Performance comparison of fixed, 1-, and 2-axis tracking systems for small photovoltaic systems with measured direct beam fraction

Abstract

The performance, and resulting economic, advantage offered by tracking systems for photovoltaic systems has not been third-party verified. Consumers are forced to rely on tracking manufacturer's claims which are up to 30% additional energy. We report on a side-by-side comparison of two nominally identical PV/microinverter systems; one at a fixed latitude tilt, and one on a 1-axis Zomeworks passive tracker. Preliminary results show the enhancement in power from 1- axis tracking over a fixed tilt varies from 5% - 20% with a strong direct beam fraction dependence. This result suggests a climatic dependence to tracking economics, which will be explored. A comprehensive analysis of system performance under a range of environmental conditions will be presented. This study was undertaken during fall 2011 at the Appalachian State University Solar Research Laboratory in Boone, NC (36° latitude), which houses a Class 1 pyranometer and pyrheliometer. PV power will be reported under well quantified irradiance conditions, including direct beam fraction.