Task 16 provides access to comprehensive international studies and experiences with solar resources and forecasts. It supports different stakeholders from research, instrument manufacturers as well as private data providers and utilities.
Task 16 is a joint Task with the TCP SolarPACES (Task V). It collaborates also with the Solar Heating and Cooling (SHC) and with Wind Task 51.
Aside from the key accomplishment – the 4th Edition of the Solar Resource Handbook, which concludes the work of the last three years of the Task –, one official Task paper was published (Lauret et al., 2024).
Despite the growing awareness in academia and industry of the importance of solar probabilistic forecasting for further enhancing the integration of variable photovoltaic power generation into electrical power grids, there is still no benchmark study comparing a wide range of solar probabilistic methods across various local climates. Having identified this research gap, experts involved in the activities of IEA PVPS Task 16 agreed to establish a benchmarking exercise to evaluate the quality of intra-hour and intra-day probabilistic irradiance forecasts. The tested forecasting methodologies are based on different input data including ground measurements, satellite-based forecasts and Numerical Weather Predictions (NWP), and different statistical methods are employed to generate probabilistic forecasts from these.
The exercise highlights different forecast qualities depending on the method used, and more importantly, on the input data fed into the models. In particular, the benchmarking procedure reveals that the association of a point forecast that blends ground, satellite and NWP data with a statistical technique generates high-quality probabilistic forecasts. Therefore, in a subsequent step, an additional investigation was conducted to assess the added value of such a blended point forecast on forecast quality. Three new statistical methods were implemented using the blended point forecast as input. To ensure a fair evaluation of the different methods, we calculate a skill score that measures the performance of the proposed model relative to that of a trivial baseline model. The closer the skill score is to 100%, the more efficient the method is.
Overall, skill scores of methods that use the blended point forecast ranges from 42% to 46% for the intra-hour scenario and 27% to 32% for the intra-day scenario. Conversely, methods that do not use the blended point forecast exhibit skill scores ranging from 33% to 43% for intra-hour forecasts and 8% to 16% for intra-day forecasts. These results suggest that using (a) blended point forecasts that optimally combine different sources of input data and (b) a post-processing with a statistical method to produce the quantile forecasts is an effective and consistent way to generate high-quality intra-hour or intra-day probabilistic forecasts.
Additionally Task experts collaborated actively in the new Agri PV action group, co-organised the PVPMC Workshop in Copenhagen, August 20-21, 2024 and organised a side event at the EU PVSEC 2025 in Vienna (Sept.25th).
After the publication of the main result of the Task – the 4th Edition of the Solar Resource Handbook in October 2024 – the next update will be started. The 5th Edition is foreseen for mid-2027.
With in the activities the work will be ongoing. The two Task meetings will be held as hybrid meetings in Europe (Paris, Bern).
Three reports are foreseen for late 2025: one about image-based benchmarks (based on satellite images), an update of the firm power generation report and an update of the online code archive.
One workshop will be given about solar data processing using open-source tools in the framework of the PV modelling workshops.
The three years period will end in mid-2026. Therefore, a new work plan will be defined until the end of 2025.
International collaboration and consensus on developing and managing these data sets will expedite the high penetration of solar technologies, and improve markets for these technologies. Large scale PV plants now need accurate resource and forecast data due to high investment costs. Therefore Task participants will focus on the following two scientific issues:
High frequency variability and high quality needs are also important issues for the planning and the operation of Concentrating Solar Thermal facilities and CPV, which will be a focus of the Task as well. In addition, the development of bankable data sets for system sizing and accurate continuous data sets for performance evaluation are important to Solar Heating and Cooling technologies, and will also be a focus of this task.
The main goals of Task 16 are to lower barriers and costs of grid integration of PV and to lower planning and investment costs for PV by enhancing the quality of the forecasts and the resources assessments. Solar resources are introducing the highest share of uncertainty in yield assessments.
To reach this main goal the Task has the following objectives:
The scope of the work in Task 16 concentrates on meteorological and climatological topics needed to plan and run PV, solar thermal, concentrating solar power stations and buildings
The work programme of Task 16 addresses from scientific meteorological and climatological issues to high penetration and large scale PV in electricity networks, and also includes a strong focus on user needs. Dissemination and user interaction is foreseen in many different ways from workshops and webinars to paper and reports and online code archives or Wikipedia.
The work programme of the proposed Task 16 addresses on one side scientific meteorological and climatological issues to high penetration and large scale PV in electricity networks, but also includes a strong focus on user needs and for the first time a special dissemination subTask. Dissemination and user interaction are foreseen in many different ways from workshops and webinars to paper and reports.
The project requires the involvement of key players in solar resource assessment and forecasting at the scientific level (universities and research institutions) and commercial level (companies). A consortium of 51 institutions of 19 countries has been formed. This includes large science centres like DLR, NREL or Fraunhofer, universities like State Univ. of New York, Mines ParisTech or Univ. of Jaen, national weather services like DWD, BOM or DMI and data providers like Solargis, Vaisala or Meteotest.
The project involves key players in solar resource assessment and forecasting at the scientific (universities, met services and research institutions) and commercial level (companies). The work plan is focused on work that can only be done by international collaboration, like definition and organisation of benchmarks, definition of common uncertainty and variability measures.
The work programme is organised into three main technical subtasks (subtasks 1 – 3) and one dissemination subtask (subtask 4), including three to four activities.
The following list includes the updated plan for the 3rd phase from mid-2023 until 2026.
