A Study on Uncertainty to Direct Normal Irradiance of Typical Meteorological Year Data

Abstract

Typical meteorological year (TMY) data consist of hourly values of solar radiation and meteorological elements over a 1 year period. This reflects the long term meteorological characteristics because it is derived from a long term meteorological database. The data were produced by applying the Sandia method and weighting factor of National Renewable Energy Laboratory (NREL) by new and renewable energy resource center in Korea Institute of Energy Research (KIER), and it was registered as the qualified reference standards in 2015. The reliability of the solar radiation is important as weighting factor of the solar radiation in the TMY data is 50%. The hourly global horizontal irradiance (GHI) among the solar radiation was provided by Korea Meteorological Administration (KMA), and direct normal irradiance (DNI) was predicted by applying Reindl-2 model. The uncertainty of the DNI is higher than the experimental value as it is a predicted value. The GHI, extra-terrestrial radiation, and zenith angle were surmised as the principal factors of uncertainty. The uncertainty on the zenith angle was highest among the 3 factors. The procedure of the uncertainty evaluation obeyed the guide to the expression of uncertainty in the measurement (GUM). The uncertainty on the DNI of TMY data in Daejeon was calculated and analyzed in this paper.