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What is UL 3700, and which plug-in solar kits are certified?
UL 3700 is the US safety standard written specifically for plug-in solar: panels and a microinverter that connect to a normal wall outlet. Published in December 2025 with certification available since January 8, 2026, it requires the plug to de-energize within one second of being unplugged, the system to stop in a blackout, and protection against overloading the circuit it is plugged into. As of 2026-10-17, 8 products sold or announced in the US carry a UL 3700 claim, and most are certified at the component level rather than as a whole kit.
Key facts - UL 3700 is an Outline of Investigation (the first stage of a UL standard); UL Solutions says certification to it already satisfies state laws that require a nationally recognized lab.
- First certified product: the Hoymiles HiFlow Pro microinverter, July 2026. APsystems EZ1-LV (CSA) and the Mango Power S kit (Intertek, September 2026) followed.
- 4 states require UL 3700 or a whole-system certification: Maine, New Hampshire, New Jersey, Vermont. 7 others accept any nationally recognized lab certification.
- UL 3741 is a different standard (rooftop rapid shutdown) and has nothing to do with plug-in kits.
- The 2026 National Electrical Code still does not recognize plug-in PV; the next edition is 2029. State laws fill the gap by statute.
What does UL 3700 actually test?
A normal grid-tie inverter is certified to UL 1741: it makes clean 60 Hz power and shuts off within milliseconds when the grid goes down. That protects utility line workers. It does not look at what happens inside your apartment when you plug a power source into an outlet. UL 3700 adds four things UL 1741 never evaluated:
- User contact. The plug's blades must be dead within one second of being pulled out, even in full sun. Hoymiles quotes under 34 V within one second for the HiFlow Pro.
- Branch-circuit protection. Your breaker only sees current flowing into the circuit from the panel. Solar injected at an outlet bypasses it, so the combined current can exceed the wire's rating without ever tripping anything. UL 3700 requires the system to limit or detect this.
- Bidirectional ground-fault behavior. Standard GFCIs assume one-way flow and can be "blinded" by reverse current. The outline requires ground-fault shutdown that works both ways.
- Outdoor construction, labeling, and overload and reverse-flow protection for the whole assembly, not just the inverter.
The practical consequence, per UL's own engineers, is that current UL 3700 products use a dedicated or proprietary receptacle rather than any old outlet. UL's Joe Bablo put it bluntly in May 2026: "I know they want to say 'No electrician, no permits.' We're not there."
UL 3700 vs UL 1741 vs UL 3741
| Standard | What it covers | Relevant to plug-in solar? |
|---|
| UL 1741 (and 1741 SB) | The inverter itself: electrical safety, anti-islanding, grid-interactive behavior; SB adds IEEE 1547-2018 smart-inverter functions | Yes, as the baseline. Every legitimate kit has a UL 1741 (or CSA/ETL-to-UL 1741) inverter. On its own it does not address the outlet or your wiring. |
|---|
| UL 3700 | The complete plug-in system: user contact, branch-circuit interconnection, bidirectional flow, shock, construction, labeling | Yes. This is the plug-in standard. Listing category ODCZ on UL Product iQ. |
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| UL 3741 | Photovoltaic Hazard Control: rapid-shutdown alternative for rooftop arrays under NEC 690.12(B)(2), mostly commercial flat roofs | No. A different product class. Ignore it when shopping for a kit. |
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Which products carry UL 3700 as of 2026-10-17?
Read the wording carefully. "Compliant" is the maker's claim. "Certified" or "listed" means a lab issued a certificate. "Component" means the microinverter was tested, not the whole kit with panels and cable.
| Product | Type | UL 3700 status (as stated) | Other listings | Availability |
|---|
Bright Saver
180 W Plug-in Solar Kit | kit | component-compliant microinverter | whole system not certified; UL 1741 | Announced / pre-order |
Bright Saver
360 W Plug-in Solar Kit | kit | component-compliant | system not certified; UL 1741 | Announced / pre-order |
Hoymiles
HiFlow Pro plug-in microinverter | microinverter | 'first UL 3700-compliant plug-in microinverter in the US' (Hoymiles) | certified vs compliant disputed; lab not named | Announced / pre-order |
Mango Power
Mango Power S PIPV 1200W Kit | kit | certified by Intertek (press release 2026-09-18) | UL 1741 / UL 1741-SB / IEEE 1547 / UL 62109-1 / CEC; NEC 690.12 RSD | Announced / pre-order |
APsystems
EZ1-LV plug-in microinverter | microinverter | 'CSA Certified to UL3700 standards' (APshop) | CSA C/US listed; UL 1741, UL 1741SB, IEEE 1547; NEC 690.11/690.12 | Sold out |
US Solar Supplier
810W Balcony / Plug-In Kit (Runergy 405 W x2 + APsystems EZ1-LV) | kit | EZ1 'CSA certified to UL3700 standards' (component) | EZ1: CSA C/US to UL 1741 / 1741SB / IEEE 1547 | Sold out |
US Solar Supplier
900W Plug-In Kit (Philadelphia Solar 450 W bifacial x2 + EZ1-LV + IntegraRack) | kit | component only | EZ1 CSA C/US | Unclear |
US Solar Supplier
1180W Plug-In Kit (Hanersun 590 W x2 + EZ1-LV + Sunmodo NanoRack or IntegraRack ground) | kit | component only | EZ1 CSA C/US | Unclear |
Source for each claim is on the kit comparison page. We refresh this table monthly and when a certification is announced.
Which state laws require UL 3700?
| State | Certification language in the law |
|---|
| Maine | UL 3700 listing/certification, OR comparable NRTL standard, OR configured per NEC adopted by Electricians' Examining Board; inverter shuts off after 0.2 s |
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| New Hampshire | certified by a nationally recognized testing laboratory to nationally recognized safety standards applicable to DER and plug-in solar systems (UL 3700 not named) |
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| New Jersey | listed or certified to UL 3700 or a comparable standard or combination of standards by an NRTL; anti-export feature |
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| Vermont | UL 3700 or equivalent NRTL certification; installed/operated per IEEE 1547-2018 with regional default settings; anti-islanding |
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| California | certified as a plug-in PV system by UL or equivalent NRTL; certified isolation/anti-backfeed feature; most recent NEC and California Electrical Code |
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| Colorado | labeled and listed by a nationally recognized testing laboratory; >391 W devices must be UL labeled and listed to be sold/leased/rented on or after Jan 1, 2027; anti-islanding feature |
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| Connecticut | UL or equivalent NRTL; UL 1741; NEC (NFPA-70); IEEE 1547; State Building Code; anti-islanding; consumer warning on export billing |
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| Maryland | certified by Underwriters Laboratory or an equivalent nationally recognized testing laboratory |
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| New York | listed or certified by an accredited NRTL as a complete plug-in photovoltaic system to a standard; NYS fire prevention and building code and manufacturer instructions; anti-energizing feature |
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| Utah | certified by Underwriters Laboratories or an equivalent nationally recognized testing laboratory; meets most recent NEC; anti-islanding feature |
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| Virginia | certified by a nationally recognized testing laboratory as described in 29 C.F.R. 1910.7 or equivalent; most recent NEC; anti-export feature |
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Two practical effects. First, Bright Saver does not ship its kits to Maine, New York or Vermont, because those states want the whole system certified and the Bright Saver kit is certified only at the inverter level. Second, the Mango Power S, the first kit with a whole-system UL 3700 certificate (Intertek, September 2026), is the product most likely to unlock those states first, and California's 2027 market expects "UL or equivalent" products to be on sale by spring 2027.
Does UL 3700 make a kit legal?
No. Certification is one condition. Legality comes from your state law (or, without one, your utility's interconnection agreement) and includes the wattage cap, notification rules, and where you may plug it in. Check your state's page for the full set of conditions.
What to do if a listing is unclear
- Ask the seller for the certificate number and the lab (UL, CSA or Intertek).
- Look it up: UL Product iQ (category ODCZ) for UL; CSA Group and Intertek keep searchable directories too.
- If the seller only says "UL certified" with no standard named, treat it as a UL 1741 inverter at best. It may be fine electrically but will not meet a UL 3700 requirement.
Frequently asked questions
Is UL 3700 an official standard?
It is an Outline of Investigation, the first stage of a UL standard, published in December 2025. UL Solutions began certifying products to it on January 8, 2026 and says that certification counts for state-law compliance. The full consensus standard may take a year or more to finish.
Does my kit need UL 3700 to be legal?
It depends on the state. Maine, New Hampshire, New Jersey, Vermont write UL 3700 (or a full-system certification) into their laws. California, Colorado, Connecticut, Maryland, New York, Utah, Virginia accept "UL or an equivalent nationally recognized testing laboratory" certification, which a UL 1741-listed inverter can satisfy. States with no law have no certification rule at all, only your utility's interconnection terms.
What is the difference between "UL 3700 compliant" and "UL 3700 certified"?
"Compliant" is a manufacturer's claim that the product was designed to the outline. "Certified" or "listed" means an accredited lab (UL, CSA, Intertek) tested it and issued a certificate you can look up. Only the latter satisfies a state law that requires certification. Check UL Product iQ under category ODCZ, or ask the maker for the certificate number.
Is UL 3741 the same thing?
No. UL 3741 is the Photovoltaic Hazard Control standard for rooftop rapid shutdown, mostly used on commercial flat roofs. It has nothing to do with plug-in kits, even though some bills and search results confuse the two numbers.
Can a UL 1741 inverter be plugged into an outlet safely?
UL 1741 covers how the inverter behaves on the grid (it shuts off in a blackout). It does not evaluate what happens to your branch circuit, your GFCI, or the exposed plug blades. That gap is exactly what UL 3700 was written to close, which is why UL 3700 kits use a receptacle that de-energizes the plug within one second of being unplugged.