The sun

Solar energy is harvested using solar radiation, so it becomes necessary to understand solar radiation and how it interacts with the energy conversion devices to produce widely usable energy.  Hence, we start with understanding some facts about Sun. Sun, the largest member of the solar system with about 15 million kelvins temperature at its core and 6000K temperature at the surface, is a sphere of intensely hot gaseous matter. 3.8 x 1026 W of energy is radiated from it and roughly about 1.7 x 1018 W of energy reaches the earth. This energy is generated from the fusion reactions taking place at its core. It is approximately 1.5 x 108 km away from earth and at any given time, half of the earth is lit by the sun’s radiation.

$F( \lambda ) \ =\ \frac{2\pi hc^{2}}{\lambda ^{5}\left( exp\left(\frac{hc}{\lambda kT}\right) -1\right)}$