Grid-Relieving Effects of PV Battery Energy Storage Systems with Optimized Operation Strategies

The German distribution grids are facing a rising number of installations of private photovoltaic (PV) systems. Simultaneously, the number of installations of PV panels in combination with battery energy storage systems (PV BESS) is increasing. With appropriate operation strategies that consider grid limitations PV BESS have the potential to provide grid relief and thus reduce overall system cost. The effect of solar power generation units on the low voltage grid depends on the amount of installed generators, but also on the operation strategy of connected storage systems. The implemented operation strategy of the BESS determines the extent to which grid-relief can be achieved with storage systems. A model of a distribution network based on field data is combined with the model of a PV BESS. The combined tool is used for power flow analysis. With this model of the whole distribution system, different penetration rates for PV systems as well as for PV BESS are simulated and the resulting influence on the grid is examined. Results show that a grid-oriented operation strategy can gain significant relief of the low voltage grid and therefore reduce otherwise necessary grid reinforcements in the near future. At the same time, these operation strategies do not lead to a significant decrease of the overall energy throughput of the PV BESS over the total lifetime of the system. This means the economics of such a system are only slightly influenced by the application of a grid-relieving strategy