| | | Battery storage boosts viability of south-facing solar facades
Researchers in Germany have examined how battery storage could help façade PV systems move beyond their niche market by 2030. Their findings show that a large majority of south-oriented façades in Europe could be equipped with vertical solar arrays combined with batteries.
October 13, 2025 Emiliano Bellini
A BIPV solar facade in Madrid
Image: Hanjin, Wikimedia Commons, CC BY-SA 3.0CC BY-SA 3.0
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Scientists from Germany's Institute for Solar Energy Research Hamelin (ISFH) have examined how battery storage can enhance the performance of south-oriented photovoltaic (PV) facades and have found that integrating batteries significantly improves the economic feasibility of these vertical solar systems, which are often dismissed as too costly or insufficiently productive.
“In our study, we were able to clearly show that battery storage is an important driving factor behind the economic viability of the PV facades,” the research lead author, Dennis Bredemeir, told pv magazine. “We were able to demonstrate this by performing our calculations both with and without battery storage in the building energy system. Without the battery storage, the share of PV modules on the south facade is very low throughout Europe. However, adding the battery to the same scenario results in a share of PV modules on the south facade well-above 80% for large parts of Europe. This can be clearly linked to the favorable seasonal generation profile of facade PV.”
Bredemeir and his colleagues conducted their techno-economic cost analysis for 2030.
“For PV, we assumed capital expenditures (CapEx) of €760 ($882)/kW, while for battery storage we assumed €150/kWh. At this low cost, battery storage is being built throughout Europe, thereby enabling the potential of the south facade to be realized. Interestingly, there is a recent publication indicating that even this low cost assumption might be too pessimistic,” he said, referring to the study “ Are we too pessimistic? Cost projections for solar photovoltaics, wind power, and batteries are over-estimating actual costs globally,” published in Applied Energy by scientists of Finland's LUT University.
The German researchers did not include public incentives in their calculation, with the optimization being based on Capex, operational expenditures (OpEx), electricity retail prices and revenues from feeding excess electricity into the grid.
“We use a value of €0.02/kWh for the feed-in tariff, because we assume that this will be a realistic value that can be achieved on the electricity spot market in 2030,” Bredemeier explained. “Under these assumptions facade PV can be economically viable without subsidies. This is in comparison to PV on east- or west-facing rooftops. If, however, a south-facing rooftop is available, this is fully utilized before any other surface is used.”
The academic conducted a sensitivity analysis for the costs of facade modules in relation to standard modules.
“For this purpose, we have assumed 20% higher costs for the facade modules compared to the standard modules,” he stressed. “Our findings show that even with these higher costs, solar facades are being built in many places. Of course, the attractiveness of PV on facades would decrease if even higher costs for BIPV modules were assumed. However, the particular advantage of BIPV modules is that, in addition to generating electricity, they also provide functions of a facade and thermal insulation.”
The researchers presented a case study for a single-family house (SFH) with tilted roofs and no shading of PV modules. The 3.5-4.5 kW solar facade is assumed to feed surplus power into the grid or store it in the battery, with grid electricity used only when neither solar generation nor stored energy is available.
The analysis showed that, without battery storage, the ratio of installed PV power on south facades to the total installed PV power is around 30% in large parts of Europe, while adding batteries was found to results in a pronounced increase this share to around 80%.
“The south facade becomes the sole utilized surface in many regions especially between 45°N and 65°N,” the scientists further explained. “Even with the assumption of 20% higher CapEx for PV installations on facades, the share of south facades is still around 50% in the aforementioned region. This result becomes even more pronounced when adding an additional heating and cooling demand to the building.”
Their work is presented in the paper “ Falling costs for battery storages make facade photovoltaic systems more attractive for prosumers,” published in Applied Energy
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