X3-ULT-15K
The Solax X3-ULT-15K is a 15 kW three-phase hybrid inverter from the X3-Ultra series, designed for commercial and industrial (C&I) applications. With 3 MPPT and 6 string inputs, maximum DC current of 36 A per MPPT, PV oversizing up to 200%, EPS backup <10 ms, compatibility with HV batteries up to 2.8 MWh, and a 10-year warranty.
The Solax X3-ULT-15K is a 15 kW three-phase hybrid inverter from the X3-Ultra series by Solax Power. Designed for commercial and industrial (C&I) applications that require high power, flexibility in PV field management, and large storage capacities, it is the reference choice for energy managers and professional installers on systems over 10 kW with integrated storage.
Why choose the Solax X3-Ultra for C&I applications?
The X3-Ultra series introduces 3 MPPTs with a total of 6 string inputs (2/2/2 configuration), with a maximum DC current of 36 A per MPPT — significantly higher than the X3-Hybrid G4 series inverters. The 200% PV oversizing allows up to 30 kWp to be installed on a 15 kW inverter, maximizing production and battery charging simultaneously. The 200% PV input is managed to ensure both 100% AC output power and 100% power for storage charging at the same time.
Solax X3-ULT-15K Technical Specifications
| Nominal AC Power | 15 kW |
| Series | X3-Ultra |
| Number of MPPTs | 3 |
| Strings per MPPT | 2 (2/2/2 configuration) |
| Maximum DC Voltage | 1000 V |
| Max DC Current per MPPT | 36 A |
| PV Input Oversizing | 200% |
| Battery Compatibility | HV (voltage 180–800 V) |
| Maximum Storage Capacity | up to 2.8 MWh with TB-PBOX |
| EPS Function | Integrated (<10 ms) |
| Per-phase Management | Independent (0 W – 10 kW per phase) |
| Micro-grid Function | Supported |
| Protection Rating | IP66 |
| Operating Temperature | -35°C to 60°C |
| Dimensions | 696 × 526 × 240 mm |
| Weight | 47 kg |
| Warranty | 10 years |
Independent Three-phase Management per Phase
A distinctive feature of the X3-Ultra is the independent power management for each phase: it is possible to adjust the power from 0 W up to 10 kW on a single phase, reducing three-phase imbalance and optimizing distribution to loads. This makes it ideal for C&I systems with significant single-phase loads connected to a three-phase grid.
Advanced EPS Backup and Micro-grid
The EPS switching time is less than 10 ms, ensuring power continuity even for sensitive loads (servers, UPS, industrial instrumentation). The micro-grid function simulates the grid and keeps string inverters active during off-grid periods, allowing the photovoltaic system to continue operating even in the absence of the public grid.
Frequently Asked Questions
How many batteries can be connected to the Solax X3-ULT-15K?
The X3-ULT-15K supports HV storage systems with voltage between 180 and 800 V. With the Solax TB-PBOX system, the maximum capacity reaches 2.8 MWh — a unique feature for a hybrid inverter of this size, making it suitable for large C&I installations with significant storage needs for energy arbitrage or nighttime self-consumption.
What is the difference between the X3-ULT-15K and the X3-HYBRID-15.0-D?
The 15 kW X3-Hybrid G4 is designed for the advanced residential market: 2 MPPTs, 30 kg weight, compact size, 10-year warranty. The X3-ULT-15K is intended for the C&I market: 3 MPPTs with 36 A per MPPT, 47 kg, independent per-phase management, storage capacity up to 2.8 MWh, EPS under 10 ms. It is a distinctly different product in terms of target and performance.
Is the X3-ULT-15K suitable for installations on industrial warehouses with heat pumps?
Yes, this is one of its ideal applications. The intelligent energy management supports optimization of self-consumption for highly variable loads such as heat pumps. Per-phase control allows heavy single-phase loads to be powered without penalizing the three-phase balance of the system.
Is the X3-ULT-15K compatible with Solax T-BAT HV batteries?
Yes, the X3-Ultra series is compatible with Solax HV batteries with a voltage range of 180–800 V. For high storage capacities, the TB-PBOX system allows battery racks to be connected for up to 2.8 MWh. Check the specific compatibility with the chosen battery model in the updated Solax technical notes.
Can the X3-ULT-15K operate in full off-grid mode?
The X3-Ultra’s micro-grid function allows the grid to be simulated and keeps the photovoltaic system active in the absence of the public grid. Loads are powered by the combination of PV production and battery discharge. It is not an inverter designed for pure off-grid systems, but the micro-grid function makes it suitable for installations with frequent blackouts or in areas with an unstable grid.
