If you’re going off-grid, you’re going to need to reduce your energy consumption. That includes hot water — one Maine solar company lists water heaters as something to never consider running on an off-grid power system.
When planning a change to off-grid living, or if you want to reduce the energy you use heating water at an on-grid home, you have a number of systems to choose from. The federal energy department provides calculator tools to get an idea of what systems will cost and detailed explanations of how some of them work.
Propane
Propane heaters are a popular, simple choice for people living off-grid who are looking to add backups for their solar systems. It’s not too hard to hook up or modify portable heaters designed for campers and cabins.
Most of these options are “tankless” or on-demand, meaning that the water is heated when you need it, rather than stored. That saves the energy that would go into keeping extra water warm.
Propane options will probably be $100-200 more expensive each year than oil or natural gas, according to Efficiency Maine, but $100 less than an electrically heated tank.
Your wood stove or boiler
If you don’t want to rely on propane or already use a wood stove in the colder months, it’s fairly simple to install a metal pipe system in or around the stovepipe or the back of the stove to heat water in a storage tank.
If you put the copper piping inside the stovepipe, more creosote builds up and presents a fire risk. Wrapping the outside is safer, but both options should have pressure release valves.
There are also connection kits for an outdoor wood boiler to provide hot water. Note that the state regulates them. Similar systems exist for pellet stoves, too, and Efficiency Maine provides rebates for stove installation.
In these systems, the water will get extremely hot, so be careful and plan for providing cold water, too. Look into a range boiler for storage, which is lined with stone and can withstand the higher temperatures of wood-heated water.
The rocket stove
This modified wood stove design is gaining ground with homesteaders. It can also be modified into a heater for the whole house, and should use much less wood than a conventional stove. Heat travels through several chambers and creates clean, radiant warmth.
Crafty homesteaders have adapted the copper pipe method from woodstoves to rocket stoves, too.
Sunlight on a bag?
There are a number of ways to heat your water directly under the sun, such as a “camping shower,” or a black bag of water kept in the sun to heat up (likely best suited to Maine in the summer). Any dark container in sunlight will get warm, a simple principle you can adapt to different DIY systems.
You will want insulated storage tanks to keep this water at temperature.
Heated tubes
Flat plate solar collectors are one popular version among several that use the principle of the black bag in the sun in a more technical system. Basically, they’re tubes inside a panel with a special coating.
They can be mounted on your roof or the ground; to withstand Maine’s winter temperatures, antifreeze can be added to the tubing. Variations on this idea include exposed tubes connected to a tank.
Some of these may not be able to heat all the water you need, but they can produce close to three-quarters of it.
There are risks in creating any of these setups on your own if you’re inexperienced, and your town’s code may not allow all of them.
