Solar Cell : Distribution of solar radiation in the world .

The intensity of solar radiation outside of the Earth's atmosphere depends upon the distance between the sun and the Earth.The Earth's atmosphere reduces the insulation through reflection, absorption (by ozone, water vapour, oxygen and carbon dioxide) and scattering (caused by air molecules, dust particles or pollution). In good weather at noon, irradiance may reach 1000W/m2 on the Earth's surface. This value is relatively independent of the location. The maximum insolation occurs on partly cloudy, sunny days. As a result of solar radiation reflecting off passing clouds, insolation can peak at up to 1400W/m2 for short periods. If the energy content of solar radiation is added up over a year, this gives the annual global radiation in kWh/m2 .This value varies greatly depending upon the region. Some regions at the equator reach values in excess of 2300kWh/m2 per year, whereas Southern Europe receives maximum annual solar irradiance of 1700kWh/m2 and Germany gets an average of 1040kWh/m2. In Europe there are significant seasonal variations that are seen mainly in the difference between summer and winter.