Thermal Solar Energy Collectors: Types, Uses, and Components

Do you know what a solar thermal collector is?

A solar thermal collector is a part of a solar thermal installation. Its function is to capture radiations from the sun and convert those radiations into thermal energy. 

Sometimes the solar panel of this type is also known as a thermal solar panel. 

Solar thermal energy installations or solar energy collectors are classified into several types based on their purpose. 

Following are some of the most common uses of solar collectors:

  • – Pool water heating
  • – Heating systems
  • – Electricity production in large solar thermal power plants
  • – Domestic hot water ( DHW) 

Similarly, depending on their use, thermal solar energy collectors are also of several types. 

Intrigued? Would you like to go into the details about the types of thermal solar collectors and explore their benefits? 

If so, this guide will answer all your questions. Dive in!

Types of Solar Thermal Collectors

There are three major types. Let us learn about each of the types in detail:

1. Flat Plate Collectors

The solar radiation received on a surface is captured by flat plate solar collectors and used to heat a fluid. 

The heat loss is often decreased because of the greenhouse effect. The core of the thermal solar collector of this type is made of a series of metal tubes that are vertically oriented and conduct cold water in parallel. 

The pipes are connected by a horizontal pipe at the bottom to intake cold water, and another similar pipe is connected at the top to the outlet.

There is a cover at the top to encase the tubes. It is generally double glass and has an insulating material at the bottom. 

Solar energy collectors of this type are used in low-temperature installations, typically below 79 degrees Celsius. For instance, they are used for heating the water in swimming pools.

2. Evacuated Tube Collectors

Evacuated tube solar energy collectors are similar to the Flat plate solar collectors discussed above. 

However, here glass tubes are present instead of metal tubes. These tubes made of glass are encapsulated in another glass tube with a vacuum in between for installation. 

The cost of this type of solar energy collector is high, but its performance is better.

3. Concentrating Collectors

The radiation received on a relatively large surface is captured by this type of collector. Parabolic troughs or flat mirrors on a smaller surface are used to concentrate these radiations. 

The objective of concentrating solar energy collectors is to focus the solar radiation received on a surface at a single point so that high temperatures can be obtained. 

This thermal solar panel is useful for high and very high-temperature solar installations. 

Also, these are employed to generate water vapour with very high pressure, as seen in a thermal power plant of conventional type.

What are the Components of a Flat Plate Solar Collector?

Following are the constituting elements of a standard solar collector:

  1. The cover: A standard solar energy collector comes with a transparent cover. It is generally formed out of glass, but plastic is sometimes used. Its purpose is to minimise the loss of heat by thermal radiation and convection. 
  1. Air channel: It is an empty space whose function is to separate the absorbent plate from the cover.  
  1. Absorbent plate: It is the component of flat plate solar energy collectors. An absorbent plate’s function is to absorb solar energy and transmit it to the circulating liquid in the pipes. The main feature of the plate is that its solar absorption must be high and thermal emission must be low.
  1. Tubes or ducts: These components of solar energy collectors are in contact with the absorber plate. Consequently, making more energy exchange possible. The liquid circulates through the pipes, gets up, and goes to the accumulation tank. 
  1. Insulating layer: The function of this layer of solar collectors is to avoid and minimise losses from the system by covering it. 
  1. Accumulator: This is an optional component. But, most flat plate thermal collectors nowadays have it.

Uses of Solar Energy Collectors

Let us now understand the various uses of a solar thermal collector:

  • – The main function of solar energy collectors is to supply hot water for DHW and generate electricity.
  • – For solar energy collectors used for heating and domestic hot water, the domestic water is tanked by solar storage tanks that contact the fluid with the help of a coil. 
  • – The stored heat energy is allowed to be transferred by a coil to the water without contaminating it. 
  • – This water can be employed to complement the floor heating of the rooms or can be used as hot water in rooms. 

Hot water can be supplied in abundance by thermal solar collectors. But the usual heating methods cannot be completely replaced by it due to the absence of solar energy during the night. 

Solar energy collectors designed to generate electricity require the heat exchanger to be heated until it is boiling. 

The thermodynamic phase change of the liquid gets completed and goes to the gaseous phase. Thereafter, it is directed to a thermoelectric turbine that transforms steam movement into electrical energy. 

This solar system is also known as solar thermodynamics and needs large spaces for the installation of thermal solar panels. These types of solar plants have been installed in deserts. 


The Use of solar energy for homes and the commercial sector is rapidly emerging as one of the most efficient and environmentally friendly energy types. 

Heating with the help of solar energy collectors is an excellent method of making use of renewable energy while operating thermal solar panels. 

This technology has innumerable advantages, and we hope that this article gives you an insight into the functions of solar energy and its advantages.


Q. What are the savings that come with thermal solar energy collectors?

Around 60% of the domestic hot water requirement should be fulfilled by a solar thermal system. 

This gives way to financial savings and curbing carbon emissions.

Q. Which solar thermal collector is the most efficient?

The most efficient solar thermal collector is the evacuated tube collector. 

Q. Which is the most expensive thermal collector?

Hot water solar collectors are the most expensive type of solar collectors. They have metal or glass tubes with a vacuum. This lets them operate flawlessly in colder temperatures.