Last October, Colorado State Representative Lesley Smith, while visiting her husband’s family in Germany, observed a novel sight: a solar panel adorning the balcony of an apartment building, a common feature in a country that has embraced small-scale household solar with an estimated 4 million units installed. This simple yet effective technology involves connecting one or two solar panels, equipped with a microinverter, directly into a household electrical outlet, allowing individuals to generate clean energy from their patios or balconies to offset a significant portion of their electricity consumption. The relatively low cost of this equipment, often in the hundreds of dollars, and its ease of installation make it an attractive option for both homeowners and renters seeking to reduce their energy bills and environmental footprint. However, in the United States, a complex web of regulatory and market barriers has historically hindered the widespread adoption of this "balcony" or "plug-in" solar technology.

That landscape appears poised for a significant shift as lawmakers in 27 states, including Colorado’s Rep. Smith, have introduced legislation this year aimed at facilitating the adoption of plug-in solar systems. These measures seek to empower individuals to harness solar energy and subsequently lower their utility costs. Cora Stryker, co-founder of Bright Saver, a prominent advocacy group for plug-in solar, highlighted its potential in the Western United States, where it offers a pathway to tap into the region’s abundant solar resources while mitigating the impact of escalating electricity prices. Western states leading this legislative charge include Alaska, Washington, Oregon, Idaho, Wyoming, California, Arizona, Colorado, and New Mexico, although as of late February, bills in Washington, Arizona, Wyoming, and New Mexico had not advanced.

The impetus for this growing movement in the U.S. can be traced to Utah, which enacted the nation’s first plug-in solar law last year, a measure that passed unanimously. This pioneering legislation from Utah serves as a blueprint for many of the current state-level proposals. It effectively exempts plug-in solar devices from costly and time-consuming permitting requirements, such as the interconnection agreements typically mandated for rooftop solar installations. Furthermore, Utah’s law establishes wattage limitations for these systems, absolves utilities of liability for installations made by individuals, and mandates that the devices meet national electrical safety standards.

The philosophy underpinning Utah’s legislation, introduced by Republican State Representative Raymond Ward, is rooted in the principle of minimizing governmental obstruction to individual energy choices. "Everybody that wants one should be able to buy one," Ward stated, emphasizing his belief in enabling widespread access to this technology. In Germany, individuals utilizing balcony solar systems typically see their initial investment recouped within approximately five years, a timeframe Ward suggested could be even shorter for residents in states experiencing particularly high electricity rates, such as Alaska and California.

Representative Smith, a Democrat, anticipates that as state regulations become more accommodating, a greater number of manufacturers will develop and offer plug-in solar products, thereby simplifying the process for consumers to purchase and install these systems. Currently, she notes, readily available plug-in solar kits are not common in major retail outlets like Costco or Home Depot, despite considerable interest from constituents who are reportedly already seeking out or even building their own DIY plug-in kits. Smith expressed optimism that the passage of legislation in Colorado, and its subsequent adoption by other states, will stimulate the market and drive broader availability.

The inherent appeal of these proposed bills, according to Stryker, lies in their reliance on market-driven solutions rather than public subsidies or funding, a characteristic that could foster bipartisan support. "This is a market-driven solution," she asserted, adding, "We really just have to strip down regulations, make them make sense for these little systems, and then market forces will drive this."

While Utah’s groundbreaking law and the numerous bills inspired by it effectively address regulatory hurdles, plug-in solar technology also faces the challenge of establishing a robust and universally accepted product safety standard. UL Solutions, a prominent organization that certifies thousands of electrical products to ensure their safe use, plays a crucial role in this regard.

When Utah’s legislation was enacted in March 2025, a specific UL standard for plug-in solar devices was not yet in place. However, in January, UL released a preliminary standard encompassing safety and certification criteria for these devices. This new standard, which is currently active for certification purposes though not yet fully finalized, is a critical element for the plug-in solar bills being considered this year, as they all reference the need for UL or equivalent national safety certification. Although no plug-in solar products have undergone certification under this new standard yet, Ken Boyce, vice president of principal engineering at UL, confirmed that manufacturers can now submit their products for testing and certification.

Despite the progress in establishing a safety standard, some advocates, including Representative Ward and Ken Hutchings of CraftStrom, a Houston-based plug-in solar company, contend that the current iteration of the UL standard may be overly restrictive and could impede the widespread market adoption necessary for the technology’s success. Ward specifically pointed to a UL requirement that an electrician must be involved in the installation process, which, he argued, undermines the fundamental appeal of plug-in solar—the ability for users to simply connect the device and operate it akin to other household appliances. Hutchings echoed these concerns, noting that the standard’s limitations on home battery capacity and other aspects could create unnecessary costs and obstacles. CraftStrom intends to seek certification under the standard once it is finalized, but in the interim, they are certifying their products based on existing standards for their component parts, such as inverters.

"Done well, (the UL standard) could give regulators and utilities a clear framework and reduce uncertainty," Hutchings commented, adding a cautionary note: "Done poorly, it could constrain useful storage capacity and add cost and friction in ways that slow adoption of otherwise safe plug-in solar solutions." The ongoing refinement of these standards will be pivotal in determining the trajectory of plug-in solar technology in the United States, balancing safety with accessibility and market growth.