One of the main things we tell people when they’re looking to power a full time off-grid lifestyle is that our solar kits aren’t designed to handle water heating – so no hot water cylinders! They use a LOT of power, so it’s typically not cost effective to have an electric hot water cylinder off-grid. Learn more about what not to run on solar.
So how else can you heat water off-grid?
There’s 3 main ways to do it: a non-electric solar solution, an on-demand gas heater, or a woodburner.
Off Grid Solar Hot Water:
This option can have varying levels of complexity, but they are all essentially a variation of keeping water in a black container in the sun. The cheapest and simplest method is the classic solar camping shower – a black bag (usually about 20L) with a handle and a spout that you fill with water and leave in the sun, which you can hang up and open the tap for a shower. These work best in summer, as they require a decent amount of time to heat up on a hot sunny day and don’t get as hot as other options, so they’re best left for camping trips.
For a longer-term solution, the best off-grid solar hot water solution is ‘evacuated tube solar’, which uses evaporation and condensation cycles to move heat to the top more efficiently that a solid block of copper. They work well even in cloudy conditions.
Solar thermal panels run water through black pipes under glass. A lo-fi option that some people use it just a coil of black alkathene pipe left on the ground! This method can work well, but like the shower it struggles to get hot on cloudy and cold days, so it’s usually paired with another method.
On-demand gas heater:
Like solar, this method can be used to heat water off grid for camping and full-time living alike. Many off-gridders will start off with a simple instant gas hot water camping shower, also known as a portable califont. It’s a very simple unit – you attach an LPG bottle to the gas inlet, run a hose into your water source, and all you need is a 12V battery to run the included pump. Then you’re ready to have a nice hot shower with a proper shower head, and you can set the temperature as you like! Depending on your water source, you may need to filter the water to ensure the longevity of the unit. These need to be used in a ventilated area, so many off-gridders will make a quick outdoor shelter with a roof and walls, so it can be safely used year-round.
You can also get these units as a permanent solution, plumbed into your building’s gas, water, and power. They’re known by the names “califont” and “instant hot water”.
Gas powered hot water is typically the easiest solution to heating water off grid, as it doesn’t require a sunny day or a fire to be burning all day.
A number of homesteaders will use a woodburner with a wetback for heating water off grid. The water pipes run around the back of the woodburner and heat the water whenever the fire is burning. This works great if you’re likely to have the fire going all day every day, but this isn’t practical in smaller spaces over summer, so is often supported by another method.
One solution that off-gridders love is the woodfire outdoor bath or spa. There are several companies making a dedicated spa with an attached woodburner for heating it, but heaps of off-gridders make their own! Using a secondhand bathtub, they either make a fire underneath (for cast-iron tubs!) or plumb in a length of copper pipe that spirals around a woodburner to heat the water. Everyone who does this agrees that there’s nothing quite like a warm bath under the stars!
Of course, there’s always the classic off grid bucket shower method! Heat up some water over the gas cooker or campfire and pour over cups of water or use a washcloth. It’s simple and effective for the early days of your off-grid lifestyle, but far from the most luxurious option!
One thing to keep in mind with all of these options for heating water off grid is what happens to your grey water. Many off-gridders run their greywater onto non-edible plants, so they use bio-degradable soaps and other products that won’t bother the garden.