Renewables
Study shows performance gap in utility-scale bifacial solar
Research from Spain reveals a significant shortfall between nominal and actual bifacial gains in utility-scale photovoltaic installations.
Key points
- A study analyzed two years of operational data from a 50 MW bifacial solar plant in Spain.
- Effective bifacial performance was found to be 13% to 15% lower than nominal values.
- Higher temperatures and variable irradiance levels heavily influenced rear-side generation efficiency.
What happened
A joint research team from the Universitat Politècnica de València and engineering firm Grupotec has examined the disparity between nominal module bifaciality and real-world performance. According to pv magazine, the study analyzed operational records from a 50 MW bifacial photovoltaic plant equipped with single-axis trackers in Spain, alongside data from four additional solar sites in Spain and the United Kingdom.
While the reference plant modules featured a nominal bifaciality factor of 0.70, the researchers found the time-weighted average effective bifaciality reached only 0.610. The irradiance-weighted average dropped further to 0.599, representing a 13% to 15% reduction from nominal specifications.
Why it matters
The research indicates that mounting configurations, temperature and irradiance levels significantly affect how rear-side generation contributes to overall power output. At irradiance levels exceeding 600 W/m², effective bifaciality fell below 0.60.
Although spring and summer months brought higher absolute rear-side contributions due to increased irradiance, the corresponding rise in module temperature reduced conversion efficiency. Additionally, the study noted that regulatory figures, such as Spain's Royal Decree 997/2025 bifacial factor, function more as administrative conversion coefficients than accurate reflections of operational output.
What comes next
The authors recommend that energy yield models and DC-side system designs incorporate the temperature and irradiance dependencies of effective bifacial performance rather than relying on constant nominal factors.
Original reporting
This article draws on the following reports. Read them in full on the publishers’ sites.
Context from CEII
Renewables are the fastest-growing part of the world’s energy system. The COP28 goal is to triple capacity by 2030, and solar mini-grids are the fastest route to power for millions of people without electricity.
47.0% of electricity in Spain was renewable in 2021Countries in this story
Written by the CEII Desk, the Centre’s automated newsroom, from the reporting credited above and CEII’s own data. Facts are attributed to their sources; the publishers have not reviewed this article. Spotted an error? Tell our editors.
