Published on May 17, 2022. Updated on May 18, 2022

Advantages and disadvantages of a solar hot water heater

Are you thinking about getting a solar hot water system, but are unsure if it's worth it? Do you want to know if solar water heaters are worth the money?

It really depends on where you live, your climate, and your budget. 

In this article, I go over the advantages and disadvantages of solar hot water heating systems. In the end, you will know if a solar hot water heater is worth it to you. 

If you want to know everything possible about solar hot water heaters, check my complete solar water heating guide

Watch my video and learn all about solar hot water heaters! 

Advantages of a Solar Hot Water Heater

There are several advantages to using a solar hot water heating system, especially if you live off the grid. 

However, solar water heaters are great for those wanting to contribute to a more sustainable lifestyle and are good for saving on energy bills. 

You Could Get A Rebate On Your Solar Water Heating System

The Consolidated Appropriations Act of 202 provides a renewable energy tax credit for solar energy systems, including solar hot water heaters. 

The tax credit is 26% for systems installed after 2019 and before 2023. 

The credit only applies to the solar water heater and does not cover any water heating system within the house, such as plumbing and preexisting water heaters. 

The system requires the Solar Rating and Certification Corporation (SRCC) certification.

The credit does not apply to heating swimming pools or hot tubs. 

Apply by filing Tax Form 5695 with your tax return. 

Solar hot water heater with holding tank

Heat Your Water For (Practically) Free With Solar Energy

Once you have your solar water heater set up, it costs practically pennies to run. The only parts requiring energy are your water pump and your solar controller. 

Running a solar water heater costs about $100 per year. A traditional water heater costs about $600 per year in electricity. You will save on average $500 per year running an active solar water heater (source). 

If you are running a passive solar water heater - which is a heater that uses convection to move the water instead of a pump - the expense to run it is virtually zero dollars. 

The standard solar hot water heater (without an antifreeze system) costs about $6000, including installation. Therefore, your system will be paid off in about ten years. A prefab solar water system will last about twenty years, so you will save around $5000 over the lifetime of the unit, not including any repair costs. 

You can always build a DIY solar water heater for near pennies! 

diy solar hot water batch tank

Solar Water Heating Is Environmentally Friendly

Prefabricated solar water heaters use 90% less energy than their electric counterparts. Passive solar water heater systems use virtually no energy, as it relies on convection to move the hot water. . 

Imagine if half of the homes in America switched to solar water. We would save a ton of electricity!

If you build your own solar hot water heater, you can recycle used materials. The DIY build is way more green than buying a prefab. 

Solar Water Heaters Are An Off-Grid Friendly Appliance 

Solar water heaters are most excellent for off-grid applications. You can install one wherever there is full sunlight. 

Heating and cooling systems are costly in energy, and every kilowatt is precious when you live off the grid. 

A passive solar hot water system is ideal for your water heating needs for your cabin or homestead.  

You Can Use Solar Panels To Supply Additional Energy As Needed

Prefabricated solar water heaters can be wired in with standard PV solar panels to supply energy if the solar water heating panels are not getting enough sun. 

Using this method ensures that you will have uninterrupted hot water no matter the outside conditions. 

Although a solar water heater sounds amazing after reading all of these advantages, there are serious disadvantages that make a solar water heater not worth it to many people. 

solar hot water heating panels

Disadvantages of a Solar Hot Water Heater

It's pretty obvious that you need sun for your solar system to work. But it's a glaring factor that must be considered. 

Certain climates are not really suitable for solar water heaters unless you modify them with antifreeze closed-loop systems. 

Solar Hot Water Heaters Do Not Work At Night

When the sun is not shining, your solar water heater is not making any hot water. This is why you need an additional water collector for the heated water to transfer into and stay warm. 

You can also plumb your solar water heating panels into your existing water heater. This will allow the heating panels to supplement the traditional water heater, but you will still have hot water when it cools off at night. 

Regions closer to the equator will have more reliable water heating throughout the years, as daylight hours stay more consistent than regions in the north. 

Solar Hot Water Heaters Do Not Work When It's Cloudy

You need intense direct sunlight for the water to get warm enough in your solar hot water heating panels. 

Cloud cover will ruin any chance of getting your water up to hot temperatures. 

Again, having a backup method for water heating is essential. This could be assistance from PV solar panels that supply electricity when the weather isn’t cooperating. 

Prefabricated Solar Water Heaters Are Expensive

A prefabricated active solar hot water heating system costs about $3,000 for the unit and another $3,000 to install.

A prefabricated active solar hot water heating system with a closed-loop antifreeze system shoots up to about $10,000 or more for the unit and installation. 

When looking at how much savings your solar water heater will provide over a traditional water heater, it may not really seem worth the expense, especially for a system in a cold climate. 

active solar hot water heater installed on roof

Solar Water Heaters Don’t Work Well In The Winter

If you live in a climate that experiences lots of freezing weather for a large portion of the winter, then a solar hot water heating system probably isn’t suitable for you. 

Any type of DIY solar hot water heater will freeze up in the winter. However, you can use a DIY water heater during the summer, then winterize it for the freezing months. 

A prefabricated system can be used in cold climates, but it must have a closed-loop antifreeze system. This system uses the same technology as radiant heating. 

An HVAC professional could install one for you. But the prices are pretty high and probably not worth it. 

Learn more about this topic in my in-depth article about how to protect your solar water heater from freezing

Are Solar Hot Water Heaters Worth It? 

In my professional opinion, DIY solar hot water heaters and small prefabricated solar water heaters are worth it. 

If you build your own solar water heater, you have nothing to lose. You can salvage materials and build one for free. If you place your solar collector tank above your solar heating panels, you don’t even need a water pump. Passive DIY solar water heaters are absolutely worth it. 

A prefabricated solar water heater without an antifreeze system installed in a warmer climate, like Arizona, Texas, or California, is worth it. The system will pay for itself within a handful of years and will last for many years to come, essentially giving you “free” hot water for your household. 

If you live in a freezing climate, a region where it rains a lot, or an area that is foggy or has a marine layer consistently, than a solar hot water heater may not be worth it. 

For wintry climates, you can use a DIY solar water heater for the warmer months and then winterize the system. For areas that don’t see a lot of sun, you can use a solar water heater to supplement your preexisting traditional water heater. 

A prefabricated solar water heater that requires an antifreeze closed loop system will likely not pay for itself in cold climates. It it prone to breaking down which will require professional diagnostics and repair.

If you live in a wintry climate, check out my other solutions for off-grid water heaters

Sun boiler hot water heating systems in India

Regina Cal is a solo homesteader on 30 acres in Southern Arizona. She specializes in off grid water system design, homestead gardening, minimalism, and self-sufficiency.

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