SRCC OG-100 and OG-300 are the North American certification programs for solar heating products, operated by ICC-SRCC. OG-100 certifies individual collectors from ISO 9806 test data; OG-300 certifies complete residential solar water heating systems and adds annual energy ratings for around 200 North American locations. US model building codes and incentive programs reference both.
What is SRCC certification?
SRCC — the Solar Rating & Certification Corporation, today part of the International Code Council as ICC-SRCC — is North America's certification body for solar heating products. Its two operating guidelines split the market cleanly: OG-100 for collectors as components, OG-300 for complete residential solar water heating systems. Certified products are listed in a public directory with their rated performance, giving specifiers, code officials and incentive administrators a verified reference — the same role Solar Keymark plays in Europe.
OG-100 vs OG-300: what is the difference?
| Aspect | OG-100 | OG-300 |
|---|---|---|
| Scope | Individual solar collector | Complete residential SWH system |
| Technical basis | ISO 9806 laboratory test data | System design review + performance modelling |
| Output | Collector thermal ratings across standard categories | Annual energy ratings for ~200 North American sites |
| Typical user | Commercial projects, component specifiers | Homeowners, installers, code officials |
OG-100 answers "how much heat does this collector produce?" — with kBtu/day-style ratings across standardised climate and temperature categories. OG-300 answers the homeowner's real question, "how much energy will this system save at my location?", by rating the whole package — collector, tank, controls, freeze protection — at roughly 200 reference sites from Miami to Anchorage. Thermosiphon packages such as thermosiphon systems certify under OG-300 like pumped systems.
Why do US codes and incentive programs require SRCC?
Because the model codes name it. The IBC, IRC, IMC and IPC — the code family most US states adopt — reference ICC-SRCC certification for solar thermal installations, as do California's Title 24 building standard and the ENERGY STAR criteria for solar water heaters. The federal residential clean energy credit named SRCC certification as the qualifying evidence for residential solar water heating until it ended for systems installed after 31 December 2025, and state and utility rebate programs continue to reference the listings — though program rules change, so verify the current requirements before claiming any credit. The practical rule mirrors Europe's: no listing, no permit sign-off, no incentive.
How does SRCC relate to Solar Keymark and ISO 9806?
Both schemes drink from the same well. ISO 9806 is the single global collector test standard, and one accredited laboratory campaign can feed a Solar Keymark certificate in Europe and an OG-100 listing in North America — the IEA SHC's "one test, many markets" principle. The markets themselves justify the double certification: IEA SHC counts 544 GWth of solar thermal capacity operating worldwide, and its 2025 report notes double-digit installation growth in Türkiye, Mexico and Brazil. Solimpeks certifies its Konya-built collectors under both schemes — Solar Keymark for Europe, SRCC for North America — as part of serving customers in 96+ countries.
How does a manufacturer get OG-100 or OG-300 certified?
The OG-100 path: test the collector to ISO 9806 at an accredited laboratory, submit the data and design documentation to ICC-SRCC, pass the review, and maintain the listing through surveillance and factory quality requirements. The OG-300 path adds system-level work: the complete package is documented, its components must be certified or qualified, and system performance is modelled to produce the site-specific annual ratings published in the directory. Changes to any certified component — absorber, glazing, tank — must be notified, which is why certified product lines stay deliberately stable.
Frequently asked questions
Do I need OG-300 to get incentives for a residential solar water heater in the USA?
Residential incentive programs typically require OG-300 system certification, or at minimum OG-100 certified collectors within a qualifying system. Program rules differ by state and utility and change over time, so check the current requirements before purchase.
Is Solar Keymark accepted instead of SRCC in North America?
Not directly — US codes and programs reference ICC-SRCC listings, not the European mark. But because both build on ISO 9806, the same laboratory test data can support an SRCC application, cutting the cost and time of entering the North American market.
What does an OG-300 rating actually tell a homeowner?
The expected annual energy delivery and savings of the complete system at reference locations near yours — roughly 200 sites across North America are rated. It turns competing systems into directly comparable numbers instead of brochure claims.
Is SRCC the same as ENERGY STAR?
No. ENERGY STAR is an efficiency labelling program that uses SRCC certification as its qualification evidence for solar water heaters. SRCC certifies and rates the product; ENERGY STAR badges qualifying models for consumers.