Worldwide solar radiation benchmark of modelled surface irradiance

Modelled irradiance data based on satellite products is frequently used in solar energy applications and atmospheric sciences. This kind of data is offered by many different institutional or commercial providers, and currently it is not possible for users to independently identify the best provider for their specific application and location. This work presents a benchmark of satellite-derived global horizontal irradiance (GHI) as well as direct normal irradiance (DNI) at 129 ground-based radiation measurement stations distributed globally. High temporal resolution data (1 min) from these stations from between 2015 and 2020 has been quality controlled by a team of experts using a comprehensive set of best practices and newly implemented quality control procedures. The ground stations provide measurements of GHI and DNI and/or diffuse horizontal irradiance (DIF) from 25 different providers or networks. The 129 stations are spread out worldwide with 31 stations in Africa, 31 in Asia, 27 in North America, 20 in Europe, 13 in Australia, 5 in South America and 2 in Antarctica. GHI and DNI data from eleven different commercial or open-access radiation models is compared against these stations’ high-quality ground data. Additionally, one common measurement year is used to perform a site adaptation of the model datasets. The site adaptation is based on the empirical quantile mapping method and is the same for all test data sets. The comparison of the raw model data as well as the site adapted data is conducted at both 60-min and 15-min temporal resolutions. The performance of the raw and site-adapted data is analysed with respect to different regions and climate zones. Users can rely on the results of this work to make an informed decision about which surface radiation model(s) and data providers are most suited for their application.