ISO 24194:2026

This document specifies three procedures to check the performance of solar thermal collector fields. This document is applicable to most collector types addressed by ISO 9806. This includes glazed liquid heating flat plate collectors, evacuated tube collectors, and tracking, concentrating collectors. However, certain limitations apply in comparison to ISO 9806, specifically concerning wind and infrared sensitive collectors (WISC), hybrid collectors, and air collectors:

• WISC collectors are included only when both wind speed data measured on the collector plane and longwave radiation data are available.

NOTE            Such data is rarely available in practical applications.

• Hybrid collectors (“collectors co-generating thermal and electrical power” in ISO 9806, commonly PVT) are excluded. The reason is that their thermal performance in real-world operation depends on the operation of the electrical part: If the electrical part is switched off, limited, or curtailed for any reason, while the thermal part remains active, this would lead to an overestimation of the thermal power output, based on performance parameters determined under MPP conditions (maximum electrical power generation), as specified in ISO 9806.
• Solar air heating collectors (SAHC) are excluded due to the complexity of accurately assessing their performance: Testing and evaluating SAHC performance is complex, because it requires accounting for the enthalpy difference in the primary loop. Additionally, their thermal efficiency is highly dependent on mass flow rate, and their performance is tested at three different air mass flow rates, resulting in three separate parameter sets. For the ISO 24194 Power Check, this makes it challenging to select the appropriate parameters for estimating thermal power output.

This document specifies procedures for performance check of the thermal power output of the collector field as well as on the daily yield and annual yield of the collector field. For the three procedures, this document specifies how to compare a measured output with the calculated one.

The document is applicable to collector fields of all sizes.