Quality Assurance Procedure for Solar Radiation at Minute Resolution
Abstract
This article proposes a quality assurance (QA) procedure for evaluating measurements of global horizontal, diffuse horizontal, and direct normal irradiances. The QA is based on BSRN-recommend quality tests and other tests, divided into physical, comparatives, and refining tests. The comparatives tests evaluate the relationships among the three main radiation components, comparing the measured series with a validated clear sky model to define what of the three components of radiation are with problems. Four stations situated in Pernambuco, Brazil and Gobabeb, Namib have been qualified using the proposed QA. The results show that the direct normal irradiance series can present a considerable percentual of outliers due to soiling in pyrheliometers. For solar stations without periodic maintenance, the series of direct normal radiation measured by pyrheliometers can have more soiling problems than the others components of radiation, measured by pyranometers.