Executive Summary
For many engineers, one question frequently arises when reviewing solar thermal documentation:
Is EN 12975 still relevant, or has it been replaced by ISO 9806?
The short answer is:
Yes, EN 12975 remains relevant—but its role has changed.
Today, ISO 9806 serves as the primary international standard for laboratory testing of solar thermal collectors, including liquid PVT collectors. EN 12975:2022, however, continues to play an important role by defining engineering requirements for product labeling and installation documentation within the European framework.
For professional engineering projects, these two standards should be viewed as complementary rather than competing.
Evidence Classification
| Evidence Type | Source |
|---|
| Measured Data | Intertek Test Report No. 240312065GZU-001 |
| Standard Requirements | ISO 9806:2017, EN 12975:2022 |
| Engineering Judgement | European engineering specification practice |
| Best Practice | Request both the ISO 9806 laboratory report and documentation complying with EN 12975 |
Short Answer
Quick Summary
Yes.
EN 12975 is still relevant because it addresses engineering documentation and product information that are not the primary purpose of ISO 9806.
A complete technical evaluation generally requires:
- ISO 9806 laboratory testing
- EN 12975 documentation requirements
- Independent laboratory verification
- Engineering review
Engineering Note
Many articles incorrectly describe EN 12975 as an “obsolete testing standard.”
That is an oversimplification.
Although ISO 9806 has become the principal laboratory test method, EN 12975 continues to provide requirements for engineering documentation and installer information referenced in current European practice.
Engineering Takeaway
Do not think in terms of:
ISO 9806 or EN 12975.
Think instead:
ISO 9806 plus EN 12975.
What Does EN 12975 Cover?
Quick Summary
Unlike ISO 9806, which focuses on laboratory testing, EN 12975 emphasizes the information needed to install, identify, and safely operate a collector.
Product Labelling
According to the Intertek evaluation, EN 12975 requires the collector label to include information such as:
- manufacturer name
- model designation
- serial number
- year of manufacture
- peak power
- maximum operating pressure
- collector weight
- heat transfer fluid volume
These items help engineers, installers, and maintenance personnel identify the product throughout its service life.
Installation Documentation
EN 12975 also requires that collectors be supplied with installation instructions or technical documentation covering items such as:
- collector dimensions
- transport and handling
- approved heat-transfer media
- hydraulic connections
- mounting procedures
- stagnation temperature
- operating temperature limits
- allowable mechanical loads
- maintenance requirements
- installation angle
- climate class
- impact resistance information
The Intertek report concludes that the submitted labeling and installer documentation were checked against EN 12975:2022 Clauses 6.2 and 6.3.
Evidence Callout Box
Measured Evidence
The independent Intertek assessment verifies that:
“The labelling and instruction manual was checked according to EN 12975:2022 clause 6.2 & 6.3.”
This provides objective evidence that the product documentation was reviewed as part of the conformity assessment process.
ISO 9806 vs EN 12975
Quick Summary
The two standards perform different engineering functions.
Neither replaces the other.
Engineering Comparison Table
| ISO 9806 | EN 12975 |
|---|
| Laboratory testing methods | Product documentation requirements |
| Measures thermal performance | Defines labeling requirements |
| Measures hydraulic performance | Defines installer information |
| Measures durability | Defines technical documentation |
| Produces engineering data | Supports installation and maintenance |
Engineering Note
An engineer designing a system primarily relies on ISO 9806 performance data.
An installer commissioning the collector relies heavily on EN 12975 documentation.
Both contribute to a successful project, but at different stages of the product lifecycle.
Engineering Takeaway
ISO 9806 tells engineers how the collector performs.
EN 12975 tells installers and owners how the collector should be identified, installed, and maintained.
How the Solis PVT Test Report Demonstrates Compliance
Quick Summary
The Intertek report illustrates how laboratory testing and documentation review are combined within a single engineering evaluation.
Evidence Callout Box
Measured Evidence
The report includes:
- ISO 9806 thermal performance evaluation
- pressure-drop measurements
- terminology definitions
- engineering drawings
- laboratory photographs
- calibrated test equipment
- EN 12975 labeling review
- EN 12975 installer manual review
Together, these provide a comprehensive technical record supporting engineering assessment.
Engineering Comparison Table
| Engineering Requirement | Evidence in the Intertek Report |
|---|
| Thermal performance | ✓ ISO 9806 performance testing |
| Hydraulic performance | ✓ Pressure-drop measurements |
| Product labeling | ✓ EN 12975 review |
| Installation manual | ✓ EN 12975 review |
| Engineering drawings | ✓ Included |
| Laboratory photographs | ✓ Included |
| Test equipment traceability | ✓ Calibration records included |
Decision Tree
Engineering Takeaway
A high-quality technical package should include both independently measured performance data and complete engineering documentation.
This combination reduces uncertainty during design, procurement, installation, and long-term maintenance.
