Screening and Flagging of Solar Irradiation and Ancillary Meteorological Data

Abstract

International audienceSolar irradiance and ancillary meteorological data is frequently measured by automatic weather stations for use within solar resource assessment for solar power plants. High accuracy measurement data are required for comparison and adjustment of satellite data and derivation of the expectable long-term mean value of the solar resource. Thus, utmost diligence must be taken during the measurement process and data evaluation to achieve data quality required for project financing. The combination of automatic data screening and manual flagging by an expert in at least daily frequency in close collaboration with a local station operator is the most recognizedway to detect impacts on measurement data and paves the way for post-correcting data treatment where necessary and reasonable. This is the preferred and recommended procedure, resulting in highestdata quality. The presented work is also understood as a basis for ongoing development and discussion among the corresponding expert group about screening of irradiance and ancillary meteorological data and its corresponding flagging. A common understanding and wide conformity about the screening process and flagging of data would be aspired

Calibration methods for rotating shadowband irradiometers and optimizing the calibration duration

“…For each data channel 10 min mean values are calculated from the recorded 1 min averages: performing the calibration in 10 min time intervals reduces the signal deviation between reference and RSI at intermediate skies which results from the distance between the sensors and moving clouds. Then a screening algorithm performs a quality check of all recorded channels as recently presented in Geuder et al (2015). Among other tests, the quality check tests and marks if measured values are physically possible, if their fluctuation (or lack of it) is realistic and if the data points have been manually flagged/commented during the measuring period.…”

IEA SHC Annual Report 2014

“…As noted in the discussion under B1 above, a paper on Quality Control (QC) and flagging has been published (Geuder et al, 2014). Besides automatic QC procedures, the importance of manual screening of the data by an expert is discussed, including the required fast methods to document additional information during the daily control.…”

“…The draft of this manual has undergone internal review and will be finalized in 2015 as an online publication. A corresponding publication (Geuder et al, 2014) that was presented at the SolarPACES 2013 conference has been reviewed and is now available online. Contributions to the general best practices document for solar resource assessment and forecasting concerning measurement devices, to be published by NREL in 2015, have also been provided.…”

Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications: Second Edition

“…Corresponding tests for radiation data are documented in a number of publications, including Long and Dutton (2002);Maxwell et al (1993); Wilcox and Cormack (2011);Journée and Bertrand (2011);Espinar et al (2011);. Auxiliary data of direct interest can also be tested as explained in Geuder et al (2015). The main parameters discussed there are: logger and battery voltage, logger temperature, speed of ventilation units, and meteorological measurands such as wind speed and pressure.…”