IEC 62862-3-2:2018 specifies the requirements and the test methods for the characterization of a large-size parabolic-trough collector. This document covers the determination of optical and thermal performance of parabolic-trough collectors, and the tracking accuracy of the collector one-axis tracking system. This test method is for outdoor testing only. This document applies to parabolic-trough collectors equipped with the manufacturer-supplied sun tracking mechanism.