Guide
UL 3700 and plug-in solar
UL 3700 is an outline standard for interactive plug-in photovoltaic systems and UL Solutions launched a certification program on January 8, 2026. This page explains what the standard requires, which states reference it, and which kits are listed or only claim compliance.
- CheckedOct 14, 2026
- Sources read14
- DataPVGIS · EIA · state bills
What UL 3700 covers
UL 3700 is an Outline of Investigation for interactive plug-in PV equipment and systems; UL Solutions presents it as a framework for how plug-in systems must be built, evaluated for safety and safely installed, and the program launched on January 8, 2026. The Standards & Engagement entry titles the document "UL LLC Outline of Investigation for Interactive Plug-In PV (PIPV) Equipment and Systems" and marks it "UL Outline© 2025 UL LLC."
The outline requires features to mitigate accidental contact with hazardous electric parts, promote safe installation, protect against overloads and prevent electric current from flowing in the wrong direction. It also establishes construction, performance and labeling criteria to help manufacturers design plug-in solar products meeting safety standards.
UL 3700 references other UL standards such as leakage current, attachment plugs and receptacles, and ground-fault circuit interrupters, and the UL standard process is under continuous maintenance so referenced work may change over time.
- Mitigate accidental contact with hazardous electrical parts.
- Protect against overloads and reverse or unintended current flow.
- Construction, performance and labeling criteria for whole systems.
Which states name UL 3700
The enacted laws in Maine, New Jersey and Vermont name UL 3700, each with an alternative: a comparable standard or an equivalent certification by a nationally recognized testing laboratory. UL Solutions positions the standard as a framework that can support state legislative and regulatory efforts, and its press release uses the phrase "plug-in solar systems certified to UL 3700."
Some sellers and trackers report other states condition shipping on whole-system UL 3700 certification; Bright Saver lists California, Maine and Vermont in that group. Most state laws that address plug-in solar set a size limit rather than mandating a single national standard.
- Laws in effect on October 14, 2026: Utah (HB 340), Maryland (HB 1532), Vermont (S 202), Maine (LD 1730), Colorado (HB26-1007), Connecticut (HB 5340).
- Signed, taking effect later: California (SB 868), New Hampshire (SB 540), Virginia (HB 395 / SB 250), New Jersey (S 2368).
- Awaiting the governor’s signature: New York (S 8512A / A 9111C).
- Most size limits are 1,200 W; Colorado sets 1,920 W, and Maine 420 W without an electrician. Some laws specify AC output and others do not state AC or DC.
| State | Status | Size limit | Certification named | Utility notice |
|---|---|---|---|---|
| California | Signed | 1,200 W AC | certified as a plug-in photovoltaic system by Underwriters Laboratories or an equivalent nationally recognized testing laboratory; National Electrical Code; California Electrical Code | Utility may require it |
| Colorado | In effect | 1,920 W | labeled and listed by a nationally recognized testing laboratory; UL labeled and listed to be sold above 391 W from January 1, 2027 | Utility may require it |
| Connecticut | In effect | 1,200 W | certified by Underwriters Laboratories or an equivalent nationally recognized testing laboratory; UL 1741; IEEE 1547; National Electric Code (NFPA-70); State Building Code | The act does not mention notice to the utility; it bars requiring the utility's approval. |
| Maine | In effect | 420 W AC; up to 1,200 W under conditions | UL 3700, a comparable standard from a nationally recognized testing laboratory, or a setup that follows the National Electrical Code adopted by the Electricians' Examining Board | Required above 420 W |
| Maryland | In effect | 1,200 W | certified by Underwriters Laboratory or an equivalent nationally recognized testing laboratory | Required |
| New Hampshire | Signed | 1,200 W AC | certified by a nationally recognized testing laboratory to nationally recognized safety standards for distributed energy resources and plug-in solar generation systems | The utility may set up a way for customers to report the system's wattage after installation; the information is for notification only. |
| New Jersey | Signed | 1,200 W | UL 3700, a comparable standard, or a combination of standards for plug-in photovoltaic safety and grid-parallel operation, listed or certified by a nationally recognized testing laboratory | The law does not say |
| New York | Awaiting signature | 1,200 W AC | accredited nationally recognized testing laboratory | Required |
| Utah | In effect | 1,200 W | certified by Underwriters Laboratories or an equivalent nationally recognized testing laboratory; National Electrical Code | The law does not say |
| Vermont | In effect | 1,200 W AC | UL 3700 or an equivalent certification by an equivalent nationally recognized testing laboratory; IEEE 1547-2018 | The law does not say |
| Virginia | Signed | 1,200 W | certified by a nationally recognized testing laboratory (29 C.F.R. § 1910.7) or an equivalent; National Electrical Code | Required |
Which kits are certified or claim it
The kit table below gives full entries; this section summarizes UL 3700 status as of October 14, 2026. Manufacturer press releases and UL Solutions’ program materials are the primary sources for published listings; many sellers advertise compliance without a published UL 3700 certificate for the whole kit.
Hoymiles and its HiFlow Pro microinverter are announced as UL 3700-compliant and a Hoymiles inverter subassembly certification was reported in July 2026. Several sellers state their kits meet UL 3700 but no whole-system UL listing is published on their store pages.
Many popular kits list UL 1741, IEEE 1547 or Rule 21 instead of UL 3700; a seller claim is not the same as an issued UL 3700 certificate.
- Listed or announced: Hoymiles HiFlow Pro microinverter (manufacturer announcement and reported subassembly certification).
- Claims of compliance (seller statement, no UL 3700 listing found): pluggedsolar kits; Craftstrom kits; Bright Saver kits (Bright Saver also describes a subassembly claim).
- No UL 3700 status published on seller pages: EcoFlow kits, Mango Power kit, Zendure kit.
| Kit | UL 3700 | Other standards named | Checked |
|---|---|---|---|
| EcoFlow STREAM Microinverter | Not published | UL 1741 | Oct 14, 2026 |
| EcoFlow STREAM Microinverter + 400 W solar panel | Not published | UL 1741 | Oct 14, 2026 |
| EcoFlow STREAM Microinverter + 2 × 400 W rigid panels | Not published | UL 1741 | Oct 14, 2026 |
| Mango Power Mango Power S 1200W Plug-In Solar Kit | Not published | CA Rule 21 (UL 1741-SA), IEEE 1547:2018 (UL 1741-SB), CSA C22.2 | Oct 14, 2026 |
| Zendure SolarFlow Kit | Not published | — | Oct 14, 2026 |
| pluggedsolar 400 W plug-in kit (2 × 200 W, APsystems microinverter) | Claimed by the seller | UL 1741, UL 3700 | Oct 14, 2026 |
| pluggedsolar 800 W plug-in kit (4 × 200 W, APsystems microinverter) | Claimed by the seller | UL 1741, UL-3700, UL 3700 | Oct 14, 2026 |
| pluggedsolar 1,200 W plug-in kit (6 × 200 W, APsystems microinverter) | Claimed by the seller | UL 1741, UL 3700 | Oct 14, 2026 |
| Craftstrom 800 Watt Eco-Line Plug&Play Solar | Claimed by the seller | UL 1742 (as written, ETL), IEEE 1547 | Oct 14, 2026 |
| Craftstrom 1200 Watt Eco-Line Plug&Play Solar | Claimed by the seller | UL 1742 (as written, ETL), IEEE 1547 | Oct 14, 2026 |
| Craftstrom 1600 Watt Eco-Line Plug&Play Solar | Claimed by the seller | UL 1742 (as written, ETL), IEEE 1547 | Oct 14, 2026 |
| Craftstrom 2kW Solar + 3kWh Battery Plug-In Kit | Not published | UL 1742 (as written, ETL), IEEE 1547 | Oct 14, 2026 |
| Bright Saver Balcony Solar Kit 180 W (one panel) | Claimed by the seller | UL 1741, UL 3700 (subassembly claim) | Oct 14, 2026 |
| Bright Saver Balcony Solar Kit 360 W (two panels) | Claimed by the seller | — | Oct 14, 2026 |
How to check a UL 3700 listing
UL Solutions’ program materials (launched January 8, 2026) and manufacturer press releases document UL 3700 certifications; seller pages may advertise compliance but often do not show a UL 3700 certificate number. Ask the seller for the UL 3700 certificate number and whether it covers the inverter only (a subassembly) or the whole kit.
Some manufacturers have earned UL 3700 subassembly certifications for inverters even when a whole-system listing is not published. Compare any seller claim with the manufacturer announcement and UL Solutions’ program materials, and consult the kit table to see which listings are published and which are seller claims.
- Ask the seller for the UL 3700 certificate number and whether it covers the inverter only or the whole system.
- Check the manufacturer press release and UL Solutions’ program page (program launched January 8, 2026).
- Compare seller statements with the kit table: kit list.
Questions
What safety features does UL 3700 require?
UL 3700 requires features that mitigate accidental contact with hazardous electrical parts, promote safe installation, protect against overloads and prevent electric current from flowing in the wrong direction (UL Solutions).
Which states require UL 3700 for plug-in solar?
Maine, New Jersey and Vermont name UL 3700 in their laws, each allowing a comparable or equivalent certification. Bright Saver reports that California and Maine (along with Vermont) require whole-system UL 3700 certification before kits can ship; check the state text or the state pages for the exact requirement and dates.
Can plug-in kits supply power during an outage?
UL Solutions said certified plug-in systems "could be used to provide back-up power for essential devices during outages," but UL 1741 anti-islanding requires systems to stop producing electricity when grid power is interrupted to protect line workers.
How large can plug-in systems be where laws exist?
Where laws are in effect on October 14, 2026 most set a 1,200 W size limit; Colorado’s law sets a 1,920 W limit. Some bills specify AC output and others do not state AC or DC explicitly.
How do I tell if a kit is truly UL 3700 certified?
Ask the seller for the UL 3700 certificate number and whether the certificate covers the whole system or only an inverter subassembly. Confirm the certificate against the manufacturer press release and UL Solutions’ program materials (program announced January 8, 2026).