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Solar Hot Water

Many people have heard about solar panels to generate electricity, but did you know that there are solar water heaters as well? These water heating systems work by heating an antifreeze mixture and transferring heat to your water.

It isn’t completely off the grid, as water still might have to be heated up to a better temperature, or during a cloudy day or night, but it is a great way to help the climate and reduce your energy demands. If you want to learn more about solar water heaters, how to pick one for your home, and how the components that make up these systems work, keep reading. 

What Is a Solar Water Heater?

Also known as solar domestic hot water systems, solar water heaters are the solar option to replace the current water heater in your home. On the surface, they work similarly to your regular water heater, warming up water and sending it into your home wherever you may need it via pipes.  

Solar water heaters aren’t super well-known, because a lot of people in the United States prefer to purchase solar systems that improve energy efficiency for their whole home instead of just their water.  

Solar water heater on the roof of a building against the background of the sky. Using solar energy to heat water

However, if heating water is one of your main energy draws and you want to save a little money, it is much cheaper to install a solar water heater, and it allows you to still reap benefits. Plus, it allows you to extend the life of your boiler by 60%.

A good solar water heater can cover 90% of your water heating needs in the summer and anywhere between 40% and 60% in the other months. 

It is important to note that solar panels and solar water heaters are not a ‘one or the other’ situation all of the time. While they both take up roof space, if you have enough room, you can easily get both. 

How Much Solar Hot Water Can Save You

Most people find that, on average, a solar water heater can save you at least 50% on your utility bill. If you don’t use a lot of very hot water and you live in an area with a lot of sun, the amount can go up to as high as 80%.

One of the other big benefits, price-wise, is that you are protected from price hikes and fuel shortages. Also, water can be heated during peak sun hours and, if insulated well enough, stays warm for the evening hours to avoid drawing extra power during some expensive time-of-day charges. 

Another prime benefit is if you are thinking about selling or refinancing your home. Having a solar water heater can drastically up the cost of your home and make it more profitable. 

How Do Solar Water Heaters Work?

The main difference between a traditional water heater and a solar water heater is how they heat the water. Traditional water heaters pull the power or use natural gas to heat the water in the tank. Meanwhile, solar water heaters use the sun to heat water. 

It works by pulling the water up to the collector that keeps the water in the sun. As the water heats up, it gets moved to a tank and the cooler water moves to the top to get warmed up. 

While your water still has to be heated up more via traditional options, it raises the water’s temperature to reduce the amount of power you need to get there. 

Types of Solar Water Heaters

Active Solar Water Heaters

As the name suggests, the system is actively moving the water around in the solar water heater. They do this via an electric pump. These are usually more costly and have the potential to break down more often since they have more parts to maintain. 

However, active solar systems are a good idea to have if you live in an area where it gets cold during the winter. Passive water heaters usually have bigger tanks, which increases the chances of it freezing.

Active water heaters reduce the chances of freezing and allow you to not have to worry about it during the winter months.  Active water systems are also lighter and don’t have to be put on the roof, since they can be pumped through your system via electricity. 

Passive Solar Water Heaters

Passive solar water heaters move water around via convection instead of electricity. Since hot liquid tends to rise, circulation can occur naturally. As the hot water rises, the cold water gets put in an ideal place to heat up. Then the water swaps again, helping to maintain a relatively consistent temperature.

solar hot water vector

Since there are no electrical parts, passive systems are usually cheaper. They also have a lower chance of breaking, since there aren’t as many parts to break. 

Parts of a Solar Hot Water System

Collectors

Collectors are the areas where heat is generated. They are the part usually attached to the roof. They work similarly to electrical solar panels but instead of generating electricity, they generate heat and put it into liquid sitting in the collector that then gets transferred to piping so it can go inside and transfer the heat to your water. 

You can install multiple collectors based on how much sun you get and how much hot water you use. Like traditional solar panels, there are a variety of sizes. 

solar hot water

There are two main types, which are flat plates and evacuated tubes. Flat plates generally are cheaper but don’t catch as much sunlight due to only one side interacting with the sun. This makes them less efficient in colder situations.

Evacuated tubes are more expensive but get more sunlight and take up less space. However, they are also more fragile and heavier. Usually, these collectors have a sort of antifreeze mixture inside of them that is easier to warm up. 

Heat Exchanger and Storage Tank

This is where the water is moved to once it is heated up. The heat gets transferred from the heat exchanger to the water inside the storage tank. The antifreeze mixture transfers the heat and then moves back up to the collector. 

Controller System

The controller system helps to make sure the water doesn’t get too hot, and it also stops water from freezing in the winter. This works because it stops cycling cold water when the antifreeze mixture isn’t getting to a hot enough temperature.

A lot of the system is controlled by a valve to keep everything regulated. It is a safety feature to make sure nothing gets damaged or hurts the user that works by using a thermostat of some sort to read the water temperatures both coming in and going out. 

Backup Heater

Every solar heater has to use a backup heater. This is because it is rare that you get enough heat to fully heat water just using a solar heater. Plus, this allows you to have hot water even when it is dark or cloudy out. 

This heater usually connects to the grid and works like a traditional water heater whenever your water isn’t warm enough. This usually only accounts for 20% of your hot water use per year. 

Installing and Maintaining the System

What Are the Most Popular Brands of Solar Water Heaters?

Some of the best solar water heater brands are:

  • Duda
  • Rheem
  • Sunbank
  • Apricus
  • Sun Earth
  • Heliatos
  • Northern Lights
  • OREAD
  • Smart Pool

How To Select the Right Solar Water Heater

When selecting a solar water heater, it is important to keep in mind a few things. This can help you select the right water heater. 

Solar water heater installed

Key points to keep in mind are:

  • Do you live in a cold environment?
  • Do you have the space on your roof? 
  • How much weight can your roof hold?
  • How much money do you have to spend on the system?
  • What size will you need based on how much hot water you use in a day?
  • Do you want a powerful system or one that needs less maintenance and is cheaper?

Improving Energy Efficiency

Just getting the solar system isn’t often enough. If you live in a colder area, you may want to look at insulation materials to put around your system. This reduces heat loss and makes your system run at a much higher efficiency. It also reduces the chances of freezing even more. 

However, you can also remember that solar water heaters are already improving your energy efficiency by a lot. Heating and cooling systems are the most power-demanding parts of our home. While ACs and heaters are the biggest draws, water heating follows along closely behind them. 

FAQ

What are the benefits of solar hot water systems?

– Reduced carbon footprint
– Reduced utility bills
– Takes up less space than solar panels
– Cheaper than solar panels
– High efficiency
– Get back tax credits and incentives
– Increases the value of a home for refinancing or selling

What are the warranties offered on solar hot water systems?

Unfortunately, solar hot water systems do not have as long of a warranty as solar panels. They are often only 2 to 3 years. However, they are starting to improve, and some are reaching 10 years or more. 

What are the payback periods for solar hot water systems?

For the average person, it only takes 2 to 3 years to pay back your entire hot water system. While initially, this wasn’t great because the warranty was only about that long, with the warranties now going up to ten years, that easily gives you seven years of pure profit. 

Are solar hot water systems eligible for government rebates or incentives?

Just like solar panels, solar hot water systems are eligible for government rebates or incentives. The incentives work similarly, with a 22% to 26% tax credit to offset the cost of a solar system for your home. Your local area may also do something to offer a tax break or incentive to get solar. 

What are the risks associated with solar hot water systems?

– Large upfront costs of around $7,000
– Need a lot of roof space
– Doesn’t help much on cold and cloudy days
– Maintenance can be expensive

What are the best solar hot water systems on the market?

By far, one of the most recommended solar systems on the market is anything by Duda. The one that will work best for you depends on the size and kind you need, but this brand comes highly recommended. 

Some examples of their products are:

– Duda Solar 200-liter water heater active split system
– Duda Solar 180-liter passive water heater
– Duda Solar 30-tube water heater