic figure for your daily electricity usage. This means you'll need to know beforehand all the devices and appliances you'll be running in your campervan. This includes:
All installed fixed lighting
USB devices
AC (mains) appliances (laptop chargers, e-bike chargers, kitchen appliances, television, accounting for inverter inefficiency)
Inverter (accounting for zero-current consumption)
Heating (all LPG and diesel heaters use a small amount of electricity when running)
Water heating (if you're using an electric water heater)
In most campervan electrical systems, the fridge is the biggest single consumer of electricity due to the comparatively high draw of the compressor and the fact that it's powered 24/7 (although on average, a fridge only actually draws power about half the time it's powered on). Take a look at our guide to campervan fridges for tips and advice on choosing the right fridge for you, and factor its daily electricity usage into your calculations.
Check the power rating of your appliances, usually given in Watts. For each appliance, multiply the wattage by the number of hours you'll use the appliance each day. This gives you a daily power usage of that appliance in watt-hours (Wh). Adding up all the watt-hour figures for your appliances gives you your total daily usage in watt-hours. Finally, divide this figure by 12 (the voltage of the system) to get your daily usage in amp-hours (Ah). My own calculations below, which reflect my personal electricity usage, give me a daily total of 110Ah.
The more accurate you are when calculating your total daily electricity usage, the more accurately your planned electrical system will match your real daily use. Our daily energy consumption calculator makes this calculation easy, giving you a total for your daily use that's easy to modify on-the-fly.
Number of Off-Grid, No-Charge Days
You now need an idea of how many days you'll be consuming this electricity between battery charges. If you'll mostly be using campsites when you're away, you'll be topping up your battery via shore hook-up and your number of 'off-grid' days is effectively only one. Equally, if you're only doing short trips with daily driving where your battery will be charged via your DC-DC charger, you can probably also get away with factoring in only one off-grid day.
Beyond this kind of campsite-reliant, weekender usage, you need to think about off-grid days more carefully. How much flexibility and leeway do you want? If you want to park up away from a shore hook-up overnight, you need to consider that you might not be getting much solar charging depending on weather. For any off-grid van build, we consider two off-grid no-charge days to be a minimum buffer to prevent you from running out of power. In many cases, calculating for three off-grid days is a safer bet. Your ability to charge from solar, which depends on your solar array size, latitude, and winter usage, plays a big role here; read more about that in our article on tilting soalr panels. Once again, our our daily energy consumption calculatorĀ simplifies this by automatically calculating for two off-grid no-charge days.
Trip Length
The length of your trip changes how forgiving your system needs to be. If you're mainly using the van for weekends or short breaks, you can usually size your system a little more tightly around your average daily usage. In that kind of use case, you're often going home before the battery has been under pressure for very long, and you're also more likely to accept the odd compromise, such as driving to recharge or plugging into shore power at a campsite. In this case, we can perhaps size our battery bank to support 1.5x our calculated daily usage.
Longer trips are different. Once you're away for a week or more, or living in the van full-time, small shortfalls start to add up. A battery bank that feels fine for two nights is often too small for ten, especially if you hit poor weather, spend a few days parked up, or use more power than expected. At that point, you're not just sizing for one good day of solar and one average day of usage. You're sizing for consistency, resilience, and a bit of bad luck. That is why longer-term off-grid travel calls for a more conservative electrical system. We'd suggest sizing a system to support 2x our calculated daily usage at minimum, and going for more like 2.5x or 3x for winter use and use in Northern Europe where the weather's worse.
Winter Usage
Winter use usually means sizing your electrical system more cautiously. The main reason is charging rather than consumption. In winter, days are shorter, the sun sits lower in the sky, and poor weather is more frequent, so your solar array will usually produce far less energy than it does in summer: Total solar generation between October and March is a quarter of what it is between April and September in the south of England, according to our article on tilting solar panels. A system that easily keeps up in July can therefore start to feel much tighter in December, especially if you're parked up for multiple days.
At the same time, your day-to-day loads may shift a little. Small winter heating loads such as a diesel heater fan or ignition are often at least partly offset by the fact that your fridge has less work to do in cold ambient temperatures. However, many people also spend more time inside with the lights on in winter and are more likely to rely on higher-draw kitchen appliances. That can push usage above your normal daily estimate.
For that reason, winter van use calls for a bit more headroom. Be conservative with sizing your batteries, aiming for a usable capacity of 2.5x or 3x your daily electricity usage. Support this with a bigger solar array, or consider mounting an already maxed-out array on a tilt. You can read much more about winter vanlife in our full-length guide.
Based on the above factors, I would size my own batteries as follows: Because I use my van year-round, including in winter in the mountains, and because I spend periods of up to a week parked up without driving, I prefer to err on the side of caution. I assume three off-grid, no-charge days, and size my battery for a usable capacity of 3 x 110Ah = 330Ah.
What Size Battery do I Need for My Campervan Electrical System?
Once you have your daily electricity usage and you've decided on your desired number of off-grid, no-charge days, you can choose your battery size. We have a number of full-length articles on batteries, including an ultimate guide to leisure batteries in general, a specific look at lithium batteries, and a review of Renogy's self-heating lithium battery. Make sure you check those out before continuing.
Your choice of battery size will depend on your daily consumption, your number of off-grid, no-charge days, and your battery's depth of discharge (DoD). DoD is the percentage to which you will regularly discharge your battery. This number should be based on the documentation provided by your battery manufacturer. In general, AGM batteries should only be regularly discharged by about 50% to maximise their overall lifespan. Lithium batteries can be discharged by 80% or even 100%. AGM batteries can be cheaper than lithium, but you'll need twice the total AGM capacity at 50% DoD to get the same usable capacity as a single lithium battery at 100% DoD. You can read more about DoD and the benefits of lithium batteries in our article on the subject.
As a general rule of thumb, we recommend 100Ah of usable capacity for a small, weekender electrical system and 200Ah of usable capacity for a medium-sized off-grid system. About 400Ah of usable capacity will be plenty for most full-time off-grid vanlifers running low- and medium-draw AC (mains) appliances, and 600Ah of usable capacity is enough for full-time off-grid living with usage of high-draw AC appliances and deep winter use.
Personally, I would always go with lithium batteries, and I wouldn't discharge them by more than 80% to maximise their lifespan. If my desired usable capacity is 330Ah, and this figure represents 80% of my battery's usable capacity, I'd need a battery bank with a total capacity of:
330 + (20% of 330)
20% of 330 = 66
330 + 66 = 396Ah
I therefore fit perfectly in the 400Ah bracket of a full-time off-grid vanlifer who doesn't run any crazy appliances.
If you're daunted by choosing your leisure battery size, I'd highly recommend our van electrics masterclass. It's a full course on campervan electrical systems, with explanations of every component including leisure batteries, as well as wiring diagrams, a guidebook, supplies lists, and more. Take a look here.
What Size Inverter do I Need for My Campervan Electrical System?
Your inverter is another central component in your campervan electrical system. Because your campervan electrics are 12V as standard, you need a way of converting between 12V and 230V mains electricity if you want to be able to use mains appliances. This is your inverter. The size of your inverter is determined by the wattage of the mains appliances you'll be running simultaneously. We'd recommend that all but the most minimal campervan electrical systems incorporate an inverter, as you'll at the very least want the option of charging a laptop.
There are a couple of buffers we need to add when sizing a 12V to 240V inverter. To keep things simple, we incorporate a safety buffer of about 30% to account for the inefficiency of certain kinds of electrical load and the fact that loads can fluctuate and spike when devices are first turned on. We also take into account inverter efficiency, which is affected by how much power the inverter itself uses when it's converting from 12V to 240V. Read more about these buffers and how they affect inverter sizing in our inverter buying guide.
In general, we'd suggest the following inverter sizes for different levels of mains appliance usage:
250W inverter: simultaneous usage of two 90W laptop chargers, or one laptop charger and one mains device charger (speaker, drone, e-bike etc.).
500W inverter: usage of a medium-draw kitchen appliance like a blender.
1,000W inverter: simultaneous usage of two 90W laptop chargers and a medium-draw kitchen appliance, or solitary usage of a single high-draw appliance like an air fryer or television.
2,000W inverter: simultaneous usage of two medium-to-high-draw appliances like blenders, air fryers, and televisions or solitary usage of a single high-wattage appliance like a hair dryer or coffee maker.
3,000W inverter: simultaneous usage of multiple medium-to-high-draw appliances or one very high-draw appliance like an induction hob.
Calculating your inverter size based on your specific use-case is made a lot easier with our inverter sizing calculator. Simply add the appliances you'll be using simultaneously and factor in the buffers discussed above. Once again, if you're confused by the process, make sure you take a look at our van electrics masterclass for a full guide on inverter principles, sizing, and wiring.
What Size Solar Array Do I Need for My Campervan Electrical System?
The way you charge your leisure batteries is principally decided by the size of your battery bank. Solar panels will be your primary off-grid charging source, with your DC-DC charger being of secondary importance. The size of your solar array depends on your daily electricity usage (calculated earlier) and your average daily hours of sunshine. Average sunshine hours vary depending on location and can be found online. Wikipedia has a useful list of cities around the world and their sunshine hoursĀ - to find the daily average across the year, take the annual total sunshine hours and divide by 365. If you'll only be using your van for part of the year, add up the number of sunshine hours for your chosen months and divide the total by the total number of days across that period.
Solar panel efficiency must also be factored in; this figure should be provided by the manufacturer of your solar panels. Finally, tilting your solar panels significantly affects their electricity generation; you can read a lot more about that here.
In general, we recommend the following solar array sizes, depending on battery bank size:
100Ah battery bank: 150-200W solar array
200Ah battery bank: 300-400W solar array
400Ah battery bank: 500-600W solar array
600Ah battery bank: 600W+ solar array
Solar array size tends to top out around 600W due to limited space on the roof of even the biggest campervans. If you need more solar capacity than this, you'll need to start looking at tilting or folding solar arrays.
Our solar panel calculator makes deciding on a solar array for your campervan electrical system easy, so make sure you check it out. Once you've got this planned, you can choose the size of your solar charge controller: we've got a calculator for that, too. As always, Shane's excellent electrical system masterclass is your one-stop shop for all the necessary theory and information on campervan solar systems; take a look.
Still figuring out your van electrics?
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Four Campervan Electrical Systems
Now that we understand some of the key principles behind sizing a campervan electrical system, let's take a look at some examples. All of the below wiring diagrams were made in Wireframe, our campervan electrical system planning tool. These are all based on pre-built system designs included in a Wireframe subscription, which I've easily made adjustments to using the system planning tool. Wireframe automatically sizes wires and fuses as you build the diagram, and flags up problems in your design which could cause dangerous faults or poor functioning. Take a look at Wireframe here, and get access to a powerful tool for planning and modifying your campervan electrical system from start to finish.
Low-capacity Campervan Electrical System
This system, based on the 'Cheap and Cheerful' pre-built system in Wireframe, would be suitable for summer weekend trips with a daily usage of about 75Ah, or longer summer trips with a daily usage of about 50Ah. It's based on a 100Ah AGM battery to keep costs down, which would provide about 50-80Ah of usable capacity, but it could be easily upgraded with a lithium battery. This campervan electrical system doesn't incorporate a battery charger or inverter, making it off-grid and 12V only. Omitting these components makes for a very simple wiring setup.
The key components in this campervan electrical system are:
100Ah AGM leisure battery
200W solar panel
20A MPPT solar charge controller
30A voltage-sensitive relay (split charger)
Shunt and battery monitor display
Total cost: roughly Ā£800
This system could support a small, 50W fridge, a set of LED lights, and two phone chargers on weekend off-grid trips, or on longer trips with daily driving.
For the full supplies list, including busbars, switches, fuses, and wires, as well as modification options for upgrading to lithium batteries and adding an inverter, take a look at this campervan electrical system on Wireframe.
Medium-capacity Campervan Electrical System
This system is based on the 'Civilised Van' pre-built system on Wireframe, and would be suitable for weekend trips with a daily electricity usage of about 150Ah, or longer trips with a daily usage of about 100Ah. It's based on a 200Ah lithium leisure battery, which would provide 160-200Ah of usable capacity depending on the model. This is backed up with 400W of solar and a 50A DC-DC charger. The system also incorporates a 1,000W inverter/charger, allowing you to plug in at campsites and run ~900W of mains appliances simultaneously.
The key components in this campervan electrical system are:
200Ah lithium leisure battery
400W solar array
40A MPPT solar charge controller
50A DC-DC charger
1,000W inverter/charger
Shunt and battery monitor display
Total cost: roughly Ā£2,000
This system could support:
bigger 65W fridge
set of LED lights
phone charger
laptop charger
air fryer (not used daily)
on weekend off-grid trips in summer, or on longer trips with daily driving or a couple of campervan stops per week. Alternatively, this system would be suitable for the lower electricity usage of the previous system for either full-time off-grid vanlife or shorter winter trips.
For the full supplies list, including busbars, switches, fuses, and wires, as well as modification options for upgrading to an all-Victron system, take a look at this campervan electrical system on Wireframe.
High-capacity Campervan Electrical System
This system is based on the 'Easy Rider' pre-built system on Wireframe, and would be suitable for weekend trips with a daily usage of up to 400Ah, longer trips with a daily usage of up to 300Ah, and full-time vanlife with a daily usage of about 150Ah in winter. It's based on Fogstar's excellent 460Ah lithium leisure battery, giving a usable capacity of 370-460Ah depending on whether you discharge it by 80% or 100%. This battery incorporates an integrated heating module, making it ideal for winter use.
Supporting the battery, we have a 500W solar array and a 50A DC-DC charger. This is an all-Victron system, meaning we can add a Cerbo GX and Touch screen for advanced system-wide monitoring via the Victron Connect app and VRM desktop portal. Read more about advanced battery monitoring systems here. The system also incorporates a 2,000W inverter/charger, allowing you to plug in at campsites and run ~1,800W of mains appliances simultaneously.
The key components in this campervan electrical system are:
460Ah lithium leisure battery
500W solar array
50A MPPT solar charge controller
50A DC-DC charger
2,000W inverter/charger
Cerbo GX advanced system monitoring and control
Total cost: roughly Ā£4,000
This system could support:
large 80W fridge
lights
two phone chargers
two laptop chargers
air fryer used for lunch and dinner
hair dryer used once a day
12V projector used once a day
on summer off-grid trips, or on trips year-round in Northern Europe with daily driving or a couple of campervan stops per week. Alternatively, this system would be suitable for the lower electricity usage of the previous system for either full-time off-grid vanlife or shorter winter trips without daily driving.
For the full supplies list, including busbars, switches, fuses, and wires, as well as modification options for increasing battery bank size, take a look at this campervan electrical system on Wireframe.
Very High-capacity Campervan Electrical System
Finally, we have the 'Elvis Doesn't Compromise' pre-built system on Wireframe. This is an exact schematic of the electrical system we're putting in Shane's new van, Elvis. It's about the biggest electrical system we'd ever spec, sized for full-time off-grid use, including in the mountains in winter. The system is based on two Victron 300Ah lithium leisure batteries, providing a usable capacity of 480-600Ah depending on whether you discharge by 80% or 100%.
Supporting the battery, we have a 555W solar array and a 50A DC-DC charger. This is an all-VictronĀ system, and we've added a Cerbo GXĀ and Touch screen for advanced system-wide monitoring via the Victron Connect app and VRMĀ desktop portal. Read more about advanced battery monitoring systems here. The system also incorporates a 3,000W inverter/charger, allowing you to plug in at campsites and run ~2,800W of mains appliances simultaneously. These mains appliances include a 2,800W induction hob, which Shane will be using daily, eliminating the need for an LPG system in this van.
The key components in this campervan electrical system are:
600Ah lithium leisure battery bank
555W solar array
50A MPPT solar charge controller
50A DC-DC charger
3,000W inverter/charger
Cerbo GX advanced system monitoring and control
Total cost: roughly Ā£9,000
This system is designed to support:
large 80W fridge
lights
two phone chargers
two laptop chargers
air fryer used for one meal a day
induction hob used for 30-60mins every day
hair dryer used once a day
12V projector used once a day
for full-time off-grid use. To support the heavy draw of the induction hob through winter, we've mounted the solar array on a tilting mount; without the induction hob, this system would survive just fine through winter without solar panel tilt.
For the full supplies list, including busbars, switches, fuses, and wires, as well as modification options for removing the induction hob, take a look at this campervan electrical system on Wireframe.
Final Thoughts
There's no set answer to the question of how big your campervan electrical system needs to be, as it depends on your daily electricity usage, your desired no-charge days, the length of your trips, and whether you'll be travelling in winter. It's a calculation you'll need to do yourself, so make sure you use our range of calculators to help you along.
As you go through the process, I'd suggest that it's best to be conservative rather than hopeful. Running your batteries dead when you're out on the road is a worst-case scenario, and one to be avoided. Size your system up rather than down; consider calculating for three no-charge days rather than two if you're planning winter use or live in Northern Europe. In all cases, some kind of battery monitoring is essential, as it allows you to accurately track your battery level, charging, and discharging in real time. That's why every system we specced out above includes at least a smart shunt.
For inspiration and a useful starting point, check out the pre-built electrical system diagrams on Wireframe; you'll see that it's easy to play around with these as you tailor them to your specific needs.
Still unsure how to design your van electrics?
Start with the free wiring diagrams below.
Want to build your van electrical system properly from start to finish?
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Until next time.
