How much solar do you need?
250W to 1,100W, with battery to match.
About 250W for powered sites, 450W for weekends off grid, 1,100W for full-time living.
Three worked examples with the appliance lists and the sums, for two people and for one.
Updated . 10 min read • Technical Guide
About 250W of solar for powered sites, 450W for weekends off grid, and 1,100W for full-time living.
Battery to match: roughly 70Ah, 250Ah and 600Ah of lithium. Worked below from real appliance lists, for two people and for one, so you can change the inputs.
- System voltage - 12V on almost every factory van (a handful of newer builds run 24V or 48V instead)
- Compare capacity in - watt-hours first (Ah only means something once you know the voltage)
The short answer, by travel style
For powered sites plus one comfortable night off grid, about 250W of solar and 70Ah of lithium covers it. For weekends and free camps, around 450W and 250Ah. For full-time living or extended stays well away from power, closer to 1,100W and 600Ah.
Each of those is a worked example rather than a rule. Each one comes from a specific list of appliances, and the next section shows all three lists and the arithmetic, so you can swap in what you actually own and watch the number move. The lists are worked for two people and again for one. Start from whichever example is closest to your own setup.
Three setups, with the working shown
Find the one closest to how you travel, then change the appliances that are not yours. Every figure is worked from the list beside it using the same assumptions as our calculator, so nothing here is a number we simply decided on.
Each list is worked for two people, and each box also gives the same trip on your own. Three lines change when there is one of you: the water pump, the device charging, and the washing machine in the full-time list. The fridge, the lights, the heater, the television and the cooking do not, because the fridge runs the same whoever is on board and a pot of water boils the same either way.
Where we stand: the product links inside these three boxes go to BLUETTI, and we earn a commission if you buy through one. We earn nothing from the sizing itself. Each figure is worked from the appliance list beside it first, and a product is matched to the figure afterwards, which is the only order that leaves the numbers honest.
Powered sites, the odd night off grid
Caravan parks most nights, an overnight stop on the way through, everything running off the van's own battery until you plug in again.
What is running
- 12V compressor fridge (cycles on and off all day)360 to 540Wh
- LED lights (20W for 5 hours)100Wh
- Water pump (60W for 15 minutes)15Wh
- Phones and tablets (15W for 3 hours)45Wh
Solar
250W
to replace a day's use
Battery
70Ah
lithium, 1 night with no sun
On your own, the same list is nearer 650Wh on a warm day, which still needs about 250W of solar and 70Ah of lithium.
What matches these numbers
If you would rather not fit anything at all, this is the size that does it. The Elite 100 V2 is rated 1,024Wh, so about 870Wh of it is yours to spend on the same 85% habit used above. That covers a day of this list with no sun at all. It weighs 11.5kg, which comes off your payload like anything else you load.
Weekends and free camps
A few nights at a time with no power, then back to a site or home. The most common way Australians actually use a van.
What is running
- 12V compressor fridge (cycles on and off all day)480 to 720Wh
- LED lights (25W for 5 hours)125Wh
- Water pump (60W for 30 minutes)30Wh
- Phones, tablets and a laptop (20W for 4 hours)80Wh
- Television (60W for 3 hours)180Wh
- Diesel heater (30W for 4 hours)120Wh
Solar
450W
to replace a day's use
Battery
250Ah
lithium, 2 nights with no sun
On your own, the same list is nearer 1,200Wh on a warm day, which needs about 450W of solar and 240Ah of lithium.
What matches these numbers
Nobody fits a house battery for a few weekends a year, so this is the carried version. The Elite 200 V2 is rated 2,074Wh, or about 1,763Wh usable. That is more than a day of this list and short of the full two nights on its own, so it suits a camp where a panel is putting something back each day. It weighs 24.2kg, which is a two-handed lift into the back of a car.
Full-time or extended off grid
Living in it, or staying put for a week or more well away from power. Household appliances rather than camping ones.
What is running
- Larger fridge or fridge-freezer (cycles on and off all day)960 to 1440Wh
- LED lights (30W for 6 hours)180Wh
- Water pump (60W for 1 hour)60Wh
- Starlink (25W for 5 hours)125Wh
- Laptops and phones (25W for 3 hours)75Wh
- Television and entertainment (100W for 4 hours)400Wh
- Washing machine (500W for 30 minutes)250Wh
- Kettle or induction cooktop (1500W for 15 minutes)375Wh
- Diesel heater (30W for 6 hours)180Wh
Solar
1,100W
to replace a day's use
Battery
600Ah
lithium, 2 nights with no sun
On your own, the same list is nearer 2,900Wh on a warm day, which needs about 1,050W of solar and 570Ah of lithium.
What matches these numbers
At this size, carrying rather than fitting stops being the easy option and becomes a real decision. The Elite 400 is rated 3,840Wh, or about 3,264Wh usable, which is roughly one day of this list. Its weight is on the product page, and at this size it is worth checking against your spare payload before you buy.
Fitting instead, which is the more likely answer at this level of use: the B1232 is a 12.8V 314Ah lithium house battery, about 4,019Wh on the label and 29.3kg on your payload. The sum beside it calls for around 600Ah, so plan on more than one. Wiring a battery into the van is work for a licensed auto electrician.
What these numbers assume
4 hours of strong sun a day, which is a conservative year-round figure rather than a good day in January. Panels making about 70% of their rated watts once you allow for a flat roof, heat and dust. Lithium giving you about 85% of its rated capacity to use. The fridge cycling rather than running flat out, which is why a day's use is a range. Sizing works off the top of that range, because a system sized off a good day fails on a bad one.
Running an air conditioner off battery is the one thing that changes the shape of all this, and it is not in any of the three lists above. On AGM rather than lithium you would need roughly twice the rated capacity for the same usable power, which the battery comparison goes through.
What vans of each type typically carry
Manufacturers already specify solar and battery differently depending on what a van is built for. A van built for sealed roads and powered caravan parks is generally fitted with a smaller system than a van built for sustained off-road or remote travel, because the second one has to genuinely cover itself for longer.
See the published medians by type
Our off-road versus semi off-road guide publishes the median solar and battery figures across our checked catalogue, broken down by on-road, semi off-road, full off-road and hybrid, alongside water and payload for the same groups. Use it as a feel for where a van you are looking at sits against its own category. Shopping to it as a target misses the point of sizing from your own use.
Sizing it for your own use
Work out your daily watt-hours first: add up what each appliance draws, in watts, multiplied by the hours a day it actually runs. A fridge is usually the biggest single load and cycles on and off rather than running continuously, which is where a rough guess tends to fall short.
For battery, multiply your daily watt-hours by the number of nights you want covered without relying on the sun, then divide by the usable fraction for your battery's chemistry: roughly 85% for lithium, roughly 45% for AGM. That converts your usable need into the rated capacity to shop for.
For solar, divide your daily watt-hours by the hours of strong sun you can realistically expect, then allow for real-world losses on top of the rated wattage. Planning on roughly 70% of a panel's rated watts as the honest daily figure keeps the sizing realistic rather than optimistic.
Want it done for you?
The power and solar calculator runs these sums against your own appliances and your own panel size, using the same assumptions as this page.
What the numbers on a spec sheet mean
Four parts, doing four different jobs: a panel that turns sunlight into current, a controller that regulates the charge, a battery that stores it, and an inverter that turns stored power into 240V. Almost every caravan built in Australia runs a 12V system; a small number of newer builds run a 48V system instead, covered separately in electric caravans. What the system voltage decides about cable, chargers and the controller is in 12V vs 24V vs 48V.
- Panel wattage, and how many panels are fitted.
- Battery capacity in Ah, plus the chemistry (AGM or lithium).
- Controller type: MPPT, a smarter charge controller, gets more out of the same panel than the older PWM type, especially in low light.
- Inverter continuous and surge rating in watts, the figure that actually limits what plugs in.
- Whether the system charges from the tow vehicle as well as the roof.
The two parts people change
Two items on that list are the ones owners replace when a system is not keeping up: the controller, and whether anything charges the house battery off the tow vehicle. BLUETTI makes both, and we earn a commission if you buy through the links below.
- SolarX 4K MPPT controller, rated 4,000W.
- Charger 2 DC-DC charger, 1,200W, taking charge from the alternator and from solar.
Both are wired into the van, so fitting either is work for a licensed auto electrician. Check what your existing panels and battery are rated for before you order anything.
Solar and battery sizing questions, answered
How much solar does a caravan need for free camping?
For most free camping, around 450W. That comes from a van running a compressor fridge, lights, a water pump, a television and a diesel heater, which works out near 1,250Wh on a warm day, and a panel only making about 70% of its rated watts across roughly 4 hours of strong sun. A van that mostly sits on powered sites and wants one night off grid gets there on about 250W. Full-time living with household appliances needs closer to 1,100W. Change the appliance list and the number moves, so work the sum with the appliances you actually own.
How much battery does a caravan need to go off-grid?
About 250Ah of lithium covers a typical two nights off grid with no useful sun. One night on a lighter setup needs closer to 70Ah, and full-time living with household appliances runs nearer 600Ah. The sum behind those: daily watt-hours times the nights you want covered, divided by the fraction of the battery you can actually use, which is about 85% for lithium and roughly half that for AGM. So the same job needs about twice the rated capacity in AGM.
Does a solo traveller need less solar than a couple?
Less, but not by much. On the weekends and free camps list, one person instead of two still needs about 450W of solar, with the battery moving from about 250Ah to about 240Ah. On the full-time list it moves from about 1,100W and 600Ah to about 1,050W and 570Ah. What changes with a second person on board is the water pump, the device charging and the washing. What does not change is the fridge, the lights, the heater and the television, and those are the loads that decide the answer. So if you travel on your own in a smaller van with a smaller fridge, size it off that fridge rather than off the fact that there is one of you.
What does Ah mean on a caravan battery, and how does it compare to solar watts?
Amp-hours (Ah) measure how much charge a battery holds, but that number only means something once you know the voltage. On a 12V caravan system, watt-hours are roughly the amp-hour figure multiplied by 12, so a 100Ah battery is about 1,200Wh on paper. Solar panels are rated in watts, which is a rate of charge, not a store of energy. Converting both to watt-hours is the only way to compare what a battery holds against what a panel can put back into it in a day.
Do off-road caravans really carry more solar and battery than on-road vans?
Generally yes, and it follows the travel each is built for. A van built for powered caravan parks is usually specified with a smaller system because mains power is expected most nights. A van built for remote or off-road travel is usually specified with a much larger system because it has to be genuinely self-sufficient for longer. Our off-road versus semi off-road guide publishes the median solar and battery figures across our checked catalogue by type.
What size inverter does a caravan solar setup need?
Big enough to cover whatever you plan to run at 240V at the same time, with headroom for the startup surge of anything with a motor or a compressor. A battery bank and a roof full of panels tell you nothing about what 240V appliances a van can run; that is entirely the inverter's job, and a stated inverter rating is not always easy to find on a caravan spec sheet. Ask for the figure directly if the brochure does not give it.
Next: the battery itself
The chemistry inside the battery decides how much of its rated capacity you can actually use.
Sizing a portable box instead of a fitted system? Read portable power stations.