The radiation mechanism from the DC side of a photovoltaic (PV) power generation system is investigated at frequencies between 150 kHz and 30 MHz. To determine the source of the outbreak of the common mode noise, the balancing of the PV measurement model, which is composed of a PV panel and a 2-m-long DC cable, is measured by the mixed-mode S-parameter method. Results showthatthe PV model has good balance. Then, a balanced PV simulation model is proposed. To express the common mode noise, the input signal is supplied to only one of the two wires of the PV simulation model. To confirm the validity of the PV simulation model, the current flowing in the DC cable and the magnetic field from the PV simulation model are compared with those of the PV measurement model. A good agreement between the measured and simulation results is obtained. The PV simulation model is valid for evaluating the radiation noise from the DC side of the PV power generation system. Moreover, the effect of the frame wire of the PV power generation system on the radiation noise is evaluated. The radiation noise from the PV power generation system will strengthen or weaken depending on the layout of the frame wire, especially at low frequency. The radiation noise from the PV power generation system with a plurality of PV panels is also investigated. The peak of the frequency spectrum of the radiation noise shifts to lowfrequency when the number of PV panels is increased.