Tips and Tutorials

How Does a Solar Water Heater Work?

Written by Shikha Mehta

Did you know you can save 4,000 watts of electricity every day if you use a solar water heater? A typical electric geyser consumes that much of electricity till 3 hours a day. We aren’t just heating the water is coming through the taps, but also the atmosphere outside.

Solar water heaters use the energy of the sun to give hot water. On average, it can heat water up to 212°F, though you won’t require more than 130°F. It provides hot water for your bath as well as in the kitchen and washing machine. One solar heater is sufficient for the entire house.

However, a geyser might restrict itself to only 1 bathroom.

Now before we get into how the heater works, let’s first get to know more about solar energy.

What is solar energy?

If you’re looking for a formal definition, we can say:

It is a renewable energy that can convert sunlight into electricity. You have to install a solar power panel that uses either photovoltaic cells or concentrated solar power systems for the process.

Design of a Solar Water Heater

A solar heater consists of the following components:

  • A thermal panel or collector: The solar panel is installed on the roof that collects cold water. It absorbs sunlight and converts it into heat. As a result, the temperature of the water present in the collector rises. Now, it is ready to transfer to the storage area.
  • A water tank: As the name suggests, it is a large open container that stores water heated by the device. It is the storage area of the device from where you get hot water in your taps.
  • A circulating pump: It is the pipe that fills up the tank with heated water.
  • A thermal regulator: This ensures the functioning of the heater to a great extent. When the water present in the collector is hotter than that present in the tank, it transfers the same through the pump. It ensures only heated water reaches the tank.
  • A drainback reservoir: This reservoir collects hot water creating a contingency or back up. It supplies hot water only when the water on the panel. On cloudy or cold days when the sun’s impact is low, the drain back reservoir will have enough hot water in it to supply in the kitchen and bathrooms.

Solar Power Generation

A solar system for power generation can be of 2 types:

  1. Concentrated Solar Thermal System: This uses several lenses and mirrors to trap sunlight and convert it into heat.
  2. Photovoltaic System: It consists of a panel made of photovoltaic cells that convert sunlight into electricity.

How do the Different Types of Heaters Work?

There are 3 types of solar heater systems that function in their own way:

  1. Direct Circulation System: This kind of system is more suitable for areas where usually you don’t have a freezing winter for a long time. On sunny days, they pump water from the storage to the collectors. On a cold day, water is drained down from the collector to provide freeze protection. The hot water is recirculated from the storage tank.
  2. Indirect Heating System: This kind of system has a water-ethylene glycol solution or water-propylene glycol solution. These are freeze-proof fluids that transfer their heat through a heat exchanger to the potable water. Hence on a freezing winter day, this hot fluid will heat the water. This ensures you get enough hot water even if the winter is long.
  3. Air System: This is also a type of indirect system which consists of a fan. The heat trapped by the system will raise the temperature of the air. The fan transfers this to the air-to-water heat exchanger.

Solar power generated water heaters can save on a lot of electricity and conventional energy. It also efficiently provides you with hot water on cold days.

You can choose the appropriate design and system of the water heater on the basis of:

  • The weather conditions in your town, and
  • The type of roof you have.

Now that we have understood a solar water heater working, let’s see if it is worth it.

How Much Does a Solar Water Heater Cost?

A single piece of solar water heater price starts from $2,000 and can go up to even $5,000. The capacity of such a solar geyser would be at least 100 litres per day. Even though it seems expensive as compared to an electric geyser, there are certain savings that compensate for the high price:

Savings on Electricity Bill: A typical electric geyser consumes 4,000 watts of electricity in a day. This means that when you replace it with a solar water heater, you save $14.40 a month.

Lasts Longer: An electric geyser that you may purchase for $300 and spend an additional $15 through the electricity bill every month will last for 10-15 years at the most. However, a solar geyser will last at least 15-20 years.

Saving the Planet: Even though this doesn’t count on your money, it indirectly does count on your life. We have endangered life on this planet for ourselves by contributing to greenhouse emissions. With eco-friendly devices, we take small steps towards saving the planet from global warming and pollution.

So, even though the cost of a solar water heater is high, you are paying it once in 20 years. There is no additional cost that you pay through bills or inhaling more greenhouse emissions.

The only reason why most eco-friendly devices are costlier is because they are one-time purchases needing very little or no maintenance.

How to Buy a Solar Geyser?

Even though an electric geyser costs less, you actually spend money behind it for as long as you use it. However, solar geysers are a one-time investment that last longer. Still, because they cost more you need to make your purchase decision wisely.

Following are the factors you need to consider when buying a solar geyser:

Energy Efficiency: The water heater should be made of material that can tap maximum solar power, like silicon and glass. It should be able to generate enough electricity through solar energy for heating the water.

Capacity: This is closely related to the efficiency of the heater. Depending on the efficiency, it can heat more and more water in a day. Ideally, the capacity should not be less than 100 litres per day. Good quality solar geysers even have a capacity of 250 litres per day.

Warranty: Usually, these water heaters require very little maintenance. Rarely does a problem occur with these devices. This is the reason why they last longer than electric geysers. However, they must have a warranty of around 5 years.

Cost: The cost of the solar heater must match the capacity and efficiency. You cannot pay $5,000 for a heater that has a capacity of 100 litres per day. Check how long the device will last and make comparisons before making your final decision.

Installation: Usually, a costly solar geyser comes with free installation. One may say that the installation cost is included in the price of the solar water heater. On the other hand, cheaper devices may include an additional installation cost.

After taking all these factors into consideration, you can finally make a purchase that is worth. It is best when you find a solar geyser for sale, as it may fit your budget.

How to Make a Solar Water Heater?

If you still find solar geyser prices high, you still do have an alternative way of saving on your electricity bill. There’s another way of obtaining a solar water heater – DIY or do-it-yourself. Yes, you can make your own water heater that uses solar energy if you don’t find a solar geyser for sale.

This DIY solar water heater will not even cost you $100. Here’s how you can go about it:

Step 1. Gather the following materials:

  • An electric tank
  • Black paint
  • Pipes
  • A box made of plywood
  • A sheet of glass
  • Insulation material
  • Mountings
  • A hinged lid

Step 2. Use the black paint on the inner and outer walls of the tank.

Step 3. Place the sheet of glass on top of the box.

Step 4. Create holes on the box for fitting pipes.

Step 5. Use insulation material to cover the box and the hinged lid too.

Step 6. By this time the paint will dry completely. This is when you place the tank in the plywood box.

Step 7. Ensure that cold water enters the tank from the bottom and hot water moves out from above.

Step 8. Using the mountings, place the entire unit on the roof or terrace.

Solar power will save out on global warming. The biggest solar park is under construction in India, Dholera that will produce 175 GW of green electricity.

While solar power is replacing coal and solar water heaters are replacing geysers, there are solar cookers in the market that can replace ovens and LPG stoves.

Isn’t a one-time investment behind a renewable source of energy more convenient than a monthly payment of electricity bill?

About the author

Shikha Mehta

I discovered my talent in writing while I was in high school. Since then, I discovered the joy of sharing your knowledge with people around you. This is the reason why I love making my contributions to Insights of Technology. Being a certified content writer, I have been writing on several topics, science & technology being one of my favorites.

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