New Hampshire joins growing contingent of states with laws on ‘plug-in solar’

On Thursday, Gov. Kelly Ayotte signed a bill establishing guidelines in New Hampshire law for the use of portable, socket-compatible solar devices.

The technology has seen broad adoption in Germany, where it is hailed as a democratizing and renter-friendly form of solar power. Smaller and typically cheaper than a standard rooftop array, some models may be installed at a standard wall outlet. But the features that make this form of solar energy accessible also create certain safety concerns that legislators said Senate Bill 540 was intended to address. 

Plug-in solar, as defined by the bill, is portable, connected to a home’s wiring through an impermanent plug such as a standardized or specialized socket, and used to offset on-site electricity use. The technology is sometimes called balcony solar, a reference to the scaled-down size and output that allow the tech to fit places like the German balcony railings it is known for adorning.

SB 540, from prime sponsor and Dover Democrat David Watters, caps the tech at one unit per metered customer, with a maximum power output for each device of 1,200 watts. It also requires balcony solar installed in New Hampshire to comply with safety standards set by a national testing laboratory, such as UL Solutions, which certifies electric appliances for consumer use. 

UL Solutions has outlined certain risks associated with balcony solar, such as its potential to overload a home’s circuitry, creating a fire hazard, or the risk that plugs could remain dangerously energized even when the device is not plugged in. The laboratory outlined safety features for the devices that it says address these and other risks, and has initiated a testing and certification program for the appliances.

More from this section

Coldest Julys in New Hampshire since 1895

Cities with the most UFO sightings in New Hampshire

Balcony solar proponents say a major benefit of the technology is the ability it confers for users to access solar power directly and without coordinating with their utility — as is required for larger, wired-in solar arrays through a contract known as an interconnection agreement. SB 540 protects that feature of balcony solar, prohibiting utilities from requiring interconnection agreements for the appliances. It also forbids utilities from imposing their own fees or requirements on customers’ use of the technology, or from requiring customers to seek utility approval to use one. 

But utilities still have an interest in knowing how much balcony solar is in use, in part to allow them to model demand, representatives said at hearings on the bill earlier this year. The bill allows the companies to create their own platforms for customers to document the size of their plug-in arrays once they are installed. It also protects utilities from liability if a customer’s plug-in solar device causes damage or injury.

The New Hampshire Department of Energy is tasked with communicating rules and requirements for balcony solar to the public. That includes spreading awareness that “connecting unlisted systems or connecting systems in a manner not in accordance with the state building code or manufacturer instructions may affect a customer’s homeowners or renters insurance coverage,” according to the bill.

The New Hampshire State Building Code Review Board is directed by the bill to adopt new codes reflecting national testing laboratories’ guidance on the portable arrays as that guidance is released.

Ayotte’s signing of SB 540 puts New Hampshire alongside a handful of other U.S. states that have adopted laws to regulate the technology, including three others in New England: Maine, Vermont, and Connecticut. Massachusetts and Rhode Island are also weighing such laws. The first state to adopt legislation on plug-in solar was Utah, which passed its own regulations in 2025.