Introduction  To achieve "carbon peaking and carbon neutrality" goals, the total installed capacity of wind and photovoltaic power generation in China will have to be increased by more than twice the current level by 2030. The international community has reached a consensus on developing solar energy resources and other kinds of renewable and clean energy vigorously. In this article, taking Fang County in Hubei Province as an example, a refined evaluation of solar energy resources is conducted and the technical exploitable capacity is calculated by combining reanalysis data and terrain data to provide data support for the appropriate development and utilization of solar energy resources.

  Method  The reanalysis data of nearby ERA5 were corrected and a radiation grid product with an accuracy of 0.1°×0.1° was produced based on the radiation observation data obtained from 2012 to 2020 in one radiation observation station (Station A) located in the county. A geographic information-based radiation model was established by using GIS technology and considering factors such as slope, aspect, altitude, and their impact on radiation. Based on Landsat TM/ETM/OLI remote sensing image data and incorporating land use type data, the limitations of photovoltaic development and the availability of different land types were discussed.

  Result  The built model can satisfactorily reflect the actual radiation situation. The model simulation results are compared with the actual observation data in two other radiation observation stations (Station B and C) in the region and the results are that, considering the overall situation throughout the year, the annual average relative errors of Station B and Sstation C is 5.7% and 3.4%, respectively, and from the perspective of the monthly radiation, the relative error of Station B is between 2% (January) and 14.1% (August), and that of Station C is between 0.1% (February) and 15.4% (June).

  Conclusion  Based on the simulation results, it is clear how solar energy resources are distributed in Fangxian County. Spatially, there are more resources in the windy region of the central valley and fewer resources in the high-altitude mountainous areas in the south and north, with an annual total radiation of 4.00~4.13 GJ/m². It is calculated that the exploitable area for photovoltaic power generation in Fangxian County is 60.7 km², and the technological development capacity is 4.501 GW.