Empowering collective self-consumption in multi-family houses: user-based multi-use of residential battery storage systems

Despite the significant potential, the implementation of a shared use of photovoltaic systems (PVS) and battery storage systems (BSS) in multi-family houses (MFH) is lagging behind expectations, primarily due to previously existing legal barriers. This research examines the user-based multi-use of PVSs and BSSs as a form of collective self-consumption in MFHs under German §42b EnWG. Static allocation of the PVS and BSS capabilities among the MFH’s households (HH), mapping the past German legal framework, is compared with forms of dynamic allocation mapping the adapted legal framework due to German ‘Solarpaket I’. Two MFHs are modelled and simulated: an average MFH based on statistical data and an existing MFH from the MELANI research project. The simulation results show that the fully dynamic allocation achieves the highest self-consumption and self-sufficiency quota across all scenarios, significantly enhancing the direct use of PVS energy. Technically, this strategy maintains low BSS utilisation and minor impacts on cyclic ageing while optimising the flexibility of the PVS and BSS. Economically, it provides the highest cost-effectiveness by reducing the dynamic levelized cost of energy and the total cost of electricity for both entire MFHs and most HHs. Overall, the conducted techno-economic analysis demonstrates that a fully dynamic allocation of the PVS and BSS capabilities, utilising the adapted German legal framework, is the most promising approach for implementing the concept of collective self-consumption in MFHs.