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

We report on an updated field trial of a novel method for measuring global horizontal irradiance (GHI), direct normal irradiance (DNI), diffuse horizontal irradiance (DHI), and reflected horizontal irradiance (RHI) using an array of reference cells with no moving parts. The technique, similar to previously explored methods using multi-pyranometer array concepts, uses multiple reference cells facing different directions together with an analysis model that fits the data from the sensors to determine GHI, DNI, DHI, and RHI. In previous work we reported on a first test of this approach at a single site. In this work we report further progress with this method, including an updated configuration of the reference cell array that offers improved sensitivity, an updated analysis that does not require site-specific training, and early field test results from prototypes installed at two different locations with different latitude.