UL 1703 / UL 61730

UL 1703 and UL 61730 are safety standards for photovoltaic (PV) solar panels published by Underwriters Laboratories (UL). These standards define the testing and certification requirements that solar panels must pass before they can be sold and installed in the United States.

UL 1703 was the original US safety standard for flat-plate PV modules, covering electrical safety, fire resistance, and mechanical stress testing. It has been largely replaced by UL 61730, which harmonizes with the international IEC 61730 standard while adding US-specific requirements. UL 61730 includes two parts: Part 1 covers construction requirements (materials, spacing, labeling) and Part 2 covers safety testing (dielectric withstand, wet leakage, temperature cycling, humidity freeze, mechanical load, fire resistance, and more). As of 2023, UL 61730 is the primary standard referenced in the NEC for PV module safety certification. Panels that were certified under UL 1703 remain valid, and many carry dual certification. For homeowners, the key takeaway is simple: always ensure the panels in your solar proposal carry UL 61730 or UL 1703 certification — this is non-negotiable for a code-compliant installation.