Solar Water Heater Type


How many different types of solar water heaters are there?

What are some of the qualities that set them all apart from each other?

What are some of the similarities and differences between the passive and active types of solar water heater?

There are four main types of solar water heaters. Two of these are active, and the other two are passive. Passive solar heaters heat water without the need for a pump, while active solar heaters require a pump and energy in order to operate.

Most of these heaters incorporate many of the same parts, including tanks, pumps, solar panels, and pipes. However, their functions vary considerably from one to the next.

Some of these heaters are better for certain climates or household conditions than others. Understanding the types of solar heaters available can make it easier to pinpoint the right choice for any given situation.

Read on to learn which solar water heater type is right for you.

Option #1

Direct Circulation System (Active)

In this type of heater, solar panels are mounted on the roof of the home and used to feed energy to the pump. The pump draws cold water through the inlet and up to the solar heater. Once heated, the water is returned to the tank for storage.

How does it work?

  1. While the sun is out, this heater moves water to the collector from the storage tank. This offer does not pump water when the sun is not out.
  2. This heater keeps itself from freezing by flushing heated water from the storage tanks periodically. Energy from the solar heater is required to do this.

What are its important functions?

  • This type of heater pumps water as needed while the sun is up and flushes itself when this is required.
  • The heater also stores hot water for use later on during the night, when the sun isn’t available for heating. This choice can store quite a bit of hot water at a time.

What are its limitations?

  • This system may not work well in places where temperatures get below freezing often. Since it uses its own energy to flush the system with hot water and prevent freezing, it may use more energy than it stores during very cold temperatures. It’s best in locations where freezing doesn’t happen regularly, or for extended periods.

Option #2

Indirect Circulation System (Active)

In this type of heater, water is stored in a tank which is fed via a pump attached to a solar panel. The solar panel is also attached to a closed-loop antifreeze heating unit. There is a coil inside the tank that helps to power the heat transfer, and the tank also has separate hot and cold water lines running from it to the house.

How does it work?

  1. This type of heater moves an antifreeze solution throughout the loop of the heater to gather heat. That heat is then used to warm up the water as needed.
  2. The heater must be used with the right type of antifreeze solution, which may vary depending on the specific heater model.

What are its important functions?

  • This type of heater is ideal for families with a larger hot water need, or who use a lot of hot water at night when the sun isn’t available.
  • It can also be routed for use in a heated pool or spa when it isn’t being used for the water inside the home.

What are its limitations?

  • This type of water heater uses quite a bit of energy in order to operate, so it may not work well for areas without a lot of sunlight. There is a chance it could consume too much energy without providing enough output when used in places where it can’t gather enough sun.

Option #3

Integral Passive Solar Heater (Passive)

This type of heater includes a water containment area that is housed within a structure and covered with a solar panel. The panel gathers heat and uses that heat to warm the water inside the structure. There is an outlet at the top of the unit, and an inlet at the bottom from which the water is drawn.

How does it work?

  1. Cold water drips through a tube or channel in the heater into a collection tank, where it is heated naturally by the sun and the outside temperature.
  2. When the water gets hot enough, it is taken to an energy-powered heater via pressure rather than through the use of a pump.

What are its important functions?

  • This type of heater can make smaller volumes of warm water at a time, so it doesn’t cool down as easily or as quickly as it might with some others.
  • This heater can be mounted entirely on the ground if necessary.

What are its limitations?

  • Although in some areas the energy-powered heater may be skipped entirely, it is required in places where the temperature gets very cold during the year. This type of heater may be limited by property without a lot of direct sunlight, such as a yard with many trees blocking the sun.

Option #4

Passive Thermosyphon Solar Heater (Passive)

This type of heater usually contains a large tank at the top and a collector unit at the bottom. The collector is generally made up of tubes and covered with a single solar panel, although the size and makeup of this part of the heater may vary from model to model.

How does it work?

  • This option is a pumpless method of heating water that works best in places with higher temperatures and a lot of sunlight. Water collectors are heated naturally by the sun and then transfer that heat to the water inside.
  • When they’re full, the water moves from the collectors to the heater’s storage containment. The hotter the water becomes naturally, the more frequently it will transfer.

What are its important functions?

  • This type of heater warms water as needed by the house.
  • It can also store heated water for future use.

What are its limitations?

  • This type of heater cannot function properly when temperatures are too low or when the sun is not out for an extended period of time. It is only suitable for climates with a lot of regular sunlight and warm temperatures.


Now that you’ve learned about the different solar water heater types, you may be ready to choose the one that’s right for your needs. There’s a lot to remember when learning about these types of heaters, however, so take your time and do your research before committing to one.

How do you know which type of solar water heater is right for you? How can you be sure? Here are a few tips to remember:

  • Indirect heating systems don’t freeze as easily as direct ones, so if you live in a very cold climate, indirect is the way to go.
  • Passive systems are better for households with a lot of daytime activity, while the sun is up, since they heat as needed.
  • Homes without a lot of yard space should choose a style that can be roof mounted.

There may be other considerations to remember as you choose your water heater, too. Keep these suggestions in mind as you narrow down your options.

Additional Research:

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