Hoymiles launches first UL 3700 balcony solar inverter
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- Hoymiles launched the HiFlow Pro, the first US microinverter certified to meet UL 3700, North America's first safety standard specifically for plug-in photovoltaic systems, officially published in December 2025.
- UL 3700 was created because plug-in solar sends electricity backward through a home outlet — the opposite of normal power flow — creating a risk of energizing the grid during outages and endangering utility workers.
- 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 passed a bill still awaiting the governor's signature, and nearly 30 states have introduced related legislation.
- The HiFlow Pro delivers up to 721.08 kWh annually per 360W unit, with static MPPT efficiency of 99.8% and dynamic efficiency of 99.5%, according to Hoymiles.
- Up to four HiFlow Pro units can operate in parallel across separate outlets, allowing a system to reach 1,200 watts total and 2,403 kWh annual output, subject to state and local limits.
- The 4-lb microinverter sets up via Bluetooth and Wi-Fi in under a minute, carries a NEMA Type 6 enclosure rating, and operates from -40°F to 149°F after 250,000 hours of reliability testing, per Hoymiles.
- Balcony solar is already hugely popular in Europe, especially Germany, giving renters and apartment dwellers a lower-cost alternative to conventional rooftop arrays.
Why it matters: With UL 3700 now in place and eight states already on board with plug-in solar laws, renters, apartment dwellers, and homeowners barred from rooftop installs finally have a code-compliant product path to generate their own electricity. Hoymiles CEO Dr. Yang Bo called the launch 'a new benchmark for residential solar,' and the HiFlow Pro's parallel scalability up to 1,200W gives small-space adopters room to grow without waiting for a conventional rooftop permit.
