what is the difference between radiation and insolation
Answers
Answer:
Solar radiation is all the radiant energy emitted by the sun.
Insolation is the total solar radiation that reaches the earth's surface. It is measured by the amount of solar energy received per square centimetre per minute.
Electromagnetic nature of solar radiation
Here we give an introduction to physics of solar radiation and solar insolation. The complete concept of harnessing solar energy to generate electricity is based upon the phenomenon of solar radiation.
It is this radiation from the sun, together with a few more factors, which is the reason why life exists on earth. Solar radiation is electromagnetic in nature and is the radiant energy emitted from the sun.
The total frequency spectrum of this electromagnetic solar radiation covers visible light and near visible radiation (UV Rays, Infrared Rays, X-Rays, etc.). The visible light and heat supports life on earth while much of the near visible harmful radiation is deflected away by the earth’s atmosphere.
Solar radiation – The source of never ending energy
Sun produces its energy by the, never-stopping, nuclear fusion reaction, which converts approximately 700 million tons of hydrogen to helium per second.
This process creates massive amounts of heat and it is due to this heat that photons are emitted. Each emitted photon travels a very short distance before being absorbed by another molecule, which by a similar process, emits another photon. This process of absorption and re-emission continues and the photons keep moving forward, finally being able to reach the outer space at the sun’s surface.
What is Direct Normal Irradiance (DNI)?
Direct Normal Irradiance (DNI) is the amount of solar radiation received per unit area by a given surface that is always held perpendicular to the incoming rays.
The amount of irradiance can be maximized by keeping the receiving and electricity-generating surface – the PV module – on optimal track with the movement of the sun and thus of the sun rays.
What is solar insolation?
During the process of nuclear fusion, the sun produces energy that in form of electronicmagnetic waves (radiation).
Solar insolation is affected by factors such as atmosphere, angle of the sun and distance. The thinner the atmosphere in which the sun is passing through, the more the insolation.
Insolation is also at its highest when the sun is directly overhead in an area. This is also the shortest distance between the sun and an area. When the angle of the sun to an area increases, the distance increases, and a lot of energy is lost through reflection.
Insolation refers to the quantity of solar radition energy received on a surface of size X m² during an amount of time T.
In the photovoltaic industry it is commonly expressed as average irradiance in kilowatt per square meter (kW/ m²) or – taking into account the time factor – kilowatt hours per year per kilowatt peak kWh/(kWp*year).
Solar insolation map
A solar insolation map is a chart showing the average daily hours of solar insolation in an area.
World insolation maps show the amount of solar insolation in a given area at a given time. An example of an insolation map can be seen below.
As can be seen from the map, insolation is highest in equatorial regions where the sun is more likely to be overhead, and lowest in Polar Regions where the angle of the sun to the earth is greatest