Iec 61724-1 Pdf

[Katrine Freggiaro]

The2021 version of the standard recognises that the solar irradiance measurement is one of the weakest links in the measurement chain. For Class A systems, it specifies the Class of pyranometer that may be used, including requirements for dew and frost mitigation, azimuth and tilt angle accuracy. It also defines cleaning and calibration intervals for pyranometers. Furthermore, the standard defines requirements for measurement of module- and air temperature, wind speed and direction, soiling ratio, and (AC and DC) current and voltage.

IEC 61724-1:2021 requires pyranometer dew and frost mitigation for class A monitoring systems. Why? Pyranometer domes are made of glass. When facing the sky on a clear night, glass temperature tends to go below dewpoint, so that water condenses on the dome. Heating and ventilation of solar radiation sensors keep the glass temperature above dewpoint and free from dew and frost deposition. This significantly increases the reliability of the measured data. There is an exception for locations where dew and frost is expected for less than 2 % of annual GHI hours.

The following tables offer an overview of the main elements of the IEC 61724-1 monitoring classification system, its requirements for solar radiation measurement and which pyranometers comply in which accuracy class.

You may have heard of the IEC 61724-1 standard to promote international uniformity in PV (photovoltaic) system performance monitoring. But why was it created, and what does it mean for you? In this interview with PES (Power & Energy Solutions), Matt Perry, Technical Product Manager for the Renewable Energy Group, details what you should know about the IEC 61724-1 Class A standard.

It may seem trivial to quantify with high accuracy and low uncertainty the amount of solar radiation that reaches the PV module surface given recent advancements in satellite and radiometric technologies; however, one must consider the seemingly random nature of solar radiation.

The behavior of solar modules is, of course, directly related to the amount of solar radiation that reaches the solar module, but it is also dependent on other meteorological parameters such as ambient temperature and wind. The power performance of PV modules is rated under standard test conditions, typically defined as 1000 W/m2, 25 Deg C cell temperature, and AM 1.5 spectrum. Short circuit current, open circuit voltage, cell temperature, and maximum power performance coefficients are all typically determined in controlled laboratory settings. However, modules rarely, if ever, operate under STC conditions. The only way to predict or verify performance of a PV system is to correct power-producing expectations to the weather.

Therefore, for analysts or grid/plant operators to produce high-confidence performance analytic or ground-truthing of satellite data, they rely on on-site measured data for input into their respective PV modelling exercise.

The IEC 61724-1 standard is the second revision of a guideline established to promote international uniformity in PV system performance monitoring. The completely revised and updated version introduces a monitoring system classification that specifies measurement parameters and sensor requirements, according to PV project size or monitoring objectives. The revised standard may be the first to present standardized methodologies for performing soiling measurements and calculating soiling loss indices.

In the previous answer, I mentioned several areas that if not properly mitigated will lead to lower-quality data sets, but perhaps one common mistake seen in monitoring would be lack of redundancy, particularly in plane of array irradiance on single-axis tracker sites and back of module temperature measurements.

This is one benefit of IEC 61724-1. In attempts to help eliminate this mistake, it provides guidance on the relation between system size and the minimum number of pyranometers and back of module sensors necessary to achieve Class A accuracies.

To name a few, in the near future, I expect to see new soiling measurement and analysis techniques, more distributed generation or microgrid sites using an all-sky camera combined with system management, and more spectral measurements as PV module developers develop ways to utilize this data.

But, I still see people in both science and industry, dedicating their work to making a difference in the world, and this is what I enjoy most, this comradery I enjoy with my community, making better sensors and dataloggers, working toward higher-value data, streamlining cost and implementation.

It 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. IEC 61724-1 was launched in March 2017 and has some comparisons with the new ISO 9060:2018 standard that is planned to be launched this year. Both standards define Class A, B and C but with a different meaning

There are two reasons for the extra steps prescribed by IEC 61724-1 to comply with an optimal Class A: reliability of data and availability of data. To achieve this, dew, frost, soiling and instrument deposition as such should be prevented, and customers have to do good product maintenance. You should at least do all of the below:

If you are aiming for the IEC 61724-1 Class A we have the perfect product bundle for you: the new CVF4 ventilation unit combined with the SMP10 smart pyranometer. With this combination your solar monitoring will be 100 % IEC compliant.

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We all witness the constant increase of Solar PV projects and there is an increasing global requirement of low cost and effective weather monitoring station which comply with international standards. With this growing increase in PC investment and development, the industry is becoming more aware of the importance of performance monitoring. Optimal energy output of a PV plant is essential to ensure an adequate return on investment and this can only be assured with continuous performance monitoring of the yield and efficiency of PV plants. In addition, scheduling ongoing maintenance can be more appropriately planned with effective monitoring.

The performance monitoring concerns the area with the greatest impact i.e. Solar IRradiance. There are other parameters suc as ambient temperature, wind speed & direction, Rainfall could also contribute toward performance of PV plant. All these meteorological parameters shall be continuously monitored to find out the effect of shadowing, soiling and panel temperature on the performance.

To ensure the industry is able to optimize future PV performance, the International Electrotechnical Commission (IEC) released a new standard in 2017: Photovoltic system performance-Part 1: Monitoring (61724-1). This standard details the minimum requirements to achieve a specific classification of the accuracy of the PV plant monitoring.

We as an experts in Meteorological monitoring make measurement affordable. We have launched our brand new developed weather monitoring system PVMX-100 specially for Rooftop Solar PV plants with standard measurement parameters--

PVMX-100 has an innovative and compact design for PV monitoring. This low cost system is very simple to install and to connect to any inverter or SCADA system. It has TCP/IP MODBUS data output for connection with your SCADA network and also has optional datalogging feature in SD Card. We also provide GPRS based data transfer to any cloud server.

The system includes EKO ML-01 Si-pyranometer which is supplied with calibration compliant to the international standards defined by ISO/IEC17025/9847. Panel temperature, Ambient Temperature and other components are also supplied with NABL Accredited certificates.

PVMS-100 is fully compliant with IEC 61724-1 standard and very cost effective solution for developers, EPC contractors, system integrators. We also have additional wind speed & direction, Rainfall data monitoring in PVMX-200 series systems.

The purpose of outdoor PV testing is to compare the available resource to system output and thus to determine efficiency. The efficiency estimate serves as an indication of overall performance and stability. It also serves as a reference for remote diagnostics and need for servicing.

The irradiance measurement for outdoor PV performance monitoring is usually carried out with pyranometers. Some standards suggest using PV reference cells. Reference cells are (with some minor exceptions) unsuitable for proof in bankability and in proof of PV system efficiency. Pyranometers are and will remain the standard for outdoor solar energy monitoring.

The International Energy Agency (IEA) and ASTM standards for PV monitoring recommend pyranometers for outdoor PV monitoring. PV reference cells do not meet IEC 61724-1 class A requirements for irradiance measurement uncertainty: their directional response makes them systematically overestimate daily radiant exposure in J/m2 (or Whr/m2 ) by more than 2 %, larger on hourly basis.

Our pyranometer selection guide offers practical guidelines for choosing a pyranometer. The application of pyranometers in PV system performance monitoring according to IEC 61724-1 is highlighted as an example. Sensors specific for diffuse radiation and meteorological networks are also addressed in this selection guide.

A pyrheliometer is used to measure Direct Normal Irradiance (DNI). DNI is defined as the solar radiant flux collected by a plane unit surface normal to the axis pointing towards the centre of the sun, within an optical angular aperture. DNI is composed of the solar irradiance within the extent of the solar disk (half-angle 0.266 1.7 %) plus some circumsolar radiation.

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