SMA Sunny Tripower X 12 kW Three-Phase Inverter 3 MPPT
12 kW three-phase string inverter from the SMA Sunny Tripower X series, with 3 independent MPPTs, up to 18 kWp of photovoltaic generator and integrated System Manager (monitoring and control of 5 SMA inverters and one meter, without an external datalogger).
Maximum efficiency 98,2%, IP65 protection with C5 corrosion category, DC switch-disconnector and SMA ArcFix arc-fault detection as standard. CEI 0-21 certified; above 11,08 kW, an interface panel with external SPI is still required.
The SMA Sunny Tripower X 12 (STP 12-50) inverter is a 12 kW three-phase transformerless string photovoltaic inverter, with 3 independent MPPT trackers and integrated System Manager function. It is the entry size of the X series: suitable for large residential systems, agricultural installations and initial commercial systems up to a 18 kWp photovoltaic generator.
12 kW in Italy: what CEI 0-21 requires
With 12 kW of nominal power, the system exceeds the 11,08 kW threshold set by CEI 0-21. From that value upwards, the interface protection integrated in the inverter is no longer sufficient: an external SPI is required, with a dedicated interface device (DDI), a relay calibrated according to the standard and a test report to be attached to the connection application submitted to the distributor. The coupling switch that SMA declares for simplified grid protection meets German requirements and does not replace the interface panel required in Italy: it must be budgeted together with the inverter. If, on the other hand, the system remains below 11,08 kW, the external panel is not required and it is worth considering a smaller size.
STP 12-50 technical specifications
| Nominal AC power (230 V, 50 Hz) | 12.000 W |
| Nominal / maximum apparent power | 12.000 VA / 12.000 VA |
| Maximum PV generator power | 18.000 Wp STC (DC/AC ratio 1,5) |
| Maximum input voltage | 1.000 V |
| MPPT range / nominal voltage | 210-800 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 |
| Nominal / maximum output current | 17,4 A / 20 A |
| AC connection | Three-phase 3-(N)-PE, 220/380 - 230/400 - 240/415 V |
| Maximum / European efficiency | 98,2% / 97,6% |
| Standard protections | DC disconnector, grid and ground fault monitoring, DC reverse polarity, all-current-sensitive RCMU, AFCI SMA ArcFix |
| Protection rating / corrosion | IP65, category C5 (IEC 61701) |
| Operating temperature | -25 °C / +60 °C |
| Noise level / night-time consumption | 59 dB(A) max / below 5 W |
| Connections | DC SUNCLIX, spring-cage AC, Ethernet (2 ports), WLAN, Modbus SMA and SunSpec, Speedwire |
| 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 |
How to size the strings
The MPPT range starts from 210 V, the lowest in the X series: this is the model that accepts the shortest strings, useful on fragmented roof sections or roofs with multiple orientations. As an indication, with modules of around 34 V Vmp and 41 V Voc, each string can include from 8 to 20 modules, remaining within 1.000 V in cold conditions.
Pay attention to the current: each MPPT accepts 2 strings but the usable current is 24 A. Two strings of latest-generation TOPCon modules, which reach 14-15 A of current at the maximum power point, exceed that value and the inverter limits production during peak hours. With high-current modules, it is advisable to distribute the strings across all three MPPTs, or knowingly accept slight summer clipping.
What is needed to complete the system
- Interface panel with SPI, DDI and test report, mandatory above 11,08 kW
- DC field panel with disconnectors, fuses and 1.000 V surge arresters if the strings come from long external routes
- Type 2 or type 1+2 DC surge arresters that can be integrated into the inverter (optional SMA kits)
- SMA Energy Meter or Sunny Home Manager 2.0 for self-consumption and grid feed-in limitation
- Roof or ground mounting kit, if the installation is not wall-mounted
Frequently asked questions
Is the Sunny Tripower X 12 sufficient to comply with CEI 0-21?
No, not on its own. The inverter is CEI 0-21 certified, but with 12 kW of power it exceeds the 11,08 kW threshold: the standard requires an external interface protection system, with a dedicated interface device and test report. The inverter alone covers the requirement only in systems that remain below that threshold.
How many panels can I connect to an STP 12-50?
The limit is a 18.000 Wp generator, i.e. approximately 36-40 modules of 450-500 W, distributed over 3 MPPTs with a maximum of 2 strings each. The 50% oversizing compared to 12 kW AC is provided for by SMA and improves yield during low-irradiation hours.
Can I add a storage battery?
The Sunny Tripower X is a pure photovoltaic inverter, without a battery input. Storage is added on the AC side with a dedicated battery inverter, which works alongside the existing photovoltaic system: this is the typical retrofit solution and does not require the DC field to be rebuilt.
Is an external datalogger required for monitoring?
No. The integrated System Manager function monitors and controls up to 5 SMA inverters and an energy meter, for a maximum of 135 kVA, with direct access to Sunny Portal powered by ennexOS. Only above those numbers is an SMA Data Manager required.
Does the inverter continue to operate during a blackout?
No. Like all grid-connected string inverters, it disconnects when the grid is unavailable. To have power during an outage, a battery and an inverter capable of forming an island grid are required.
