Researchers from the Chinese energy company Yunnan Longyuan New Energy have proposed a new methodology for the designing of utility-scale PV plants in hilly or mountainous regions.
In particular, they conducted a simulation study of a south-oriented mountain PV farm located in the southern Chinese city of Pu’er, in the Yunnan province. High-resolution digital elevation model (DEM) data were obtained via unmanned aerial vehicle (UAV) photogrammetry to establish a three-dimensional terrain model.
“A 3D terrain model was constructed using Rhino software, and quantitative PV analysis conducted through the PVsyst platform quantifies key operational factors impacting system efficiency—including temperature loss, irradiance loss, and shading loss,” the group explained. “These findings provide actionable decision-making support for PV array maintenance and optimization in complex terrain areas.”
Meteorological data, including mean annual temperature, precipitation, and solar radiation for Pu'er, were obtained from Meteonorm software. The hill had a mean altitude of 1,037 meters above sea level, and the simulated solar park on it was separated into two parts: Region A has a convex terrain of 1,175 m2, with an average slope of 20.378°, and 456 installed PV panels. Region B had a concave terrain with an area of 561 m2 and an average slope of 17.703°. The number of PV panels on this part was 216.
Each panel was an n-type monocrystalline panel with a power of 575 W and an efficiency of 22.3%. The external dimensions of this component are 2,278 mm × 1,134 mm × 30 mm, and the effective light-receiving area is approximately 2.58 m². Four inverters are set up, each connected to 12 PV strings, and each PV string consists of 14 PV panels, forming a complete array design for the entire system. The maximum conversion efficiency of the inverters was 99%.
“The open and well-ventilated terrain in convex mountain Region A demonstrates superior thermal performance, with an annual energy loss of 38.1 kWh per module, compared to 39.5 kWh in the concave mountain Region B,” the academics explained. “The overall efficiency of the photovoltaic array in Region A is higher than that in Region B; the loss caused by the temperature rise of a single photovoltaic panel was reduced by 3.5%.”
The convex Region A was found to achieve 65.5% lower shading coverage and 66.9% reduced electrical losses relative to the concave Region B. Moreover, the results show that the performance gap is most evident in January, with Region A producing 66.4 kWh per panel compared to Region B's 64.3 kWh. During the winter solstice, Region A maintains minimal losses of 0.1% for both direct radiation and electrical, while Region B experiences substantially higher losses of 1.0% and 6.9%, respectively.
“System-level evaluation confirms that the open terrain configuration in Region A not only enhances individual panel performance but also optimizes overall system efficiency,” the researchers emphasized. “The shading-related electrical loss in Region A (-0.4%, 3.57 kWh per panel) is dramatically lower than in Region B (-2.9%, 26.3 kWh per panel), which reveals the importance of considering mountainous terrain in photovoltaic array design.”
According to the group’s economic analysis, the total initial investment in the system is CNY 918,140 ($129,977) with an annual operating cost of CNY 15,000. It achieves payback in 6.8 years and yields a net profit of CNY 2,567,853.92 over its 20-year lifespan. Furthermore, the system generates 10.39 million kWh of electricity, enabling a reduction in carbon emissions by 10.58 million kg compared to conventional coal power.
The scientists presented their findings in “Simulation study of a 386.4 MW mountain photovoltaic power plant: a case study,” published in Scientific Reports. Scientists from China’s Yunnan Longyuan New Energy and Yunnan Agricultural University have participated in the study.
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