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Researchers from Japan have analyzed the warming effect of the photovoltaic system on the land surface temperature around the Kushida River basin over ten years and have found that this value increased by an average of 2.85 ºC.Scientists from Japans Kyushu University have studied land surface temperature (TST) trends due to PV installation around the Kushida River basin, located in central Japan and composed of three regions: the city from Matsusaka, Taki Town and Meiwa Town. They used convolutional neural networks (CNN) to identify PV installations from aerial images and remote sensing to measure temperature changes.
“We designed a composite analytical model based on remote sensing and machine learning technology to quantify the impact of solar panels on the thermal environment in areas with different geographical characteristics,” they explained. “This model identifies ground-mounted solar panels using publicly available data and studies the spatial distribution of different types of solar panels and changes in surrounding surface temperature.”
The area investigated by the researchers covers a total area of ??767.62 km2, of which forests and croplands account for about 81%. They used high-resolution aerial photographs to identify photovoltaic installations and compiled statistical results to determine their distribution. They also performed monthly surface temperature analyzes using Landsat series satellite data in Google Earth Engine (GEE) and evaluated surface temperature changes at PV installation sites over different seasons and years, during 10 years.
Furthermore, using statistical tools and models, such as geographically weighted regression (GWR) and ordinary least squares (OLS) models, spatial factors influencing temperature changes were identified. The analysis took into account factors such as normalized difference vegetation index (NDVI), building density (BLD), population (POP), distance to rivers (WA) and elevation (DEM), as well as the size of photovoltaic installations.
“The study found that the LST around PV installations that were built between 2013 and 2023 increased by an average of 2.85°C,” the research team states. “From a seasonal perspective, the effect of LSTD is more pronounced (+3.35ºC) in the warmer months and more moderate (+2.5ºC) in the colder months.”
By quantifying the effect of different factors on the heating of the photovoltaic zone, scientists discovered that elevation, building density, NDVI, photovoltaic zone and distance to waterways are those that have the greatest correlation with the LST differences in suburban plant zones. Of all the factors, elevation had the most significant effect.
“The suburban areas, where each independent variable showed the highest correlation in GWR, are the industrial areas of the city, suggesting that industrial production is more likely to influence the temperature increase effect of PV compared to other activities urban," they noted. “At the same time, it was confirmed that the topography and vegetation cover within the basin are closely related to the temperature increase effect. The installation of photovoltaic energy in high areas and regions with high vegetation cover tends to mitigate its impact on the LST.”
Their conclusions were presented in “ Evaluating the thermal environmental alterations due to photovoltaic installations in the Kushida River basin, Japan, ” published in the journal Environmental and Sustainability Indicators . |
