SMA Sunny Tripower X 20 kW Three-Phase Inverter 3 MPPT
20 kW three-phase string inverter SMA Sunny Tripower X, 3 independent MPPTs, generator up to 30 kWp, nominal output current 29 A.
Maximum efficiency 98.2% (European 97.9%), integrated System Manager with Sunny Portal ennexOS and SMA Dynamic Power Control for dynamic regulation down to zero feed-in. IP65, ArcFix and DC disconnector as standard; requires interface panel with SPI.
The SMA Sunny Tripower X 20 (STP 20-50) inverter is a 20 kW three-phase string photovoltaic inverter with 3 independent MPPTs and a generator of up to 30 kWp. It is the benchmark size for low-voltage commercial photovoltaics: warehouses, refrigerated storage facilities, workshops and farms with constant daytime loads, where return on investment depends more on the share of self-consumption than on selling energy to the grid.
Zero export and dynamic regulation
When the grid operator limits or prohibits export, the Sunny Tripower X 20 works with SMA Dynamic Power Control: paired with an SMA Energy Meter installed at the point of common coupling, the inverter reads the flow to the grid in real time and continuously reduces active power down to zero export. The same logic manages reactive power with Q(U) curves or adjustable cosphi, required in various grid connections above 20 kW. All without external logic: the control is built into the inverter, which also acts as System Manager for the entire system.
STP 20-50 technical specifications
| Nominal AC power (230 V, 50 Hz) | 20.000 W |
| Nominal / maximum apparent power | 20.000 VA / 20.000 VA |
| Maximum PV generator power | 30.000 Wp STC (DC/AC ratio 1,5) |
| Maximum input voltage | 1.000 V |
| MPPT range / nominal voltage | 345-800 V / 580 V |
| Minimum / start 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 | 29 A / 36,6 A |
| AC connection | Three-phase 3-(N)-PE, 220/380 - 230/400 - 240/415 V |
| Maximum / European efficiency | 98,2% / 97,9% |
| Grid regulation | SMA Dynamic Power Control, zero export, Q(U), Integrated Plant Control |
| Standard protections | DC disconnector, grid and ground fault monitoring, DC reverse polarity, all-current sensitive RCMU, SMA ArcFix AFCI |
| Protection rating / corrosion | IP65, category C5 (IEC 61701) |
| Operating temperature | -25 °C / +60 °C |
| Connections | DC SUNCLIX, spring-cage AC, Ethernet (2 ports), WLAN, Modbus SMA and SunSpec, Speedwire, 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 |
The AC side: the part that is often underestimated
With 20 kW, the nominal output current is 29 A per phase and reaches 36,6 A during transients: the AC line, residual-current circuit breaker and cable cross-section must be sized based on that value and the actual length of the run, not on the nominal value. At this size, the interface panel with calibrated SPI relay, interface device and test report is also mandatory, because the power is well above the 11,08 kW threshold of CEI 0-21. The inverter’s internal protections (DC disconnector, RCMU, ArcFix) cover the device, not the interface with the distributor.
String sizing
The MPPT range starts at 345 V, the second highest in the series: long strings are required, roughly from 11-12 modules upwards with cells of about 34 V Vmp, and no more than around twenty to remain within 1.000 V at minimum winter temperatures. With six total strings (2 per MPPT) and 500 W modules, the permitted 30 kWp can be reached without overloading, while still taking into account the usable 24 A limit per tracker.
Frequently asked questions
How is zero export achieved with this inverter?
An SMA Energy Meter or a Sunny Home Manager 2.0 installed at the point of common coupling with the grid is required. The inverter reads the flow and reduces power in real time via SMA Dynamic Power Control, without third-party devices.
Which interface panel is needed for a 20 kW system?
A panel compliant with CEI 0-21 for systems above 11,08 kW, with a calibrated interface protection relay, three-phase interface device and signed test report. The panel must be selected based on the overall power of the system and the number of inverters connected downstream.
How many modules are needed to reach the full 30 kWp?
About 60-66 modules of 450-500 W, distributed over 3 MPPTs with 2 strings each. With high-current modules, it is advisable to check that each pair of parallel strings remains close to the usable 24 A per MPPT; otherwise, on clear days, a few percentage points of production may be lost.
Can it be installed outdoors in the sun?
The enclosure is IP65 and operates up to +60 °C, so outdoor installation is permitted. Under direct sunlight, however, the electronics enter thermal derating earlier: a shaded and ventilated position, for example under the roof pitch or on a north-facing wall, maintains full power for longer.
What maintenance does it require?
Cooling is forced convection with the OptiCool system and there are no filters to replace. Routine maintenance is limited to periodic checking of tightening, cleaning the fins and checking alarms on Sunny Portal, where SMA Smart Connected automatically reports anomalies to the installer.
