Spectral mismatch correction factor (MM) is determined by average photon energy (APE). APE based on wide solar spectral ranges leads to better description of solar spectral shape. Moreover, error between corrected outdoor short-circuit current (ISC) of PV module and its ISC under standard test conditions is investigated using PV module irradiance sensor (PVMS) and/or MM, where PVMS is a single-crystalline silicon PV module. The error of muti-crystalline silicon (mc-Si) PV module is as low as about 1% regardless of the use of MM attributed to small spectral mismatch between PVMS and mc-Si PV module. On the other hand, the low error of CdTe test PV module is obtained under the use of both PVMS and MM caused by the high spectral mismatch between PVMS and CdTe test PV module. The error is further decreased, when MM is estimated from the APE based on wide ranges of the solar spectrum.