3.32-3.88 3.884,43 4.434.99 4.99-5.54 kWh/m2 kWh/m kWh/m2 kWh/m2 The mean daily solar radiation received on a horizontal surface, averaged over the year, for the us. The figure includes both the direct and diffuse components of the solar radiation 复旦大学环境科学与工程系 Department of Environmental Science and Engineering, Fudan UniversityThe mean daily solar radiation received on a horizontal surface, averaged over the year, for the US. The figure includes both the direct and diffuse components of the solar radiation