A study analyzing urban bifacial PV systems in high latitude areas found that they can generate 9-13% more electricity than monofacial panels under snow conditions, especially in winter, while also achieving lower electricity costs. The research developed a techno-economic optimization model that took into account snow effects, panel orientation, row spacing and operating modes, emphasizing sensitivity to market conditions and discount rates.
An international research team has conducted a techno-economic analysis for urban bifacial PV in high-latitude areas and found that bifacial systems can generate up to 12% more power than monofacial counterparts under snow conditions.
The scientists explained that, due to the complexity of snow effects, the scientific literature still lacks a detailed analysis of the two-sided performance in high-latitude areas.
“To fill this research gap and solve the technical challenge, we developed a new techno-economic optimal PV installation model for bifacial PV systems by considering snowfall and its melting effects, as well as two operation models: a home model and a park model,” said corresponding author Wujun Wang. pv magazine. “In addition, in this optimization model we have taken into account both the installation angle and the space between the rows, making it able to optimize both small-scale rooftop PV systems and large-scale PV farms.”
The group focused on the case study of Hammarby, a district in the Swedish capital Stockholm. Data about the electricity grid, including substations and loads, was obtained from the grid operator. Weather data were obtained from the Solcast dataset and the Swedish Meteorological and Hydrological Institute. This included data on irradiation, air temperature and snow depth.
Stockholm City’s open database provided building data, represented as simplified prismatic models. In total, 277 buildings have a roof area of more than 226,000 m2. The buildings are connected to 19 different substations, and each substation can serve a different number of buildings and different types of consumers. It is assumed that all roofs are flat and that the PV systems are installed at a fixed angle of inclination. Sun protection between the rows is also taken into account.
Image: KTH Royal Institute of Technology, Renewable Energy, CC BY 4.0
The bifacial panels considered have a maximum power of 575 W with a bifacial factor of 0.8. Monofacial reference models, with a power of 575 W and without bifacial factor, were also considered. They were all installed at a fixed slope angle, facing south, with a total loss compensation of 10%, taking into account factors such as contamination, wiring and availability. The price per bifacial panel was set at 948 SEK ($102.4), while monofacial panels were priced at 920 SEK.
The simulations took into account three electricity price levels, namely SEK 221/MWh, SEK 672/MWh and SEK 1,379/MWh, and two real discount rates – 2% and 5%. Two operating modes were evaluated: the home mode, in which electricity is produced for personal use and the surplus is sold to the electricity grid; and parking mode, where electricity is made entirely for the grid.
“Several results were very impressive,” Wang said. “First, compared to monofacial PV systems, bifacial PV systems can produce 9.1-12.8% more electricity in snow conditions, and most of this increase occurs during the winter season (December to February). Second, bifacial PV can achieve a lower levelized cost of electricity (LCoE) of 8.8 – 9.7% on average than monofacial PV. Third, the discount rate plays an important role in economic performance of both bifacial PV and monofacial PV systems, including LCoE and payback periods.”
The analysis also showed that self-sufficiency and self-consumption for a bifacial PV system are almost the same, with a difference of approximately two percentage points. Furthermore, even though its net present value (NPV) and payback period may be profitable over its lifetime, it is highly sensitive to market conditions such as electricity prices, discount rates and subsidies.
“In this study, we assume that all PV panels project toward the south, but this assumption may not work for all real PV farms due to local constraints such as topography, electricity price policy, infrastructure, and so on,” Wang noted. We therefore adapt this model to allow optimizing PV systems oriented in directions other than south. In addition, we are also working on improving the snow model and integrating an accurate PV pollution model to make this techno-economically optimal PV installation model more applicable.”
The research work was presented in “Techno-economic analysis of urban two-sided PV in a high latitude region,” in Renewable energy. Researchers from Sweden’s KTH Royal Institute of Technology and China’s Zhejiang University of Technology participated in the study.
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