The Basics of Solar Radiation

Sunlight is the Earth’s most important natural resource. It gives us light & heat, it indirectly provides us food (by supporting plants and subsequently herbivorous animals) and in our not so distance future it will support a large portion of our energy demand. So if sunlight is just so important, what exactly is it?

Sunlight starts as hydrogen atoms in the sun. These hydrogen atoms are fused into helium due to the intense pressure caused by the sun’s gravity. The energy released from this fusion is known as solar radiation. The solar radiation travels through space until it reaches earth. At this point, its intensity is significantly lower than it was near the sun as its intensity is inversely proportional to the square of the distance traveled. Then, Earth’s atmosphere filters the solar radiation and so only about 40% of the solar radiation that arrives at Earth, makes it to the surface.

Of course, the remaining intensity of the solar radiation varies significantly according to the location on earth, altitude, season, time of day and weather.

Solar Radiation Map of the USA. Picture Courtesy of NREL.

So now that we have solar radiation, what is it?

This is not a simple answer, but generally, solar radiation is the transfer of energy particles in the form of a wave. There are many types of waves, but solar radiation is composed of mainly ultraviolet, visible and infrared waves. Each type of wave has a different amount of energy, but of the total energy from the sun 53% is from IR, 44% is from visible and 3% is from UV.

Efficiently exploiting the energy from this solar radiation is key to any solar product.

Thanks to our newest team member, Yasir Diab for helping with this post.

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