What is plug-in solar? How balcony solar kits work in the US

A plug-in solar system, often called balcony solar, is a small solar kit you connect to your home by plugging it into an ordinary wall outlet. It usually has one to four panels and a microinverter, and it is sized to cover part of the power your home is already using, not to replace your utility.

Until 2025 there was no clear legal path for this in the US. Utah changed that with HB 340, and by October 2026 ten states had signed plug-in solar laws. Most cap a system at 1,200 W. See the state map.

What is in a kit

A plug-in kit has four parts, and the microinverter is the one that matters most for safety.

• Panels. Usually one to four, often 100 to 450 W each. Balcony kits use lighter frames or flexible modules and come with railing clamps or a stand.
• Microinverter. Converts the panels’ direct current into 120 V alternating current that matches the grid. State laws require it to stop feeding power if the grid goes down. Utah’s statute calls this a “device or feature that prevents the system from energizing the building’s electrical system during a power outage.”
• Cable and plug. Carries the AC output to a standard outlet. Newer certified systems are designed so the plug’s pins cannot carry live voltage once unplugged.
• Mounting. Railing hooks, wall brackets or a ground stand. In practice this decides how much energy you get, because the angle and direction of the panels matter more than any other choice. More on orientation.

Some kits add a battery that stores midday output for the evening. A battery changes the economics and the safety review, so we cover it separately in how to choose a kit.

Where the power goes

1. Sunlight → DC

   Panels

   Photovoltaic cells generate direct current.

2. DC → AC

   Microinverter

   Converts output to grid-synchronized alternating current.

3. Into home wiring

   Listed connection

   The outlet and circuit must meet the system’s listing.

4. Used at home

   Appliances

   Output offsets demand while appliances are running.

When the grid goes downA qualifying grid-tied system stops energizing the grid. It is not backup power unless the product provides a separate supported backup function.

When the microinverter pushes power into the outlet, it flows to whatever is running on your home wiring at that moment: the fridge, the router, a laptop charger. Your meter sees less demand, and that is the saving.

What plug-in solar does not do well is earn money from exports. Vermont’s law says plainly that these devices get no net metering and exported power is not compensated, and Maine excludes them from net energy billing. Maryland’s Public Service Commission warns that if your meter cannot measure power going back to the grid, the excess may count as zero or even be added to your usage. The practical rule is to size the kit to your home’s background draw. Our calculator does this for you.

How much can it power?

A small kit covers part of your household consumption while the sun is up. Panel watts describe rated power; yearly kWh describe energy. The table below is generated from the same model as our calculator.

Representative cities: Baltimore, Los Angeles and Burlington. PVGIS ERA5 typical year, no additional shade, panels and inverter of equal rated watts. Estimates use the same engine as the calculator. These sizes do not establish legal permission or a state cap.

Tilting panels toward the sky can increase production if your balcony and building rules allow it. Energy you do not use as it is produced earns no credit in our savings model. See the method.

Why it is suddenly legal

Small solar used to fall under the same interconnection rules as a rooftop system: an application, a utility review and often an electrician. That paperwork made no sense for a few hundred watts. The new state laws carve out a simpler category. Typically they:

1. Cap the size, usually at 1,200 W of output.
2. Require certification by a nationally recognized testing laboratory, increasingly to UL 3700, the first US test program written for plug-in solar.
3. Exempt the device from interconnection agreements and utility fees.
4. Replace approval with, at most, a notification form.

The details differ in ways that matter. Vermont gives tenants a defined notice process. New Jersey bars landlords and HOAs from banning the devices outright. California’s law leaves lease terms in force. New Hampshire’s law waits on a state-recognized safety standard before use is allowed. Each state page lists the exact rules with links to the statute.

Is it for you?

Plug-in solar makes the most sense if you:

• Pay a high electricity rate. In the EIA’s 2026 data, residential prices run from about 12 cents per kWh in North Dakota to over 32 cents in California and 46 cents in Hawaii.
• Have a railing, wall or patio that gets several hours of direct sun, ideally facing between southeast and southwest.
• Have an always-on load of a couple of hundred watts during the day, which most homes with a fridge do.
• Live in a state with a plug-in law, or have confirmed with your utility that it is allowed.

It makes less sense on a north-facing balcony, under heavy shade, or where your lease or building rules forbid fixtures on the railing. Read is plug-in solar worth it for payback by state, and is plug-in solar safe before you plug anything in.