Glossary · Safety and certification

What Is UL 3700? The Safety Certification for Plug-In Solar

UL 3700Outline of Investigation for Interactive Plug-In PV (PIPV) Equipment and Systems

The first US safety program written for plug-in solar: it sets construction, performance and labeling requirements for plug-in systems and their parts.

  1. CertifiedListed under the named standard in the directory of a nationally recognized testing laboratory (UL, CSA, Intertek/ETL or similar), for this model.
  2. Test report onlyThe maker publishes an independent test report, but the product is not listed as certified for this claim.
  3. Maker claim onlyNo certification listing or independent test report that we could find.
How we label a UL 3700 claim. Only a listing in a testing lab's own directory counts as certified; a certified part inside a kit doesn't make the kit certified.

At a glance

Editions
First published December 11, 2025; Edition 2 since October 1, 2026
Certification since
January 8, 2026, from UL Solutions
Covers
Accidental contact, safe installation, overloads, current flowing the wrong way
Connection
A PIPV plug into a permanently installed PIPV receptacle (Edition 1 scope)
Out of scope
Rooftop PV and systems wired permanently into the home
Where it counts
A lab's own directory listing that exact model under UL 3700

UL 3700 is what laws mean when they ask for a “certified” plug-in solar system. It’s an outline of investigation, first published in December 2025 and in its second edition since October 1, 2026. UL Solutions began certifying products against it on January 8, 2026. The program defines construction, performance and labeling criteria and requires features that protect against accidental contact with live parts, promote safe installation, protect against overloads and keep current from flowing the wrong way, including into the grid during an outage.

Why plug-in solar needed its own standard

A plug-in system pushes power into a branch circuit through a receptacle, the opposite of what home wiring was designed for. UL’s white paper names the problems: appliances can draw more current than the wiring is rated for without tripping the breaker, plug blades can be live, and ground-fault protection assumes one-way current. Its suggested answers include dedicated circuits with unique receptacles, special plug designs and power control systems. The first edition’s scope describes equipment with a “PIPV plug” for a “permanently installed PIPV receptacle”, and leaves out rooftop PV and anything wired permanently into the home. So don’t assume a certified kit goes into any ordinary outlet: some may need an electrician to add a dedicated receptacle.

A certified part is not a certified kit

California’s SB 868 asks for the device to be “certified as a plug-in photovoltaic system” (chaptered text, section 8530). A UL 3700 microinverter inside an uncertified kit doesn’t meet that. Check the exact model in the lab’s own directory, such as UL Product iQ. Our guide on how to check a UL 3700 listing walks through it.

Published by the Plugged Sun editorial team

Sources

  1. UL 3700, Outline of Investigation for Interactive Plug-In PV (PIPV) Equipment and Systems, Edition 2 (Source, UL Standards & Engagement, 2026)
  2. UL 3700, Edition 1 (superseded), scope (Source, UL Standards & Engagement, 2025)
  3. UL Solutions Debuts Testing and Certification Framework for Safer Plug-In Solar Across the United States (Source, UL Solutions, 2026)
  4. Plug-In Photovoltaic (PIPV) Systems: Safety Considerations for Residential Use (Source, UL Solutions, 2025)
  5. UL Product iQ certification database (Source, UL Solutions, 2026)
  6. SB 868: Electricity: portable solar generation devices (status, chaptered text and digest) (Source, CalMatters Digital Democracy, 2026)

Where UL 3700 comes up