What exactly is the “Solar Radiation” measurement?
The Solar Radiation or irradiance measurement is not a measure of sunshine duration but energy flow or flux from the sun’s electromagnetic radiation measured in Watts per square meter . This energy flow (insolation) is what causes heating of the earth’s surface and what makes solar power generation possible. Solar radiation is variable according to the time of year, the elevation of the sun above the horizon, and the obscuration from cloud or haze. This is measured for meteorological purposes with a horizontally level sensor surface. The higher the reading, the more energy is available for heat conversion at the earth’s surface or the generation of solar power. In the southern UK, the maximum daily possible amount of solar radiation in W/m² varies from under 400 in midwinter to nearly 1200 in midsummer (the solar irradiance above the atmosphere at the mean earth-sun distance is approximately 1370 W/m² – the solar constant). During daylight some solar radiation will penetrate even total
