Abstract: Reasonable planning of new-energy installed capacity is the foundation for achieving efficient consumption of new energy. The volatility of new energy sources poses significant challenges for the safe and stable operation of the system. To mitigate the volatility of wind and solar outputs, energy storage equipment must be added to improve system stability. Current research models for new energy installation planning mostly set a fixed energy storage capacity, which makes it difficult to achieve optimal economic benefits. This study proposes a joint planning and operation optimization method for wind, solar, and storage capacities in regional power grids, considering source load matching. First, based on k-means clustering, the most representative 24×7 h typical daily data out of 8760 h in the whole year is obtained as the basic data; second, a joint optimization model for regional grid wind, solar, and energy storage capacity planning and operation is developed considering source load matching. In the model, the optimization goal is to minimize the daily average planning cost, and a source load matching constraint is added to achieve consistency in changing trends between the total generation output and the load demand to reduce the peak shaving pressure. A matching deviation penalty mechanism is designed to reduce the source load matching deviation. Finally, a case study is conducted based on a regional power grid in Jiangsu Province, and the results show that the model can reduce system operating costs, source load matching deviation, and peak pressure. This verifies the effectiveness and feasibility of the proposed model.