Techno-economic benefits and energy storage gains of wind–solar complementary power generation: A provincial analysis in China

Wind–solar power complementarity offers an effective solution for achieving high-level renewable energy integration by mitigating supply–demand mismatches. However, existing studies lack multidimensional techno-economic benefit analysis and distinct evaluations of short- and long-duration energy storage gains from wind–solar complementarity. This study develops a novel multidimensional benefit assessment framework by incorporating a two-stage endogenous optimization model maximizing wind–solar complementarity and a cost-minimization benchmark model, thus avoiding reliance on exogenous capacity ratios. The framework explicitly incorporates short- and long-duration energy storage, thereby clearly revealing the impact of complementarity on storage technologies across different timescales. Using a province-isolated scenario as a conceptual benchmark, the study quantifies the intrinsic value of local wind–solar complementarity and the incremental benefits of interprovincial interconnection in China. Results show that wind power dominates the optimal wind–solar complementary capacity configuration, with a national average wind-to-solar ratio of 2.37:1. Wind–solar complementarity reduces the national average unit demand satisfaction cost of wind–solar deployment by 10.98 % while also enhancing system reliability, stability, and renewable energy utilization. It reduces the intraday short-duration storage capacity requirement by 79.31 % and decreases the total cost of wind–solar–short-duration storage deployment by 21.67 % nationally. However, utilizing complementarity increases the national cost of seasonal long-duration storage by over 40 %, as it requires less power capacity but more energy capacity. Interprovincial interconnection further amplifies the benefits of wind–solar complementarity and reduces energy storage requirements. This study offers valuable insights into coordinated wind–solar–storage planning by leveraging wind–solar complementarity.