Plug-In Solar Laws Explained: Wattage Limits, UL Rules and Utility Notice

Short answer: US plug-in solar laws let you connect a certified solar device of up to 1,200 watts (1,920 W in Colorado) to a standard outlet without an interconnection agreement, utility approval or fees. In exchange, the device must shut off during outages, you usually get no payment for exported power, and some states require you to notify your utility first.

Before 2025, any solar system that fed power into a home's wiring needed the same interconnection process as a rooftop array: an application, an approval, sometimes an inspection and a fee. That process makes no sense for a $600 kit, and it is the main thing the new laws remove. Here is what they change and what they keep. For the status of each state, see the 50-state map.

1. The wattage cap

Every law sets a maximum output, measured on the AC side (what the inverter pushes into the outlet), not the panel rating.

Why 1,200 W? At 120 volts it is about 10 amps, which an ordinary household circuit can safely carry alongside normal use. Germany and the UK chose 800 W for their 230-volt grids. If you are deciding between kit sizes, see 400 W vs 800 W vs 1,200 W.

2. Certification: UL, "or equivalent" and UL 3700

All laws require equipment certified by a nationally recognized testing laboratory (NRTL), such as UL, Intertek (ETL) or CSA. They differ on which standard:

• General wording (Utah, Virginia, Maryland, California): "certified by Underwriters Laboratories or an equivalent nationally recognized testing laboratory" and compliant with the National Electrical Code. In practice that has meant a microinverter listed to UL 1741, the long-standing standard for grid-tied inverters.
• UL 3700 (named in New Jersey and Maine): a newer "outline of investigation" written for plug-in solar. It tests things UL 1741 never had to: that the plug's metal prongs de-energize quickly when you pull it out, that the device stops feeding power during a grid outage, that output can't overload the circuit, and that ground faults cut power. UL Solutions launched its UL 3700 program in January 2026; Hoymiles announced the first compliant plug-in microinverter in July 2026, and APsystems and Mango Power followed.
• Small-device exemptions: Maryland and Colorado exempt devices of 391 W or less from the listing requirement (Virginia's law has a similar 391 W carve-out), and New Jersey exempts devices of 400 W or less from its UL 3700 requirement.

More detail, and the products certified so far, in UL 3700 explained.

"UL compliant" or "designed to UL standards" on a product page is not the same as "UL listed" or "certified". Look for the certificate or the listing in the lab's online directory (UL Product iQ, Intertek's Directory of Building Products or CSA's certified product listing).

3. Telling your utility

No law lets the utility make you wait for approval or charge a fee for a qualifying device. But notice rules vary:

• No notice required: Utah. The utility also may not require approval, fees or extra controls.
• Notice required before installing: Virginia. You file a notification on a form set by the State Corporation Commission; if the utility doesn't respond within 15 days, you have met the requirement.
• Notice if the utility asks: Maryland lets utilities require advance notice with documentation of the system's capacity and safety features. California lets utilities require a simple registration, which the bill's author expects to be a free online form.
• Disconnect switch: Virginia and Maryland let utilities install a locking disconnect switch in some cases (for example, where there is more than one device), and Maryland may charge you for it.

Even where notice isn't required, telling your utility costs nothing and avoids surprises if a meter technician spots the system. The full state-by-state table and a notice template are in do you need to tell your utility?

4. The outlet and the outage rule

Laws describe a device "designed to be connected to a building's electrical system through a standard 120-volt outlet" (Utah's wording). That excludes hardwired systems, which still go through normal interconnection, and 240-volt plugs. Every law also requires that the system cannot energize the building's wiring during a power outage. This protects line workers and is why plug-in kits stop producing when the grid goes down, unless they include a battery with a separate backup outlet. Our guide Is plug-in solar safe? explains what happens inside the wall.

5. Net metering and exported power

Plug-in systems are generally excluded from net metering. Utah and Virginia say so expressly, and California's law waives interconnection without guaranteeing any export credit. On a sunny afternoon, power your home doesn't use at that moment flows back to the grid for free. That is why real savings depend on how much of the output you use yourself, and why bigger is not always better.

6. Landlords, HOAs and local permits

Most laws regulate the utility relationship and say nothing about landlords. The exceptions:

• Virginia: landlords with more than four rental units can't prohibit a tenant from installing a device on the exterior of their unit, but can set reasonable rules on size, placement and manner. Tenants must give seven days' notice.
• New Jersey: landlords and HOAs can't prohibit devices but may impose reasonable restrictions on size and placement; municipalities can't ban them or require permits.
• Colorado (from January 1, 2027): landlords and HOAs can't unreasonably block devices that are properly secured; tenants must notify the landlord.
• Vermont: tenants give 10 days' notice; landlords can set reasonable restrictions; covenants and zoning can't ban devices.
• New Hampshire: compliant systems don't need a building permit.

Maryland's and California's laws expressly leave leases and HOA rules in place. See Can my landlord stop me? and balcony solar and HOA rules.

Utility liability and your responsibility

Utah, New Hampshire and other states state that the utility is not liable for damage or injury caused by a plug-in device. Virginia makes tenants responsible for damage their device causes. In other words, the law makes plug-in solar easier, but the safety of your installation is on you, which is a good reason to choose certified equipment and follow the installation steps carefully.

Laws that need one more step

Signing is not always the end. New Hampshire's use only becomes legal once its Department of Energy certifies that a recognized electrical standard exists, and the City of Dover asked residents in September 2026 to wait until that happens. New Jersey gave its Board of Public Utilities until March 1, 2027, to implement its law. We update each state's page when these steps happen.

Frequently asked questions