This International standard specifies the requirements and the test methods for the characterization of a large-size parabolic-trough collector. This standard 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 standard applies to parabolic-trough collectors equipped with the manufacturer-supplied sun tracking mechanism. The testing method in this standard does not apply to any collector under operating conditions where phase-change of the fluid occurs. This standard applies to the whole collector. The different component/elements (such as the receiver, reflector, tracker, structure) should be tested separately by current testing methods when available.