Falling costs for battery storages make facade photovoltaic systems more attractive for prosumers

Photovoltaics (PV) is a key technology in the transformation of the energy system with a large share being installed on rooftops. However, suitable roof space is becoming increasingly scarce. PV systems on facades partially remove these space limitations. Facades offer significant additional potential, but their widespread use is hampered by higher costs and lower annual yields. We model the energy system of free-standing buildings in Europe and optimize the dimensioning of system components. We show that the inclusion of a battery storage results in a pronounced increase of the economic value of PV on south-facing facade surfaces. This is because the battery's short-term storage and the seasonally favorable generation profile of facade PV systems complement each other. If there is no south facing roof available for PV, we find facade PV shares greater than 80 % for large parts of Europe to be cost optimal with techno-economic assumptions for 2030. The share of PV on the facades increases further when an additional load for covering the heating and cooling demand is added to the building. PV systems on facades can thus play an important role in the future energy system, particularly in view of falling costs for both PV and battery storage systems. Importantly, we find that with the cost assumptions for 2030 the inclusion of a battery storage lowers the total system costs for all locations across Europe. This decrease in total system costs is particularly pronounced in Southern Europe, reaching up to 44 %.