Flexible load with the function of "virtual energy storage" can change the original load distribution over time and space and reduce the peak-to-valley difference. However, it has had no in-depth research. To this end, PV utilization can be improved by constructing a flexible load response model, and proposing a contract strategy that prioritizes the transfer of flexible loads during peak hours to the peak period of PV output. Secondly, this paper builds a coordinated planning model for energy storage and PV that takes into account flexible loads, so as to give full play to the complementary nature of flexible load "peak shaving and valley filling" and optical storage timing. Finally, a 10 kV 37-node actual distribution network is simulated. The results show that from an economic point of view, flexible load has more advantages than energy storage. It can effectively reduce the energy storage capacity configuration and improve PV absorption capacity. This work is supported by the National Key Research and Development Program of China (No. 2017YFB0903403).