Control strategies for combined photovoltaic — Energy storage systems connected to the grid

There are two distinct motivations for combining a photovoltaic (PV) system with an energy storage system (ESS). The first is motivated by a prosumer, who desires the highest return on their investment by carefully managing when they charge the ESS, use energy within the household and export to the grid to maximize favorable export tariffs. The second is motivated by the grid operator, where a smoother output power from a combined PV-ESS residential system is desirable to minimize fluctuating power on the distribution grid and the corresponding issues this causes. This paper will develop and implement two control strategies for combined PV-ESS based on these two motivations. Simulation results based on real irradiance data will be presented and comments provided on the usefulness of each strategy. Ultimately the results show that it is possible to achieve the motivations of either the prosumer or utility, but not both simultaneously. With increasing penetration of PV systems into the utility grid, that may or may not be integrated with ESS, developing ways to manage this intermittent energy resource becomes important.