IEC 61724-1: Sensor Maintenance Guide

While using sensors for monitoring PV plants is recommended by the IEC 61724-1 Monitoring Standard, which outlines the required quantities and specifications, it also provides guidelines for proper maintenance to ensure accurate sensor usage and reliable performance monitoring of PV plant.

IEC 61724-1 Standard for performance monitoring of PV Plants

IEC 61724-1 is an essential standard that provides a framework for the performance evaluation of photovoltaic (PV) systems, and its implications extend into sensor maintenance for optimal functionality. This standard aims to ensure that the sensors used in PV systems are accurately measuring and reporting data, which is crucial for system monitoring and efficiency.

What Sensors are Required According to IEC 61724-1 Standard?

For a detailed Sensor Requirements for PV Plant Performance Monitoring as per IEC 61724-1, refer to our previously written article: “IEC 61724-1:2021 Sensor Requirements for PV Plant Performance Monitoring”.

The most important sensors that the IEC Standard refers to are: The Irradiance Sensors including the pyranometers, the Module Temperature Sensors, The Ambient Temperature Sensors, the Wind Speed Sensors, and the Wind Direction Sensors. So, what are the Maintenance guidelines for these sensors?

Sensor Maintenance Guidelines as per IEC 61724-1

The IEC standard outlines the maintenance requirements for each sensor in a Meteorological Weather Station used for monitoring the performance of the PV Plant.

Maintenance Requirements of Irradiance Sensors

The IEC 61724-1 Standard emphasizes the importance of routine inspection of sensors which includes checking for soiling, misalignment, and other fault conditions. For Class A monitoring systems, the front-side sensors shall be inspected weekly as per the IEC Standard.

The detailed Maintenance instructions need to be defined by the manufacturer. Refer to the user manual of Irradiance Sensor & Thermopile Pyranometers for checking the guidelines defined by SEVEN Sensor.

Recalibration of sensors is part of maintenance as well, and it must be conducted, as per IEC Standard, in a manner that minimizes downtime and sensor outages in order to prevent interruption of monitoring. The effective methods mentioned in this standard are:

• Exchanging installed sensors with new or recalibrated units
• Performing on-site recalibration of sensors where possible
• Providing redundant sensors and alternating laboratory recalibration schedules.

The recalibration frequency recommended in IEC61724-1:2021 is:

• For Class A systems, sensors shall be recalibrated once every 2 years, or more frequently per manufacturer recommendations.
• For Class B systems, recalibrate sensors according to manufacturer recommendations.

While the guidelines are more general in the 2021 version of IEC61724-1, it was detailed in the previous version of 2017, including a specific table for Irradiance Sensor Maintenance Requirements.

In addition to the above table, the older version of IEC 61724-1 some important considerations for Irradiance Sensor maintenance such as minimizing the offline time of the sensors sent for laboratory recalibration by using redundant sensors or backup sensors to prevent interruption of monitoring, considering that cleaning the irradiance sensors without cleaning the modules can result in a lowering of the measured PV system performance ratio which is already considered in some contracts that requires the sensors be maintained in the same state of cleanliness as the modules…

Maintenance Requirements of Temperature Sensors

As the Temperature Sensors do not require a specific maintenance procedure, the IEC Standard defers maintenance and recalibration rules to the manufacturer. Refer to user manuals of Module Temperature Sensors & Ambient Temperature Sensors of SEVEN Sensor to follow the maintenance instructions.

In case you would like to have an idea about the Maintenance requirements of Temperature sensors in the older version, you can check the tables below which specify the recommended intervals to recalibrate or replace the Temperature sensors.

Maintenance Requirements of Wind Sensors

Similar to temperature sensors, As the Wind Speed & Direction Sensors don’t have specific Maintenance procedure outlined in the IEC Standard. Maintenance instructions are determined by the manufacturer. Refer to user manual of Wind Speed Sensors & Wind Direction Sensors of SEVEN Sensor to follow the detailed maintenance guide.

The older version of IEC 61724-1 also mentioned that the recalibration rules of the wind sensors must be defined by the manufacturer.