In order to keep our power grid stable and to market solar power on the stock exchange, precise projections and forecasts of photovoltaic generation are becoming increasingly important. To improve this, the Fraunhofer Institute for Solar Energy Systems ISE and the transmission grid operator TransnetBW have set up a network of measuring stations in the “PV-Live” project, with which the current irradiation conditions in the grid area are recorded every minute. These data are also very valuable for solar energy meteorology research.
The project partners are now making the first quality-controlled data sets with measured values since September 2020 publicly available.
For “PV-Live”, the Fraunhofer ISE research team developed a measuring station which uses pyranometers to record the global radiation on the horizontal and the temperature as well as — with three differently oriented silicon reference cells — the radiation on inclined surfaces as the basis for simulated PV power values. In the control area of the Baden-Württemberg transmission system operator TransnetBW, a total of 40 of these measuring stations were installed at intervals of 15 to 35 kilometres by March 2019. The stations are located at project partners and companies, but also at municipal utilities of cities in Baden-Württemberg. The radiation values are transmitted from the measuring stations in real time every minute, quality controlled at Fraunhofer ISE, converted into PV power and made available to TransnetBW. The collected data is combined with satellite-based irradiation values to provide a spatially and temporally high-resolution picture of the current PV generation and thus the resulting feed-in to the power grid.
“The novel concept for the measuring stations and data acquisition was developed in close cooperation between Fraunhofer ISE and TransnetBW,” explains Dr. Florian Dinger, head of special tasks Algorithms and Forecasts at TransnetBW. “We see the cooperation between industry, science and society as an important pillar of the energy transition. Accordingly, we are making the new high-resolution dataset available to the public research community of solar energy meteorology.”
Quality controlled minute values of solar irradiation for differently inclined surfaces
The dataset of readings taken every minute since September 2020 has now been published. Before publication, the irradiance and temperature data go through a quality control scheme with algorithms specially adapted for this data set. The automated real-time data processing and quality control were set up together with Mondas GmbH, a spin-off of Fraunhofer ISE. The datasets are available for use by researchers and other interested parties. Measurement data will continue to be collected and reviewed and published as monthly updates.
“Thus, for the first time, research in solar energy meteorology has a temporally highly resolved measurement data set of solar irradiance at its disposal, which covers the entire area of Baden-Württemberg. This allows investigations of spatial and temporal fluctuations and smoothing effects, which are very important for feeding solar electricity into the power grids,” explains Dr. Elke Lorenz, Group Leader Energy Meteorology at Fraunhofer ISE.
Another special feature of “PV-Live” is the simultaneous measurement of solar radiation with differently oriented sensors. While meteorological measuring networks usually measure in the horizontal plane, these inclined sensors record the solar radiation as it impinges in practice on solar modules installed on roofs or in ground-mounted systems. This is relevant, for example, for the development and validation of models for radiation at the level of the solar module.