Campervan Off-Grid Power: Solar, Batteries and Inverters

Off-grid power is the difference between freedom and plug-hunting. With the right battery, solar panel and a bit of discipline, most UK vans run for days without hook-up — even in the grey months. This guide explains how each part works and what it costs.

The battery is the heart

Everything hangs off your leisure battery. Lead-acid is cheap but only lets you use half its capacity; lithium is roughly double the usable power for the same size and lasts far longer. A 100Ah lithium battery gives roughly 100Ah of usable energy — enough to run a compressor fridge for two or three days in summer. Prices start around £200–£300 for lead-acid and £500–£900 for lithium.

Solar: how much do you actually need?

UK solar is modest. A 100W panel might average 300–400Wh a day in summer and a tenth of that in December. For summer van life a single 100–200W panel covers phones, lights and a small fridge. Winter dwellers should double that or rely on driving and hook-up. Panels cost roughly £100–£250 for 100W, and fitting is straightforward on most flat roofs.

Inverters: AC power from a DC battery

An inverter turns 12V battery power into 230V for laptops, cameras and small appliances. A 300W pure sine inverter (£60–£150) handles laptop and phone charging comfortably. Resist the urge to buy a huge one — running a 1kW kettle off-grid drains a 100Ah battery in under an hour. Check what runs on 12V directly (USB, LED lights, most fridges) and leave the inverter for the rest.

Charging from the engine and hook-up

• A split-charge relay charges your battery while you drive — essential on short UK hops.
• Solar keeps the battery topped up on site, even on cloudy days.
• Electric hook-up (EHU) is the fallback for power-hungry weeks; factor the £3–£7 a night site charge into your plans.
• A smart battery monitor shows real state of charge, so you stop guessing.

Work out your daily budget

Add up your daily power use: fridge (~30–50Ah/day in summer), lights (a few Ah), phones (1–2Ah each) and a laptop (1–2Ah). If the total exceeds what solar and driving return, you will be borrowing from the battery — and lithium does not like living empty.

Winter is a different game

In a UK December, solar barely registers. That is when hook-up, driving and a decent alternator charger matter more than panels. If you plan to live off-grid through winter, a larger lithium bank and a proper campervan heating setup matter more than extra solar.

Battery monitors are the best £40 you will spend. Knowing your state of charge turns guesswork into planning.

For a sense of what base vehicles offer in terms of battery capacity, browse motorhomes for sale and compare the specs.