ASTM E2939-13(2023) PDF

Overview

ASTM E2939-13(2023), "Standard Practice for Determining Reporting Conditions and Expected Capacity for Photovoltaic Non-Concentrator Systems," provides standardized procedures for calculating and reporting the expected capacity of photovoltaic (PV) systems operating under natural sunlight in specific geographical locations and periods. This standard is essential for organizations and professionals involved in the performance assessment, commissioning, and acceptance testing of PV installations. It supports consistent comparisons between predicted and measured system capacities, ensuring reliable performance evaluation and system verification.

Key Topics

• Expected Capacity Determination The standard outlines how to derive the expected power rating of a specific PV system by applying meteorological data (such as plane-of-array irradiance, ambient temperature, and wind speed) and system-specific performance models. This data helps predict operational output for given periods.

• Selection of Reporting Conditions Reporting conditions, including solar irradiance, temperature, and wind speed, are critical for consistent system capacity measurement. The standard provides guidance on selecting these conditions based on historical or measured meteorological data, aligned with the duration of the performance simulation period.

• Performance Simulation and Data Alignment It is essential for the simulation period and data collection period (referenced in ASTM E2848) to match. Misalignment can render capacity comparisons invalid.

• Comparison for Acceptance Testing By comparing the expected capacity (predictive) against the measured capacity (actual, as per ASTM E2848), stakeholders can determine if a new or existing PV plant meets acceptance criteria.

• Documentation and Reporting The standard also specifies minimal reporting requirements, including descriptions of the modeling approach, resource data sources, meteorological parameters used, and the statistical quality of regressions applied.

Applications

This standard has significant practical value for:

• PV System Commissioning & Acceptance Ensures that newly installed systems are tested against robust, location-specific capacity expectations, supporting fair acceptance testing and contract fulfillment.

• Performance Benchmarking Enables consistent benchmarking and comparison between expected and measured outputs, contributing to operational transparency and system optimization.

• Quality Assurance Facilitates quality control in ongoing operations by verifying that existing PV systems perform within expectations tied to historical meteorological conditions.

• Reporting Transparency Provides a clear methodology for documenting and communicating expected versus actual performance to stakeholders, investors, or regulatory bodies.

• Design and Planning Useful in project planning for predicting performance, aiding in feasibility studies and investment decisions using robust, data-driven metrics.

Related Standards

• ASTM E2848 - Test Method for Reporting Photovoltaic Non-Concentrator System Performance. This is a companion document detailing the measurement of PV system output, which should be used in conjunction with ASTM E2939.
• ASTM E772 - Terminology of Solar Energy Conversion. Reference for definitions relevant to PV systems and meteorological factors.
• IEEE 1547 - Standard for Interconnecting Distributed Resources with Electric Power Systems. Provides requirements for the safe interconnection of PV systems.
• International Standards Principles - Developed following internationally recognized guidelines per the World Trade Organization TBT Committee.

Keywords: photovoltaic capacity reporting, ASTM E2939, PV system expected capacity, acceptance testing, performance modeling, reporting conditions, non-concentrator photovoltaic systems, meteorological data analysis, ASTM PV standards.