Deriving a Latitude-Optimized Pyranometer Calibration Factor

Work in recent years has produced improvements in determining the solar resource by better characterizing the responsivity of pyranometers. The calibration process can characterize a common responsivity dependency on the solar zenith angle, which can then be used to compensate for sensor variations during instrument deployment. However, daily compensation throughout the range of zenith angles might not be necessary for applications requiring only annual irradiance. This paper describes a method of identifying a measurement bias due to latitude of deployment and optimizing an instrument's clear-sky responsivity for annual solar radiation measurements based on the relationship between solar zenith angles and the latitude.