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The US’s first UL 3700 balcony solar microinverter is here
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- DeepHorus
Hoymiles has launched the HiFlow Pro, the first microinverter in the United States to receive UL 3700 certification, North America’s new safety standard for plug-in balcony solar systems. This milestone marks a significant step for the residential solar industry, as it provides a clear compliance path for manufacturers and a consistent safety benchmark for utilities and consumers. The product is designed to work with portable solar panels that plug directly into standard electrical outlets, offering a low-cost alternative to rooftop arrays.
Plug-in balcony solar has already gained substantial traction in Europe, particularly in Germany, where it enables renters and homeowners alike to generate their own electricity without major installations. In the United States, the technology has faced legal hurdles because existing regulations were crafted for larger rooftop systems. UL 3700, published in December 2025, directly addresses this gap by establishing the first North American safety standard specifically for plug-in photovoltaic systems.
As of July 2026, eight states—Utah, Maine, Virginia, Maryland, Colorado, Connecticut, Vermont, and New Hampshire—have signed plug-in solar legislation into law. New York's legislature has also passed a balcony solar bill, still awaiting the governor’s signature. Nearly 30 states have introduced related legislation, signaling growing regulatory support for this technology.
The HiFlow Pro microinverter incorporates maximum power point tracking (MPPT) to optimize energy harvest under changing conditions, with static efficiency rated at 99.8% and dynamic efficiency at 99.5%. It operates at low voltage, weighs only 4 pounds, and has a NEMA Type 6 enclosure rating, allowing operation in temperatures from -40°F to 149°F. The device can be set up via Bluetooth and Wi-Fi in under a minute.
A single 360W HiFlow Pro can produce up to 721.08 kWh annually, and up to four units can operate in parallel on separate outlets, achieving a total output of 1,200 watts and 2,403 kWh per year. However, state and local regulations may limit expansion capabilities. Hoymiles emphasizes that rigorous testing, including 250,000 hours of reliability tests, ensures product durability.
“By introducing the first UL 3700-compliant plug-in microinverter in the US, we’re not only launching a new product – we’re helping establish a new benchmark for residential solar that combines simplicity, safety, and high performance,” said Hoymiles CEO Dr. Yang Bo. This certification addresses safety concerns such as preventing backfeeding electricity into the grid during outages, which could endanger utility workers.
Looking ahead, balcony solar is unlikely to power entire homes, but it offers a practical entry point for renters, apartment dwellers, and homeowners unable to install rooftop panels. As more states adopt supportive legislation, the market for plug-in solar is poised to expand. The HiFlow Pro’s UL 3700 compliance removes a key barrier, potentially accelerating adoption across the country.
