Energy yield from vertical bifacial solar panels
Vertically mounted, bifacial solar panels have a different energy yield profile than conventional solar panels. Instead of having one peak during midday, there are two energy peaks in the morning and in the afternoon. The energy yield varies a lot with different factors, such as latitude, surface reflection (albedo) effect of the roofing material and local fraction of diffuse light. So far, existing simulation programs are not fine-tuned for this technology. By collecting data from several pilot installations all over Europe and developing models based on this, our aim is to achieve realistic predictions of the yield.
Methods and main findings
Research installations
Our research installations are placed all over Europe, so we can gather data for different latitudes and climate conditions.
Simulations and estimations
Existing simulation programs are not fine-tuned for vertical, bifacial PV and predict less energy than it is actually produced by vertical solar panels.
The role of albedo
Our vertical solar panels have a considerable low height and are mounted close to the ground.
For this reason, the role of the reflected radiation from the ground plays a more important role in the energy yield than with conventional panels.
Research installations
We've placed vertical solar panel research installations on rooftops in different climates and under different solar conditions from Tromsø in the north of Norway to Alicante in Spain.
For each location we observe different energy yields, which helps us understand and evaluate the different factors influencing the yield.
Simulations and estimations
Vertical solar panels have a different energy production profile. Compared to conventional monofacial solar panels, typical factors influencing energy yield have a different impact on the energy production, such as:
- The angle of the sun is optimal in the morning and afternoon
- Vertical panels can catch the lower sun in the winter better
- Latitude changes the angle of the sun and therefore the production profile
- Climate conditions
- Albedo
The role of albedo
For conventional systems, the ground reflectance (albedo) factor would not be considered important for the energy yield.
The energy yield of vertically mounted solar panels, however, is highly influenced by the albedo of the underlying surface. By testing the energy yield of pilot installations with different roofing materials, an estimation of the albedo weighting can be done.
The vertical solar energy unit
Learn more about the VPV Unit from Over Easy Solar