Inside the Science: How Researchers Measured Vertical Bifacial Solar Performance
Most claims about vertical solar performance trace back to marketing material or short-term demonstrations. The 2024 peer-reviewed study "Comprehensive study on the efficiency of vertical bifacial photovoltaic systems: a UK case study," published in Scientific Reports by researchers Ghadeer Badran and Mahmoud Dhimish at the University of York, is different: it is described by its authors as the first full empirical assessment of a vertically mounted bifacial photovoltaic system, tracked over an entire year rather than a handful of days.
8/18/20263 min read
The experimental setup
The study monitored a vertically mounted bifacial system made up of 36 series-connected heterojunction photovoltaic units with a combined output of 1.5 kW under standard test conditions, installed on the rooftop of the university's Physics Tower. The ground beneath the array was covered in white gravel, chosen specifically for its high albedo, or reflectivity, to increase the diffuse light reaching the rear side of the bifacial panels. Rows were spaced 50 centimeters apart based on prior simulation work aimed at balancing shading against ground-reflection gains. The system was tracked from February through December 2023 and compared against a vertical monofacial system and a conventional tilted monofacial system of equivalent capacity.
Daily and seasonal findings
The paper's abstract reports a daily power output increase of roughly 7% to 10% over the vertical monofacial comparison system, and a substantially larger 22.9% to 26.9% improvement over the tilted monofacial system during early morning and late afternoon hours specifically. Averaged across full seasons, the vertical bifacial system's gain over the tilted system ranged from about 14.8% in summer up to 24.5% in winter, with the researchers noting that the design's low-angle light capture is particularly effective when the sun sits closer to the horizon, as it does through much of the winter at UK latitudes.
Wind and structural testing
Beyond energy output, the researchers ran computational fluid dynamics simulations on the array's structural stability, testing wind speeds up to roughly 27 meters per second, equivalent to extreme storm conditions. The vertical system was found to maintain low lift forces under these conditions, which the paper's authors describe as an advantage over tilted arrays, whose angled surfaces can behave more like airfoils and generate greater aerodynamic lift in high winds.
Why the researchers say this matters
The study's authors frame the core advantage of vertical bifacial technology as its ability to capture and use both direct and diffuse, reflected light throughout the day, rather than relying primarily on direct overhead sun the way conventional tilted panels do. They also note that the system's generation profile, weighted toward morning and evening rather than midday, aligns more closely with typical residential and commercial demand curves, a pattern that can help ease pressure on the grid during conventional midday solar oversupply.
What this means for site evaluation
Independent, peer-reviewed, full-year performance data is relatively rare in the vertical solar field, since the technology is still young. This study provides one of the more rigorous data points available for evaluating whether vertical bifacial systems can deliver a real performance advantage outside of idealized conditions, particularly in temperate, cloud-prone climates similar to those found across much of Central and Northern Europe.
Key takeaways
Peer-reviewed and full-year: tracked from February to December 2023, not a short demonstration.
Meaningful morning and evening gains: up to roughly 27% higher output than tilted panels in low-light hours.
Strongest in winter: seasonal gains peaked in winter conditions with low sun angles.
Structurally tested: CFD simulation found low lift forces even at extreme wind speeds.
Demand-aligned generation: output pattern matches typical morning and evening electricity use.
FAQ
Is this study specific to one location, or broadly applicable?
The measurements were taken in York, UK, but the underlying mechanism, capturing diffuse and low-angle light more effectively than tilted panels, applies broadly to temperate climates with significant cloud cover and low winter sun angles.
Did the study account for wind and structural safety?
Yes, the researchers ran computational fluid dynamics simulations testing the system's structural stability at extreme wind speeds, in addition to measuring energy performance.
How is this different from earlier vertical solar claims?
The study is a peer-reviewed, full-year empirical assessment rather than a short-term demonstration or manufacturer claim, which gives its findings more weight for technical evaluation.
Discuss the research with Lumiton Solar
If you'd like to understand how these findings relate to a specific project, Lumiton Solar can walk through the technical detail and how it applies to your site.