Guide to Solar Water Heaters

Water heaters are a staple comfort in any household. Although choosing between types of water heaters can be tricky. There are multiple types of water heaters that vary in their operation and efficiency. Solar water heaters are becoming a common option for a home water heater. We’ll explain how solar water heaters operate, along with the positives and negatives of water heating.

How do solar water heaters work?

Solar water heaters utilize the sun to preheat the water before it enters your water tank. They can come in a variety of designs that vary in their operation. As there are different types of collectors and storage tanks between the systems.

Types of Collectors

Batch collectors also called Integrated Collector-Storage (ICS) systems heat water in dark tanks or tubes inside an insulated box. The box will store the water, even for long periods without water drawn. A tempering valve regulates the temperature by mixing it with cold water to prevent it from being scalding hot. Although batch collectors aren’t recommended for tropical climates.

Flat-plate collectors:

These are made of copper tubes that are fitted to flat absorber plates. They are typically laid out in a parallel series of tubes that are connected at the ends by the inlet and outlet manifolds. Everything is within an insulated box which is covered by tempered glass. They are regularly large enough to hold 40 gallons of water.

Evacuated tube collectors:

These work like thermos for drinks. Where a glass or metal tube that contains the water or heat transfer fluid, is surrounded by a larger glass tube with a vacuum between them. These collectors are the most efficient and work well in cloudy conditions and even temperatures as low as -40°F. They are pricier when compared to other collector types.

water heater roof
Harvesting the sun's warmth, drop by drop: Navigate the Guide to Solar Water Heaters for an eco-friendly flow in every home

Types of Circulation Systems

Direct systems:

Circulate water through the solar collects where they are heated. The heater water will be stored in a tank or sent to a tankless water heater, or even used directly. These are suitable for warmer climates.

Closed looped / Indirect systems: 

Use a non-freezing liquid to transfer the heat of the water heated by the sun from the solar collectors to the storage tank. These systems are suitable for climates with freezing temperatures.

Active / forced-circulation systems use electric pumps, valves, and controllers to move water around.

Passive systems:

Use natural convection to move water from collectors to the storage tank as the heat builds up.

What are the positives and negatives of solar water heaters?

There are positives and negatives to using solar water heaters. Understanding them will help you decide if solar water heaters are suitable for you.

solar water system


Savings on your water heating bills will be a big upside. Similar to solar panels for your electricity. Using the sun for the heating will help you avoid using electricity, gas, or other fuel to heat your water. These savings will add up over time, making your initial investment worth it.

The reduced need for maintenance will be another bonus. While you will need to replace the antifreeze liquid and have it inspected by a contractor from time to time. The amount of maintenance work will be minimal at best.

Reliability and longevity are similar to photovoltaic (PV) solar panels. Solar water heaters that are well kept can run for more than 20 years.

The environmentally friendly operation of solar is another plus. As climate change is a growing concern, reducing our own carbon emissions helps reduce our footprint and the overall fight against climate change. Solar hot water systems are a clean way of heating water without using fossil fuels.



The cost of solar heaters is more expensive upfront when compared to other water heater types. Although rebates and incentives like the federal ITC can help offset a portion of the cost. It is still a consideration.

Climate will affect the performance of your system. As the system relies on the sun’s rays to heat the water, sunny weather is ideal for the system. Systems with colder climates should install a backup heater in case of cloudy and snowy weather. Although sunny and tropical areas tend to benefit more.

The solar hot water system doesn’t generate electricity. Solar water heaters are different from PV solar panels. As heaters use the sun’s rays for heat, while PV solar panels use it to generate electricity for your property. If you’re aiming to generate electricity for your home. PV solar panels offset the energy for your whole home and electric water heater.

solar water system diagram
solar water heaters

Solar Generation

Is it worth changing to a solar water heater?

If you’re considering changing to a solar water heater. You will get to enjoy the benefits of reduced bills, reliability, and clean operation. Although similar to PV solar panels, you will need to consider your area’s climate and the system’s upfront cost. Your existing water heating system will also be a factor. If your water heater is electric, consider going for a PV solar energy system. Your entire home will benefit from it rather than just limit it to your water heater.

Get started with solar energy today

If you are looking to start your transition to solar energy, we are here to help. Our website also has a free online estimate tool that generates a personalized report for you from a simplified questionnaire. That report will contain the potential savings you can net, and the cost of a solar energy system installed on your property.

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