Solar Hot Water Heaters Winter

Do Solar Hot Water Heaters Work in Winter?

Having a solar hot water heater is a great idea as it has many benefits, like reducing energy costs. However, while a solar hot water heater is beneficial, the question is – do solar hot water heaters work in winter?

During the winter months, solar water heaters aren’t going to generate as much hot water as they would during the hot summer months. The systems that are installed in the snow states come with freeze protection, which means the snow is going to melt off of your heater before it slides off of your roof.

How Well will the Solar Water Heater Work During the Winter?

While solar water heaters are great, they’re not meant to completely replace water heaters. The solar water heater will be able to heat up to 80% of the water you use throughout the year. From the months of April through September, almost all of the hot water you use will be solar heated because this is the warm months.

However, during the winter, this percentage is going to drop – depending on where you live, the amount of water being heated by the sun can drop to as low as 10% – this is to be expected on those short cold days in December.

This is the reason why every solar water heater that is installed in the United States is going to be connected to a traditional water heater. This is to make sure your hot water needs are met, even in the dead of winter.

Will the Solar Water Heater Freeze?

If you live in the northern states that are prone to freeze, you may be concerned with your solar water heater freezing. As long as the solar water heater is installed properly, it should be designed so that it doesn’t freeze during the winter months.

In cold climates, there are numerous ways you can prevent the solar water heater from freezing. One of the methods used is known as the drainback system method – with this method, water or an antifreeze mixture will be circulated.  When the sun stops heating the water or when it’s just too cold outside, a temperature sensor combined with a pump will be used to drain the fluid from the system. Another method involves using a non-toxic antifreeze mixture and circuiting it through the collector, which will indirectly heat the water in the tank through a heat exchanger, instead of circulating water.

Should I Use a Solar Water Heater if I live in a Cold State?

Even if you live in a cold state, using a solar water heater is a good idea. Take Massachusetts as an example – this state has long cold winters, and despite this, they rank one of the top states in America for solar water heater installations.

How Long will the Solar Water Heater Last?

As long as you keep your solar water heater properly maintained, the system could last for 20 years or more. By doing regular maintenance on your water heater, this will extend the life of the system. There are some systems out there that can last even longer than 20 years. Believe it or not, some systems that were installed in the 1970s are still running.  By comparison, a conventional water heater can last up to 15 years.

Will Low Temperatures have an Effect on the Solar Water Heater?

Even during the winter months, with good insulation, the sunshine will heat the water. Even if the outside temperature is below freezing, you will still have hot water. The hot water in the tank is caused by the radiation energy the sun puts out. However, if you’re dealing with a cloudy day, the heating capacity of most solar heaters will be reduced.

There is no form of technology to suck out more heat from the sun during the winter months. However, you may be able to enhance the amount of sunlight you have hitting the right area by using mirrors so that those fewer hours of direct sunlight you have during the cold winter months can be utilized.

What it all boils down to is the quality of insulation you’re dealing with and how much heat you can store in the system.

Recommended Winter Setups

For those of you that live in the coldest regions, we recommend a closed loop system with some form of refrigerant or oil being used as the heat transfer liquids. Any water that is in a solar collector could become a problem. Just in case your solar heater fails you, you should have a conventional heater installed so you won’t ever have to worry about not having hot water.


How well your solar water heater works during wintertime will all depend on where you live. Naturally, if you live in a state like Florida or California, your solar water heater will work fine without having to do much. However, if you live up north in a state like Michigan or Ohio, then the amount of water that is heated from the solar water heater is going to decrease.

Chances are, if you live in an area where the temperatures are known for dropping below freezing, then the solar water heater you had installed is already set up to handle such conditions.

In cold climates, for example, they may install closed-loop indirect systems, which use a heat transfer liquid. A lot of the regions that have the coldest winter temperatures aren’t lacking sunlight in the winter, so making sure your water heater functions properly throughout the year is the main issue of freeze prevention.