A capacity expansion planning model integrating hybrid PV-storage stations with grid export constraints

This paper evaluates the integration of tightly coupled photovoltaic-plus-storage stations subject to export constraints in power systems experiencing high renewable energy sources (RES) penetration levels. The power output limitations imposed on the hybrid photovoltaic (PV) and storage installations stem from the restricted available electrical space of the system to accommodate new RES capacity. A suitably developed capacity expansion planning model optimizing the energy mix of the Greek power system for a 90% RES penetration target is developed to perform the study. Analysis considers the climate conditions of 35 historical years to avoid skewing the obtained results due to the peculiarities of a single climatic year. Simulation results show that in the absence of power output limitations for PV-storage stations, around 31 GW of RES units are required, occupying equivalent electrical space and necessitating upgrades to the existing grid. Conversely, when export constraints are applied to hybrid stations, the required electrical space to accommodate renewables is reduced by ~17%, with the export limit of the PV-storage configurations being as low as 30%. An additional annual system cost reduction of 5.2% is also obtained compared with a baseline case where PVs and storages cannot be effectively coupled within the algorithm.