A three-phase hybrid inverter combines PV conversion, battery charging and discharging, grid interaction and backup output in one unit. The low-voltage (48V-class) version adds a design choice that affects the whole system: the battery bus runs at roughly 51.2V instead of several hundred volts.
Quick summary
- Best fit: homes and light commercial sites with a three-phase supply that want solar, storage and backup in one system, and prefer 48V-class batteries.
- Main trade-off: at 48V, battery current is high. Cable sizing, battery-bank paralleling and protection deserve more attention than on high-voltage designs.
- Distinguishing features (per the HB3 series datasheet): 100% three-phase unbalanced output, typical 10 ms transfer to backup, an independent generator interface, and up to 15 units in parallel.
- Before ordering: confirm battery-side limits for your chosen power rating on the product page. They differ by model.
Why choose a low-voltage three-phase hybrid inverter?
High-voltage battery systems reduce current and cable losses, but they bring their own constraints: the battery must be a matched high-voltage stack, expansion is usually modular within one vendor's ecosystem, and servicing a high-voltage DC string requires stricter procedures. Low-voltage systems trade the other way:
- Touch-safer battery bus. A 48V-class bus is generally easier to handle during commissioning and maintenance.
- Flexible battery expansion. Standard 51.2V modules can be paralleled to scale capacity, for example the 51.2V-100Ah rack-mount battery or the 51.2V-230Ah rack-mount battery.
- Chemistry choice. The HB3 series datasheet states compatibility with lead-acid, lithium and gel batteries with a built-in battery management function. This is useful when retrofitting an existing bank.
- Familiar retrofit path. The datasheet lists PV system renovation among the application scenarios.
The cost is current. The table further below shows the arithmetic.
Key features, and what each means in practice
100% three-phase unbalanced output
Many residential three-phase hybrid inverters cap the load on a single phase at a fraction of rated power. The HB3 series datasheet lists support for 100% unbalanced output. In a house this matters when a single-phase load (an induction hob, a water heater, a well pump) runs on one phase during an outage. Check which phase your backup circuit is wired to, and confirm the single-phase limit for your exact model on the product page.
UPS-class switching
The datasheet gives a typical transfer time of 10 ms and describes three output modes: grid-connected, off-grid and bypass. Ten milliseconds is typical for a hybrid design, but it is not a guarantee that every device will ride through. Sensitive equipment such as servers or medical devices should still have its own UPS.
Working modes
The datasheet lists Self Use, Selling First, Back-Up Mode, Force Time Use and a Composite Pattern. A practical way to choose:
- Self Use: maximises on-site consumption. Usually the best starting point where export tariffs are low.
- Selling First: prioritises export. Suitable only where the feed-in rate justifies it and local rules allow it.
- Back-Up Mode: keeps the battery reserved for outages. Sensible in areas with an unstable grid.
- Force Time Use: charges or discharges in scheduled windows, which suits time-of-use tariffs.
Battery care features
Two features target battery lifetime. The first is a battery soft start, which avoids closing impulse current on the DC side. The second is a charge/discharge current conversion with low ripple, which the datasheet presents as a way to improve battery life. SUNOHOO's datasheet compares both against a "general product". I recommend asking for the underlying test data if ripple is a deciding factor for your project.
Generator interface, anti-reflux and grid adaptation
An independent multi-function generator interface lets a diesel or gas generator be integrated without extra switching hardware. Two anti-reflux functions help where export to the grid is restricted. The datasheet also states support for normal operation under weak-grid conditions, which is relevant in rural areas with voltage fluctuation.
Parallel operation
Up to 15 units can be paralleled, with split-phase group grid support. This is how a site grows from household scale toward small commercial loads. For larger systems, see the small industrial and commercial hybrid inverter (29.9kW–63.5kW).
Specifications at a glance
The values below come from the HB3 series datasheet for the 15.5kW reference model. They show the platform's PV-side and AC-side capabilities. Battery-side values for the 48V models are on the product page, and specifications are subject to change without notice.
| Parameter | Value | Why it matters |
|---|---|---|
| Rated output power | 15,500 W (17,050 VA max apparent) | Top of the 5–15.5 kW range |
| AC output | 220/380 Vac or 230/400 Vac, 3L+N+PE, 50/60 Hz ±5 | Covers common European and Asian grid standards |
| Max PV input power | 31,000 W | Allows PV oversizing of roughly 2:1 relative to rated AC |
| Max PV voltage / start voltage | 1000 Vdc / 120 Vdc | Low start voltage extends the generating day |
| MPPT voltage range | 120–850 Vdc | Flexible string length design |
| PV max input / short-circuit current | 30A+30A / 34A+34A | Check against your module's Isc |
| Efficiency | 98.2% max PV conversion; 97.5% European; MPPT up to 99.9% | Manufacturer-stated figures |
| Power factor / THDi | >0.99 at rated power (adjustable 0.8 leading to 0.8 lagging) / <3% | Grid-code friendliness |
| Off-grid overload | <110% continuous; 110–120% for 1 min; >120% for 10 s | Motor start-up headroom |
| Environment | IP66; −25 °C to 60 °C (derating above 45 °C); up to 4000 m (derating above 2000 m) | Outdoor installation; plan for derating in hot or high sites |
| Communication | RS485 / CAN / DRM standard; optional 4G / WIFI / GPRS | Battery BMS link and remote monitoring |
| Size (W×D×H) / mounting | 590 × 200 × 488 mm / wall-mounted | Needs a sturdy wall and ventilation clearance |
| Warranty | 5 years standard; 10 years optional | Confirm terms in your contract |
The engineering point that matters most: battery current at 48V
Current equals power divided by voltage. On a nominal 51.2V bus, the DC current needed to deliver a given power is large. The estimates below ignore conversion losses (real current is somewhat higher) and are simple arithmetic, not product specifications.
| Continuous power | Approx. DC current |
|---|---|
| 5 kW | about 98 A |
| 8 kW | about 156 A |
| 10 kW | about 195 A |
| 15.5 kW | about 303 A |
What this means for system design:
- Battery modules must be able to deliver the current together. A single 100Ah module with a modest continuous rating will limit a large inverter. Paralleling modules shares the load, so the number of modules is set by power as well as by energy (kWh).
- Cable and busbar sizing is a safety item. Use correctly rated DC cable, short runs, properly torqued lugs and DC-rated fuses or breakers. Voltage drop and heating at these currents are real.
- Back-up peak loads need margin. The overload window in the table above helps with motor starts, but the battery must be able to supply the surge too.
- Often, you will not run at full power. A household rarely draws its inverter's rated power continuously, so many sites only need to design for the realistic peak. Measure your load profile instead of sizing from the nameplate.
A practical sizing sequence
- List critical loads and their starting currents (pumps, compressors, air conditioners).
- Choose the inverter rating from the largest realistic simultaneous load plus margin, and check the single-phase limit if backup loads sit on one phase.
- Size PV within the input power, voltage and current limits. Verify string open-circuit voltage at your coldest expected temperature stays below 1000 Vdc.
- Size the battery for both energy (hours of backup or daily shifting) and power (the module count needed to meet the DC current).
- Plan communication. Confirm the battery BMS protocol matches the inverter's RS485/CAN settings before purchase.
- Check local grid rules for export limits, certification requirements and metering, and set the anti-reflux function accordingly.
When this inverter is not the right choice
- Single-phase supply: choose a single-phase model such as the single-phase hybrid inverter (10kW–12kW) or the single-phase hybrid inverter (3kW–8kW).
- High-voltage battery preference: see the three-phase hybrid inverter (8.5kW–30.5kW).
- Very high continuous power with a small battery: at 48V, current limits can make a high-voltage design the more economical option.
Installation and commissioning checklist
- Mount on a wall that can carry the unit's weight, keeping clearance around the enclosure. Plan for derating if the site is hot, above 2000 m, or in direct sun.
- Install current transformers (CT) on the correct phases and in the correct direction. Wrong CT placement is a common cause of incorrect export control and metering readings.
- Separate the backup (emergency) circuit from the grid-connected loads at the distribution board, as shown in the application diagram.
- Set the battery type and charging mode (three-stage, equalisation or self-adaptive BMS) to match the battery manufacturer's instructions.
- Connect the remote monitoring module if needed and confirm the settings before leaving the site.
- Have a qualified electrician carry out and sign off all work in accordance with local regulations.
About SUNOHOO
Zhejiang SUNOHOO Technology Co., Ltd is a subsidiary of Zhejiang SUNOREN Solar Technology Co., Ltd (Stock Code: 603105). According to the company website, it offers off-grid photovoltaic energy storage, hybrid energy storage, portable power stations and home inverter series, with 1400+ projects, a team of 400+ and 160+ R&D patents. You can read more on the company profile, the technology and R&D page, and the service and FAQ page. Browse the full household energy storage range and the energy storage batteries to see how inverters and batteries are matched.
Frequently asked questions
Can it work with lead-acid batteries, not only lithium?
The HB3 series datasheet states compatibility with lead-acid, lithium and gel batteries. Always follow the battery manufacturer's charging parameters, and confirm the configuration with SUNOHOO's team for your specific model.
Can I use it outdoors?
The datasheet lists an IP66 protection degree and an operating range of −25 °C to 60 °C, with derating above 45 °C. Even so, shaded and ventilated mounting positions help keep the unit at full output on hot days.
Can I add a generator?
Yes. The datasheet describes an independent multi-function generator interface with intelligent switching, so no separate transfer hardware is listed as required. Confirm generator size and start/stop settings with your installer.
Can I scale the system later?
The datasheet states that up to 15 units can run in parallel. Battery capacity can be expanded by adding compatible modules, within the limits of the inverter and battery BMS.
