Sunlight as its passes through the atmosphere Solar radiation is divided into direct and diffuse radiation direct radiation leads to sharp shadowing behind objects diffuse radiation has no predetermined direction of radiation The greater the proportion of direct radiation, the higher the yield of a PV system. Also, the diffuse fraction of solar radiation is important and useful. In our latitudes the annual average is about half of the radiation energy. Direct and diffuse radiation Diffuse radiation describes the sunlight that has been scattered by molecules and particles in the atmosphere but that has still made it down to the surface of the earth. If diffuse radiation occurs on earth, it can be over 1000kWh for a moment. Because direct radiation is much more intense than diffuse radiation, the amount of radiation missed by tilted solar panels is generally more than compensated for by the extra radiation gained by tracking the sun.