What Is A Solar Collector: The Chemistry Behind Solar Energy

Have you heard of the term “solar collector”? Do you wish to know what it means? Then, take your time reading what a solar collector is to help you understand better.

You would imagine how the electricity you generate through the sun absorbs in the solar panel – maybe because you have only been reading about the solar panel generating heat or electricity from the sun.

Nevertheless, there is always the first time of knowing something. However, while the solar panel is packaged as the photovoltaic cells, the solar collector absorbs the heat or electricity.

Therefore, this powerversity guide will tell you all you need to know about solar collectors without taking much of your time in this section of the article. Also, what they are, their types, benefits, drawbacks, and how to install and maintain them.

At the end of this article, you’ll know all there is to know about solar collectors.

First, let’s find out what a solar collector is.

What Is A Solar Collector: Overview

What Is A Solar Collector_ Overview

Generally, the word ‘solar collector” is also active heating. Therefore, solar collectors are flat surface devices used to generate heat.

In terms of active heating, it is very usual to use mechanical ways to harness, store and generate solar energy. The reason for this is to provide hot water in buildings or space heating.

Hence, making room for the domestic or personal heating of water. However, this process of heating the water by the solar collector transforms it into useable electricity.

Can I quickly tell you the functions of solar collectors? If yes, then read the subheading below.

Functions Of Solar Collectors

Functions Of Solar Collectors

Even more, the solar collector mostly functions in three ways to generate heat, they are:

  • Transmittance loss
  • The reflectivity of the glass cover
  • The absorptivity of the absorber plate.

Transmittance loss” results from losing some energy when radiant energy travels through the glass cover.

Moreso, the thickness, quality, and number of glass covers in the solar collector can add to the effect of transmittance loss.

For the case of reflectivity, it has to do with the amount of sunlight that reflects from the solar collector’s cover.

Then as for solar absorptivity, this depends on the optical property of the materials exposed to solar radiation.

This means solar collectors solely operate to heat fluid such as water, antifreeze, or air.

Moving on, solar collectors have three main parts, a transparent cover, coolant tubes, and an insulated backplate.

These parts are very important in converting, transferring, and generating energy or electricity.

Overall, installing solar collectors can be carried out either on the roof or near the house.

Having read through the meaning of a solar collector, it is time to consider the types of solar collectors.

Types Of Solar Collectors

Types Of Solar Collectors

A solar collector is divided into two main types and also has various sub-types

And in this article, I will discuss each of them. But, first, let’s look at the two types of solar collectors and note that solar collectors can also be seen as solar thermal collectors.

Solar thermal collectors can be classified into two, non-concentrating collectors or concentrating collectors.

Non-Concentrating Collectors

The concept of the non-concentrating collector’s technology is a very straightforward one. This concept involves the use of sunlight to warm a dark, flat surface to collect as much energy as possible.

Then, the collected energy will be transferred into the water, air, or another fluid for usage.

Moreover, non-concentrating collectors are also called flat plate collectors because they have a flat absorbing surface.

These solar collectors function in heating swimming pools, heating space, or domestic hot water.

The area that receives sunlight in the non-concentrating collectors is the same as the area absorbing the sunlight.

Likewise, people frequently employ these collectors because they diffuse the radiation scattered by atmospheric influences.

They collect direct sunlight from various angles. Again, they operate with an absorber, a transparent cover, and insulation.

The absorber comes in the form of a metal, glass, or plastic surface, primarily black color. Its function is to absorb, convert, and transfer thermal energy to the circulating cold.

For the transparent cover, it is the upper part that covers the absorber plate. It comes either in a glass form or a transparent plastic sheet form. Therefore, this allows the penetration of solar beams.

I know what your mind is telling you. You are wondering what solar beams mean – it is one of the solar radiation that produces electricity without diffusing the radiation.

On the other hand, the collector insulation consists of a material with very low thermal conductivity. The collector insulation is located at the bottom and around the sides of the collector, where it minimizes heat loss.

However, these features of the non-concentrating collector help protect the absorber from environmental damages and decrease thermal loss.

Now you know this, let’s see the types of non-concentrating collectors.

Types of Non-Concentrating Collectors

Non-concentrating collectors have two main types: flat plate and evacuated tube collectors.

Flat Plate Collector

The flat plate collector is a very common type of solar collector. Its features include an absorber, a transparent cover, and insulation.

Most significantly, the flat plate collectors come with some main component that helps distinguish them from other solar collectors. Those components are; a black surface, glazing cover, tubes, well support structure, and insulation.

Plainly, the black surface absorbs the incidence of solar energy. Meanwhile, the glazing cover transmits sunlight to the absorber.

On the other hand, the tubes contain heating fluid that helps transfer heat to the collector. Then the well-supporting structure protects the components of the flat plate collector.

Lastly, the insulation covers both the sides and the bottom of the collector to reduce heat losses.

Therefore, a flat plate collector is a device with a flat absorbing surface with an area equal to the aperture of the collector.

The “Flat plate collector” construction and design are very simple. So simply say, they are very easy to construct, install, and operate.

Majorly, you can see the flat plate collector in residential buildings where the need for hot water is large and affects bills.

The simplest flat plate collectors are the solar ponds and the solar stills. Hence, they operate by the direct utilization of solar radiation, acting simultaneously as solar energy converters.

In conclusion, it is important to predict and treat the thermal performance of the flat-plate collectors.

Still talking about the flat plate collectors, let’s see the different ways to construct a flat plate collector.

The Different Ways In Constructing A Flat Plate Collector

Basically, there are two main ways of constructing a flat plate collector they are Direct Heating System and
Indirect heating System.

Direct Heating System

The direct heating system is an open-loop system that requires water’s direct heating in a plate for various household purposes.

However, there are two methods of a direct heating system. These are the injection method and infusion method.

An injection method involves injecting high-pressure steam into a pre-heated liquid, thereby causing a fast temperature rise.

The injection technique provides room for a quick heating and cooling system and the removal of volatiles.

Likewise, the injection consumes a lot of energy and will lose its flavor if it comes into contact with hot equipment.

The infusion method involves using a distributing nozzle to push the liquid product into a high-pressure steam chamber.

However, this method has a big steam volume and a modest product volume. Hence, it spread across a large product surface area.

Indirect Heating System

The indirect heating system is a closed-loop system that requires the construction of a water tank with a spiral of pipes inside it.

The ends of this pipe are mostly connected back to the flat plate collector.

Hence, hot water from the collector flows through the pipes to enter the tank to give it heat before returning to the collector.

Still, under the non-concentrating collectors, let’s move to the evacuated tube collector.

Evacuated Tube Collector

The evacuated tube collector is the most common solar thermal technology globally.

The name “evacuated tube collector” results from the space between the heat pipe and the pressure-proof glass of the collector.

These collectors have an absorber strip placed in an evacuated, pressure-proof glass tube. Therefore, this collector is a type of vacuum collector that does not allow heat to escape through it.

Most times, these collectors look like long glass test tubes, and they have heat pipes inside of them to carry the working fluid. This pipe releases a fluid that evaporates even at a low temperature.

Therefore, the steam heats each pipe of the collector and warms up the fluid in the main pipe. Hence, generating heat.

In essence, the heat transfer fluid directly from the collector’s absorber to a U-tube system.

However, let’s see the types of evacuated tube collectors.

Types Of An Evacuated Tube Collector

Basically, the evacuated tube collector has two main parts. These are direct flow evacuated-tube collectors and the heat pipe evacuated-tube collectors.

Direct Flow Evacuated-Tube

The direct flow evacuated-tube collector is a type of collector where the heat pipe inside of it is bent in a U-shape form. Inside the U-shape, one arm of the U-pipe acts as an inlet while the other arm act as the outlet.

Likewise, the inlet allows cold water to flow through it so that the glass tube of the collector can heat it and pass it out of the heat tube.

Finally, the U-pipe cannot be easily replaced because fluid flows directly into each pipe.

Heat Pipe Evacuated-Tube

Heat pipe evacuated-tube collectors is a type of collector where the heat pipe is usually attached to an absorber inside a vacuum-sealed glass tube.

The heat pipe is filled with water and a small quantity of alcohol. Then, this combination heats up to absorb solar radiation.

With this, the water and alcohol form a vapor that will rise to the top of the pipe. After this, the heat energy from the vapor is transferred to a connecting manifold or a copper heat exchanger.

At this point, the vapor then cools down to become liquid and gets back in the pipe from the manifold to reheat again.

If you agree with the above explanation, let’s move on to concentrating collectors.

Concentrating Collectors

The concentrating collectors are the opposite of the non-concentrating collectors. They are the type of collectors used in concentrated solar power (CSP) systems.

The concentrating collector requires a reflective surface to control sunlight in a small area. Hence, the converting and absorption of heat happens from this small area.

After this, this collector converts the heat into the water to produce steam for powering a steam turbine-generator to generate electricity.

Likewise, concentrating collectors have a larger area that receives solar radiation than the area that absorbs sunlight.

The receiving area of the concentrating collector is in the form of a mirror focusing on the absorber.

In most cases, this absorber of the concentrating collector is the pipes carrying the working fluid.

“Active collector” is another name for the concentrating collector because it requires a solar tracking system. Therefore, this collector works with the sun’s movement by the day.

If you want your tracking system to track better, you should mount the concentrating collectors in a standstill position.

Overall, there are some collectors that look like flat plate collectors, and these types are positioned directly on building surfaces.

Moving on, I will take you to the types of concentrating collectors.

Types Of Concentrating Collectors

The main types of concentrating collectors are the parabolic trough, power tower receiver, parabolic dish collector, and fresnel lens collector.

Parabolic Trough Collector

Parabolic trough collector (PTC) also line focus collector can rotate on an axis to track the movement of the sun. This collector uses a mirror with a parabolic cylinder shape to concentrate and reflect the sun’s radiation on a receiver.

These receivers are tubes along the focal line of the parabolic cylinder. More so, the receiver absorbs the radiation and converts it into thermal energy.

A fluid medium then collects this energy and circulates it within the receiver tubes.

Lastly, you can induce this method of parabolic trough collector both for thermal energy collection or to generate electricity.

Power Tower Receiver

Power tower receivers (PTR), also known as power receiver systems, are large-scale plants used to power a steam cycle. Likewise, the component of solar power towers is a large array of sun-tracking mirrors or heliostats.

The heliostats help to focus the direction of sunlight onto a reliever at the top of the tower. Then, this receiver heats fluid to generate steam.

Moreover, this stem will power a conventional turbine generator to generate electricity.

Finally, the advantage of this collector is that it collects all energy at one location and saves it on transport networks.

Parabolic Dish

A parabolic dish collector (PDC) has a shape similar to a satellite dish. These collectors have a mirror that looks like a reflector and an absorber at its focal point.

Likewise, the PDC uses the mirror-like reflector to focus and reflect solar energy into the collector. Overall, this collector concentrates sunray onto the receiver with the use of a computer and the use of axis tracking.

Fresnel Lens

The most common device used to achieve concentration is the Fresnel lens.

Fresnel collectors are types of linear concentrating collectors. Therefore, they make use of a linear reflector and receiver.

The receiver and reflector operate with a single-axis tracking heliostat to generate energy.

You can position the fresnel collectors horizontally to track the sun. Moreover, this method helps the receiver absorb sunlight without the need to move it.

Lastly, the angles of the fresnel lens collector help bring radiation to a line focus. However, the lens is usually made of extruded acrylic plastic sheets.

Done with the types of concentrating collectors. So don’t quit reading yet.

Here is the solar collector benefit.

What Is A Solar Collector: Prons And Cons


Using a solar collector to heat water comes with various benefits, and these benefits are:

Firstly, the use of a solar collector will help give an unlimited amount of energy. What the solar collector needs to do is to harness sunlight and convert it to usable energy.

Secondly, using a solar collector will help save the cost of energy as there will be remarkably less energy for heating water and space heating.

Also, using a solar collector will help reduce fossil fuel consumption. Therefore, it takes direct energy from the sun to heat water.

In the solar collector system, energy from the sun does not cost anything. So, it saves electricity costs.

Moreover, the thermal collectors require less space because a typical house requires two or three to function.

Another benefit is that this solar collector has high efficiency of about 8% of the sun’s radiation. Meanwhile, that is what it requires to turn water into heat energy for domestic use.

Likewise, this solar collector requires very low maintenance after installation. Therefore, it reduces the cost of maintenance.

Overall, solar collectors are very cheap to install because it requires only two or three panels to function properly.

That said, let’s move on to its drawbacks.


Solar collector has their drawbacks, and they include:

The first disadvantage of this solar collector is that heating water is very expensive. This implies that it will take a large amount of energy to generate heat.

Likewise, there is no flexibility for the solar collector as it can only heat water. Moreover, it requires annual maintenance to ensure parts of the collector perform very well.

Also, solar collectors require direct sunlight to function. Hence it does not function on cloudy, rainy, or foggy days.

Finally, the installation of the solar collectors requires the use of a new hot water cylinder.

With this, we are going to see how to install and maintain a solar collector.

What Is A Solar Collector: Installation And Maintenance

What Is A Solar Collector_ Installation And Maintenance

The installation of solar collectors depends on many factors.

These factors include resources, climate, local building code requirements, and safety issues. Therefore, the best option is to have full knowledge about a solar collector.

In addition, employ an engineer with good experience installing solar collectors.

Also, proper solar collector maintenance will help prolong its lifespan and keep it running smoothly.

What Is A Solar Collector: My Final Thought

What Is A Solar Collector_ My Final Thought

For clarity, a solar panel has an object called a solar collector that collects and absorbs heat or electricity. With the help of the solar collector, the energy generated from the sun can absorb and then converted into useable energy.

That is to tell you that a solar panel does not work in isolation. There are still other components or objects you will find helping absorb the energy it collects from the sun.

Meanwhile, in the absorption process, the solar collector also works with the flat plate collector, as seen in the transparent box enclosure. When the energy is absorbing, the cover plate at the top of the box maintains the overflow or loss of heat or electricity.

Furthermore, the solar collector can be used in a variety of places such as energy companies, residential applications, and industrial applications.

In most cases, for cleaning, bathing, and even cooking.

Lastly, even in solar farms, the users use it to distribute the heated liquid that the solar collector converts into electricity to other customers.

And that is that about a solar collector; I hope you found this PowerVersity guide helpful?

If you found it helpful, kindly share your thoughts with the “Leave a Reply” form found towards the end of this page.

Finally, visit our Electricity & Renewables page to read more guides like this.

What Is A Solar Water Heater

Chinenye Mbam
Chinenye Mbam is a Content Writer for PowerVersity.com. She has a B.Sc in Mass Communication. Chinenye loves typing, movies, cooking, dancing, and she is open to learning new skills. Chinenye writes reviews, buying guides, and best pick articles for PowerVersity.com.
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