Quality control of solar radiation and sunshine measurements – lessons learnt from processing worldwide databases

As a result of an exponential increase in the application of solar water heating, and more recently solar PV systems, measurement of the available solar radiation resource is gaining rapid momentum. New databases are being created and many of these are being made available via Internet. Up-to-date series of these data are also being sought by architects and building services professionals for better design of buildings. However, in many instances due care is not being exercised with respect to quality control of the measured dataset. Two major activities that utilized large databases of solar radiation, sunshine and cloud-cover have recently been concluded within Europe – the European Solar Radiation Atlas and the Chartered Institution of Building Services Engineers (London) Guide on ‘Weather and Solar Data’. This article provides an account of the research undertaken towards development of robust techniques for identi” cation of erroneous data and their substitution using validated methods for generating radiation and sunshine data. Such substitutions are required to complete the time-series of data when the latter are either con” rmed as being of questionable quality or are found to be missing due to station downtimes.