What is Solar Radiation ?

Do you know what solar radiation is all about? This article will explain all you need to know about solar radiation.

It is a fact that there will be no earth without solar radiation. This is because all living things on earth depend on sunlight for survival.

Sunlight warms the planet, provides food for plants and animals, and provides us with the energy our bodies need to function.

This article will discuss a comprehensive breakdown of solar energy, including what solar radiation is, how to measure solar radiation, the benefits of solar energy, and lots more.

So, to have full knowledge about this topic, keep reading.

Solar Radiation: Overview

Solar Radiation_ Overview

In a simple term, I will say that solar radiation has to do with all the light and energy from the sun. Also, it is often called sunlight or solar resources.

Solar radiation is the energy the sun produces through electromagnetic waves—consequently, the light and heat we use, get to us through solar radiation.

Furthermore, this solar radiation is captured and transformed into energy helpful to men, such as electricity and heat. This process involves the use of many technologies.

However, the economic operation and technical feasibility of these technologies at a specific location rely solely on the available solar resource.

In addition, the amount and level of solar radiation that a body of water or a location receives lie on so many factors. Those factors are season, latitude, time of the day, altitude, and cloud cover.

Note that not all radiation from the sun reaches the earth’s surface. Instead, most of the radiation is scattered in the atmosphere.

More so, you can absorb solar energy directly from the sun at the surface, known as direct radiation. Also, the light scattered already from the atmosphere is referred to as indirect radiation.

There are many forms of solar radiation. The electromagnetic spectrum explains the various types of light waves that the sun produces.

Though the light waves you see are in the ocean, they travel from one place to another. However, they still have their differences.

How is Solar Radiation Measured?

How is Solar Radiation Measured_

Solar radiation is usually measured in frequency or wavelengths (Light travels in a wave).

Wavelength is the distance from peak to peak, and it is measured in nanometers (nm). On the other hand, frequency is the wavelength cycles per second, and it is measured in hertz(HZ).

Moving further, bands that have shorter wavelengths emit higher frequencies. Similarly, the ones with a longer wavelength will take a longer time to complete a cycle, which produces less frequency.

Note that the energy of the wavelength goes higher with the frequency and reduces with the size of the wavelength. In other words, longer wavelengths are less energetic than shorter ones.

That is, infrared radiation is less energetic than ultraviolet radiation. As a result of the extra energy, shorter wavelengths tend to cause more harm than longer ones.

Furthermore, when a wavelength has more energy, it will be easier to disrupt the molecule that absorbs it. Also, the highest energy, ultraviolet light, can cause damage to DNA and some other important cellular structures.

Basic Principles Of Solar Radiation

Basic Principles Of Solar Radiation

The sun distributes light to every location on earth, at least for some part of the year. Some factors are responsible for the amount of solar radiation that reaches any location on the earth’s surface.

Those factors are-

  • Geographic location
  • Season
  • Time of the day
  • Local landscape
  • Local weather

Since the earth is spherical, it strikes the surface at various angles, which range from 0 degrees to 90 degrees. In the period when all the rays of the sun are vertical, the surface of the earth receives all the energy.

However, when the sun’s rays are in a slanty form, it will take a longer time to travel through the atmosphere. Due to this, the rays become scattered and diffuse.

Furthermore, as a result of the roundness of the sun, the cold polar regions find it not possible to get a high sun. Also, due to the tilted axis of rotation, it is bad that those areas receive no sun for some years.

Proceeding, the earth has an eccentric orbit around the sun, and the orbit is usually closer to the sun during some times of the year. Anytime the sun is close to the earth, the earth’s surface usually gets extra solar energy.

In addition, the earth is closer to the sun during summer in the southern hemisphere. On the contrary, the earth is closer to the sun when it is winter in the northern hemisphere.

Although, the vast ocean modifies the colder winter and hotter summer than you will be expecting to see in the southern hemisphere due to this difference.

Overall, one of the important components determining the amount of sunlight the earth receives is the 23.5 degrees tilt in the earth’s axis of rotation.

Types of Solar Radiation

Types of Solar Radiation

The type of solar radiation depends on the form in which it reaches the earth.

Direct solar radiation-

Direct radiation is the type of radiation that penetrates the atmosphere and reaches the earth’s surface without experiencing scattering in the atmosphere. Scattered radiation is the opposite of direct radiation.

Diffuse solar radiation

This type of radiation reaches the earth’s surface after several deviations in its course. Examples are gases in the atmosphere.

Reflected Solar Radiation

This type of solar radiation is the fraction of the solar reflected by the earth’s surface (albedo effect).

Depending on the type of light

Infrared rays (IR)

They have a longer wavelength than visible light. Also, they are invisible to the human eys, and they are produced by anybody with a temperature greater than 0o Kelvin.

This occurs on or around March 23 and September 22 each year.

Visible rays (VI)

They produce light in the form of colors that the human eye can perceive. The colors are- red, orange, yellow, violet, blue, cyan, etc.

Ultraviolet (UV) Rays

These types of rays are the ones that the human eye can see, and they have a high impact on the skin, such as wrinkles, burns, and spots.

Ultraviolet rays are divided into three subcategories.

Firstly, Ultraviolet A (UVA). These are the ones that easily pass through the atmosphere. However, most of these rays reach the surface of the planet.

The second one is Ultraviolet B (UVB). This type does not easily pass through the atmosphere. Instead, this ray gets to the surface and is responsible for severe skin damage.

Thirdly, Ultraviolet C (UVC). It does not penetrate the atmosphere at all, and this is because the ozone layer absorbs it.

The UV Index And The Effects Of The Sun On Your Skin

Humans are often exposed to UV radiation, mostly UVA and UVB radiation, which is very harmful to the skin. The major way we usually measure the negative effect of this radiation on humans is the global solar UV index (UVI).

Additionally, this index is in the range of 1 to 11. However, the higher the index is, the higher the chances of damaging the skin or eye.

You can easily get a sunburn, skin cancer, or premature aging when exposed to these rays. Also, the people with a lighter prototype are more prone to suffer from the effect.

As a result of the effect, UV is a necessary and differential element in raising public awareness of the disadvantages and effects on humans.

Furthermore, after explaining the effect of UV rays, here are the protective measures to reduce these rays’ risk.

The first and most effective step is to stay away from the sun in the middle of the day. However, always remain in the shade and drink much water if it demands it.

Put on protective clothing such as caps, and hats, or ensure you carry parasols to protect your face, eye, and neck. Also, always wear light garments.

Make sure you are always with your protective sunglasses. Also, if you have certified lenses with a wraparound design and side panels, you can use them.

Lastly, use a sun protection cream with a sun protection factor higher than 15. However, you should choose according to the prototype of your skin.

Half an hour before you go out, apply it very well on your skin and repeat as much as possible.

Direct and Diffuse Solar Radiation

As sunlight penetrates through the atmosphere, some of it is scattered and absorbed by-.

  • Water vapor
  • Air molecule
  • Clouds
  • Dust
  • Pollutants
  • Forest fires
  • Volcanoes

This refers to diffuse solar radiation. Meanwhile, the solar radiation that gets to the earth’s surface without scattering is the direct beam solar radiation.

The addition of diffuse and direct solar radiation is known as global solar radiation. More so, atmospheric conditions have the power to lessen direct beam radiation by 10 percent on clear and dry days.

Additionally, it can reduce it by 100 percent on thick and cloudy days.


Scientists measure the degree, level, and amount of sunlight falling on different locations several times of the year. After that, they further estimated the amount of the sun that regions with the exact latitude and similar climates are getting.

Furthermore, total radiation on a surface or a horizontal surface following the sun is the most common measure of solar energy.

Solar electric (photovoltaic) system radiation data is generally expressed in kilowatt-hours per square meter (kWh/m2). However, solar energy estimates can alternatively be represented in watts per square meter (W/m2).

In addition, radiation data for space heating and solar water heating are usually represented in Btu/ft2 (British thermal units per square foot.


The solar resources across the US are enough for PV(photovoltaic) systems. This is because they utilize both direct and scattered sunlight.

The level of power produced by any solar technology at a given site relies on the level of the sun’s energy get to it. Consequently, solar energy tends to work very efficiently in the southwestern United States, which receives the highest level of solar energy.

Progressively, I will be explaining the benefit of solar energy.

Benefits of Solar Energy

Solar radiation produces solar energy, and we get many benefits from using solar energy.

Solar energy comes with many advantages, including financial benefits, and reducing your electric bills. There are some other benefits to enjoy from solar energy, and I will explain them.

Reduce Air pollution

One of the advantages of solar energy is that it reduces air pollution. Using fossil fuels creates lots of air pollution, making the environment unhealthy.

Places like California, China, New York, and any area whose geography consists of mountains and valleys will give you a clear picture of these scenarios.

Dirty air and smog are harmful to your health, environment, and aesthetics.

Interestingly, solar panels help to eliminate air pollution. Your panels create clean energy that is good for your health and does not negatively affect your environment.

Reduce Water Usage

Most energy sources that do not use fossil fuel to operate use water as their resource—both Hydropower and nuclear energy use much water to produce electricity.

It will often require a dam to control the water flow and electricity production. This dam has the possibility of creating a problem that will have a high impact on the local ecosystem.

Fortunately, solar panels give you enough energy with no need for water or a negative effect on the ecosystem. Aside from that, the US Office of Energy and Renewable Energy believes that solar energy systems will reduce water consumption in at least 36 states.

This would solve the water scarcity problems that many states are experiencing intensely.

Reduces Dependence On Nonrenewable Energy Sources

Another benefit of using solar energy is reducing our dependence on nonrenewable energy sources such as fossil fuels. Aside from fossil fuels emitting harmful substances to the environment, nonrenewable sources will eventually run out.

Due to this, switching to renewable energy will help our environment and our species.

Improves Humanity’s Health In The Long-run

The US Office of Energy Efficiency and Renewable Energy not only believes that solar energy can minimize water scarcity. They also think estimate that cleaner air has a positive effect on the health of humans.

They estimate that solar energy could save more than 25,000 lives. That is because cleaner air keeps our lungs healthy and clean.

Helps Fight Climate Change

Another benefit of solar energy is that it helps to fight climate change. The continual dumping of pollutants and additional CO2 into the air can affect our planet.

This makes it difficult for the environment to clean the air. In addition, as the carbon count goes higher, likewise will our retention of heat from the sun.

The changing air condition will always affect different climates, which will result in warm, other to cool—making weather patterns all over to be more volatile.

In conclusion, solar energy is the best way to prevent the effect of climate change. It reduces our CO2 emissions and releases lesser pollutants into the air.

Pros and Cons of Solar Radiation

Pros and Cons of Solar Radiation

Solar radiation has to do with all the energy that the sun produces. However, using solar energy does have advantages but also disadvantages.

In this section, I will be discussing the pros and cons of solar energy.


Solar Energy is good for your health

Radiation that comes from the sun is good for our health. Solar radiation provides vitamin D, improves the effectiveness of your body system, and lots more.

Saves money on energy bills

Sadly, the cost of electricity keeps increasing at a high rate. An average household usually spends over £1,000 on electricity and gas per year.

Interestingly, using solar power can reduce half of the amount you are spending on electricity. Since electricity is becoming more and more expensive, this is an opportunity to create your electricity at a cheaper rate.

Renewable clean energy source

The main reason people are switching to solar is the ability to generate clean energy without impacting the environment. In addition, the sun is an unlimited source of energy, so all you need to do is buy and install your solar panels.

After installing it, it produces clean, renewable energy that does not cause harm to the environment.

Little or no maintenance

One of the advantages of solar power systems is that they require little or no maintenance. This is because these systems do not have moving parts and minor mechanical elements.

Due to this, they do not require much maintenance as long as you buy quality panels and properly install them.


  • Requires a south-facing roof.
  • Can be affected by British weather.
  • Not all roof configurations are suitable for solar panels.
  • Uses a lot of roof space.
  • Can put buyers off.
  • High upfront cost.
  • Resource intensive production.

Conclusion Of Solar Radiation

Solar radiation has to do with the sun’s energy, which comes in light, rays, etc. Sunlight is essential for every living thing on earth to survive.

While sun radiation can serve as a source of renewable energy, reduces air pollution, and has a significant benefit to our health, to mention but a few, it also has its downsides.

Sometimes sun rays can be too harsh on the skin, leading to mild to severe skin conditions. To avoid that, take precautionary measures to safeguard your skin from this danger.

This is all you need to know about solar radiation.

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Victor Akin-Ojo
Victor Akin-Ojo is the founder and the Lead Editor of PowerVersity.com. Before he started PowerVersity.com, Victor worked in the IT industry for close to 15 years. He worked mainly as field Engineer on Installation of VSAT, Wimax Technologies, including but not limited to, Power Maintenance Sector for close to 10 years – Designing an electrical installation for Homes, Private and Government Offices and more.


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