AS NZS 61724.1 pdf download

AS NZS 61724.1 pdf download.Photovoltaic system performance
1 Scope
This part of IEC 61 724 outlines equipment, methods, and terminology for performance monitoring and analysis of photovoltaic (PV) systems. It addresses sensors, installation, and accuracy for monitoring equipment in addition to measured parameter data acquisition and quality checks, calculated parameters, and performance metrics. In addition, it serves as a basis for other standards which rely upon the data collected.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-1 31 , IEC TS 61 836, ISO 9488 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1 sample data acquired from a sensor or measuring device 3.2 sampling interval time between samples 3.3 record data recorded and stored in data log, based on acquired samples 3.4 recording interval τ time between records 3.5 report aggregate value based on series of records 3.6 reporting period time between reports 3.7 irradiance G incident flux of radiant power per unit area Note 1 to entry: Expressed in units of W·m −2 . 3.8 in-plane irradiance G i or POA the sum of direct, diffuse, and ground-reflected irradiance incident upon an inclined surface parallel to the plane of the modules in the PV array, also known as plane-of-array (POA) irradiance Note 1 to entry: Expressed in units of W·m −2 . 3.9 global horizontal irradiance GHI direct plus diffuse irradiance incident on a horizontal surface Note 1 to entry: Expressed in units of W·m −2 . 3.1 0 circumsolar immediately surrounding the solar disk 3.1 1 direct normal irradiance DNI irradiance emanating from the solar disk and from the circumsolar region of the sky within a subtended full angle of 5° falling on a plane surface normal to the sun’s rays Note 1 to entry: Some DNI measurement instruments have a field of view with a subtended full angle of up to 6°. Note 2 to entry: Expressed in units of W·m −2 . 3.1 2 circumsolar ratio CSR fraction of measured direct normal irradiance (DNI) emanating from the circumsolar region of the sky, i.e. within the angular acceptance of the DNI sensor but outside the solar disk 3.1 3 diffuse horizontal irradiance G d or DHI global horizontal irradiance excluding the portion emanating from the solar disk and from the circumsolar region of the sky within a subtended full angle of 5° Note 1 to entry: Some diffuse irradiance measurement instruments exclude a circumsolar region within a subtended full angle of up to 6°. Note 2 to entry: Expressed in units of W·m −2 . 3.1 4 in-plane direct beam irradiance G i,b in-plane irradiance emanating from the solar disk and from the circumsolar region of the sky within a subtended full angle of 5°, excluding scattering and reflections.
4 Monitoring system classification
The required accuracy and complexity of the monitoring system depends on the PV system size and user objectives. This document defines three classifications of monitoring systems providing varying levels of accuracy, as listed in Table 1 . The monitoring system classification shall be stated in any conformity declarations to this standard. The monitoring system classification may be referenced either by its letter code (A, B, C) or its name (high accuracy, medium accuracy, basic accuracy) as indicated in Table 1 . In this document, the letter codes are used for convenience. Class A or Class B would be most appropriate for large PV systems, such as utility-scale and large commercial installations, while Class B or Class C would be most appropriate for small systems, such as smaller commercial and residential installations. However, users of the standard may specify any classification appropriate to their application, regardless of PV system size. Throughout this document, some requirements are designated as applying to a particular classification. Where no designation is given, the requirements apply to all classifications.