The first residential vanadium redox flow battery system in Scandinavia was installed in Gladsaxe by Aarhus University and VisBlue Aps with support from the Energy Technology Development and Demonstration Program (EUDP) of Denmark. The flow battery has a nominal power output and capacity of 5 kW and 30 kWh respectively and is coupled to a 50 kW peak photovoltaic array. This solar plus storage system is integrated in a ten apartments building that already complies with the Danish Nearly Zero-Energy Building (NZEB 2020) energy performance requirements.

In this work, the performance of the vanadium redox flow battery system is reported for two periods, the first between February-December 2017 and the second between February-August 2018. Performance for different periods is analyzed based on the energy balance provided by the battery inverter and the data acquired from the flow battery. The energy balance is also used to map the consumer behavior in order to develop: 1) seasonal flow battery control strategies and 2) battery power and capacity optimal sizing methods. Since the flow battery operated intermittently during 2017 before final commissioning in February 2018, the photovoltaic array was coupled to a 7.4 kW lead-acid battery pack during specific periods. An overview of the lad-acid battery performance during these periods is also reported.

Finally, several technical challenges including coupling the vanadium redox flow battery with the battery inverter, stack leaks and remote monitoring of critical operating parameters are briefly discussed.