This is Sol-Ark's 18K-2P hybrid inverter — a 48VDC battery-based system built for whole-home backup and solar self-consumption, with enough continuous output to run large HVAC and well-pump loads. It suits homeowners and installers who need split-phase 120/240VAC power with battery backup and grid interaction.
The 18K-2P is a hybrid inverter: it operates grid-tied with battery backup, not an off-grid-only unit. It carries UL 1741 listing for interconnection and is referenced by the manufacturer as having multiple UL 9540 certifications at the system level (battery + inverter combination) — UL 9540 does not apply to the inverter as a standalone device. Note: If you would like to review the manufacturer Product Specifications, Warranty, Brochure, etc., for this system, please refer to the "Resources (System Manuals and Warranty)" Tab above on this page.
Critical Power & Interconnection Requirements
- AC Output: 120/240VAC and 120/208VAC, split-phase, 50/60Hz.
- Battery Input: 48VDC nominal. Compatible with Lead-Acid or Lithium battery technology.
- Continuous AC Output: 18,000W. Peak Surge Power (10s): 36,000W. Do not size continuous loads against the surge figure.
- Max. Passthrough Current (Grid to Load): 200A.
- Backup Transfer Time: 5ms.
- Max. STC Rated PV Power: 28,800W across 3 MPPT inputs. MPPT Operating Voltage Range: 150 - 425V.
- NOT compatible with 12V or 24V battery banks — 48VDC only.
- NOT an off-grid-only inverter — this is a grid-interactive hybrid platform with NEM grid sell-back support where permitted by the utility.
On split-phase 120/240V hybrid installs, neutral-ground bonding is the most common source of nuisance GFCI trips and failed inspections — the inverter's internal bonding must match whether you're in a Backup (off-grid) transfer state or Grid-tied state, and getting this wrong leaves you with floating neutrals or double-bonded neutrals depending on transfer status. Verify bonding configuration with a Digital Multimeter checking neutral-to-ground continuity in both grid-connected and backup modes before energizing loads — this prevents downstream GFCI nuisance tripping and protects against failed AHJ inspection. This directly ties to NEC Article 690 (PV system disconnects and rapid shutdown) and NEC 706 (energy storage systems); confirm your neutral-ground bonding strategy against your utility's interconnection standard before commissioning.
Key Benefits
- 36,000W (10s) surge rating starts large motor and compressor loads — HVAC compressors, well pumps — without a separate soft-start device.
- 5ms backup transfer time keeps sensitive electronics running through a grid outage.
- Supports both DC and AC solar coupling in the same platform — useful for retrofits onto existing grid-tie arrays.
- IP65 / NEMA 3R enclosure rating supports outdoor wall-mounted installation.
- CEC efficiency rated at 92.4%; max efficiency rated at 97.6%.
- Parallel RJ45 ports allow multiple units to be stacked for higher whole-home capacity.
Technical Table
| Spec | Value | Unit |
|---|---|---|
| Continuous AC Output | 18,000 | W |
| Peak Surge Power (10s) | 36,000 | W |
| AC Output Voltage | 120/240, 120/208 | V |
| Nominal Frequency | 50 / 60 | Hz |
| DC Battery Voltage (Nominal) | 48 | V |
| Max. Charge / Discharge Current | 255 | A |
| Max. STC Rated PV Power | 28,800 | W |
| MPPT Operating Voltage Range | 150 - 425 | V |
| Max. Usable Combined MPPT PV Power (per MPPT) | 125 | -- |
| Start-Up Voltage | 36 | V |
| Number of MPPT Inputs | 3 | MPPT |
| Max. Passthrough Current (Grid to Load) | 200 | A |
| Backup Transfer Time | 5 | ms |
| Max. Efficiency | 97.6 | % |
| CEC Efficiency | 92.4 | % |
| Enclosure Rating | IP65 / NEMA 3R | -- |
| Operating Temperature Range | -40 to +60 (-40 to 140) | °C (°F) |
| Weight | 34 x 19.4 x 12 | in (dims) |
Note: See "Resources (System Manuals and Warranty)" Tab above for full specifications.
Compatibility & Fitment
- Compatible battery chemistries: Lead-acid and Lithium.
- DC battery input: 48VDC nominal only. NOT compatible with 12V or 24V battery banks.
- BMS communication supported via CANbus / RS485 / MODBUS RTU for closed-loop lithium battery integration.
- Supports parallel stacking of multiple units via dedicated RJ45 parallel ports.
- Supports both AC-coupled and DC-coupled PV — suitable for new installs or retrofits onto existing solar.
- Multifunction GEN port supports generator input with Automatic Generator Start (AGS).
- Grid sell-back (NEM) supported where the local utility permits interconnection — NOT a standalone off-grid-only inverter.
- WiFi / 4G / Bluetooth / Ethernet dongle referenced by manufacturer for monitoring connectivity — confirm inclusion with your resources documentation; [NEEDS VERIFICATION] on whether the monitoring dongle ships standard or as an accessory.
Compliance & Environment Table
| Category | Listing / Code |
|---|---|
| Interconnection / Utility | UL 1741 |
| System-Level ESS (with certified battery) | Multiple UL 9540 Certifications |
| PV DC Disconnect Switch | NEC 690.5 (Ground Fault Detection), NEC 240.15 |
| PV Rapid Shutdown | NEC 690.12 |
| PV Arc Fault Detection | NEC 690.11 |
| Surge Protection | DC Type II / AC Type III |
| Enclosure Rating | IP65 / NEMA 3R |
FAQ
Can this inverter sell power back to the grid?
Yes. The Sol-Ark 18K-2P supports NEM (net energy metering) grid sell functionality where your utility allows it. Interconnection settings must match your local utility's requirements.
What battery voltage is required?
This unit is a 48VDC battery system. It is compatible with Lead-Acid and Lithium battery technology. It is NOT compatible with 12V or 24V battery banks.
Can I parallel multiple units together?
Yes. The 18K-2P includes dedicated parallel RJ45 ports for stacking multiple units. Refer to the manufacturer datasheet and installation manual for parallel configuration limits.
Is this UL 1741 listed for utility interconnection?
Yes, the 18K-2P carries UL 1741 listing for grid interconnection. It also carries multiple UL 9540 certifications when installed as part of a certified system-level ESS configuration with compatible batteries.
Does this inverter support both DC and AC solar coupling?
Yes. The 18K-2P supports both DC-coupled and AC-coupled solar, making it suitable for new installs and retrofit systems where existing grid-tie solar is already in place.
Warranty & Registration
Manufacturer warranty terms are referenced in the source documentation but the specific year duration is not machine-clear from the provided datasheet extract. [NEEDS VERIFICATION] on exact warranty year term. Register your unit through Sol-Ark's product registration channel referenced in their resources library. For full warranty language, refer to the "Resources (System Manuals and Warranty)" Tab above on this page. Closed-loop battery communication (CANbus/RS485/MODBUS with supported BMS) is required to maintain full warranty coverage on integrated battery performance claims — confirm your battery brand's closed-loop compatibility before commissioning.
