Off-Grid Hot Water: How Do You Get It? (UK Guide)
Off-grid homes get hot water from a mix of sources: solar thermal panels, a wood stove with a back boiler, an instant gas or diesel heater, or an electric immersion run off surplus solar. Most people combine two or three, leaning on the sun in summer and on wood, gas or diesel through the winter.
Solar thermal
Roof-mounted collectors heat your water straight from sunlight, and they do well in the UK from spring through to autumn. The catch is the winter, when you will need a backup, so solar thermal suits fixed homes with roof space rather than vehicles.
A wood stove with a back boiler
If you already heat your space with a wood burner, a back boiler can heat your water at the same time.
It is the winter workhorse of off-grid hot water: cheap to run if you have your own wood, and hottest at exactly the time of year you need it most.
Gas or diesel on demand
An instant heater gives you hot water the moment you turn the tap, which is why almost every van, boat and cabin has one.
LPG has always been the popular choice, but a lot of people are now switching to diesel, especially if they have already moved off gas for their fridge and cooking. Running a single fuel means one less type to find, carry and store, so the decision often comes down to what else on board already burns the same thing.
Electric immersion from surplus solar
When your panels are making more power than you can use, a diverter can send that surplus to an immersion heater, which is about as close to free hot water as you will get.
It works best in summer, but it can still earn its keep in winter, as long as your electrical system is big enough or you have backup power to top it up. Match the whole lot to your home: a van leans on gas or diesel, while a fixed house can run several of these together.
Frequently asked questions
Can you have a proper hot shower off-grid?
Yes, easily. Most off-grid showers run off an instant gas or diesel heater, or a pumped cylinder heated by solar or a back boiler. The things to manage are water pressure, which a small pump sorts, and not drawing more hot water than your system can reheat.
Can you run an electric shower off-grid?
Rarely. A mains electric shower pulls 8 to 10 kilowatts, far more than most off-grid battery and inverter systems can supply. Off-grid homes almost always use a gas or diesel instant heater, or a pumped hot-water cylinder, in its place.
Is diesel or gas better for off-grid hot water?
Neither is best for everyone. Gas is widely available and simple, while diesel appeals to people who already run a diesel heater or engine and would rather manage a single fuel. If you have moved off gas elsewhere on board, diesel often makes more sense.
Do off-grid heat pumps work for hot water?
They can, but they draw a fair amount of power, so they suit homes with a large solar and battery system rather than vans or small cabins. For most off-grid setups, solar thermal, a wood back boiler or an instant gas or diesel heater is simpler and cheaper.