Bi-Level Optimal Configuration of User-Side Shared Energy Storage Considering Load Shifting and Fair Cost Allocation

With high renewable penetration, independent user-side storage suffers from low utilization and high investment. Shared energy storage (SES) addresses this by aggregating multi-user demand. This paper proposes a bi-level optimal configuration method for user-side SES considering the conflicting interests between the investor and users. The upper level maximizes the investor’s annual revenue by optimizing SES capacity and power, while the lower level minimizes users’ comprehensive energy cost via charge/discharge scheduling and load shifting. The bi-level model is transformed into a single-level mixed-integer linear programming (MILP) problem using strong duality theory, and the Shapley value method ensures fair cost allocation based on marginal contributions. Case studies on a community with three typical user groups show that, under the considered time-of-use price and cost parameter settings, the proposed method outperforms independent storage in the studied scenarios, reducing total user costs by 12.8% and increasing investor revenue by 1.9%; with a 30% load shifting capability, investor revenue rises by 13.2% and user costs drop by 0.78%. The Shapley value-based allocation guarantees fairness while quantifying the actual costs of multi-category users jointly using SES.