Storage dispatch optimization for grid-connected combined photovoltaic-battery storage systems

A linear programming (LP) routine was implemented to optimize the energy storage dispatch schedule for demand charge management in a grid-connected, combined photovoltaic-battery storage system (PV+ system). The LP leverages PV power output and load forecasts to minimize peak loads subject to elementary dynamical and electrical constraints of the PV+ system. We simulated a broad range of PV+ designs (in terms of battery capacity and peak load reduction target) and performed a cost benefit analysis to quantify the net present value (NPV) of the battery storage system. We compared the financial benefits of our optimized energy storage dispatch schedule with a simple off-peak/on-peak, charging/discharging strategy. Significant financial value was attained over the lifetime of the battery by the application of PV power output and load forecasts in the computation of the energy storage dispatch schedule. The NPV of the battery array increased significantly (in the range $200k-$400k for some PV+ configurations) when the storage was operated on the optimized schedule compared to the off-peak/on-peak schedule. These gains were attributed to increased battery lifetime and reduced demand charges under the optimized dispatch schedule.