X3-ULT-19.9K
The Solax X3-ULT-19.9K is a 19.9 kW three-phase hybrid inverter from the X3-Ultra series, optimized to remain below the regulatory threshold of 20 kW. With 3 MPPTs, 6 string inputs, max DC current of 36 A per MPPT, PV oversizing up to 200%, HV storage up to 2.8 MWh, and EPS backup <10 ms.
The Solax X3-ULT-19.9K is a 19.9 kW three-phase hybrid inverter from the X3-Ultra series. Designed for commercial and industrial (C&I) applications that require high power with integrated storage, it is positioned between the 15K and 25K models of the same range, offering the same advanced 3 MPPT architecture with independent phase management.
Solax X3-ULT-19.9K Technical Specifications
| Nominal AC Power | 19.9 kW |
| Series | X3-Ultra |
| Number of MPPTs | 3 |
| Strings per MPPT | 2 (configuration 2/2/2) |
| 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) |
| Protection Rating | IP66 |
| Operating Temperature | -35°C to 60°C |
| Dimensions | 696 × 526 × 240 mm |
| Weight | 47 kg |
| Warranty | 10 years |
Why 19.9 kW?
The 19.9 kW size is specifically designed to stay below the 20 kW threshold which, in many European countries—including Italy—determines different regulatory regimes for grid connection and GSE procedures. This allows you to have the maximum possible power while remaining within the most favorable regulatory regime.
Frequently Asked Questions
Why did Solax create the 19.9 kW model instead of 20 kW?
The 20 kW threshold in Italy (and in many European countries) marks the boundary between different regulatory regimes: below 20 kW, the system falls under simplified connection procedures with many distributors, while above 20 kW, more stringent technical requirements apply (CEI 0-16, additional interface protections, etc.). The 19.9 kW model is optimized to stay below this threshold while maximizing available power.
Is the X3-ULT-19.9K different from the X3-ULT-15K?
Structurally identical (same dimensions, same 47 kg weight, same X3-Ultra chassis), the difference is in the nominal power: 15 kW vs 19.9 kW. The 19.9K allows PV generators up to ~40 kWp with 200% oversizing, compared to ~30 kWp for the 15K. Same 3 MPPT architecture, same HV storage capacity up to 2.8 MWh.
How many kWp of panels can be connected to the X3-ULT-19.9K?
With 200% oversizing, it is possible to connect up to about 40 kWp of photovoltaic generator. This configuration allows you to simultaneously charge the battery to 100% and supply 100% power to AC loads, maximizing the use of solar energy produced during peak hours of the day.
Is the X3-ULT-19.9K suitable for large warehouse installations?
Yes, it is one of the ideal applications. On warehouses with available surfaces from 30–60 kWp and a three-phase contract, the X3-ULT-19.9K with HV storage allows you to maximize daytime and nighttime self-consumption, optimize power demand from the supplier, and manage heavy loads such as compressors, machinery, and industrial air conditioning systems.
Is the X3-ULT-19.9K compatible with Solax T-BAT HV batteries?
Yes, the X3-Ultra series is compatible with Solax HV storage systems (voltage 180–800 V). With the TB-PBOX system, the maximum capacity reaches 2.8 MWh—ideal for industrial installations that require large energy reserves for arbitrage or nighttime operational continuity.
