The utility model discloses a boost compensation system for widening the MPPT voltage range of a solar cell panel string. The grid-connected inverter comprises a high-frequency DC-DC boosting device,the high-frequency DC-DC boosting device adopts a direct-current side to take electricity, and the high-frequency DC-DC boosting device and a solar cell panel set string are connected in series and jointly provide direct-current voltage for the grid-connected inverter, so that the solar cell panel set string works at the maximum power point. The grid-connected inverter is ensured to always work atthe maximum power point voltage Umpp of the battery assembly, the generating capacity of the whole system is improved, the size of the system is reduced, and the system cost is reduced.