The invention relates to an inverter, a distributed convergence box and a limited power control system and method. The limited power control system comprises a plurality of distributed convergence boxes and the inverter, wherein one end of each distributed convergence box is connected with one or more of battery panel assemblies so as to access a power input to the connected battery panel assembly, the inverter is connected with the other end of each distributed convergence box and is used for determining limited power percent according to a power control instruction when the power control instruction is received, sending the limited power percent to the connected distributed convergence box and sending a power raising instruction or a power reduction instruction to the distributed convergence boxy according to a comparison result between sum of output powers of the plurality of distributed convergence boxes and a designated threshold power in the power control instruction, and the distributed convergence box is used for changing output limited amplitude of a voltage ring to adjust an output power according to the received limited power percent and the power raising instruction orthe power reduction instruction. By the limited power control system, the circuit conversion efficiency of a distributed photovoltaic system can be improved.