The purpose of this standard is to provide procedures and guidelines for acceptance testing of complete parabolic-trough collector (PTC) solar thermal power plants on the uncertainty level given in the ISO/IEC Guide 98-3, Guide to the Expression of Uncertainty in Measurement. It is applicable to acceptance testing in such power plants, as well as in any other scenario in which their features must be known. This standard establishes the measurement instrumentation and techniques for determining the following parameters required for acceptance of complete solar thermal power plant features: " Available solar radiation " Plant electricity consumptions " Net electricity generation " Non-solar energy " Net plant performance Other parameters that characterize the solar thermal power plant system features are not dealt with in this standard, but are the subject of other complementary standards. This standard is applicable to solar thermal power plants of any size that employ parabolic-trough collector concentrating systems, where the Sun is the main source of energy, and all elements and systems are operative. Such power plants may optionally have non-solar energy sources, such as natural gas or other renewable energies, and a thermal storage system.