Calculation of Solar Irradiance and Design of Optimum Angle for Photovoltaic Arrays

When the location of fixed photovoltaic array is clearly defined,the optimum tilted angle of PV array depends on whether PV system is on-grid or off-grid.According to Hay's anisotropy model of the sky scattering irradiance,a new analysis method of solar irradiance and installation angle-Ecotect visual analysis software is used for studying the optimum angles of photovoltaic arrays for on-grid and off-grid PV systems.The results show that for on-grid systems,the best installation angle is usually less than the local latitude;while for off-grid systems,the installation angle for "balanced loads" is larger than the local latitude and what's more,for "summer-type loads,the best installation angle is less than that of on-grid systems and for "winter-type" loads,the best installation angle is larger than that of normal load.