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UL 3700: The Plug-In Solar Safety Certification Explained
UL 3700 is the US safety framework written specifically for plug-in (balcony) solar. If you're buying a kit, it's the most important thing to check.
What UL 3700 is
In January 2026, UL Solutions launched a testing and certification program based on UL 3700, the Outline of Investigation for Interactive Plug-In Photovoltaic Equipment and Systems. It sets construction, performance and labeling criteria for plug-in solar, including overload protection and preventing a kit from backfeeding power into household wiring when it shouldn't (UL Solutions).
Which states require certification?
- Vermont requires UL 3700 certification.
- Maine's law references UL 3700 by name.
- California requires UL or equivalent certification.
- New Jersey requires certification by a nationally recognized testing laboratory, and the system must stop exporting during outages.
- Maryland exempts very small systems (about 391 W or less) from its certification requirement.
Rules differ, so check your state on our laws by state page.
Safety checklist before you plug in
- Look for the certification mark on the product and its listing — not just "UL compliant" in an ad.
- Stay within your state's wattage limit.
- Follow the manufacturer's instructions for which outlet to use; don't use extension cords or power strips unless the manufacturer allows it.
- Mount panels securely so wind can't move them — especially on balconies above walkways.
- Older or unusual wiring? Ask a licensed electrician to check the circuit first.
- Never modify the kit or open the inverter.
Frequently asked questions
What is UL 3700?
UL 3700 is an Outline of Investigation for interactive plug-in photovoltaic equipment and systems. UL Solutions launched a certification program based on it in January 2026 to address plug-in solar risks like overloads and backfeeding.
Is a UL 1741 inverter enough for plug-in solar?
UL 1741 covers inverters in general, and some state laws refer to it. UL 3700 was written specifically for plug-in systems. Check which certification your state's law names.
Last updated October 6, 2026.