Types of Solar Water Heaters

by | May 7, 2024

Are you looking for a solar water heater, that is not only cost-effective, and reliable but also environmentally friendly? With so many different types of solar water heater available in the market, it can be confusing.

These different types of solar water heaters save you money on your energy bills, require minimal maintenance, and have a long lifespan.

From active solar water heaters to drain-back systems, each provides unique solutions to meet your diverse hot water demands. Some types of solar water heaters rely on pumps, while others use direct heat energy.

These different types of solar water heaters also lowers your operational cost, helping you save 25%- 40% in winter and up to 75% in summer.

We have discussed all the popular solar water heater types, their applications, how they are working and their costs. Let’s look into them in detail.

Types of Solar Water Heaters

Typically, a heat transfer system, a storage tank, and solar collectors comprise a solar water heater.

Solar water heaters come in two primary varieties:

  • Active systems: This employs pumps to move fluid between the collectors and the storage tank.
  • Passive systems: They rely on convection to naturally transfer hot water from the collectors to the tank. 

A)- Active Solar Water Heating System

Active solar water heating systems use pumps or other devices to circulate the fluid. The fluids circulate between the solar collector and the storage tank. This is more efficient for areas with colder climates or more hot water demand. 

There are two types of active solar water heating systems:

1. Direct Circulation System

It is also known as open-loop systems. It is simple in design and operation. In this system, the water is circulated directly through a solar collector. Here it is then heated by the sun. Once it is heated, it is circulated back to the storage tank. It is now ready for use. This system works well in climates that are not prone to freezing temperatures.


  • Housing complex: It is popular in residential areas. It is comfortable for homes in mild climate areas.
  • Swimming pools: It is widely used for heating swimming pools. It helps in maintaining a comfortable temperature in the pool.


 A basic direct circulation system can cost around INR 5,000- INR 15,000. A larger system can cost around INR 15,000 – INR 30,000.


2. Indirect Circulation System

It is also known as Closed-loop system. It is popular in areas with high freezing temperatures. In this system, an antifreeze heat-transfer liquid is pumped through solar collectors. This absorbs the heat from the sun. This fluid is then circulated to a heat exchanger. Here it transfers its heat to the water in the storage tank. This helps the water to not freeze during cold climates.

This system is also versatile and reliable for areas with unstable temperatures.


  • Residential Complex:  It is suitable for houses in areas with cold climates. It ensures smooth water heating even in high freezing temperatures.
  • Industries: It is commonly used in industries that require hot water. Food processing, manufacturing and agriculture are some of them.
  • District heating:  It is utilised in district heating systems. The hot water is distributed to various buildings, hence an indirect system is preferred.


A basic indirect water system costs around INR 20,000 to 40,000. A larger and more advanced system can cost around INR 40,000 – INR 1,00,000.


B)- Passive Solar Water Heating Systems

Passive systems use convection and conduction to heat water without any mechanical components.  They are simple to install, are more reliable, and last longer than active solar water heaters.

There are two types of passive solar water heating systems:

1)- Integrated Storage Collector

In this system, the cold water enters the tank in time of sunlight. It is then heated up and goes to the storage tank above for usage.

It is suitable when cost and space is taken into consideration. It is also effective in areas with ample sunlight, providing hot water even in times of crisis.


The cost varies from INR 50,000 – INR 1,50,000 depending on use and size. For commercial purposes it can vary from INR 1,50,000 – INR 5,00,000 depending on area and size.


2)- Thermosyphon System

This system creates a natural convection loop. The solar collector is installed below the storage tank. When the sunlight heats the water, it flows above to the storage tank. Naturally, when the water cools down, it flows back to the collector for heating purposes.

In this system, no pumps are needed.  They are highly reliable and require low maintenance since they work without mechanical parts. They are ideal in areas with high levels of sun radiation.


The cost can vary from INR 75,000 – INR 2,50,000 depending on size and use. For industrial purposes the cost can vary from INR 2,50,000 – INR 10,00,000 depending on use and size.


C)- Drain Back Systems

Drain Back System is another solar water heating system. It has various benefits like efficiency, freeze prevention, and simple design. A drainback system involves solar collectors filling with a heat transfer fluid that circulates throughout the system.

 When there is sun, water in the drain back system runs through the solar collectors. The water in the collectors drains back to the storage tank when the sun sets. Hence it is known as the Drain Back system.

Drain back system prevents freeze when the system is not in operation. It is efficient to collect the maximum heat and store water. Drainback systems are comparatively simple in design and adaptable to different climates. It increases the lifespan of the system by reducing corrosion.


  • Commercial Buildings:  It is installed in various commercial setups like hotels, hospitals, and resorts. It helps in meeting the hot water demands of multiple occupants. This helps maintain efficiency and has environmental benefits.
  • Industries:  It is used in industries where hot water is required for manufacturing, cleaning etc.


A drain back system can cost around INR 1,00,000 – INR 3,00,000 depending on the uses, area and size. For commercial purposes it can cost around INR 3,00,000 – INR 10,00,000 depending on size and requirements.


Storage Tank and Solar Collector

The storage tank is an important part of the solar water heater. It stores heated water until it is needed for use.

A Solar Collector is the heart of solar water heating system. It is a device that absorbs sunlight and converts it to heat for use.This heated fluid is pumped to the storage tank where it is stored for later use.

There are three types of solar collectors:

1)- Flat-Plate Solar Collector

  • It is a very popular kind of solar collector. It is a dark-coloured flat plate made of metal or polymer.
  • It consists of tubes and channels to circulate fluid. A transparent cover above absorbs the sunlight and reduces heat loss.
  • It is budget-friendly and suitable for moderate to warm climates.

2)- Evacuated Tube Solar Collector

  • It is another common solar collector. It is made of various rows of clear glass tubes arranged in parallel. Each row has an absorber tube inside it.
  • It is suitable for colder climates or areas with less sunshine.

3)- Integral-Collector Storage System

  • It is also known as ICS or batch systems.It consists of a Solar collector and Storage Tank in one single unit.
  • It consists of an insulated box where the water is heated directly. Then it naturally goes up to the storage unit where it can be taken for use. 
  • It is a cost-effective choice for smaller applications and areas with mild-freeze climates to avoid freezing outdoor pipes.


Continued adoption of sustainable practices is important for both current and future generations. With the challenges posed by climate change and environmental degradation, solar water heaters emerge as a crucial solution offering significant benefits.

For homeowners, solar water heaters mean reduced electricity bills and a lower carbon footprint. Likewise, businesses can benefit from lower operational costs and corporate sustainability. Moreover, using solar water heaters helps preserve natural resources for the future. 

In conclusion, solar water heaters or any renewable energy source is a greener solution. Proper installation ensures optimal performance with potential cost savings and environmental benefits, making it a worthy investment. We all should embrace sustainable energy practices. Make a positive impact on the environment by choosing solar water heaters.

Bhuwan Bhatia

Bhuwan Bhatia

Bhuwan Bhatia, an engineering graduate with a diverse background, has been passionate about entrepreneurship since age 13. Founder of edtech startup Technoshaala, Bhuwan now focuses on leading his innovative water management startup, FLOTAA, in Kanpur to create sustainable solutions.
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