Solar Water Heaters

What is Solar Water Heaters?

Solar water heaters sometimes called solar domestic hot water systems can be a cost-effective way to generate hot water for your home. They can be used in any climate, and the fuel they use is sunlight which is free.

How They Work?

The rays of the sun strike the collectors, they are converted into heat waves. that heat energy is then transferred to the water storage tanks, where it heats the water until is it called upon for use. In simple words you can say that rays from the sun shine on the panel collectors that subsequently transfer that heat to the water storage tank.

There are two types of solar water heating systems

  • FPC –Flat Plate Collectors
  • ETC- Evacuated-tube collectors

Solar water heating systems include storage tanks and solar collectors.

Storage Tanks and Solar Collectors

Most solar water heaters require a well-insulated storage tank. Solar storage tanks have an additional outlet and inlet connected to and from the collector. In two-tank systems, the solar water heater preheats water before it enters the conventional water heater. In one-tank systems, the back-up heater is combined with the solar storage in one tank.

Two types of solar collectors are used for residential applications

Flat-plate collector

Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers. Unglazed flat-plate collectors — typically used for solar pool heating — have a dark absorber plate, made of metal or polymer, without a cover or enclosure.

Evacuated-tube solar collectors

They feature parallel rows of transparent glass tubes. Each tube contains a glass outer tube and metal absorber tube attached to a fin. The fin’s coating absorbs solar energy but inhibits radioactive heat loss. These collectors are used more frequently for U.S. commercial applications.

Solar water heating systems almost always require a backup system for cloudy days and times of increased demand. Conventional storage water heaters usually provide backup and may already be part of the solar system package. A backup system may also be part of the solar collector, such as rooftop tanks with thermosyphon systems. Since an integral-collector storage system already stores hot water in addition to collecting solar heat, it may be packaged with a tankless or demand-type water heater for backup.

Schematic diagram:

Why Solar Water Heating?

Electricity or natural gas water heating Solar Water Heating
Pay 100% of hot water heating bill
Eliminate up to 80% of bill
Surrender to continued rising energy costs
Enjoy a constant increasing savings in non- taxable income
Add zero equity to your home
Increase home's value through your investment
Make monthly payments for hot water with no return on investment
Profit from an income generation opportunity that produces a monthly positive cash flow
Contribute to air pollution and add heavy toxic metals into the air and water
Utilize a safe, free, non-polluting energy source

Benefits

  1. These systems use solar enegy which is a free and renewable source of energy
  2. Sunny and warm places with high insolation values solar water heating sysem are very cost effective.
  3. Relatively good payback period
  4. These systems have low maintenance costs

Difference between FPC and ETC water heaters

FPC ETC
Long lasting as they are metallic but are expensive
Fragile but cheaper
Can work in colder regions with sub zero temperature but will need and anti freeze solution
Very good for colder regions when the tempeature is sub zero
In places with salty water a heater exchanger is required with FPC system
Require regular cleaning where the water is salty.