A team of researchers at the Germany-based organization, Fraunhofer Center for Silicon Photovoltaics CSP, has discovered that photovoltaic (PV) elements on building facades can be useful to supplement the power supply.

Solar PV modules are usually found on rooftops, where typically solar irradiation is the highest. According to scientists, if these facades are appropriately designed and integrated, they deliver 50% more energy than the existing types of wall-mounted PV elements.

“For one thing, they make use of otherwise unused space, and for another, the energy they collect can usefully supplement the power supply. Currently, however, little advantage is taken of this opportunity, as the sun usually shines on facades at an unfavorable angle, and the elements themselves tend not to be aesthetically appealing,” notes the study.

The researchers at the Fraunhofer Center for Silicon Photovoltaics CSP, together with architects at the Leipzig University of Applied Sciences (HTWK Leipzig), presented a solar facade proving the concept of adding PV elements on façade could be a game-changer.

The HTWK architects developed the idea and designs. They answered questions as to how solar modules have to be tilted to capture as much solar irradiation as possible, how large the modules need to be, and how many solar cells should they ideally include? The findings were presented in a 2×3 meter demonstrator made of aluminum composite panels featuring a total of nine embedded solar modules.

The researchers, in collaboration with HTWK Leipzig and TU Dresden, also developed suitable options for integrating photovoltaic elements in concrete facades, which are specifically made of carbon concrete. Carbon concrete is a material developed by a consortium of more than 150 partners in the “C3 – Carbon Concrete Composite” project. The required stability of the concrete comes from carbon fibers rather than steel wires, states the study.

“At Fraunhofer CSP, we analyzed how photovoltaic elements can best be mounted on these kinds of carbon concrete facades – that is, how to obtain the optimum result when combining this novel concrete with the production of solar energy,” said Sebastian Schindler, project manager at Fraunhofer CSP.

The researchers came up with three different concepts and methods for integrating the PV elements in facade sections. The study also demonstrated that the solar modules could either be included directly when casting the concrete sections or be laminated on or bonded to the concrete slabs. The modules can also be attached to the concrete slabs using stud fasteners, screw connections, or other means, facilitating easy removal for maintenance or repairs.

“We were able to demonstrate that all three mounting options are technically feasible,” added Schindler.

Pointing out the challenges, the researchers said that they had to ensure that the method used to produce the concrete sections is compatible with the required dimensional accuracy of the PV modules.

This is done by casting the concrete parts with a depression that is perfectly sized to accommodate a module. In this way, the desired orientation for solar irradiation and the overall design are preserved, states the official statement.

“The dimensional accuracy should be implemented directly in the concrete section,” underlined Schindler.

The scientists further pointed out that it is also important that the PV modules aren’t fastened where the concrete is particularly thin or where the carbon fibers are located, as this would impair the strength of the facade elements.

The Fraunhofer experts are now working on commercial solutions for integrating PV modules into precast concrete slabs, and the researchers are conducting endurance tests on both the PV components and the interface with the concrete to ensure the mounting hold permanently.

In addition to the experiments, simulations are also being made to calculate how the concrete and the attachment point of the PV element heat up at high temperatures, or what wind and pressure load the solar module must withstand.

In February 2020, Mercom reported that a team of researchers at the Chinese Academy of Sciences had developed a technique that could increase the power conversion efficiency of organic photovoltaic (OPV) solar cells to 17%.

Previously, it was reported that a team of research scientists from the Australian National University (ANU) had had a breakthrough in the efficiency of solar cells, an outcome multiple entities around the world are incessantly attempting to achieve. The efficiency of a solar cell refers to the part of the energy from sunlight (photons) that can be converted into electricity by the solar cell.

Image credit: Fraunhofer