Hoymiles HiFlow 391W Pro LV 120V 1-in-1 series Plugin Microinverter
- Plugin balcony solar, no permit required.
- Start voltage 22V , maximum current input 14A
- Plug-and-play design allows for fast and easy installation, reducing labor costs and installation time.
- Built-in Wi-Fi & Bluetooth module enables remote and local commissioning for different installation scenarios
- Works with the S-Miles Home app to customize your smart home solar system
- Integrated rapid shutdown and isolated transformer improve system safety and eliminate the risk of arc faults
The first US microinverter certified to UL3700, 3 parallel to 1200W, 120V plug-and-play.
HiFlow 391W Datasheet
Hoymiles HiFlow Pro LV 391W Plug-in Solar Microinverter
The Hoymiles HiFlow Pro LV 391W (HMS-391-1WM-LV) is a compact, single-panel plug-in solar microinverter designed for balcony, patio, garden, and small residential solar systems. Featuring 391 VA rated AC output, 120V grid compatibility, built-in Wi-Fi and Bluetooth, and 99.8% MPPT efficiency, it provides efficient solar energy conversion with convenient smartphone monitoring.
With 95.5% peak conversion efficiency, IP67 outdoor protection, integrated rapid shutdown, and fanless cooling, the HiFlow Pro LV 391W offers a practical solution for compact, grid-connected solar applications.
Key Features
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391 VA AC Output: Converts solar panel DC electricity into 120V AC power.
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Solar Panel Compatibility: Supports compatible 300W–510W+ PV modules.
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Plug-and-Play Design: Simplified connectivity for approved small solar installations.
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Built-in Wi-Fi & Bluetooth: Monitor solar production through the Hoymiles S-Miles Home App without an external DTU.
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High Efficiency: 95.5% peak conversion efficiency and 99.8% nominal MPPT efficiency.
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Outdoor-Ready: IP67 / NEMA 6 protection with quiet, fanless cooling.
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Integrated Safety: Rapid shutdown and galvanically isolated transformer design.
Technical Specifications
General Information
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Brand: Hoymiles
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Series: HiFlow Pro LV
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Model: HMS-391-1WM-LV
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Product Type: Plug-in Solar Microinverter
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Rated Output: 391 VA
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Nominal AC Voltage: 120V
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Grid Frequency: 60 Hz
DC Input
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Recommended PV Module Power: 300–510W+
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Maximum DC Input Voltage: 65V
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MPPT Operating Voltage Range: 16–60V
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Start-up Voltage: 22V
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Maximum Input Current: 14A
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Maximum Short-Circuit Current: 25A
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MPPT Trackers: 1
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PV Inputs per MPPT: 1
AC Output
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Rated AC Output Power: 391 VA
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Rated Output Current: 3.26A
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Nominal Output Voltage: 120V
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Operating Voltage Range: 90–150V
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Nominal Frequency: 60 Hz
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Operating Frequency Range: 55–65 Hz
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Default Power Factor: >0.99
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Adjustable Power Factor: 0.8 Leading to 0.8 Lagging
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Total Harmonic Distortion (THD): <3%
Efficiency & Performance
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Peak Efficiency: 95.5%
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Nominal MPPT Efficiency: 99.8%
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Nighttime Power Consumption: <50 mW
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Cooling: Natural Convection (Fanless)
Communication & Monitoring
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Wireless Connectivity: 2.4 GHz Wi-Fi and Bluetooth
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Monitoring Platform: Hoymiles S-Miles Home App
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External DTU Required: No
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User Interface: LED Indicator and Mobile App
Physical & Environmental
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Dimensions (W × H × D): 7.17 × 6.46 × 1.18 in (182 × 164 × 30 mm)
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Weight: 4.0 lbs (1.8 kg)
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Enclosure Rating: IP67 / NEMA 6
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Operating Temperature: -40°F to +149°F (-40°C to +65°C)
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Cooling Method: Passive, Fanless
Connection & Safety
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AC Connector: Flex-S3 Field Connector
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Cable Gauge: 14 AWG
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Plug Type: Type B
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Transformer: Galvanically Isolated High-Frequency Transformer
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Rapid Shutdown: Integrated
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Listed Standards: UL 1741, UL 3700, IEEE 1547
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Cybersecurity Standard: ETSI EN 303 645
Applications
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Balcony Solar Systems: Compact solar generation for residential balconies where permitted.
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Patio & Terrace Solar: Small outdoor solar installations with compatible PV panels.
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Garden Solar Systems: Single-panel solar generation for garden spaces.
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Residential Solar Projects: Small grid-connected solar systems using approved installation methods.
Why Choose the Hoymiles HiFlow Pro LV 391W?
The Hoymiles HiFlow Pro LV 391W combines efficient solar conversion, smart wireless monitoring, compact construction, and outdoor-ready protection in one plug-in microinverter. It is an ideal choice for compatible small residential solar installations where grid connection is permitted.
Shop the Hoymiles HiFlow Pro LV 391W at Self2Solar and build your compact solar power system with confidence.
Downloads and Documentation
Datasheet
Hoymiles HiFlow Pro LV Datasheet
Installation Guide
Hoymiles HiFlow Pro LV Quick Installation Guide
Certification
Hoymiles HiFlow UL 3700 Certificate
Warranty
Hoymiles HiFlow Pro LV Warranty
About Hoymiles
Hoymiles is a global MLPE (Module Level Power Electronics) solution provider, specializing in module-level inverters and storage systems. With a vision of a clean, sustainable future, we strive to lead the smart energy industry through our rugged technology and reliable products.
With our driven engineer team, 1200+ global experts, and distribution & service network spanning North America, South America, Europe, Asia, Africa, and Oceania, Hoymiles has empowered homeowners and professionals in more than 100 countries and regions to join the journey to true open energy.
Frequently Asked Questions
What is the Hoymiles HiFlow Pro LV 391W?
The HiFlow Pro LV 391W (HMS-391-1WM-LV) is a single-panel plug-in solar microinverter that converts DC power from a compatible solar panel into nominal 120V AC electricity, with 391 VA rated output.
What solar panels are compatible with the HiFlow Pro LV 391W?
Hoymiles recommends commonly used PV modules rated from 300W to 510W or higher. The selected module must stay within the inverter's 65V maximum input voltage, 14A maximum input current, and 25A maximum short-circuit current.
Does the HiFlow Pro LV 391W require an external DTU?
No. Built-in 2.4 GHz Wi-Fi and Bluetooth support commissioning and monitoring through the Hoymiles S-Miles Home App without an external DTU.
Can I plug the HiFlow Pro LV 391W into a standard 120V outlet?
The inverter is designed for nominal 120V grid operation and includes plug-in connectivity. Installation must still comply with the manufacturer instructions, branch-circuit requirements, local electrical code, permitted connection methods, and utility interconnection rules. A standard household outlet is not automatically approved in every jurisdiction.
Can the HiFlow Pro LV 391W provide power during a utility outage?
No. It is a grid-connected microinverter and must shut down when the utility grid is unavailable. It does not provide independent backup power.
Can I connect a 500W solar panel to the HiFlow Pro LV 391W?
Yes, if the panel's voltage and current remain within the inverter's published DC input limits. The inverter's maximum rated AC output remains 391 VA, so excess potential panel output may be clipped.
Can multiple HiFlow Pro LV 391W microinverters be used together?
Multiple units can be used in a properly designed system, but the permitted quantity depends on the 3.26A rated output current per unit, branch-circuit rating, continuous-load rules, manufacturer instructions, local code, and utility limits. Do not assume every 120V outlet can support multiple units.
Can a battery connect directly to this microinverter?
No. The HiFlow Pro LV 391W is a grid-connected PV microinverter, not a battery inverter or charge controller. Battery storage requires a separately designed compatible storage system.
Can the HiFlow Pro LV 391W be installed outdoors?
The microinverter has an IP67 / NEMA 6 enclosure and fanless outdoor-rated construction. Connectors, cabling, receptacles, mounting, and the complete installation must also meet the manufacturer's instructions and applicable outdoor electrical requirements.
What warranty applies to the Hoymiles HiFlow Pro LV 391W?
The product is covered by the applicable Hoymiles manufacturer warranty. Review the current warranty document linked in Downloads and Documentation, and retain the invoice, model information, and serial number for warranty support.
Customer Installations
