European Transmission System Operators (TSOs) face a surge in battery connection requests, and some have introduced hosting capacity maps to guide project developers toward optimal grid integration areas.

This paper presents a novel concept called joint hosting capacities, which maximises the total hosting capacity for batteries, no matter how many are connected and whatever their simultaneous injection. Additionally, joint hosting capacities are defined for any maximum number of limitations (or curtailment) imposed to plants because of network congestions. Since any combination of setpoints is allowed within hosting capacities, this approach ensures robustness to changes in business models over years by battery operators. Hence, joint hosting capacities are expected to reflect the actual transfer margins of the grid in a more accurate way than existing capacity maps.

The mathematical description of the approach is presented as an optimisation problem, which is intractable for real-world networks. Therefore, an efficient algorithm is exhibited to overcome this limitation. Although it delivers slightly suboptimal capacities, these are valid with respect to network thermal limits and the maximal number of batteries limitations that was initially selected. Finally, the feasibility and effectiveness are validated on a representative network, specifically the French 400 kV network.