Overview
EN ISO 22975-3:2014 (ISO 22975-3:2014) - Solar energy - Collector components and materials - Part 3: Absorber surface durability - specifies a qualification procedure to assess the long-term behaviour and service life of selective solar absorbers used in vented flat-plate solar collectors. The standard focuses on changes in optical performance (notably solar absorptance and thermal emittance) and defines a failure criterion based on loss of these properties. It was adopted by CEN as EN ISO 22975-3:2014 and is intended for systems operating under conditions typical of domestic hot water systems and combisystems.
Key topics and requirements
- Scope and intent: Determine durability and estimate service life of absorber surfaces in realistic operating conditions.
- Failure criterion: Qualification based on measurable changes in optical properties - solar absorptance and thermal emittance - that affect collector performance.
- Durability test methods:
- Thermal stability testing to evaluate resistance to high temperatures.
- Condensed-water and humidity testing to assess resistance to condensation and high humidity.
- Corrosion testing in high-humidity air containing sulfur dioxide (SO2) to simulate polluted atmospheres.
- Measurement and sampling: Procedures for sampling, conditioning, and measuring optical properties are specified (see normative annexes).
- Qualification procedure: Tests are independent and can be used individually or combined; results are compared against shortest acceptable failure times based on design service life.
- Supporting material: Normative annexes provide test procedures for absorptance/emittance measurement and guidance on apparatus design.
Applications
- Product development and validation of new absorber coatings and surface treatments.
- Factory and third‑party qualification testing to support product claims for absorber surface durability.
- Comparative assessment of selective solar absorbers for specification in solar thermal collectors, solar domestic hot water systems, and combisystems.
- Informing life‑cycle expectations for designers, system integrators and asset owners seeking reliable solar collector performance.
Who should use this standard
- Solar collector and absorber manufacturers
- Test laboratories and certification bodies
- R&D teams developing selective absorber coatings
- System designers and specifiers in solar thermal and DHW markets
- Regulators and procurement organizations requiring evidence-based durability data
Related standards
- EN ISO 22975 series (other parts under preparation cover evacuated tubes and heat-pipe durability)
- ISO/TC 180 outputs for solar energy standards
Using EN ISO 22975-3:2014 helps stakeholders ensure absorber surfaces meet quantifiable durability requirements, reducing performance risk in long‑term solar thermal applications.
