June 16, 2025, 10:45 am | Read time: 5 minutes
Photovoltaic systems (PVA) aren’t just for rooftops—or for balconies in the case of balcony power plants—but also for facades. Two founders are presenting their PV concept with “Mo Energy” on “Die Höhle der Löwen,” a German TV show similar to “Shark Tank.” myHOMEBOOK consulted experts to find out who might benefit from this system.
“Everyone knows about rooftop photovoltaics–but we’re thinking further. Every facade can produce energy,” explains Alexander Moosbrugger (51) from “Mo Energy Systems.” Together with Manuel Hehle (37), he presents an intelligent mounting system for photovoltaic facades on “Die Höhle der Löwen” (The Lion’s Den). The goal of the two founders: to open up new markets and bring the energy transition “to the wall”–literally. For this, they need a grant of 800,000 euros from the Lions. In return, the founding duo offers ten percent of their company shares.
How the PV System for the Facade Works
The system consists of two components–a flexible substructure for various facade substrates and framed or frameless PV modules. The installation is designed so that any craft business can install it, from carpenters to electricians. For “Die Höhle der Löwen,” the founders have also developed a DIY facade set for private homeowners who want to equip their house facade with PV modules themselves.
What’s Behind “Mo Energy Systems”
“Mo Energy Systems” acts as a coordinator and supplier for a network of installers, skilled craftsmen, and assembly teams in the German-speaking region. The company supplies the substructures and supports its partners in the setup.
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This Is How Much Yield the Founders Promise
Just six square meters of PV facade are expected to generate around 1,000 kWh per year. This corresponds to about 7,000 kilometers with an electric car or 2,500 loads of laundry. In an example calculation, the founders estimate an annual yield of around 4,200 to 4,800 kWh for a 5 kWp facade system on a sunny south side.
Especially in winter, when electricity is needed for heating, the PV facade is useful. Then the sun is low, and a PV system on the facade produces significantly more than modules on the roof. According to the example calculation, the founders estimate the yield from November to February at up to 1,400 kWh, “about 30 percent more than many rooftop systems in the same period.”
What Solar Experts Say About the Facade System
“The system can be worthwhile if, for example, no suitable roof surfaces are available,” explains photovoltaic consultant Tobias Ptok from the Consumer Center NRW upon myHOMEBOOK’s request. “For instance, the roof’s load reserve may not be sufficient, or the roof may need renovation or be heavily shaded.”
And what about the yield? “The yield of an unshaded south-facing facade photovoltaic system is about 20 to 30 percent lower than that of a south-facing photovoltaic system on a typical roof surface with a slope of about 30 degrees,” Ptok notes. However, if the facade is oriented east or west, the yield is about 50 percent lower than that of a south-facing roof system. “Regardless, installing a facade PVA can be worthwhile if a very large, south-facing area is available.”
“To what extent a photovoltaic system on a house facade is economically viable must be determined for each location,” adds Carsten Körnig from the German Solar Industry Association (BSW) upon myHOMEBOOK’s request. “The economic viability of a solar system strongly depends on location, component choice, module orientation, and self-consumption profile.”
What to Consider Before Installation
“Due to the long service life of PVA, shading of the relevant areas should be excluded for at least 15 years,” advises Ptok. Previously sunny areas can be shaded by new buildings or the growth of surrounding trees, hedges, or shrubs. Ptok advises, regardless, to ensure a “professionally executed installation of the modules.”
Additionally, it should be ensured in advance that the facade can permanently support the additional weight of the PV modules. Ptok mentions a period of at least 20 years. “For facades exposed to severe weather conditions, these conditions should be considered in the planning.” To prevent damage, the PV modules should not be installed at ground level but rather one to two meters above the ground surface.
Also important: “Contact the local building authority before starting construction.” According to Ptok, they can prohibit the installation of facade modules, for example, to maintain a uniform appearance of the respective settlement. In such cases, Ptok recommends installing so-called “All-Black” modules as a uniform black surface on the facade.
“Different building code requirements apply to photovoltaic systems on facades than to roof systems,” adds Körnig from the BSW. The fire protection requirements for the PV modules also depend on the building class and increase with the building height. Individual advice should be sought in advance for this as well.
Is the Feed-in Capacity of Photovoltaic Systems on the Facade Capped?
Balcony power plants, or plug-in solar modules for the balcony, are currently capped at 800 watts and a module output of a maximum of 2 kWp according to Solar Package 1. “This also applies if a plug-in solar device is attached to a house facade,” explains Körnig from the Solar Industry Association.
However: “A facade PVA can generally be planned in any size or with any output,” responds PV expert Ptok. “For the legal framework, it doesn’t matter whether the PVA is operated on the facade or the roof.”
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“Mo Energy Systems” on “Die Höhle der Löwen”
Whether the two founders of “Mo Energy Systems” will receive the substantial grant of 800,000 euros from the Lions will be revealed in the show on May 5, 2025 (VOX, 8:15 p.m.). All information and episodes of “Die Höhle der Löwen” can be found at RTL+.