Direct Normal Irradiance Nowcasting Methods for Optimized Operation of Concentrating Solar Technologies, DNICast
Concentrating solar technologies (CST) have proven to be very efficient sources of clean power for the electrical grid. CST include thermodynamic machines, such as the concentrating solar power (CSP: parabolic troughs, solar towers, Fresnel collectors, parabolic dishes…), or concentrating photovoltaics (CPV).
The efficient operation of CST requires reliable forecasts of the incident irradiance for two main reasons:
- First, to yield a better management of the thermodynamic cycle
- Second, the electricity production can be optimally connected to the grid.
Currently, forecasts are made by several techniques, which have their own merits and drawbacks. The uncertaintly in the forecast of the Direct Normal Irradiance (DNI) is still too large and must be reduced.
The DNICast project, brings a series of innovative components which will advance current state-of-the-art in a number of ways. These innovations can be clustered in terms of methodological progress, geographical extension and a participatory approach through the involvement of stakeholders and potential end-users.
In DNICast, methods based on information from a number of different sources such as ground measurements, all sky imagers, satellites and Numerical Weather Prediction (NWP) models will be used in an integrated way to offer more reliable DNI estimates that fulfill the requirements for the application in the field of CST. In fact, the mentioned methods have different time and spatial resolutions, and there is no single approach valid at all desired scales. Therefore a combination is needed.
To validate several methods against references accurate and reliable ground measurements of DNI and aerosol and cloud properties will be collected for sites located in the geographical areas of interest for the implementation of CST.
DNI nowcasting methods will be validated through ground measurements of DNI at different sites with high quality datasets. For the validation of the nowcasting methods metrics proposed recently by EU-funded and other international projects will be used (MACC-II, ENDORSE, IEA Solar Heating and Cooling Task 46). Another major innovation is the effort spent to collect data, to qualify them in relation with the instrument operators and to describe them with INSPIRE-compliant metadata. This effort will be twofold achieved:
- Firstly, a measurement grid at very high local spatial resolution in the area of 1 km² will be achieved. This will allow the validation of nowcasts with high spatial resolution as produced from all sky imagers.
- Secondly, a unique DNI database will be created for regions that are curently of interest for CSP plants, as the MENA region and the Arabian Peninsula.
The DNICast consortium follows an integrative approach by bringing together specialists of different working fields. Leading institutions from the communities working on CST, ground based nowcasting and DNI measurements, satellite based nowcasts and NWP cooperate to obtain the best possible results. The direct contact with potential users of the nowcasting tools (e.g.: plant and grid operators) as well as with companies providing measurement and data services for the solar industry is also part of the consortium’s approach. Key research and industrial actors have provided letters of support to the project and will closely cooperate with the DNICast consortium through their involvement in the Project Advisory Board.
Other stakeholders will be involved through a dedicated work package focusing on Knowledge Sharing and User Workshop, as well as through the project communication tools.
For more information please visit the DNICast website: www.dnicast-project.net