Overview
ISO 22975-1:2016 - "Solar energy - Collector components and materials - Part 1: Evacuated tubes - Durability and performance" is an international standard that specifies definitions and standardized test methods for materials, durability and performance of evacuated tubes used in solar thermal collectors. It is applicable to all types of evacuated tubes (including double-glass and glass–metal sealed designs) and provides harmonized procedures for quality assessment and performance characterization.
Key topics and technical requirements
ISO 22975-1 defines test categories and detailed methods covering both material inspection and whole-tube evaluation. Major technical topics include:
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Material inspection
- Visual and mechanical checks for envelope defects such as stones, knots and scratches
- Measurement methods for solar transmittance, solar absorptance and hemispherical emittance of absorber/envelope materials
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Durability testing
- Vacuum performance tests to assess maintenance of required vacuum levels over time
- Thermal shock resistance to verify integrity under rapid temperature changes
- External impact resistance to simulate mechanical impacts
- Internal pressure resistance to verify structural robustness under pressure variations
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Performance testing
- Determination of the exposure parameter used for performance evaluation
- Tests to quantify solar irradiation required for temperature increase in double-glass evacuated tubes
- Methods to determine the average heat loss coefficient for double-glass tubes
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Test documentation
- Normative test report format and informative annexes (configuration schemes and surface-area determination) are specified to ensure consistent reporting.
For each test the standard specifies scope, apparatus, procedure and required results/reporting.
Practical applications and users
ISO 22975-1 is intended for stakeholders in the solar thermal sector who need reliable, reproducible assessments of evacuated tubes, including:
- Manufacturers - product development, quality control and compliance
- Test laboratories and certification bodies - standardized testing, certification and accreditation
- System designers and engineers - component selection and system modelling using validated heat loss and performance data
- Procurement specialists and project owners - technical specification and acceptance testing of evacuated-tube collectors
- R&D teams - benchmarking materials and absorber surface treatments
Using ISO 22975-1 helps reduce technical barriers to trade and improves comparability of evacuated tube performance claims.
Related standards
ISO 22975 is a multipart series on collector components and materials. Related parts include:
- ISO 22975-2 - Heat-pipes for solar thermal application - Durability and performance
- ISO 22975-3 - Absorber surface durability
(Additional parts such as insulation material durability are under development.)
Keywords: ISO 22975-1, evacuated tubes, solar energy, solar thermal collectors, durability testing, performance testing, vacuum performance, thermal shock, heat loss coefficient, solar transmittance.
Open preview (PDF)Solar energy — Collector components and materials — Part 1: Evacuated tubes — Durability and performance