IEC TS 61724-2:2025 applies to grid-connected PV systems comprising at least one inverter.
The test evaluates the PV system only in conditions where output is unconstrained by limitations in AC power output from the inverters. This document defines a test of a PV system's power performance index (PPI). PPI, defined in IEC 61724‑1, is the ratio of a system's measured power output under test conditions to its expected output at those conditions based on the system's design.
The test is intended to be performed over a short period of typically three to five days and is typically used to satisfy a contractual performance guarantee as part of the final completion of a PV power plant. This second edition cancels and replaces the first edition published in 2016. This edition includes the following significant technical changes with respect to the previous edition:
a) Adapting the document for bifacial PV systems, in accordance with the latest edition of IEC 61724‑1 and current industry practices.
b) Adapting the test procedure to account for the limited times of unconstrained system operation which are now common because of high DC-to-AC ratios (clipping) and interconnection limits (curtailment).
c) Adapting the test procedure to achieve a test that can be performed in a short time of three to five days during favourable conditions.
d) Focusing the document more heavily on the use of modern PV system modelling software to obtain the expected performance of the system under test.
e) Simplifying the mathematical procedure for calculating the test results.
f) Clearly identifying test elections (optional choices to be made in conducting the test) and providing a template for documenting these elections.
g) Clarifying the discussion of the test boundary that separates tested variables from untested variables.
h) Expanding and clarifying the discussion of data filtering.