The future of solar energy isn’t necessarily bigger or more expensive. It’s smaller, cheaper and easy to plug into a wall outlet.
Plug-in solar has become one of the most successful clean energy projects in Europe. In Germany, an estimated 4 million households now use small, portable, “balcony” solar panels that plug directly into a wall outlet. No electrician, permit, or rooftop required; just pick up a system at the local Lidl or Aldi, and assemble it yourself, IKEA style.
Adoption of these systems grew roughly 73% in 2024 alone, and it’s not hard to see why: a single-panel system can be as inexpensive as $300 and pay for itself in as little as four years in high-energy-cost states, according to the Clean Energy States Alliance. If that model takes hold in the United States, it could do something that rooftop solar has been unable to do: make solar ownership accessible to households who never thought it possible to utilize solar power to lower their bills.
But American homes are wired differently, and this distinction matters.
Unfortunately, it’s a mistake to think plug-in solar in the U.S. will roll out as simply as Germany’s model. U.S. residential electrical systems, codes and safety requirements were built around the assumption that power only flows from the grid into the home. Plug-in solar breaks that assumption by feeding power back into the household circuit through an ordinary wall outlet, creating complex engineering questions that must be answered to ensure household safety.
A 2025 UL Solutions white paper laid out these concerns plainly. Standard branch circuit breakers are sized to catch overloads from the grid side only — they can’t “see” a solar inverter also feeding current into the same circuit, which means a combined overload could go undetected. The same is true in Germany, but in the European Union, homes are wired at 220 volts instead of 120, which means wires and circuits can safely accommodate larger loads than in the U.S.
The attachment plug itself is a concern, too, as a plug is built to go dead the instant it’s unplugged, and UL’s testing found today’s grid-interactive inverters may continue to energize the prongs of a plug for two seconds after the plug is disconnected. And in lab tests, UL found that plugging a solar device into a Ground Fault Circuit Interrupter (GFCI) outlet — the same protection required near sinks, pools and outdoor receptacles — could in some cases damage the GFCI or let current keep flowing into a ground fault for a moment after it trips.
None of this means that plug-in solar is unsafe, but rather points to the fact that the technology must be adapted to American standards, and homeowners, installers and code officials need to do their homework before treating it like any other plug-in appliance you buy off the shelf.
Fortunately, the global enthusiasm for plug-in solar means that smart folks across the U.S. are turning their attention to these problems. UL Solutions, the same organization behind the safety testing for nearly every appliance in your home, is developing a dedicated standard for this technology.
The UL 3700, the Outline of Investigation for Interactive Plug-In PV (PIPV) Equipment and Systems, is designed to address the specific gaps identified above: touch-safe output circuits, compatible GFCI protection and overcurrent protection tailored to the connection these devices have to your home. This is exactly the kind of independent, rigorous safety procedure that should underpin any new class of consumer electrical product, and it’s why we believe the technology’s promise and the need for caution aren’t in conflict, they’re two sides of the same process.
New Hampshire has an opportunity to get this right from day one. It is now one of the first states in the nation to explicitly allow plug-in solar.
Senate Bill 540, signed into law on July 2 by Gov. Kelly Ayotte, created a clear, legal pathway for plug-in solar devices up to 1.2 kW in New Hampshire by building safety requirements directly into the bill: automatic shutoff during a power outage to protect lineworkers, mandatory compliance with the state’s existing fire and electrical codes and installation according to manufacturer instructions.
The bill drew engagement not just from clean energy advocates but from the utilities and the state’s building inspectors and code officials, who are responsible for enforcing these rules on the ground. Once there are devices that have been approved as being up to American safety standards, the state will amend the building code and interconnection regulations to make sure plug-in solar is accommodated.
The law was written to allow for the regulations to catch up with the technology, before plug-in solar starts to roll out across our state. Specifically, the law makes it clear that necessary changes to the building code and interconnection rules won’t occur until the UL 3700 standard has been completed, and we can be sure that compliant devices are being manufactured.
New Hampshire doesn’t have to choose between opening up solar access and protecting public safety. SB 540 shows that these goals can reinforce each other: a technology with the ability to expand energy affordability, paired with a deliberate, forward-thinking legislative process and an evolving national safety standard built to ensure success. SB 540 represents the best of how policymaking can be done well at the State House: bipartisan legislation that expands consumer choice while taking safety seriously from the very beginning. By pairing innovation with rigorous safety standards and clear regulations, New Hampshire has created a blueprint that other states can follow.
If you’re intrigued, hold off on buying: the kits already for sale online (including on marketplaces like Temu) are not yet certified to the coming UL 3700 standard. Renters should loop in their landlord first, since nothing in SB 540 stops a property owner from restricting these systems.
And once you do install one, you’ll need to notify your utility — and if you’re an Eversource customer, know that you currently won’t be credited (and may even be billed) for power your panel exports, so sizing it below your home’s baseline electricity use matters.
Kyana Burgess is the communication coordinator at Clean Energy NH, a nonprofit advocating for the adoption of clean energy initiatives.