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UL 3700: the safety standard for plug-in solar

UL 3700 is the first US safety standard written specifically for solar kits that plug into a wall outlet. It was published in December 2025, and UL Solutions began certifying products in January 2026. Most state laws require a certified kit, so this is the label to look for.

Updated October 2026

What it checks

  • Dead plug. Pull the plug while the sun is shining, and its prongs go dead in under a second, so nobody gets a shock.
  • Grid outage. When the power goes out, the kit stops feeding power so line workers are safe.
  • No overload. The kit can’t push so much power into a circuit that the wiring overheats.
  • Weather. Heat, freezing rain and wind without leaking electricity.
  • Ground faults. Built-in sensors, like the reset button on a bathroom outlet, shut it down if electricity leaks.

Who’s certified so far

In July 2026 the Hoymiles HiFlow Pro microinverter became the first product to earn UL 3700 certification. It’s rated at 360 W per unit, so reaching a 1,200 W cap takes several units. APsystems and Mango Power have followed. In August 2026 the City of Provo, Utah noted that no complete system had yet been certified.

How to check a kit

  1. Look for “UL 3700” by name on the spec sheet, not just “UL listed”.
  2. Ask whether it covers the complete kit or one part.
  3. Check the certification in UL’s product database, or ask the seller for the certificate.
  4. Check what your state’s law requires. What the laws say.

Common questions

Are kits sold before UL 3700 unsafe?

Not necessarily, but they weren't tested against the risks specific to plugging solar into an outlet, and they may not meet your state's law.

Is UL 3700 required by law?

Laws usually say 'UL or an equivalent' certification rather than naming UL 3700, but it's the standard written for plug-in solar, so it's what to look for.

Is a kit with a UL 3700 inverter fully certified?

Not necessarily. A certified inverter is one part. Ask whether the complete kit as sold is certified.

When will certified kits be easy to buy?

Certified parts started arriving in July 2026. California's lawmakers expect compliant products in stores by spring 2027.

Sources