SMA Sunny Tripower X 25 kW Three-Phase 3 MPPT Inverter
25 kW three-phase string inverter SMA Sunny Tripower X, top size in the series: 3 independent MPPTs, generator up to 37.5 kWp, European efficiency 98.0%.
The System Manager function manages up to 5 SMA inverters and one meter, for systems up to 135 kVA, without an external datalogger. IP65 category C5, DC switch-disconnector, SMA ArcFix and I-V diagnosis as standard.
The SMA Sunny Tripower X 25 (STP 25-50) inverter is the top size in the X series: a 25 kW three-phase string photovoltaic inverter with 3 independent MPPTs and a generator of up to 37,5 kWp. It is designed for commercial and industrial low-voltage systems, often in multi-inverter configurations, where a device is needed that also acts as the control hub for the entire system.
An inverter that acts as a control center
The integrated System Manager function turns the inverter into the brain of the system: it monitors and parameterizes up to 5 SMA inverters and an energy meter, for a total power of 135 kVA, with direct access to Sunny Portal powered by ennexOS. Commissioning is centralized for all devices, parameterization is performed remotely, and active and reactive power control is handled by SMA Dynamic Power Control. On a 100 kWp system made up of four STP 25-50 units, this means no datalogger, no data cabinet, and only one IP address to manage. Above 135 kVA or six devices, an SMA Data Manager M is used.
STP 25-50 technical specifications
| Rated AC power (230 V, 50 Hz) | 25.000 W |
| Rated / maximum apparent power | 25.000 VA / 25.000 VA |
| Maximum PV generator power | 37.500 Wp STC (DC/AC ratio 1,5) |
| Maximum input voltage | 1.000 V |
| MPPT range / rated voltage | 430-800 V / 580 V |
| Minimum / start-up voltage | 150 V / 188 V |
| Independent MPPTs / strings per MPPT | 3 / 2 |
| Usable current per MPPT / short-circuit current | 24 A / 37,5 A |
| Rated / maximum output current | 36,2 A / 36,6 A |
| AC connection | Three-phase 3-(N)-PE, 220/380 - 230/400 - 240/415 V |
| Maximum / European efficiency | 98,2% / 98,0% |
| System Manager | 5 SMA inverters + 1 meter, up to 135 kVA |
| Standard protections | DC disconnector, grid and ground fault monitoring, DC polarity reversal, all-current sensitive RCMU, SMA ArcFix AFCI, I-V diagnosis |
| Protection rating / corrosion | IP65, category C5 (IEC 61701) |
| Operating temperature | -25 °C / +60 °C |
| Connections | DC SUNCLIX, spring-cage AC, Ethernet (2 ports), WLAN, SMA and SunSpec Modbus, Speedwire, multifunction relay, 6 digital inputs |
| Dimensions (W x H x D) / weight | 728 x 762 x 266 mm / 35 kg |
| Warranty | 5 years, extendable to 10, 15 or 20 years |
| Certifications | CEI 0-21 and CEI 0-16, EN 50549-1/-2, IEC 62109-1/-2, CE |
Long strings: the constraint of the large size
The MPPT window of the 25 kW starts at 430 V, the highest value in the X series. This is the downside of the power rating: long strings are required, approximately from 14-15 modules upward with cells of about 34 V Vmp, and fragmented roofs with small pitches become difficult to serve without wasting trackers. On irregular roofs, it often performs better to install two STP 15-50 units than a single 25 kW.
On the AC side, the margin is limited: the rated current is 36,2 A and the maximum is 36,6 A, just 1% more. Unlike the smaller sizes, here the inverter practically always operates at the limit of its output current, and the AC line must be sized carefully, checking voltage drop and protection coordination.
CEI 0-21 requirements and documentation
At 25 kW, the system is well above the 11,08 kW threshold: an interface panel with calibrated SPI relay, three-phase interface device and test report are required, as well as a single-line diagram and declaration of conformity for the connection procedure. In multi-inverter systems, the panel is sized according to the total power and the number of downstream inverters: this is the item most often underestimated in quotations.
Frequently asked questions
Is it better to use a single STP 25-50 or two smaller inverters?
A single 25 kW costs less per installed kW and simplifies the AC panel, but it requires long, uniform strings. On roofs with multiple pitches and different orientations, two 12 or 15 kW inverters offer six MPPTs instead of three and make up the price difference through production.
How many inverters can I manage with the System Manager?
Up to 5 SMA inverters plus one energy meter, for a maximum total of 135 kVA and 6 devices overall. Commissioning and parameterization are centralized on Sunny Portal powered by ennexOS.
What is generator I-V diagnosis?
It is a measurement of the current-voltage curve of the strings performed by the inverter itself: it makes it possible to identify degraded modules, oxidized connections or permanent shading without going up on the roof with a curve tracer. On systems of tens of kWp, it is the diagnostic tool that saves the most maintenance hours.
Does SMA ArcFix replace emergency shutdown?
No. ArcFix is arc fault protection (AFCI): it detects the arc and stops feed-in before a fire can start. Module-level emergency shutdown, when required by the fire brigade or the specifications, is implemented with rapid shutdown devices installed on the DC field.
Can the 5-year warranty be extended?
Yes, SMA offers extensions to 10, 15 or 20 years that can be purchased separately, generally within a defined period from commissioning. On a commercial system, the 10-year extension is the most frequent choice, because it covers the investment payback period.
