The solar spectrum covers a broad wavelength range, which requires that antireflection coating （ARC） is effective over a relatively wide wavelength range for more incident light coming into the cell. In this paper, we present two methods to measure the composite reflection of SiO2/ZnS double-layer ARC in the wavelength ranges of 300-870 nm （duaI- junction） and 300-1850 nm （triple-junction）, under the solar spectrum AM0. In order to give sufficient consideration to the ARC coupled with the window layer and the dispersion effect of the refractive index of each layer, we use multidimensional matrix data for reliable simulation. A comparison between the results obtained from the weighted-average reflectance （WAR） method commonly used and that from the effective-average reflectance （EAR） method introduced here shows that the optimized ARC through minimizing the effective-average reflectance is convenient and available.
