Working of Solar Water Heater

Solar Water Heater

How it Works

A solar water heater combines solar energy with electricity, gas or oil to heat water for cooking, cleaning, bathing and heating. The unit consists of a storage tank and a solar collector which collects solar heat while sitting on the roof.

Solar hot water systems can be either “active” or “passive”. Active models use pumps to circulate water to and from the heated solar collector. Passive models use heat-driven convection or heat pipes to circulate the water. When solar power is not enough to keep water above the desired temperature, the second energy source (electricity, gas or oil) kicks in. In colder climates, some solar heaters use a mixture of water and glycol. The glycol keeps the water from freezing and prevents corrosion.

What Can Go Wrong?

If hot water is not used for an extended period of time, the tank water can get extremely hot. Any glycol in the system can become acidic at high temperatures and may begin to eat away at the system’s collectors, pipes and pump. This will lead to failure of the system.

Environmental Impact

Even though a secondary energy source is often used - especially when there’s no sun - a solar hot water system is far more energy efficiency than a conventional hot water heater. Your solar water heater can reduce electricity consumption by 1,500 kilowatt hours annually, which can save you hundreds of dollars. It can also reduce carbon dioxide emission by 2,300 pounds.

Tips & Tricks

Maintenance Tips

Glycol and other similar fluids should be replaced every three to eight years, depending on temperatures the system has gone through.
Keep the collector’s surface clean to optimize energy efficiency.

Loss Prevention Tips

Consider a drain-back system, which removes fluid from the collector when you’re not using hot water. This can prevent overheating or freezing of the fluid and helps to extend the life of your system.
Listen to the fluid pumps to make sure they are running, especially when the sun is shining on the collector after mid-morning. If you can’t hear the pumps operating, there may be a malfunction with the controller or the pump. Have the system checked if this is the case.