Das Wolkenkameranetzwerk Eye2Sky

In dem Vortrag von Niklas Blum und Jonas Stührenberg wurde das Eye2Sky Wolkenkameranetzwerk einem Publikum aus Wissenschaft und Industrie vorgestellt. Hierbei wurden zuerst der Aufbau und aktuelle Status des Netzwerks erklärt. Im nächsten Schritt wurde ein Einblick in die, der Strahlungsvorhersage zugrundeliegenden, Algorithmen, wie der Wolkenhöhenerkennung, gegeben. Es folgte die Einbettung des Kameranetzwerks in die verschiedenen Forschungsprojekte am DLR und eine Diskussion

High resolution short-term solar forecasting for the integration of PV in Energy Systems

The high resolution of the Eye2Sky network allows very short-term forecasting of cloud cover, solar irradiance and PV power output. For that purpose, advanced image analysis, cloud tracking and modelling merges multiple ASI sky and cloud observations into maps of solar irradiance

Forecasting Solar Irradiance by looking at clouds from above and below

The energy meteorology measurement network Eye2Sky is a cloud monitoring system covering roughly 110x100 km in north-west Germany. It is equipped with 38 cloud cameras, solar radiation measurement stations and individual Lidar based cloud altitude measurements distributed throughout the region around Oldenburg. The system collects high-resolution information on solar radiation, tracks the variability at different locations and outputs forecasts for very short time scales. It covers a resolution range of fewer than 100 metres and less than 1 minute and supports forecasts of up to one hour (depending on the prevailing cloud height). A second data source for this region is given by images from the geostationary satellite MSG. With these images longer forecast horizons are achieved in a coarser resolution. The hybrid use of both data sources has only just begun in the community. This allows the development of new models with an improved quality of predictions. The presentation gives an overview on Helmholtz AI collaboration of DLR VE and AI collaboration with institutes DLR SP and DLR SF

PyranoCam: Simple measurement system for all components of solar irradiance in arbitrary planes

Accurate, robust and cost-efficient measurements of different solar irradiance components in arbitrary planes are of great interest for solar energy applications. A wide range of costeffective and robust measurement systems are currently available on the market. Available measurement techniques exhibit at least one of these shortcomings: intensive maintenance, high acquisition cost, increased deviations or restrictions to single planes (global tilted irradiance). PyranoCam is a robust and inexpensive setup of a thermopile pyranometer and an all-sky imager (ASI) for measurements of GHI, DHI, DNI and GTI (for any arbitrary plane

Forecasting Solar Irradiance by looking at clouds from above and below

The energy meteorology measurement network Eye2Sky is a cloud monitoring system covering roughly 110x100 km in north-west Germany. It is equipped with 38 cloud cameras, solar radiation measurement stations and individual Lidar based cloud altitude measurements distributed throughout the region around Oldenburg. The system collects high-resolution information on solar radiation, tracks the variability at different locations and outputs forecasts for very short time scales. It covers a resolution range of fewer than 100 metres and less than 1 minute and supports forecasts of up to one hour (depending on the prevailing cloud height). A second data source for this region is given by images from the geostationary satellite MSG. With these images longer forecast horizons are achieved in a coarser resolution. The hybrid use of both data sources has only just begun in the community. This allows the development of new models with an improved quality of predictions

A network of all sky imagers (ASI) enabling accurate and high-resolution very short-term forecasts of solar irradiance

The Eye2Sky network is a measurement network in north-western Germany consisting of multiple all-sky imagers (ASI), meteorological and solar irradiance measurements. The network provides high temporal and spatial resolution data for meteorological and especially solar energy related applications. With increasing photovoltaic (PV) capacity in electrical grids fluctuations in solar irradiance due to changing cloud cover may have adverse effects on the grid stability. Within Eye2Sky, new technologies and methodologies facing the demand for more accurate solar irradiance forecasts are being developed. The ASIs used in Eye2Sky record 180° field of view hemispherical sky images from fish-eye lensed cameras. Accompanied with local measurements of solar irradiance components (global, direct and diffuse) a very short-term forecast of the solar resource is possible. These nowcasts provide minutely updated information up to 20 minutes ahead with 1-minute temporal and 50 m x 50 m spatial resolution. This approach shows more precise forecasting results for the next minutes ahead compared to traditional and less detailed methods based on satellite or numerical weather prediction models. In the network, multiple ASIs are used to enlarge the spatial coverage and the forecast horizon requested by many applications. Moreover, the forecast error can be reduced with a network of cameras. In this article, the Eye2Sky network, its research results and applications are introduced

Comparison of short-term (hour-ahead) solar irradiance forecasts from all-sky imagers and satellite images

The all sky imagers (ASI) network Eye2Sky has been used for short-term solar irradiance forecasting in the urban area of the city of Oldenburg, in northwest Germany. Eye2Sky is a network of ASI and meteorological measurement instruments operated by DLR. This network is the basis for very short-term, high resolution and accurate predictions of solar irradiance in the upcoming minutes (nowcast). A high density of ASI with low spatial distances between cameras in the urban area allow an almost full coverage of the city (about 10x12 km). On the other hand, ASI-based solar irradiance nowcasts lack long forecast horizons due to their limited field of view (typically 15 minutes for single cameras). With a network of ASIs not only the coverage is increased but also the forecast horizon. Forecasting methods based on satellite images or numerical weather prediction (NWP) models are use as the standard for solar power forecasts. They provide larger spatial coverages and longer forecast horizons compared to ASI forecasts. On the contrary, due to their limited resolution and update rates the accuracy for short-term horizons and single sites is reduced. Here, we demonstrate the value of a network of ASI inside an urban environment for the spatial coverage and forecast horizon. Moreover, we show a comparison of forecast accuracy between the ASI nowcasts and the reference forecasts from satellite and a NWP model. These studies are the basis for a seamless forecasting strategy covering always finer spatial and temporal scales for intra-day applications. The main objective is to provide the highest available accuracy based on the hybridization of multiple data sources. We are looking for an intensive exchange with research and industry on the application of short-term solar forecasting in modern renewable energy driven energy systems, e.g. the use of short-term forecasts in the operation of large PV plants. Any feedback from stakeholders on their needs and requirements will support us to adapt nowcasting strategies to specific applications

Solar irradiance nowcasting based on a network of all sky imagers: the value of high-resolution data on variability information

The transition to a fossil-free energy system requires rapid installation of photovoltaic (PV) systems. For Germany, the government is targeting an installed PV capacity of 215 Gigawatt by 2030 (70 GW by 2023). This target is associated with an increased installation rate of 22 gigawatts PV per year (around three times compared to the 2021 rate). In urban areas, the majority of systems will be installed on rooftops connected to the low-voltage grid. It is therefore likely, that the majority of suitable rooftops will be equipped with PV systems in the next 10 years. In parallel, significant changes in load patterns (e.g. e-mobility, heat pumps) and the integration of battery storages can be expected. The efficient integration of the additional PV systems into the electrical grid also requires a detailed understanding of the generation profiles at different levels from the household to the transformer. Therefore, the impact of very-short-term solar irradiance variability on ramp rates and balancing effects should be investigated for scenarios with decentralized, but denser PV generation than today. Since this variability is mainly caused by small scale cloud dynamics, high resolution information on temporal and spatial cloud cover and irradiance distribution is needed. In northwestern Germany, DLR has installed and is operating Eye2Sky, a dense network of all-sky imagers (ASI). At 30 different locations, high-resolution fisheye images of the sky are taken every 30 seconds. At 10 locations, the images are complemented by radiation and meteorological measurements. The Eye2Sky network covers about 100 km x 100 km centered at the city of Oldenburg. It has a low ASI density in rural areas and a high density in city of Oldenburg, thus providing an almost complete coverage of the city. Eye2Sky is used to study solar irradiance variability in the city of Oldenburg at a high spatial (50 meters) and temporal (30 seconds) resolution. This enables simulations of single rooftop PV systems. Compared to state-of-the art radiation data sources like satellite images or numerical weather models (NWP), the camera information in Eye2Sky resolves cloud details that cause solar irradiance fluctuations on small scales down to household level. In this work, we would like to present a solar irradiance nowcasting validation from the ASI network in Oldenburg and its comparison with methods based on satellite (MSG) as well as NWP (ICON-D2) data. Emphasis will be made on the ability of the different methods to reproduce the spatio-temporal variability under different cloud condition

Solar irradiance nowcasting based on a network of all sky imagers: the value of high-resolution data on variability information

The transition to a fossil-free energy system requires rapid installation of photovoltaic (PV) systems. For Germany, the government is targeting an installed PV capacity of 215 Gigawatt by 2030 (70 GW by 2023). This target is associated with an increased installation rate of 22 gigawatts PV per year (around three times compared to the 2021 rate). In urban areas, the majority of systems will be installed on rooftops connected to the low-voltage grid. It is therefore likely, that the majority of suitable rooftops will be equipped with PV systems in the next 10 years. In parallel, significant changes in load patterns (e.g. e-mobility, heat pumps) and the integration of battery storages can be expected. The efficient integration of the additional PV systems into the electrical grid also requires a detailed understanding of the generation profiles at different levels from the household to the transformer. Therefore, the impact of very-short-term solar irradiance variability on ramp rates and balancing effects should be investigated for scenarios with decentralized, but denser PV generation than today. Since this variability is mainly caused by small scale cloud dynamics, high resolution information on temporal and spatial cloud cover and irradiance distribution is needed. In northwestern Germany, DLR has installed and is operating Eye2Sky, a dense network of all-sky imagers (ASI). At 30 different locations, high-resolution fisheye images of the sky are taken every 30 seconds. At 10 locations, the images are complemented by radiation and meteorological measurements. The Eye2Sky network covers about 100 km x 100 km centered at the city of Oldenburg. It has a low ASI density in rural areas and a high density in city of Oldenburg, thus providing an almost complete coverage of the city. Eye2Sky is used to study solar irradiance variability in the city of Oldenburg at a high spatial (50 meters) and temporal (30 seconds) resolution. This enables simulations of single rooftop PV systems. Compared to state-of-the art radiation data sources like satellite images or numerical weather models (NWP), the camera information in Eye2Sky resolves cloud details that cause solar irradiance fluctuations on small scales down to household level. In this work, we would like to present a solar irradiance nowcasting validation from the ASI network in Oldenburg and its comparison with methods based on satellite (MSG) as well as NWP (ICON-D2) data. Emphasis will be made on the ability of the different methods to reproduce the spatio-temporal variability under different cloud condition