How Can I Heat Water Off-Grid?

Heating water uses more power than most other systems in your home. Finding a way to heat water that doesn’t rely on your off-grid electricity supply can release a significant amount of your power to be used on other things.

To heat water off-grid, solar water heating panels are the most energy-efficient option. Or, if you prefer, you could use a point of use electric water heater, these use less power than whole-house systems, but you will need one per tap or hot water appliance. Your other options are propane heaters, wood-fired boilers, and ground-source heat pumps. 

Depending on how you’ve set up your home, you could use several different ways to provide heat for your home and hot water for washing. Here are the best ways to heat your water without using all your off-grid electricity:

Point of use electric water heater

These are small electric heaters that provide hot water to one fixture. They usually have a small tank of between 2 to 7 gallons and can use about 1400watts. For larger homes, it may not be practical to install several of these, but for smaller homes, one or two could provide enough hot water for taps and washing appliances.

Although these heaters still run from electricity, because they use significantly less power than whole-home systems, you may be able to install one without it being too much of a drain on your home’s power supply.

Check out my recommendations for the best equipment for solar power or water supply and plumbing.

Solar water heater

These are simple, efficient systems that use direct sunlight to warm up fluid in a series of pipes. They come in different types and some people even use the basic principles of solar heating to make their own systems. 

Some use their DIY skills to create detailed systems:

While others prefer to keep it simple:

However, if you buy one of the units commercially available, they usually consist of a series of narrow pipes arranged into a flat panel, similar in size to a large solar panel. They can then be mounted on rooves or on frames to get the best access to sunlight.

There are two main types of solar heating panels and which one you use depends on your local climate:

Direct solar water heater

These are the most straight forward option. Water is simply fed into the pipes of the heating panel and as it flows through them; the sun warms it up. Then it travels back into your home and is collected in a storage tank for use. The drawback of this type is that if you live in colder climates, the water in the panels is likely to freeze in cold weather.

Indirect solar water heater

These are specially designed for climates where freezing is expected. The tubes on the panel are filled with an antifreeze mixture, which acts as a heat transfer fluid. This fluid is then used to heat the water, which can then be used in your home.

Pros

• Solar water heaters are an efficient way to use a free energy source to provide hot water.
• They can be used alongside other systems to take the pressure off other power usages.
• Once they are set up, they’re easy to use and require very little maintenance.

Cons

• They need to be in full sunlight as much as possible, and your best spots may already be taken up by your solar panels.
• They only provide hot water when the sun is shining. 

Unlike electricity, it is harder to store excess hot water for later use. This means that solar water heaters are best used in conjunction with other systems. For example, you may be able to run an electric tankless heater for use when your solar heater isn’t working. This means you can minimize its use and save power.

However, if you choose to do this, you should ensure that you take it into account when you calculate the size of your solar panel system; otherwise, it may have too much load at a time when it’s relying on battery backup. Other alternatives could be to alternate solar heating with wood or propane heaters.

Propane heater 

Propane heaters are a good solution for off-grid homes. Because you will need to purchase the propane to run them, they are best used alongside other systems to minimize the cost.

With propane water heaters, you can choose between those with tanks or tankless systems. Tankless systems use large bursts of energy to heat water on demand as it’s needed quickly, and those with tanks heat a large amount all at once to be used throughout the day.

Tankless systems are smaller, but they usually require more power and can only supply one or two appliances at a time without becoming overloaded. Propane versions can be excellent but are often higher in price than their electric counterparts. Also, they require adequate ventilation and carbon monoxide detectors, which can drive up the cost of installation.

Pros

• Propane heaters won’t use up your solar power
• Once they are installed, you will have a steady supply of hot water when you need it, whatever the weather.
• They could be used alongside other systems

Cons

• According to Santa Energy, the average home will need between 200 to 300 gallons of propane a year to heat your water.
• Propane is an additional expenditure.
• It requires extra ventilation
• Propane units can be expensive, often between $600 to $1200.

Home Depot stock a range of excellent Rheem water tank heaters. They also help you to find the right one to match the size of your family.

Wood-fired heater

To heat water with wood, you can choose to use individual fires or install a whole home wood-fired boiler:

Heating your water with a wood boiler

For some homes, this can be a great option, but for others, it could be more trouble than it’s worth. One great benefit is that not only does a wood-fired boiler heat your water it also heats the room.

Also, they are often cheap to buy and are usually simple to install, so can be an attractive option.

Pros 

• Can be cheaper to buy and install
• Your home may already have stoves or flues
• Generally good efficiency

Cons

• Burners, chimneys, and flues need regular cleaning.
• You need to supply wood to burn.

If you’re looking for a wood burner to heat your home, the Ashley Hearth range is well made, stylish and efficient.

Ground-source heat pump

Like the solar water heaters, this is a great way to utilize a free source of heat. These systems consist of a series of pipes that run underground, collecting low levels of heat from the surrounding earth. The tubes are filled with an antifreeze mix that warms up in the pipes. This fluid is then pumped back into your home and used to heat your home.

Although the temperature of the fluid may still be relatively low, it can be concentrated using refrigerant and a compressor to create the higher temperatures necessary in your home. One of the drawbacks of this system is that unlike solar water heaters, it is mainly used as a heater and not to produce hot water for other uses. This means that you would need to combine it with other systems to supply all your heating needs.

Pros 

• Free, renewable energy is used.
• There are no emissions created by the system.
• They can be reversed in summer to provide a cooling effect.
• No fuel required

Cons

• Not often used to produce hot water for other uses.
• Requires a suitable area of land to install.

Other creative options

If you’re feeling creative, you may like to try different options to heat your water. Here is one particularly innovative way to get a large amount of hot water from a tiny wood stove:

Conclusion

There are several different ways to heat water for your home. The one you choose should match your needs, finances, and the fuel that is accessible to you.

Using free energy sources like the sun and the heat in the ground where possible could help you offset your costs. They can also be mixed with other methods to provide a useful combination effect. Although this mixed approach might be initially expensive; it will keep your costs down in the long run.

Check out my recommendations for equipment that will help you take your home off-grid.