Solar Water Heaters Heat Water Even Without Direct Sunlight—Here's How They Work

If you are considering installing a solar water heater, this information is for you. Do solar water heaters stop working completely if there is no sunshine during winter? Find out the facts.

People often start buying ACs, coolers, and refrigerators before summer begins to snag a better deal. Similarly, people purchase geysers and heaters in advance for winter, but a new alternative to the traditional geyser has now entered the market. Increasingly, people are installing solar water heaters on their rooftops. While these systems rely on sunlight to heat water, a common question arises: will the heater stop working if there is no sun?

During winter, fog often obscures the sun. If someone invests in a solar water heater and there is no sunshine for two or three days, will it stop functioning? The answer is no. Its standout feature is the ability to heat water even when the sky is cloudy. However, the speed of heating and the final water temperature may be affected by such weather conditions.

How does it heat water without direct sunlight?

The key point is that even when the sky is cloudy, sunlight does not vanish completely. A portion of the sunlight still reaches the ground—a phenomenon known as "diffused radiation." Solar collectors can absorb energy from this light and continue the water-heating process. While it may not operate with the same efficiency as it does in bright, direct sunlight, it is still capable of heating water.

Water stays hot for a long time

The tank of a solar water heater features a special type of lining. ...which helps keep the water hot for an extended period. According to reports, materials like PUF (Polyurethane Foam) are used in this layer to ensure the water stays hot for longer, even when the weather outside is cold.

Heating water using electricity

Various types of solar water heaters are available in the market. Some come equipped with an electric heating rod. The purpose of this rod is to heat the water when there is no sunlight for several days during winter; in such situations, the rod can be powered by electricity to heat the water.

However, not every solar water heater includes this rod. That said, if it is cloudy and there is no sunlight, solar water heaters do not stop working entirely, although their efficiency may be affected.