---
title: "SMA Solar Sunny Island X SI50-20 Off-grid Inverter: Specs & Datasheet | ComparePV"
description: "SMA Solar Sunny Island X SI50-20 50 kW off-grid inverter. Specs: 97.2% European efficiency, 980 V max DC input, 104.0 kg, 10 yrs warranty."
source: "https://comparepv.com/inverter/sma-solar-sunny-island-x-si50-20"
updated: 2026-01-16
---

# SMA Solar Sunny Island X SI50-20


## Identity

- **Manufacturer:** SMA Solar
- **Model:** Sunny Island X SI50-20
- **Series:** Sunny Island X
- **Rated AC power:** 50 kW
- **Type:** Off-grid
- **Phases:** Three-phase
- **Battery port:** yes


## How it compares

Compared against 243 inverters from 30 to 100 kW. Ranks are within that class.


| Measure | This inverter | Class median | Standing | Rank in class |
| --- | --- | --- | --- | --- |
| European efficiency | 97.2% | 98.2% | Weak - bottom 5% | 154 |
| MPPT trackers | - | 4 |  |  |
| Max DC input voltage | 980 V | 1100 V | Weak - bottom 7% | 211 |
| Weight per kW | 2.1 | 1.1 | Weak - bottom 9% | 205 |
| Warranty | 10 yrs | 5 yrs | Strong - top 17% | 8 |


## Specification


### AC output

- **Rated AC power:** 50 kW
- **Max apparent power:** 50.00 kVA
- **Phases:** Three-phase
- **Nominal AC voltage:** 400 V
- **Max AC current:** 101.0 A
- **Grid frequency:** 50 Hz
- **Power factor:** 1 at rated power; adjustable displacement PF: 0 (overexcited) to 0 (underexcited)


### PV input

- **Max DC input power:** 51.00 kW
- **Max DC voltage:** 980 V
- **MPPT voltage range:** 200 to 980 V


### Efficiency

- **European efficiency:** 97.2 %
- **Max efficiency:** 98.0 %


### Battery

- **Battery port:** Yes
- **Battery voltage:** 200–980 V (DC battery connection; at 400 VAC)
- **Max charge current:** 150.0 A
- **Max discharge current:** 150.0 A
- **Grid-forming:** Yes


### Physical

- **Dimensions:** 837 × 772 × 444 mm
- **Weight:** 104.0 kg
- **Enclosure:** IP65 (NEMA 4X)
- **Cooling:** forced-air
- **Noise:** 69 dB
- **Operating temperature:** -25 to 60 °C
- **Max humidity:** 95 %


### Connectivity and protection

- **Interfaces:** Wi-Fi, Ethernet, Display
- **Protocols:** Modbus TCP, Speedwire, Wi‑Fi
- **Protection:** Surge protection


### Warranty and certificates

- **Warranty:** 10 years
- **Certifications:** IEC 62109-1 (protection class I, referenced), IEC 60664-1 (overvoltage category DC II / AC III, referenced), IEC 61643-11 (surge arrester compliance, referenced), IEC 60529 (IP rating, referenced), UL 50E (NEMA rating, referenced), EU-RED Cybersecurity Directive (EN 18031-1), ETSI EN 303 645, ISO 27001 (cloud hosting, Sunny Portal powered by ennexOS), EU NIS2 Directive (referenced)


### Pros

- **Up to 97.6% efficiency - premium class** - The SI50-20 achieves a peak efficiency of 97.6%, placing it among the top-performing battery inverters in the commercial segment. By comparison, the popular Victron MultiPlus-II 48V reaches approximately 96%, and the older Sunny Island 8.0H achieves 96.5%. A higher conversion efficiency directly translates to lower energy losses and improved annual system yield.
- **Scalable to 1 MW+ AC / 5 MWh** - The modular architecture allows parallel connection of SI30-20 and SI50-20 units to build systems exceeding 1 MW AC power and 5 MWh of battery capacity. This makes it one of the few battery inverters on the market capable of serving both residential installations and C&I-class BESS projects without changing the hardware platform.
- **IP54 + full output at 45°C without derating** - The IP54 ingress protection rating enables outdoor mounting - most competing battery inverters (including the Victron Quattro) are rated IP21/IP22 and require external enclosures. SMA's active cooling technology OptiCool guarantees full rated output up to 45°C ambient temperature without power derating, a critical advantage for industrial installations.
- **Integrated DC-DC converter - broad battery compatibility** - The built-in DC-DC converter eliminates the need for rigid voltage matching between the battery bus and the AC side. It enables seamless integration with a wide range of LFP and NMC batteries from multiple manufacturers (certified battery list available at sma.de), protecting the investor from dependency on a single battery chemistry supplier.
- **Made in Germany + 10-year warranty (5+5)** - SMA is a Tier-1 manufacturer (listed on the MDAX, with over 40 years in the market). The 10-year warranty (5 years base + 5 years upon registration) exceeds the standard 5-year warranties offered by most competitors in the commercial segment and simplifies OPEX calculations for externally financed BESS projects.


### Cons

- **SI X Connection Box required for backup operation** - The Sunny Island X has a single AC connector and does not include an internal Automatic Transfer Switch (ATS). Implementing backup power - whether in off-grid or UPS mode - requires purchasing a separate SI X Connection Box, adding installation cost and an additional failure point compared to solutions with a built-in ATS (e.g., Victron Quattro, older SI 8.0H).
- **Only two power ratings available: 30 kW and 50 kW** - The SI X series does not offer units below 30 kW, making it unsuitable for typical residential installations (5-15 kW). Investors seeking an SMA solution at this scale must turn to the older Sunny Island 4.4M-8.0H generation, which features a less flexible architecture and does not benefit from the new SI X platform.


## About this series

The SMA Sunny Island X series are **battery inverters** designed for operation in both grid-connected and **off-grid** systems - where energy independence, stable power supply, and flexible system expansion are key. A crucial feature is **modular scalability**, making it easier to adapt the installation architecture to growing energy consumption or subsequent investment phases. Unlike conventional PV inverters, Sunny Island X works with energy storage systems and manages intelligent charging and discharging to consumers.

Within this series, there are no MPPTs - it is a battery inverter, not a PV inverter. String optimization regarding shading and different orientations occurs on the PV inverter side. In practice, this translates to simpler hybrid and off-grid system design, where the high European efficiency means better performance in typical operating conditions in Poland.

Monitoring and diagnostics are available via **Sunny Portal powered by ennexOS** and the web interface, while cybersecurity solutions and RED compliance enhance safety. This series is intended for demanding residential and commercial installations, including backup power supply (with the appropriate connection box). **A 10-year warranty (5+5 after registration)** facilitates cost planning over the long term.


## Questions


### How does the SMA Sunny Island X differ from a standard PV inverter?

The Sunny Island X is a battery inverter, not a PV inverter. Its function is to manage the charging and discharging of an energy storage system rather than directly converting DC power from solar panels. It has no MPPT inputs - it operates alongside a separate PV inverter and takes responsibility for energy balancing across the entire system. This distinction is critical when designing hybrid and off-grid installations.


### Does the SMA Sunny Island X support fully off-grid (island) operation?

Yes, the Sunny Island X is designed for both on-grid and off-grid operation. In island installations it can independently generate an AC grid for connected loads and, when required, operate in parallel with a generator as an additional energy source. For off-grid configurations and backup power applications, the SI X Connection Box is required.


### What power ratings does the SMA Sunny Island X offer, and can the installation be scaled up in the future?

The series is available in two variants: the SI30-20 rated at 30 kW and the SI50-20 rated at 50 kW. Thanks to the modular architecture and the SI X Connection Box, up to 16 units can be connected in parallel, achieving a combined output of up to 480 kW (30 kW models) or 800 kW (50 kW models). This makes the system readily scalable to meet growing energy demand without replacing the entire installation.


### Which battery systems is the SMA Sunny Island X compatible with?

The Sunny Island X is compatible with a wide range of energy storage systems - including Pylontech, Tesvolt, and Sunvoda - thanks to its integrated DC/DC converter, which enables adaptation to varying battery voltage levels. The maximum charging current is 150 A. This flexibility allows integrators to select the most suitable storage solution for each project without being locked into a single cell manufacturer.


### Is additional equipment required to enable backup power functionality with the SMA Sunny Island X?

Yes. Basic on-grid operation without a backup function requires no additional components - the inverter can operate as a standalone unit. However, backup power functionality requires installation of the SI X Connection Box, which serves as the AC distribution point and houses the Hybrid Controller responsible for switching between operating modes. Without this unit, transitioning to island mode during a grid outage is not possible.


### What is the warranty on the SMA Sunny Island X, and how can it be extended?

The standard manufacturer's warranty is 5 years. Following product registration on the SMA platform, it can be extended free of charge by an additional 5 years, providing a total of 10 years of coverage. The device is manufactured in Germany and complies with the RED directive, which simplifies long-term operational cost planning for both residential and commercial installations.


## Datasheet

[Manufacturer datasheet (PDF)](https://comparepv.com/datasheets/inverters/sixx-20-ds-en-25-c8e8027d49bb.pdf)


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Source: https://comparepv.com/inverter/sma-solar-sunny-island-x-si50-20