What are Pyranometer Classes? What do Class A, B, and C mean according to ISO 9060 and IEC 61724-1

Precision Solar Irradiance Measurement for PV Excellence

Pyranometers are essential sensors for measuring global solar irradiance (GHI), which includes both direct and diffuse radiation. These devices, particularly thermopile models like those manufactured by SEVEN Sensor Solution, are critical for predicting energy production, monitoring system efficiency, and calculating return on investment for photovoltaic power plants. The selection of a pyranometer is governed by international standards that categorize devices based on their accuracy, response time, and spectral sensitivity.

The ISO 9060:2018 standard establishes a clear hierarchy for pyranometer performance. Class A, formerly known as "Secondary Standard," represents the highest precision category and is required for research and high-level performance monitoring. Class B, previously "First Class," offers medium accuracy suitable for standard commercial solar fields. Class C, or "Basic Class," is designed for general observations and lower-precision applications where budget is a primary constraint. SEVEN provides specific models, such as the 3S-TP-MB-A, for each of these categories to ensure compliance across various project scales.

The IEC 61724-1 standard further clarifies how these sensors should be applied within solar monitoring ecosystems. It dictates which pyranometer class must be used based on the monitoring level of the plant. For instance, a Class A monitoring system—the highest tier for utility-scale plants—mandates the use of a Class A pyranometer to ensure data reliability. By adhering to these requirements, engineers can accurately identify system losses and optimize the performance of PV trackers and inverters.

Choosing the correct pyranometer involves balancing measurement accuracy with environmental conditions and project budgets. While Class C sensors may suffice for educational purposes, critical tasks like fault detection and financial reporting require the stability and low temperature response of Class A devices. As the first manufacturer of thermopile pyranometers in Turkey, SEVEN Sensor Solution ensures that its 3S-TP-MB series provides traceable, high-accuracy data that meets the rigorous demands of modern solar energy infrastructure.