Measuring Global, Direct, and Diffuse Irradiance Using a Reference Cell Array

We report on a field trial of a novel method for measuring global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI) using an array of reference cells with no moving parts. The technique, similar to previous work on the multi-pyranometer array concept, uses multiple reference cells facing different directions together with an analysis model that fits the data from the sensors to determine GHI, DNI, and DHI. Preliminary results show good agreement between results obtained from the reference cell array and those from reference instruments which include a pyranometer, pyrheliometer, and shaded pyranometer. The results show the potential utility of using a reference cell array to add capability to resource assessment campaigns and solar power plant meteorological stations at a low cost.