Real-life demonstration of a hybrid EV fast charging station with reconfigurable battery technology enabling renewable-powered mobility

The transition from fossil-based to fully renewable energy systems requires innovative actions and extensive testing of new solutions. Battery energy storage systems (BESSs) are sought to be of key importance for integrating variable renewable energy sources (vRES) into the grid, and help improving the flexibility of power systems. As part of the H2020 Insulae project, an innovative reconfigurable battery system has been developed in Denmark and installed in a DC hybrid charging station (HCS) located on the island of Bornholm. Besides the BESS itself, the HCS consists of a 61 kWp photovoltaic (PV) system, one grid-connected three-phase bi-directional inverter interfacing to the local AC distribution grid, and two electric vehicle (EV) fast chargers. This paper gathers the operational results and lessons learned from more than a year of demonstration, subject to high observability of all single units. The demonstration provides hands-on experience with the operation of this novel battery design embedded in a hybrid charging station. Throughout the operation period, 2008 EV charging sessions were recorded, amounting to a total charged energy of 21.8 MWh. An overall proportion of 37.7% of this energy was provided by the local PV system, defining the system’s self-sufficiency. Similarly, 90% of the PV energy was utilized for EV charging, defining the system’s self-consumption. Furthermore, the results showcase that the energy management system (EMS) specifically utilized time windows of low spot prices to import energy in periods of low PV production or high EV demand, thus, reducing operating costs. While the design of the HCS is promising, the paper discusses the drawbacks of the implemented EMS, and suggests potential improvements. Finally, the architecture of the HCS prototype is compared to three alternative layouts with respect to both operating and investment costs.