UL 3700 sounds dull. It is actually the reason plug-in solar can move forward in the US. States need a safety yardstick, and this is it. But the label gets used loosely, so read this before you trust it.
What is UL 3700?
Its full name is Outline of Investigation for Interactive Plug-In Photovoltaic (PIPV) Equipment and Systems. UL Standards published Edition 1 on 11 December 2025. An outline of investigation is a UL test method. It is not a consensus ANSI standard. A bi-national ANSI/CAN/UL 3700 standard is still being developed in Canada.
What does UL 3700 test?
UL Solutions launched a certification program for it on 8 January 2026. It covers construction, performance and labeling. The hazards it targets include touching live parts, such as plug blades that stay energized, safe installation, overloaded wiring, and current flowing the wrong way. Those are the same worries that kept plug-in solar out of US homes.
Which products have UL 3700?
The claims we found are about microinverters. Hoymiles says its HiFlow Pro is the first UL 3700-compliant plug-in microinverter in the US. APsystems says its EZ1 is CSA certified to UL 3700. Bright Saver kits use the Hoymiles unit, and the certification covers the microinverter only. We have not seen a complete kit certified. Ask for the listing, not just a logo.
What is the difference between certified and compliant?
Certified means a lab tested the product and listed it. Compliant, or compatible, is often just the maker's claim. CraftStrom's page says its 800 W kit is UL 3700 compliant, and a tracker lists its application as in progress. EcoFlow's STREAM products are listed as in progress too. Treat compliant as a hope, not a stamp. Certified products are listed under UL category ODCZ in UL Product iQ.
Do I need UL 3700 to buy a kit?
It depends on your state. Maine's law asks for devices listed or certified under UL 3700, or set up under the National Electrical Code as the state adopted it. Check the state-by-state guide. Our kit roundup notes what each maker says. For the basics, see what balcony solar is.
The quick version
- UL 3700 is a UL test outline for plug-in solar, not an ANSI standard.
- UL Solutions began certifying to it on 8 January 2026.
- The certification claims we found cover microinverters, not complete kits.
- Compliant is not the same as certified.