Solar Vs. Tankless Water Heater (What To Choose and When?)

On-demand hot water is essential for any household. With a variety of water heating options to choose from, homeowners need to consider what is going to work best for them from both a supply and cost perspective.

Solar water heaters are supremely efficient and cut water heating costs dramatically. In contrast, instant water heaters provide hot water at any point in the home when needed but require a fuel source to do this to incur a cost for operation.

The question of which one to choose for your home will depend on several factors, like the hot water demand and how many people are in the home, and the weather conditions in your area, so let’s look at each individually and see what would be better for you.

Solar Water Heater Vs. Tankless

The Solar Water Heater 

The solar water heater or solar geyser uses the sun’s thermal energy to heat the water and then supply that to the home for use. It can do this using evacuated tubes or panels, but each principle is the same.

With evacuated tubes, the tubes are covered with a coating that attracts heat and transfers it to the water or glycol that flows through them, and the hot water flows to the storage tank for use as and when required.

Types Of Solar Water Heaters

Solar Water Heater

These water heating systems are available in two types, the direct or indirect systems, and depending on where and how you want the water heater placed, will determine which one you opt for.

  • The direct system has the water tank and the tubes or collector plate on the roof, and you will see a lot of those around. These are cheaper than the indirect systems, but the indirect system is preferable for people who prefer a less prominent fixture on their roof.
  • The indirect system has the tank located under or inside the roof with the collector plates or evacuated tubes. They circulate water through the tank to maintain the required temperature.

Many of these systems can be supplied with advanced control systems that relay and record temperature data and analyze usage. They also allow the homeowner to set the seasonal fluctuations as required.

When To Opt For A Solar Water Heater Instead Of Tankless

Solar water heater

If you have a large family and bathing and showering happens daily (as it should), a 200l or 150l solar water heater would be well suited to this kind of usage. Another consideration is that the US Department of Energy advises that installing a solar water heater will cut your water heating costs by between 50% and 80%. They can last for 15-20 years.

This is a significant saving as many energy costs in an average home are allocated to water heating. It is also a completely renewable and sustainable energy source, provided you have sunlight and UV. You will continue to get hot water during the day.

When A Solar Water Heater Wouldn’t Be Advisable 

Small Home

If you have a small home with maybe one or two people only, then the upfront costs of a solar water heater may be prohibitive, and even though there would be savings on energy, the investment would take a lot longer to pay itself off.

Also, suppose your weather conditions are frequently cold or wet, and you don’t have abundant sun. In that case, your water heater may struggle to deliver hot water and will use the backup electrical element to generate hot water.

While this would not be as expensive as an electric water heater, it would not achieve optimum savings that would be seen with more ideal weather conditions.

Now, let’s consider tankless systems.

Tankless Water Heating Systems

Tankless water heater

These are on-point systems meaning that the hot water will flow directly from the faucet and not from a water storage tank. One of the greatest benefits of tankless is that they don’t require hot water connections; they only need cold water.

Tankless systems heat the water through the faucet using either electricity or gas to get the cold water hot instantly. As long as there is cold water and the tankless system has a fuel source, you will have a neverending supply of hot water at your fingertips as and when you need it!

When To Opt For A Tankless System Rather Than Solar

Tankless water Heater

The instant water heating system is a great option if you don’t have a big home with enough roof space for panels or collectors and the tank, whether on the roof or inside. Also, if you don’t have a big family and the hot water demand is not excessive that you need it stored, then the tankless system is ideal.

Should the weather in your area be cooler and experiences more inclement weather than other areas, the tankless system would be better suited. While the solar water heating system would work to some degree, the solar heater will use electricity to maintain the temperature.

The tankless system only uses the electricity or gas required at usage and then shuts off when the water supply is closed. Tankless systems would save around 30%-40% on water heating energy costs, and they have a lifetime of around 20 years, so they are durable.

When A Tankless System Is Not Suitable 

Tankless water Heater not suitable

One of the drawbacks with tankless is that if you have a lot of people all wanting hot water at the same time, you may need to install more than one to accommodate this. While they don’t cost quite as much like a solar water heater, the upfront costs can be high, especially if they are fitted to an existing home.

Tankless costs are lower when being fitted to homes being built, and if you are going to need more than one, it may become pricey.


Before choosing either system, you need to know what your actual hot water demands would be so that the system you choose can adequately supply the demand. This may take some homework on your part but is worth the time.

Regardless of which you opt for, make sure you have an adequately accredited service provider do the installation, so you can reap the benefits of cheaper hot water for many years to come.

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