Rooftop Solar Water Heater – Important Things You Should Know

Rooftop solar water heaters aren’t so popular in the United States of America. This is shocking considering these installations can lessen your fossil fuel dependence and save you some money in the process. 

Therefore in this article, we will share you with important things you should know about this technology. We will discuss what they are and things you should know before you buy one.

Rooftop Solar Water Heater

What Rooftop Solar Water Heaters Are

To give you a better understanding of what these things are and the concept they operate on; let’s paint a scenario for you. Imagine you left your bottled water in your garden on a hot summer afternoon for some hours. Visit to learn how to beat the heat in the summer without an AC. 

When you come back, you’ll find out that the liquid in the bottle has become heated. This scenario might look so simple, but the rooftop solar water heater technology operates on this concept but in a far more complex manner. 

These pieces of equipment come in different designs, capacities, prices, and efficiency. Despite their variations, they can effectively replace a large amount of electricity or gas you use in heating water with natural, free sunlight. 

Rooftop solar water heaters as you might have guessed are installed on your rooftop and designed to heat water; as simple as that. However, the process is more complex. Hence, to further understand how it all works, we will look at the types of available designs.  

Rooftop Solar Water Heaters Designs

There are three main designs, but all of them have a system of collecting sun heat, a hot water tank, backup heating when the system is unable to stay on course, and a circulation system of sorts.

Let’s look at the design types in detail: 

1. Bath Collector Design

This design heats H2O in either pipes or tubs that are painted black most time to get more solar heat. To prevent the liquid from becoming excessively hot, one can add cold H2O from time to time. 

This kind of design is perfect for very warm climates. If there is the possibility of freezing in the winter months, the H2O has to be removed to prevent system damage.

2. Flat-plate Collector Design

In this design, a black painted metal plate soaks up the heat from the sun. The hotness then moves from the metal plate to tubes that have been filled with H2O. The liquid then cycles through the tubes to the system’s storage tank and then back. Hence, hot H2O supply is maintained.

3. Evacuated Tube Collector Design

This design is said to be the most effective of the lot. H2O is placed inside a tube that is enclosed by another bigger tube with a vacuum-sealed glass. The H2O is then heated. With this arrangement, the heat loss is very negligible which is why this system is effective.

Rooftop Solar Water Heater – Important Things You Should Know 1

How Water is Heated

H2O can be heated indirectly or directly. Indirect heaters are designed with a heat transfer fluid (usually a mixture of propylene glycol and H2O) which is heated by the sun. This liquid is then transferred to the H2O in the storage tank. Click here to read more about propylene glycol-based heat-transfer fluids.

Since the transfer liquid has a lower freezing point than H2O, the system can be used in climates where freezing is a possibility. The evacuated tube collector design is perfect for such climates as it can function even at -40°F. 

The H2O in the system must be constantly cycled to ensure that the warmed water is stored and the new water is heated. This occurs via two methods: passively or actively.

Passive systems depend on the rising of hot H2O and the sinking of cold H2O. On the other hand, active systems cycle the liquid with the aid of a pump. 

Things To Consider Before Buying A Rooftop Solar Water Heater

The following are things you should consider before buying this equipment.

1. Your Roof

You must ensure that your roof is in perfect shape and is capable of receiving enough sunlight. If there is a need to change the roof, change it first. 

The type of system you buy will determine the amount of sunlight you need. However, a recommended rule is that you need a minimum of 6 hours of steady sunlight every day.

2. Get Several Quotes

Before you select your Sacramento Best Solar Water Heater, you need to get several multiple quotes. This will ensure that you get the best deal. Besides, the more installers you speak to, the more knowledge you gather regarding the performance of the system in relation to the climate of your area. 

3. Number of People in the House

The size of the heater depends on how many people will be using the equipment in your house. While calculating the precise size can be difficult, you can depend on these guidelines:

i. For 2 people, the collector plate should be at least 20sq ft. 

ii. For each added individual, the collector plate should be increased by 8sq ft. for sunnier areas and 12 – 14sq ft. for colder areas. 

iii. The tank should be proportionally sized to the collector plate: 1.5 gallons for each square foot in colder areas and 2 gallons for each square foot in sunnier areas.


Although rooftop solar water heaters aren’t popular in the United States of America, they can be very beneficial. Therefore, in the article above, we have provided you with important information you should know about these beneficial systems.

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