In 2017, 3E introduced a new satellite-based irradiation data source that makes use of the most advanced Cloud Physical Properties (CPP) models available today (https://solardata.3e.eu). Through the use of underlying cloud models considering the physical properties of the clouds, 3E has significantly improved the accuracy of the satellite-based irradiation data. Moreover, extensive validation results have shown that models compensating for satellite sun path and cloud geometry provide the highest accuracy, even at high temporal resolutions (hourly or sub-hourly data). The resulting data has shown to be comparable and sometimes even better than the one of the on-site measurements when low quality equipment is used, and/or these are incorrectly installed and maintained, making 3E’s data service the best available satellite-based irradiation data source on the market.
3E’s satellite-based solar irradiation data is constantly evaluated against the reference data from the measurement stations making it the most extensively validated satellite-based irradiation data source. Over 300 high quality meteorological stations spread across Europe and Africa are used within this Solar Data validation framework, participating in the continuous improvement of the models. Hourly, daily, and monthly irradiation for all sites are evaluated by their root mean square error (RMSE), the standard deviation of the error (SDE) and the systematic part of the error (bias). Results of these validations are presented in this white paper.
The bias error of 3E’s satellite-based solar irradiation data is overall in the order of ±2.5%. The SDE is in the order of 2-3% for monthly resolution and varies between 12% and 18% for hourly resolution depending on the region (see figure below). The value of accurate irradiation data to solar plant stakeholders is presented and different case studies are shown, illustrating different applications of high accuracy satellite-based solar irradiation data.
When integrated over relatively short periods of time (minutes, hours, or days) ISO secondary standard pyranometer measurements have the lowest uncertainty if the equipment is well installed and maintained. But satellite-based solar irradiation data comes close to the on-site measurement uncertainty over longer time periods such as months and years.
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