Solar Keymark is the leading European certification for solar thermal products, issued under the CEN Keymark scheme. It proves a collector or system was tested to EN 12975/EN ISO 9806 by an accredited laboratory and that production is inspected annually. Most European subsidy schemes — including Germany's BEG — accept only Solar Keymark-certified collectors.
What does Solar Keymark certify?
The mark covers the product family: flat-plate and evacuated tube collectors, PVT hybrid collectors, factory-made systems (EN 12976) and custom-built system components. Certification requires:
- Type testing at an accredited laboratory to EN ISO 9806 — thermal performance, durability (stagnation, exposure, thermal shock), mechanical load and safety.
- Factory production control: the manufacturer's quality system is audited, and surveillance inspections repeat annually.
- A public datasheet with the certified performance parameters (η0 optical efficiency, a1/a2 heat loss coefficients, output per m² at standard conditions).
Certificates are issued for a fixed validity period and every certificate, with its datasheet, is publicly searchable in the Solar Keymark database — a rare level of transparency that lets planners compare collectors on verified numbers rather than brochures.
Why subsidy schemes require it
Public money demands verified performance. Germany's BEG lists Solar Keymark as the accepted evidence for solar collectors (§71e GEG references testing by an ISO 17025-accredited body); similar requirements appear in Italy's Conto Termico, Poland's Czyste Powietrze and many regional programs. In France, CSTBat and Solar Keymark stand side by side. For an installer, the practical rule is simple: no Keymark, no subsidy in most of Europe.
Reading a Solar Keymark datasheet
| Parameter | Meaning | Typical flat-plate value |
|---|---|---|
| η0 | Optical efficiency (no losses) | 0.75 – 0.82 |
| a1 | Linear heat loss coefficient | 3.0 – 4.0 W/m²K |
| a2 | Quadratic heat loss coefficient | 0.010 – 0.020 W/m²K² |
| Annual output | kWh per collector at reference site | Datasheet section 3 |
Lower a1/a2 means the collector holds its efficiency as it runs hotter than ambient — the number to watch for combi systems and process heat.
Solar Keymark and Solimpeks
Solimpeks Wunder flat-plate collectors and PV-T hybrid panels carry Solar Keymark certificates issued by DIN CERTCO and Kiwa, with annual factory inspections at the Konya production site. Certificate numbers are listed on the product pages where the licence is on file and can be verified directly in the Solar Keymark database.
Frequently asked questions
Is Solar Keymark mandatory to sell collectors in the EU?
Legally, no — CE marking covers legal market access. Commercially, yes in practice: without Keymark most subsidy schemes, public tenders and many wholesalers will not accept the product.
What is the difference between Solar Keymark and SRCC?
Both build on ISO 9806 test data. Solar Keymark serves Europe under CEN; SRCC (ICC-SRCC OG-100/OG-300) serves North America and is referenced by US building codes and state and utility incentive programmes (the federal residential clean energy credit, which required SRCC certification, ended for systems installed after 31 December 2025). Manufacturers exporting to both markets certify twice from largely the same test data.
Do PVT panels get Solar Keymark?
Yes. PVT collectors are tested to ISO 9806 like any thermal collector, with the PV function covered separately by IEC standards. Solimpeks' PV-T hybrid panel is Solar Keymark certified.