Over the next few months, competition will take care of cost parity sooner rather than later and prices in the United States are likely to eventually resemble those in Europe’s more mature plug-in solar market.

Utah became the first US state to pass legislation allowing portable solar generation devices in May 2025. Maryland, Maine, Colorado, Connecticut, Vermont, Virginia, New Hampshire have since followed. Several others are also in the process of legislating, with California, Massachusetts, New York and New Jersey at advanced stages.

Renters, farm workers and any homeowner conscious of their electricity costs are ideal targets for plug-in solar, said Bentham Paulos, senior research associate for Clean Energy States Alliance (CESA). It remains to be seen how the business model will develop in the United States, but Paulos expects it to dovetail with rooftop residential solar for the moment before it branches out as a full consumer product.

“You can buy it at the store or online, but it’s not easy to ship around big silicon solar panels,” he said. “The distribution will be important. I think, frankly, that rooftop solar installers will be the first to distribute them because they already have warehouses full of solar panels and they have trucks so they can bring the panels to people’s houses. Maybe they’ll even plug it in. Eventually, we’ll get to the point where the big retailers will have them on the shelves.”

Some people are using portable power systems with flexible solar panels that can be attached to balconies using cable ties, but most of these systems are 12 V and cannot be plugged in at home, said Paulos, adding that installation was a teething problem for European plug-in solar, too. Sweden requires renters to notify their neighbors before installing balcony solar, for example. Landlords, community housing associations and renters will have to strike a workable balance in the United States.

“Another issue that’s pending is the UL certification,” said Paulos. Maine, New York and Vermont require a complete system UL3700 certification for entire plug-in solar installation components, and no vendor has achieved this yet. Many battery and inverter manufacturers are in the process of getting their UL3700 certification.

Inverters with 120 V output for plug-in systems are needed, according to Paulos. “There are plenty of inverter manufacturers and as more start putting products for plug-in systems, competition will increase and prices will go down further,” he said, adding that panels themselves are cheap and addressing inverter demand is key to cost reduction.

As states continue to enable plug-in solar, the CESA analyst said the solar industry’s competitiveness will kick in and inverter makers will step up and produce UL-certified, 120 V inverters for the US market in a matter of months.

Certified devices

Chinese manufacturer Hoymiles launched what it claims is the United States’ first UL3700 certified plug-in microinverter in July. Weighing 1.8 kg and small enough to resemble an internet router, each HiFlow Pro microinverter unit’s power output ranges from 360 W to 500 W and can be scaled up to 1,200 W (maximum of four units per system). Hoymiles said each unit offers a two-year payback period.

A spokesperson for the company told pv magazine it expects and welcomes competition in the plug-in microinverter segment, as it accelerates innovation and can help broaden consumer access to plug-in solar.

“Our focus is on building a strong product offering around safety, compliance, reliability and ease of installation, rather than competing solely on being first to market,” they said, adding that demand for plug-in systems has already been validated in Europe. “The experience in Europe gives us confidence that there is genuine consumer demand for this type of solution and that, as regulatory frameworks in the US continue to evolve, the market could follow a similar growth trajectory.”

The spokesperson said the company began its HiFlow Pro compliance work well before the market took shape. “The product is therefore the result of a deliberate, forward-looking strategy to address an emerging segment and evolving regulatory requirements, rather than a short-term response to market competition.”

In the end, plug-in solar is the industry’s response to consumer demand for low-cost convenience. “The affordability issue is really what’s driving a lot of this,” said Paulos, adding that the next phase in the plug-in solar rollout is to incorporate it into energy assistance programs for low-income households. “The whole point of plug-in solar is you do not have to be rich.”

Some organizations, like non-profit Bright Saver, are already working to bring plug-in solar to US households. Its balcony solar program has the tagline “Never choose between the planet and your wallet again.”

For a $29 monthly membership, householders can avail themselves of a balcony solar kit at cost price (currently this is $285.30 for a kit with one 180 W panel or $414.17 for a kit with two 180 W panels). Kits also include a Hoymiles 360 W microinverter, stainless steel zip ties for basic mounting, and a 15-foot power cord with a standard outlet plug, as well as a Y-cable in the two panel kits to connect them to the inverter.

Although an active membership is required to purchase the kit at cost price, there is no requirement to renew the membership once it expires. Bright Saver refers to it as a “membership” rather than a “subscription,” maintaining it is in place to support its advocacy work. Once a person purchases a kit, they are its outright owners.

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