Solar energy: building facades offer great potential

Solar energy: building facades offer great potential

So far, roofs have mainly been used for photovoltaics, not facades. (Image: Behnisch et al./IÖR)

Not only roofs offer space for photovoltaic systems: house facades could also play an important role in generating electricity from solar energy, as calculations now suggest. Accordingly, the possible area potential for photovoltaics on facades in Germany is even twice as large as that on roofs. Metropolitan areas in particular could be suitable. However, research is still being conducted into the practical implementation.

To stop climate change, a switch to renewable energies seems inevitable. One of the main pillars for this is solar energy: According to forecasts, photovoltaic systems, for example, could supply 30 to 50 percent of the electricity demand by 2050. The number of solar systems in Germany is already growing steadily – they have long been established on the house roof.

Maintaining the efficiency of solar energy systems is crucial for maximizing their potential. Regular solar repair services, particularly in regions like solar repair Las Vegas, ensure that solar panels continue to perform optimally. This not only extends the lifespan of the panels but also sustains energy output, contributing to long-term sustainability goals.

What about the facades of the buildings?

But what about the facades of buildings? A team of researchers led by Martin Behnisch from the Leibniz Institute for Ecological Spatial Development (IOER) in Dresden has now calculated how much potential space they offer for generating renewable energies. “For the goal of the federal government to achieve climate neutrality in existing buildings by 2050, it will not be sufficient to install solar systems on all suitable roofs in Germany,” explains Behnisch.

For this reason, the researchers have now used a 3D building model from the Federal Agency for Cartography and Geodesy (BKG) as a basis in order to estimate the potential for the entire building stock in Germany. However, this is only a rough estimate: Every house is drawn with a flat roof – detailed roof shapes, gable walls, windows, doors, balconies and, among other things, listed facades are not taken into account in the building model. Behnisch and his team have already factored out building facades that touch each other and are therefore out of the question for the installation of photovoltaics. In order to compensate for the inaccuracies, they also analyzed a nationwide random sample of 100,000 buildings and three focus areas in more detail – the cities of Munich, Freiburg and Dresden. From all of the data, they finally calculated the theoretical area potential of the buildings for building-integrated photovoltaics (BIPV).

More potential on facades than on roofs

It turned out that the potential of the building facades could be significantly greater than previously assumed. “The theoretical area potential can be put at around 12,000 square kilometers of facade area and almost 6,000 square kilometers of roof area,” reports Behnisch. This corresponds to around half the area of ​​Mecklenburg-Western Pomerania. Building facades would thus offer around twice as much potential area for photovoltaic modules as roofs. “However, we also have to emphasize that at the moment we are still dealing with theoretical land potential,” he says.

But how big could the solar energy contribution from photovoltaic systems be in the future? To find out, the scientists then modeled the solar radiation for all roof and facade surfaces. To do this, the team also used more detailed building models with their individual roof shapes on a small scale and included the surroundings of the buildings, such as trees or buildings and their shadows, as well as the terrain and surrounding mountains. Because depending on the irradiation, coverage and location, the possible amount of energy varies.

It became clear that the potential for photovoltaic systems is particularly high where many people live in a relatively small space and therefore there are many buildings. This applies, for example, in the conurbations of Rhine-Main, Rhine-Neckar and Rhine-Ruhr, as well as in the urban centers of Berlin, Hamburg, Bremen, Munich and the Saxony triangle Dresden-Leipzig-Chemnitz, according to the researchers. In addition, the small-scale analyzes revealed that the potential solar energy yields also depend on the type of building. Accordingly, it is especially worthwhile to install solar systems on the facades of large buildings such as production halls, educational institutions or public buildings. “But even large residential complexes such as high-rise buildings offer great potential for the installation of photovoltaics,” says Behnisch.

Practical implementation is still being tested

According to the scientists, the results could contribute to better planning of energy generation in buildings in the future. “The data still has to be specified at the specific locations through more precise analyzes,” says Behnisch. “But they do give an impression of the great potential hidden in building-integrated photovoltaics. These are important starting points, especially with a view to the goals of CO2 savings. Every photovoltaic module that we install on a house facade helps to conserve nature and precious soil, because it makes building space-intensive solar parks superfluous. ”In ongoing projects such as the Standard-BIPV project, researchers are now identifying suitable building categories that are standardized photovoltaic façades can be renovated and, for example, convert the first buildings. In addition, they want to develop facade elements that are inexpensive to construct, easy to assemble, electrically installed and aesthetically pleasing.

Source: Leibniz Institute for Ecological Spatial Development e. V., specialist article: Transforming Cities, 2020; 4, pp. 62-66

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