Vertical bifacial solar panels -energy production for different locations and latitudes
- Trygve Mongstad
- Jul 31
- 7 min read
How much energy do vertical solar panels produce?
The annual output of vertical solar panels depends strongly on location. Solar irradiation, latitude, weather patterns, orientation and the reflectivity of the roof surface all influence how much electricity a vertical bifacial system produces during the year.
The most useful comparison metric is annual specific yield, expressed in kilowatt-hours per installed kilowatt-peak, or kWh/kWp. A specific yield of 900 kWh/kWp means that a 100 kWp solar installation is expected to produce approximately 90,000 kWh of electricity in one year.
There is no single answer to how much energy vertical solar panels produce. The same vertical solar installation will deliver substantially different annual output in Tromsø, London, New York or Doha because the available solar resource and the distribution of sunlight throughout the year are different.
The VPV Yield Portal presents simulated annual specific yield for a growing selection of cities and locations around the world. The results are based on the Over Easy Solar energy yield model, and make it possible to compare vertical solar panel performance using consistent system assumptions.
This article presents a representative selection of locations from the portal. For each location, it shows the simulated annual yield of an unshaded Over Easy Solar installation under two roof-surface scenarios:
Low albedo (0.05), representing a very dark and weakly reflective surface
High albedo (0.70), representing a highly white or reflective surface
Albedo describes the proportion of incoming sunlight reflected by a surface, so selecting these two extremes outline the typical range of expected energy yield from a well-designed vertical solar system in the locations. Reflected irradiation from the roof can have a significant effect on annual production.
The figures in this article describe annual electricity output relative to installed capacity. They should not be confused with solar module efficiency, which describes how effectively a module converts the sunlight reaching it into electricity. When people search for vertical solar panel efficiency, output or performance, they are often actually looking for annual production in kWh/kWp rather than the laboratory efficiency of the solar cells.
Vertical solar panel yield by location - from north to south
The table below compares the modelled annual specific yield of an unshaded Over Easy Solar installation in 15 representative locations. All locations use the same system configuration, with vertical bifacial modules facing east and west and a bifaciality of 95%. Like this, the effect of location and roof reflectivity can be compared on a consistent basis.
The figures are annual specific yield in kWh/kWp, rounded to the nearest kWh/kWp. They are modelled results, not production guarantees or actual data. For a deeper dive into data and the factors that affect the energy yield, and for a review of data from different locations, read the article about Vertical solar energy yield.
Location | Latitude | Annual yield, low albedo | Annual yield, high albedo |
Tromsø, Norway | 69.65° N | 648 kWh/kWp | 781 kWh/kWp |
Oslo, Norway | 59.91° N | 748 kWh/kWp | 939 kWh/kWp |
Copenhagen, Denmark | 55.68° N | 819 kWh/kWp | 1,038 kWh/kWp |
Berlin, Germany | 52.52° N | 834 kWh/kWp | 1,063 kWh/kWp |
London, United Kingdom | 51.51° N | 807 kWh/kWp | 1,028 kWh/kWp |
Paris, France | 48.86° N | 903 kWh/kWp | 1,158 kWh/kWp |
Zurich, Switzerland | 47.38° N | 896 kWh/kWp | 1,161 kWh/kWp |
New York, United States | 40.71° N | 1,045 kWh/kWp | 1,372 kWh/kWp |
Madrid, Spain | 40.42° N | 1,212 kWh/kWp | 1,584 kWh/kWp |
San Francisco, United States | 37.77° N | 1,273 kWh/kWp | 1,676 kWh/kWp |
Tokyo, Japan | 35.68° N | 949 kWh/kWp | 1,252 kWh/kWp |
Doha, Qatar | 25.29° N | 1,241 kWh/kWp | 1,710 kWh/kWp |
Accra, Ghana | 5.60° N | 1,239 kWh/kWp | 1,712 kWh/kWp |
Sydney, Australia | 33.87° S | 1,155 kWh/kWp | 1,522 kWh/kWp |
Cape Town, South Africa | 33.92° S | 1,293 kWh/kWp | 1,714 kWh/kWp |
Tromsø has favourable solar angles for vertical panels during parts of the year, but its limited winter irradiation reduces total annual production. Locations such as Madrid, Doha, Accra and Cape Town receive considerably more solar energy over the year and consequently achieve higher modelled annual specific yields.
The high albedo scenario increases the simulated annual east-west yield by approximately 20% to 40% across the locations in the table. This comparison is intentionally based on two widely separated albedo values to show the potential range. Actual surfaces will normally fall somewhere between these scenarios.
The table provides only a representative selection. Simulated yield results for additional cities and countries are available in the VPV Yield Portal.
Vertical solar energy production through the year - examples from Tromsø, London, New York and Doha
Annual kWh/kWp is useful for comparing locations, but it does not show when the electricity is generated. The monthly production profiles for Tromsø, London, New York and Doha illustrate how strongly the seasonal distribution changes with latitude and climate.
The monthly graph also introduces a second orientation. East-west orientation means that the two sides of the vertical bifacial panels face east and west. South-north orientation means that they face south and north.
Orientation affects both the annual total and the seasonal production profile. In the four examples, the south-north configuration tends to shift more production towards the months with a lower sun, while the east-west configuration is generally stronger during the high-sun part of the year. The size of this effect depends on location, albedo and system geometry.
This article uses east-west orientation as this is the most common for vertical solar, but as can be seen in the monthly data, south-north may give a more evenly distributed generation over the entire year, which may be useful or valuable. For a deeper explanation of orientation, bifacial irradiance and the factors controlling vertical PV yield, see Energy yield from vertically mounted bifacial solar panels.
The daily production profile - examples for Tromsø, London, New York and Doha
Vertical east-west solar panels typically produce two daily peaks: one during the morning and another during the afternoon. The graph below shows the modelled average production during each hour of the day in June.
High albedo raises production across much of the day and reduces the relative depth of the midday dip. However, the characteristic morning and afternoon production profile remains visible in all four locations.
Together, the annual, monthly and hourly results show three different aspects of vertical solar performance: how much electricity the system produces over the year, how production is distributed between seasons, and when it produces electricity during the day.
Does vertical solar only work at high latitudes?
No. Vertical solar panels can produce good amounts of electricity across a wide range of latitudes. High latitudes can provide favourable solar angles for vertical modules during parts of the year, but latitude alone does not determine annual energy yield.
However, when we get further south, the albedo of the surface plays a bigger role. The reason is straightforward: locations further south often receive substantially more solar irradiation when the sun is at a high angle, and scattered light from the surface below becomes very important.
As discussed in another article, real-world findings for southern locations like Doha states that energy yield can reach well above 2000 kWh/kWp, higher than our estimates based on modelling.
High-latitude locations still have characteristics that suit vertical solar. Low solar angles can contribute strongly during spring, autumn, mornings and afternoons, and northern locations may offer valuable seasonal or daily production profiles. However, these advantages should not be interpreted to mean that vertical solar is exclusively a northern technology.
Vertical solar works at both high and low latitudes. The annual result depends on the complete solar climate, including total irradiation, sun path, cloud conditions and albedo, not latitude alone.
The VPV Yield Portal shows modelled results for locations ranging from Northern Europe to the Middle East, Africa, Asia, Australia and the Americas.
How the VPV Yield simulation model was developed
The results in the VPV Yield Portal are generated using Over Easy Solar’s energy-yield simulation model, developed in collaboration with the Institute for Energy Technology, IFE, in Norway. The purpose of the model is to estimate how a defined Over Easy Solar installation performs under different solar and climatic conditions.
The model is informed by measurements from 13 research and pilot installations established between 2021 and 2023. These installations covered different locations, roof surfaces, albedo conditions, orientations, row spacing and system geometries. At several sites, both solar irradiance and electrical production were measured.
Some of the research installations were designed as flexible test setups. This allowed Over Easy Solar to vary parameters such as roof reflectivity, panel spacing and orientation, and compare the simulated effect with measured changes in energy production.
This measurement basis is important because vertical bifacial systems cannot be modelled reliably by considering only the irradiation falling directly on the module. The model must also account for reflected light, the interaction between the panels, the sun path, mounting system geometry and system losses.
The portal results therefore provide a consistent basis for comparing locations. Each location is simulated using the same defined Over Easy Solar system configuration and assumptions, making it possible to isolate the effect of climate, latitude and surface reflectivity.
The figures should still be interpreted as modelled estimates, not production guarantees, nor real ata. Actual project yield is affected by local shading, roof geometry, surrounding buildings, snow, soiling, electrical design, system availability and weather variation from one year to another.
Conclusion
There is no single annual yield figure for vertical solar panels. Using the same system configuration, modelled output varies substantially between locations because annual solar irradiation, latitude, orientation/azimuth, weather patterns and roof reflectivity all affect the result.
The simulations also show that vertical solar is not limited to northern or high-latitude regions. Northern locations can benefit from favorable solar angles during parts of the year, but locations further south often achieve higher annual specific yield because they receive more solar energy overall. In the modelled examples, annual east-west yield ranges from around 650 kWh/kWp in Tromsø with a dark surface to close to 2000 kWh/kWp in high-irradiation locations with a highly reflective surface.
The most meaningful comparison is therefore not whether vertical solar works in a particular latitude band, but how a defined system performs under the actual conditions of a location. The VPV Yield Portal is made to provide modelled results for a wider selection of cities and countries using consistent assumptions.
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