PD IEC TS 61724-2-2025 PDF

Full title and description

STB PD IEC TS 61724-2:2025 — Photovoltaic system performance — Part 2: Power performance index and capacity evaluation method. Technical Specification describing a short-term test method to evaluate a grid‑connected PV system’s Power Performance Index (PPI) and capacity under unconstrained operating conditions, typically used for commissioning and contractual performance verification.

Abstract

IEC TS 61724-2:2025 specifies a standardised, short-duration (typically 3–5 day) test procedure to compare a PV system’s measured power output with its expected output under the same environmental and operational conditions. The document defines the Power Performance Index (PPI) test boundary, measurement and modelling requirements, data filtering and analysis procedures, and documentation templates. This second edition updates the method to address bifacial systems, high DC/AC ratios (clipping), curtailment, and modern PV modelling tools, and simplifies the mathematical and reporting workflow compared with the 2016 edition.

General information

• Status: Published / Current
• Publication date: 22 September 2025
• Publisher: International Electrotechnical Commission (IEC), TC 82
• ICS / categories: 27.160 (Solar energy engineering)
• Edition / version: Edition 2.0 (2025)
• Number of pages: 26

Scope

This Technical Specification applies to grid‑connected photovoltaic systems comprising at least one inverter. It defines a test of the system Power Performance Index (PPI) conducted only in periods when the AC output is not constrained by inverter limits, clipping or external curtailment. The procedure is intended for short-term verification of system power and capacity — typically to satisfy commissioning or contractual performance guarantees — and relies on measured data combined with a modelled expected output for the same conditions.

Key topics and requirements

• Definition and application of the Power Performance Index (PPI) as the primary metric for short-term power tests.
• Requirements for measurement equipment, data collection cadence and data quality checks during test periods.
• Procedures for preparing and using PV system models to generate expected output (including recommended modelling inputs and uncertainty considerations).
• Adaptations for bifacial modules and treatment of rear-side irradiance and albedo effects.
• Handling of clipping, high DC/AC ratios and curtailment — criteria for identifying unconstrained test windows.
• Data filtering, exclusion rules, and a simplified mathematical procedure for calculating test results and uncertainties.
• Clear identification of test elections (optional choices) and a template for documenting those elections and results.
• Guidance on the test boundary (which variables are controlled/tested versus excluded) and reporting requirements for contractual use.

Typical use and users

Used during commissioning, handover and contractual acceptance of utility‑scale and commercial PV plants. Primary users include EPCs, plant owners and operators, O&M providers, test laboratories, performance engineers, independent technical advisers, engineers verifying performance guarantees, financing and insurance parties, and standards committees implementing performance testing protocols.

Related standards

Part of the IEC 61724 series on PV system performance. Key related documents include: IEC 61724‑1 (Photovoltaic system performance — Part 1: Monitoring) for monitoring definitions and sensor requirements; IEC TS 61724‑3 (Part 3: Energy evaluation method) for longer-term energy evaluation; and other PV standards and guidance commonly used in commissioning and testing (for example, module qualification and safety standards used in conjunction with performance testing). The TS is produced under TC 82 (Solar photovoltaic energy systems).

Keywords

photovoltaic, PV, power performance index, PPI, capacity evaluation, commissioning test, short‑term performance test, bifacial PV, clipping, curtailment, PV modelling, data filtering, performance guarantee, IEC 61724

FAQ

Q: What is this standard?

A: IEC TS 61724-2:2025 is a Technical Specification that defines a standard short‑term test to evaluate a grid‑connected PV system’s Power Performance Index (PPI) and capacity against expected performance.

Q: What does it cover?

A: It covers test planning, measurement and modelling practices, data filtering and analysis, handling of bifacial systems, treatment of clipping/curtailment, uncertainty considerations, and reporting templates for a 3–5 day performance test under unconstrained operating conditions.

Q: Who typically uses it?

A: EPC contractors, plant owners/operators, O&M providers, performance test labs, independent technical consultants, financiers and insurers, and regulatory or standards bodies involved in PV commissioning and performance verification.

Q: Is it current or superseded?

A: The 2025 edition (Edition 2.0) is current and replaces the 2016 edition. It includes updates for bifacial systems, modern modelling practices, and procedures to account for clipping and curtailment.

Q: Is it part of a series?

A: Yes — it is Part 2 of the IEC 61724 series on photovoltaic system performance. Part 1 addresses monitoring; Part 3 addresses energy evaluation methods. The series is maintained by IEC TC 82.

Q: What are the key keywords?

A: Photovoltaic, PPI (Power Performance Index), capacity evaluation, commissioning, bifacial, clipping, curtailment, PV modelling, data filtering, IEC 61724.