OPV Facade

Organic photovoltaic (OPV) modules are mounted on the east, south and west facades and on the roof of the demonstration unit, clamped in a metal mesh.

OPV modules differ from classical PV modules mainly by the use of organic semiconductors. These work with inorganic materials such as silicon. Another advantage of OPV technology is that the modules generate electricity even when thy are partially shaded. The thin-film modules are also characterized by high flexibility in shape and color.

In addition to the classic function of generating electricity, the modules also serve as shading elements. For this purpose, both the arrangement and the size of the individual modules were determined by a parametric simulation. The target parameters of the parametric simulation were both winter and summer thermal insulation. Openings in front of the windows, which would lead to overheating of the rooms in summer, are shaded. However, they are kept as small as possible to ensure the maximum yield of solar energy input in winter.

For the parametric simulation, which determines the arrangement and size of the OPV modules, a novel approach was developed.

In the first step, the optimal shading for the room under consideration is represented by a movable sunshade in a simulation. If solar heat gain is desired in winter, the sunshade is on top. If shading is desired in summer, the solar shading is at the bottom. In addition, the footprints for potential placements of the OPV modules are defined. This is purely a design decision. In this case, diamond-shaped base surfaces were chosen.

The simulation results in the irradiance on the window surfaces at each time step and at the same time the information about the shading signal of the movable sunshade (sunshade open, sunshade closed). In the second step, the information on the total annual irradiation and evaluated annual irradiation is linked with the position of the sun at the respective time and displayed on two celestial hemispheres.

In the third step, the information is projected onto the base surfaces using surface discretization and ray tracing.

In the fourth step, the scaling factors for each ground plane are determined. The scaling factor for each footprint 𝑥 is obtained from the following calculation:

Based on the determined scalingfactors, the base surfaces are scaled to the correct size.

This approach has been implemented in a program and can be applied to other buildings at other sites, increasing the transferability of the coLLab project.