In some solar radiation, there are several types of light waves of different length. Some light can be seen by human eyes (known as visible light). and some other unvisible. Constant solar radiation above the atmosphere that magnitude occurred in 1367 W/m2 (Watts per square meter). After reaching the strong atmosper, the amount of radiation reduced as much light is lost due to absorption, reflection and so on.

The sunlight that falls into the earth's surface, in principle, can be divided into three types, namely:

• Direct rays
• Ray diffusion
• Global beam

Global beam (G) on earth is 1000 W/m2 maximum achieved when the sky is clear, while the surrounding cities up to 800 W/m2. So if the solar cell or solar module covered by cloud or shadow of another object, the cell or solar module is only just getting light diffusion.

Global Light Scheme

Strong sunlight is not always constant.When the weather is cloudy then the amount of energy produced is not much, but when the weather is sunny then the energy produced will be huge.The resulting of short circuit current solar cells is directly proportional to strong irradiation.