What plug-in solar is
A plug-in solar system is a small solar setup, usually one to four panels with a built-in or attached microinverter, that is certified as a complete system to connect to your home through a receptacle. The power it produces is used by whatever is running in your home at that moment, which reduces the electricity you draw from the grid.
It is not a set of separate parts. Do not connect separately purchased panels and an inverter to an outlet. A certified plug-in system is evaluated as a whole, including its cord and plug, its inverter controls, and its installation instructions. A panel or an inverter that is certified on its own does not make the assembled combination approved for plugging in.
How it differs from other options
- Rooftop solar is larger and permanently wired. It is installed with permits and inspections and connected under an interconnection agreement with your utility. It can cover much more of your electricity use and may qualify for net metering where your utility offers it.
- Portable power stations are batteries with their own outlets. Many can be charged from solar panels, but they power only the devices plugged into them and do not supply your home's wiring.
- Backup power systems use batteries or a generator with a transfer switch or interlock to keep selected circuits running during an outage. A plug-in solar system is not a backup system. It stops supplying power when the grid goes down.
Where it can go, and what renters should check
Plug-in panels need a spot with as much direct sun as possible and little shade, such as a balcony railing, patio, yard, or wall. South-facing locations generally produce the most. Panels must be mounted securely enough for wind, and a balcony or railing must be able to carry the load.
The system's cord should reach the outlet the manufacturer's instructions specify. Do not use extension cords, power strips, or adapters unless the instructions specifically allow them.
If you rent, get your landlord's permission in writing before you install. Vermont requires tenants to give at least 10 days' notice, and New Jersey's law (from March 1, 2027) requires 14 days' written notice. Landlords in those states may set reasonable restrictions. Condominium and homeowners' association rules can apply too. Colorado (from January 1, 2027) and New Jersey (from March 1, 2027) limit associations' ability to prohibit qualifying devices.
Production and savings: an example with assumptions
Production depends on your location, the direction and tilt of the panels, shade, and temperature. A common rough estimate is:
Annual production (kWh) ≈ panel rating (kW) × peak sun hours per day × 365 × a loss factor
Example, using stated assumptions rather than a measured result:
- Panels rated 800 W in total (0.8 kW), facing south at a good tilt, with no shade
- 4.5 peak sun hours per day, a mid-range figure for much of the United States
- A loss factor of 0.8 for heat, wiring, inverter, and dirt
0.8 × 4.5 × 365 × 0.8 ≈ 1,050 kWh a year, more in summer and less in winter. At an example electricity rate of $0.18 per kWh, that is about $190 a year, but only if your home uses all of that power at the moment it is produced. Use the rate on your own bill.
Panels hung vertically on a railing, partly shaded, or facing east, west, or north can produce substantially less. Power your home is not using at that moment flows to the grid. Several state laws keep plug-in devices outside net metering or do not pay for exported power, so plan around the power you use. For an estimate for your address and orientation, try NREL's PVWatts calculator.
Certification, circuits, and instructions
Look for certification of the complete plug-in system, not just its parts. UL Solutions publishes UL 3700, the Outline of Investigation for Interactive Plug-In PV Equipment and Systems, which sets requirements for construction, performance, connectors, ground-fault and overcurrent protection, and features that promote safe installation. Some state laws name UL 3700 or a comparable standard. Ask the seller for the certification and check that it covers the system you are buying.
Circuits matter because household branch circuits are designed for power to flow one way, from your electrical panel to your outlets. UL Solutions explains that when a plug-in system feeds power into a circuit, the current from the utility and from the solar system together can exceed the wiring's rating without tripping the breaker. It also points to plug blades that can be energized when panels are in sunlight, and to ground-fault (GFCI) protection designed for one-way current. Mitigations it describes include dedicated circuits with unique receptacles and built-in overcurrent and ground-fault protection.
- Follow the manufacturer's instructions for which outlet and circuit to use.
- Do not use a circuit that already carries heavy loads, such as space heaters or kitchen appliances, unless the instructions allow it.
- Some states require a dedicated circuit or a licensed electrician above a set size. Maine, for example, requires both for systems over 420 W.
- Any change to your wiring or electrical panel calls for a licensed electrician and may need a permit.
What happens during a power outage
Plug-in solar systems are designed to stop supplying power when the grid goes down, and most of the state laws below require it. That protects utility crews working on the lines and people handling the plug, but it means the system will not keep your lights or appliances running during an outage.
Some products pair panels with a battery that can run devices plugged directly into it during an outage. That is a separate function, so check the product's certification and instructions for how it works. Never connect a generator or any other power source to your home's wiring through an outlet.
State requirements
The rules differ by state, and several laws take effect on future dates. The State Requirements guide below separates laws in effect from signed laws that start later, lists the size limits and conditions for each, and links to the official sources. If your state is not listed, the guide explains what still applies.
Frequently asked questions
Do I need an electrician?
It depends on your state and your system. Maine requires a licensed electrician and a dedicated circuit for systems over 420 W. Anywhere, an electrician can confirm that the circuit you plan to use is suitable, and any change to your wiring or panel calls for one.
Do I have to tell my utility?
Several states require it. Maryland requires notice before installation. Maine requires notice within 30 days for systems over 420 W. Virginia (from January 1, 2027) requires notice on the State Corporation Commission's form before installation, and California utilities may require online registration (from January 1, 2027). Utilities in Colorado, and in New Hampshire from January 1, 2027, may ask you to report the system. If your state is not listed, ask your utility before you install.
Will my meter work with plug-in solar?
Some meters do not handle power flowing back to the grid the way you might expect. Vermont allows plug-in systems only where a smart meter is installed. Connecticut's law requires a warning that generation above what your home is using at that moment is charged to you as usage unless your meter allows for net metering. Ask your utility about your meter before you install.
Will I be paid for power I send to the grid?
Usually not. Utah keeps plug-in devices outside net metering, and Vermont does not compensate exported power. Virginia's law (from January 1, 2027) requires devices that do not export to the grid. Size the system so that your home uses most of its output as it is produced.
Can I add a battery?
Some plug-in products include a battery or are designed to work with one. Use only a battery that is part of the certified system or that the manufacturer approves for it, and follow its instructions. Your state's output limit still applies.
I rent. Can I use plug-in solar?
Get your landlord's written permission first. Vermont requires 10 days' notice, and New Jersey (from March 1, 2027) requires 14 days' written notice; landlords there may set reasonable restrictions. Check your lease and any association rules as well.
What size system can I use?
Most state laws listed below cap output at 1,200 W, and Colorado's cap is 1,920 W. Some states add requirements at lower sizes: 420 W in Maine, and 391 W for certain listing rules in Maryland, Virginia, and Colorado. Choosing a size close to what your home uses during the day usually gets the most value from the system.