A photovoltaic (PV) tracing system (101) is used to tracing I-V characteristics and maximum power point tracking (MPPT) performance of a PV module (107). The PV tracing system (101) comprises electronic scanning device (103) and electronic displaying device (105). The corporation between these two different devices is realized by an algorithmic micro processor. The electronic scanning device (103) comprises an adjustable resistive circuitry unit (111) which continually receives the acquired signals from the sensor (102) and delivering the signals to computer via the microcontroller (104). The corresponding outcoming signals in related to I-V characteristics and MPPT performance are then send to the computer (105) for calibrite and display.