Plug-in Solar in the US: State Laws and UL 3700

By the end of October 2026, ten US states had signed plug-in solar laws. Six of them are already in force, and four take effect in 2027. There is no federal framework, and each law is written differently: most allow up to 1,200 W through an outlet without a utility interconnection agreement, but they differ on certification, notice to the utility, landlords and batteries. On the product side, the new safety benchmark is UL 3700, an Outline of Investigation first published in December 2025. Only a handful of products have announced certification to it so far.

Why the US needs state laws

In most US states, anything that generates electricity in parallel with the grid needs an interconnection agreement with the utility, usually with an application, a review and sometimes a fee. A small kit that plugs into an outlet does not fit that process. The new state laws carve out these small devices: below a power limit, and if the device is certified by a nationally recognised testing laboratory (NRTL), the utility may not require prior approval, charge a fee or demand extra equipment.

The National Electrical Code (NEC) has not caught up. UL Solutions states that the 2026 NEC, like all previous editions, does not recognise plug-in PV. A set of proposed Tentative Interim Amendments to the NEC, which would add a definition of a plug-in PV system and rules for cord- and plug-connected power sources, was open for public comment until 20 November 2026. They are proposals, not adopted rules.

The ten states with a law

State	Law	In force	Output limit	Certification in the text	Notice to utility
Utah	HB 340 (2025)	Yes, since May 2025	1,200 W, standard 120 V outlet	UL or equivalent NRTL, and NEC	Not required
Maine	LD 1730 (2026)	Yes, since July 2026	420 W self-installed; 420–1,200 W by a licensed electrician on a dedicated circuit	UL 3700 or comparable NRTL standard	Above 420 W, within 30 days
Colorado	HB26-1007	Yes, since August 2026; HOA and sales rules from 1 Jan 2027	1,920 W, one device per wall outlet	Listed by an NRTL; from 2027, devices above 391 W must be listed to be sold	Utility may ask for it
Maryland	HB 1532 (2026)	Yes, since July 2026	1,200 W, standard outlet, one per meter	UL or equivalent NRTL	Before installation
Connecticut	HB 5340, PA 26-127	Yes, since 1 Oct 2026	1,200 W, 120 V outlet, one per meter	UL or equivalent NRTL, plus UL 1741, IEEE 1547 and NEC	Not required
Vermont	S.202, Act 149	Yes, since July 2026	1,200 W per meter	Reported: UL 3700 and IEEE 1547-2018	Not reported
Virginia	HB 395 (2026)	1 Jan 2027	1,200 W per customer	NRTL, and NEC	Before installation, on a state form
New Hampshire	SB 540 (2026)	1 Jan 2027	1,200 W, one per customer	NRTL, to national safety standards	Utility may ask for it
California	SB 868 (2026)	1 Jan 2027	1,200 W per dwelling	Reported: UL or equivalent laboratory	Not reported
New Jersey	S2368 (2026)	About 1 Mar 2027	1,200 W	Reported: UL 3700	Not reported

For Vermont, California and New Jersey, the details come from news reports and official press releases, as we could not read the enacted text.

Points that matter in practice:

"Passed" is not "in force". Virginia, New Hampshire, California and New Jersey have signed laws that do not apply yet. New York's SUNNY Act passed both chambers in May 2026 but, as of late October, had not been signed.
The limit is not always 1,200 W. Colorado allows up to 1,920 W. Maine allows self-installation only up to 420 W; larger systems up to 1,200 W need a licensed electrician and a dedicated circuit.
Most laws say "NRTL", not "UL 3700". Only some of the laws name UL 3700 directly (Maine; Vermont and New Jersey as reported). Others require certification by UL or an equivalent nationally recognised testing laboratory, and Connecticut names UL 1741. In practice, UL 3700 is becoming the benchmark that laboratories and regulators point to, but sellers should read the wording of each state's law.
Small-device exemptions. Virginia, Colorado and Maryland exempt devices of 391 W or less from listing rules that would otherwise require changes to the building wiring. New Jersey reportedly has a similar exemption at about 400 W.
Notice to the utility. Maryland and Virginia require notice before installation, and Maine above 420 W. Elsewhere it is not required, or the utility may ask for it.
Renters and HOAs. Rules vary widely. Colorado (from 2027) and New Jersey limit bans by homeowners' associations and landlords; Virginia limits bans by larger landlords but does not override HOA covenants; Vermont lets landlords set reasonable restrictions; several states say nothing.
Batteries. Maine is the only state whose law explicitly covers a plug-in battery system. The other texts we read define the device as photovoltaic and do not mention storage.
California's exemption is temporary. As reported, its exemption from interconnection rules ends on 1 January 2030 unless extended.

Bills are also moving in other states, including Massachusetts, Rhode Island and Pennsylvania, and a federal bill was introduced in October 2026. None of these was law at the time of writing.

What UL 3700 is

UL 3700 is the Outline of Investigation for Interactive Plug-In Photovoltaic Equipment and Systems, published by UL Standards & Engagement. The first edition appeared in December 2025, and UL Solutions launched its testing and certification programme on 8 January 2026. Other laboratories, including Intertek and CSA Group, also certify to it.

An Outline of Investigation is not yet a consensus ANSI standard. It is the document laboratories use to certify a new type of product while a full standard is developed. A bi-national ANSI/CAN/UL 3700 standard is in development, with no publication date announced.

According to UL Solutions, UL 3700 covers construction, performance and labelling, and addresses:

Connectors, including dedicated plug-in PV connectors and connector configurations designed for this use
Dedicated and non-dedicated circuits, and protection against overloading the circuit the device feeds into
Touch safety: no hazardous voltage on accessible contacts, for example on the prongs of an unplugged lead
GFCI protection and compatibility with ground-fault circuit interrupters in the home
Grid behaviour such as anti-islanding, by reference to UL 1741 and IEEE 1547

It can be applied to individual components, such as a microinverter, and to complete systems. Intertek lists integrated energy storage within plug-in PV equipment as in scope, with the battery parts also assessed to their own standards, such as UL 9540.

UL 3700 itself does not set a 1,200 W limit; the power limits come from the state laws.

From state law to the socket

State lawsets the power limit and the rules for utilities, landlords and HOAs
NRTL certificationUL 3700, UL 1741 or as the state requires
Notice to the utilityonly where the state requires it
Customer plugs inwithin the state's limit

The state law says what is allowed; certification by a nationally recognised testing laboratory is what lets a specific product qualify.

Which products are certified so far

By October 2026, three manufacturers had publicly announced UL 3700 certification or compliance:

Product	Announced	Laboratory	What it covers
APsystems EZ1	July 2026	CSA Group	Microinverter
Hoymiles HiFlow Pro	July 2026	Not named	Microinverter (announced as "UL 3700-compliant")
Mango Power S	September 2026	Intertek	1,200 W plug-in kit (not clear whether the whole kit or the microinverter)

These are the manufacturers' own announcements. Before listing a product, check the exact model in the certifying laboratory's public directory. Other well-known plug-in products were still listed as pending in October 2026. Note also that some rules look at the complete system, not just the microinverter: New York's pending bill, for example, requires listing as a complete plug-in PV system.

What sellers and installers should check

The state. Is the law signed, and is it in force on the date you sell or install? What is the output limit there?
The certification. Which standard and which laboratory does the state's law name? Is the exact model (kit or microinverter) listed in that laboratory's directory, not only "pending" or "compliant"?
The complete kit. If the state looks at the system, check that the combination you sell (panels, microinverter, lead, mounting) is what was certified.
The electrical side. Does the product need a dedicated circuit or a specific connector? In Maine, does the size require a licensed electrician?
Notice. Does the customer have to notify the utility before or after installation?
The property. For renters and homes in an HOA, check what the state allows and get consent where needed.
Batteries. Unless the state's law covers storage, as Maine's does, treat a battery as a separate system under the normal rules.

How VaySunic can help

VaySunic designs and manufactures microinverters, plug-in solar kits and home batteries for 230 V, 50 Hz markets such as Europe and the UK. We do not currently hold UL 3700 certification, and our products are not sold as plug-in devices in the US. A US product needs its own design (120 V, 60 Hz and US connectors) and its own certification. If you are planning a plug-in solar or storage range for the US, contact us to discuss our plans and timelines, or see our OEM and ODM programme.