Because of the vast shortage of global energy, the large-scale photovoltaic (PV) power generation has become one of the important new energy generations. Large-scale PV power generation often uses box-type substation as boosting device of raising the low-voltage alternating current of PV inverter outlet to high-voltage current. The impact of box-type substation double split-winding transformer commonly used in box-type substation on PV modules is analyzed. The conclusion that decreasing PV battery ground-to-ground voltage fluctuations can reduce the ground loop current is researched. It researches that there is a coupling relationship between the windings of two low-voltage sides of double split transformer, which causes the central point voltage synchronous fluctuations of PV inverter low-voltage windings, thereby results in battery modules noise. Finally, the feasibility and effectiveness of the above theoretical analysis are verified by simulation. This work is supported by Natural Science Foundation of Gansu Province (No. 1506RJZA104).