X3-ULT-25K
The Solax X3-ULT-25K is the 25 kW three-phase hybrid inverter from the X3-ULTRA series for C&I applications. 3 MPPT / 6 strings, 200% PV oversizing, 2 independent battery ports, micro-grid function, parallel connection up to 10 units (300 kW / 2.8 MWh). Compatible with T58 and HS36 batteries. 10-year warranty.
The Solax X3-ULT-25K is the 25 kW three-phase hybrid inverter from the X3-ULTRA series, Solax Power’s solution dedicated to the commercial and industrial (C&I) segment. It combines photovoltaic energy conversion with advanced management of high-voltage storage systems, designed for factories, shopping centers, offices, and warehouses that require large-scale energy independence.
X3-ULTRA Series: the three-phase hybrid for C&I
Unlike residential hybrid inverters, the X3-ULT-25K is designed to handle power levels typical of commercial applications. With 3 MPPT and 6 string inputs and PV oversizing up to 200%, it maximizes system yield even in configurations with multiple orientations. The two independent battery ports allow scalable expansion up to 2.8 MWh in a multi-inverter setup (up to 10 inverters in parallel). The system is AI-ready for production and consumption forecasting, and supports micro-grid functionality to operate in island mode by activating string inverters even off-grid.
X3-ULT-25K Technical Specifications
| Nominal AC Power | 25 kW |
| Type | Three-phase hybrid inverter — X3-ULTRA series |
| Number of MPPT | 3 MPPT, 2 strings per MPPT (6 total inputs) |
| Max DC current per MPPT | 36 A |
| PV Oversizing | 200% PV input |
| Compatible batteries | Solax T58 (5.8 kWh) and T-BAT-SYS-HV-S3.6 (HS36, 3.6 kWh) |
| Battery ports | 2 independent ports |
| Inverter parallel operation | Up to 10 inverters in parallel (300 kW / 2.8 MWh) |
| Micro-grid function | Yes (simulates grid for string inverters) |
| EPS switching time | < 10 ms |
| Energy management | AI-ready, VPP, programmable ToU 7×24h |
| Protection rating | IP66 |
| Dimensions | 696 × 526 × 240 mm |
| Weight | 47 kg |
| Warranty | 10 years |
Ideal Applications for the X3-ULT-25K
Ideal for photovoltaic systems with storage in C&I contexts: industrial warehouses, shopping centers, hotels, offices, large farms. The system supports the ToU (Time of Use) function, programmable hour by hour 7×24h, to optimize charging and discharging based on electricity rates. The integrated zero export function prevents unwanted grid feed-in. The system is certified for integration with the Virtual Power Plant (VPP) via SolaX Cloud.
What is included in the supply?
- Solax X3-ULT-25K three-phase hybrid inverter
- Connection cables and accessories
- Installation manual
Frequently Asked Questions
What is the difference between X3-ULT and X3-Hybrid G4?
The X3-Hybrid G4 (from 5 to 15 kW) is designed for residential applications and small commercial systems. The X3-ULTRA (from 15 to 30 kW) is the C&I version, with higher power, 3 MPPT, 200% PV oversizing, two independent battery ports, micro-grid function, and support for multi-inverter parallel configurations up to 300 kW. It shares compatibility with the same HV batteries but is designed for industrial-scale applications.
How many batteries can I connect to the X3-ULT-25K?
The X3-ULT-25K has two independent battery ports. With T-BAT-SYS-HV-S3.6 (3.6 kWh) batteries, you can expand storage capacity using stackable modules up to 13 units per stack, manageable with the TB-PBOX for configurations up to 2.8 MWh in a multi-inverter setup. Always check the maximum allowed configuration with the specific technical manual.
Does the X3-ULT-25K support backup function in case of blackout?
Yes. The X3-ULT-25K features EPS (Emergency Power Supply) function with a switching time of less than 10 ms. In case of a grid outage, the inverter continues to power loads connected to the EPS output using the energy stored in the batteries, ensuring operational continuity for priority loads.
What is the micro-grid function of the X3-ULTRA?
The micro-grid function of the X3-ULTRA allows the hybrid inverter to simulate the presence of the electrical grid even during a blackout, enabling any string inverters present in the system to continue producing photovoltaic energy. Without this function, string inverters automatically disconnect in the absence of the grid. This feature is especially useful in C&I systems with multiple inverters and storage systems.
Is the X3-ULT-25K certified for CEI 0-21 and CEI 0-16?
Yes. The X3-ULTRA series is certified for grid connection according to Italian standards CEI 0-21 (for low voltage systems) and CEI 0-16 (for medium voltage systems, where applicable). Always check the certification version available at the time of order with the distributor, as regulatory revisions may require firmware updates.
