What Is Solar Energy and How Does It Work?

We use the term solar energy to describe the radiant energy that can be found within the sun’s rays. There are several technologies that we can use to harness this energy. Once harnessed, we can use it for different purposes.

According to NASA, the sun is over 4.5 billion years old. They also estimate the sun is around halfway through its lifecycle and therefore is likely to burn for another 5 billion years or more. This makes solar energy a safe investment for those interested in alternative energy technologies.

In this article, we’ll take a closer look at what solar energy actually is and the different ways in which we can use it.

What Is Solar Energy?

We have already touched on what solar energy is, but let’s now explore that topic in a little more detail.

As the sun burns, thermonuclear reactions take place. These reactions release massive amounts of energy in the form of light and heat. This energy from the sun (solar radiation) travels through space until some of it eventually reaches the earth.

An illustration of the sun releasing solar energy.
Thermonuclear reactions release solar energy into space.

When solar energy reaches the earth, it has a number of different effects. It helps to heat our planet, grow our crops and provide a source of light. It is at this point where we can harness solar energy for other purposes such as for generating power and heating water.

What Is Solar Photovoltaics?

Solar photovoltaics (solar PV) refers to a process we can use to convert solar energy into electricity. This is the main technology used for solar power production.

How Solar Photovoltaics Works

Solar PV works by converting solar energy into electricity. The sun’s rays contain photons which are particles that transmit light or other forms of electromagnetic radiation. These photons are key for the photovoltaic process to work.

Solar panels (solar cells) are designed to absorb photons and knock them off their orbit in the process. As this happens, they become what’s known as ‘free electrons’ which have the ability to pick up current. A photovoltaic cell can then export this current as usable electricity.

A stack of solar photovoltaic panels.
Solar panels each consisting of many photovoltaic cells.

Solar photovoltaics is used all over the world. It can be found in everything from traditional rooftop solar panels to large-scale solar power plants. One of the more common uses of solar PV is in calculators. More contemporary uses of solar PV include road signs and temporary stop lights.

What Is Solar Thermal Energy?

You may have heard the term ‘solar thermal energy’ and wondered what this actually is. Well, solar thermal is a term that we use to refer to the process of heating fluids. Whilst this still uses solar energy as its source, the technology is significantly different from that of solar photovoltaics.

How Solar Thermal Energy Works

Whilst there are different solar thermal technologies in use today, the main principle of how they work is the same.

All solar thermal technologies absorb heat from the sun’s rays via a ‘collector’ and transfer it to a fluid which then becomes high temperature. This can be either water or another fluid designed for greater heat absorption. Some fluids also contain anti-freeze solutions to avoid damage to the system in periods of cold weather.

There are two main types of solar thermal collectors in use today; flat plate collectors and evacuated tube collectors. Whilst how these different collectors work is beyond the scope of this article, we have included a short explanation below:

  • Flat Plate Collectors – These transfer fluids through a network of pipes that run the length of a solar collector. The fluid directly absorbs solar radiation.
  • Evacuated Tube Collectors – These use multiple vacuum tubes to collect heat which is then transferred to the top of the collector where a single pipe containing fluid runs. It is at this point where the heat is exchanged to the fluid.
A solar thermal energy evacuated tube collector.
An example of an evacuated tube collector.

Whilst solar water heating is less common than solar power, it is gaining in popularity in many parts of the world, including the United States.

Can Solar Thermal Energy Generate Power?

Whilst solar thermal energy always refers to the process of using solar energy to heat a fluid, the technology can still be used to generate power on an industrial scale.

There are several types of solar thermal power plants in use today. All of these power plants start by using solar energy to heat water. This is done on an industrial scale to intensify the solar thermal effect and create a super-heated fluid.

The heat from the super-heated fluid is then transferred to water which boils and produces steam. The steam is then fed to a turbine which begins to turn a generator which then produces electricity.

A parabolic mirror solar thermal power plant.
A parabolic mirror solar thermal power plant.

If you are interested in the different types of solar thermal power plants and how they work then this website has a great article covering the topic.

Which Solar Energy System Is Best?

Which solar energy system is best depends on your needs and what you hope to achieve.

If you are looking at generating solar power for your home, then a solar photovoltaic system is the right decision. You wouldn’t be able to use solar thermal energy to produce enough electrical power in a residential setting.

Should you prefer the idea of using solar energy to provide a source of hot water for your home, then you might want to look into installing solar thermal technologies.

As with all renewable energy technologies, solar energy has a number of pros and cons associated with it. It is always best to fully explore this topic and take additional advice from a professional before choosing to invest in the technology.


To sum up, solar energy is a renewable energy source that we can use for different purposes. It can help to generate power and heat water for our homes, all whilst supporting life on earth.

The use of solar technologies is key in helping to reduce our reliance on fossil fuel alternatives such as coal, oil, and gas. Generating electricity from the sun and making use of solar heating also helps to reduce pollution and reduce the intensity of global warming.