IEC 61215-2: 2016 is an international standard about testing photovoltaic (PV) module reliability, in which the thermal cycle (TC) test item mainly has focused on thermal stress interaction of PV modules between different materials. At TC testing different stages, except for high working current (Imp), low current (Max. 1 %*Imp) has been turned on continuously as monitor current in order to evaluate the field operation situation of photovoltaic modules. In this paper, the test programme are designed meticulously and I-V data&EL pictures test results are discussed according to the influence level of monitor current on PERC, HJT and TOPCon modules. Three types of PV modules have performed the respective I-V characteristics and thus the values of Isc, Voc and Pmp have appeared different trends.