Integration of Battery and Hydrogen Storage with a Grid-Connected Photovoltaic System in Buildings

University dissertation from KTH Royal Institute of Technology

Abstract:     The integration of Photovoltaic (PV) with buildings changes the previous electricity consumers into prosumers. The reduced PV subsidies and the grid stable operation requirements are pushing prosumers from direct exportation to self-consumption of the produced electricity. Electricity storage increases the self-consumption, while comes with higher investment. During the system planning stage, the benefits of storage should be clarified to prosumers. The storage type, the storage capacity and the system operation strategy should be determined at the same time.    This thesis dealt with a grid-connected PV-storage system and proposed an optimization method, which simultaneously determined the storage capacity and rule-based operation strategy parameters. This method eliminated the necessity of forecasting and could be easily implemented. A typical residential building in Sweden was taken as a case study. Different operation strategies as well as two storage technologies – battery storage and hydrogen storage – were compared.    For the battery storage system, the proposed battery hybrid operation strategy, which carries out the conventional operation strategy during warm months and the peak shaving strategy during cold months, provides the best performance in Self Sufficiency Ratio (SSR) and Net Present Value (NPV). For the hydrogen storage system, the hydrogen hybrid operation strategy outperforms other studied operation strategies under different scenarios, which have optimistic or pessimistic cost assumptions of the hydrogen storage system.    The comparison between hydrogen storage and battery storage suggests that battery storage has much better performance in SSR and NPV under the pessimistic cost scenario. Under the optimistic cost scenario, battery storage and hydrogen storage achieve comparable performance in SSR and NPV. However, hydrogen storage is more favorable when considering reducing the prosumer’s negative impact on the grid.

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