SMA Sunny Island SI6048-US Inverter (Grid-Tied or Battery)

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'SMASMA Sunny Island SI6048-US-10 Battery-based or Grid-Tied Inverter | 5750 watts | 48V | 60 Hz |Smartformer compatible

The SMA Sunny Island inverters are bi-directional battery-based inverter/chargers that can be used completely off-grid, or for battery backup in grid-tie systems with Sunny Boy grid-tie inverters.

The Sunny Island includes sine wave output power and low idle losses as well as a 100 A battery charger, and offers an integrated data monitoring system with battery disconnect.

Grid-Tie System Backup with AC Coupling

The Sunny Island can provide backup power for critical loads during utility grid blackouts. Combined with a Sunny Boy grid-tie inverter system and a bank of batteries, the Sunny Island will enable the PV array to power loads and charge the batteries. As an “AC-Coupled” system, the AC output of a Sunny Boy grid-tie inverter is connected to a critical-loads subpanel rather than the main panel. The subpanel is also connected to the AC output of one or more Sunny Island inverters. Under normal conditions, the power from the PV array and the Sunny Boy inverters passes through the subpanel and the Sunny Island’s built-in transfer switch on its way to the grid, without loss of efficiency. Likewise, grid power can pass the other direction when needed. During a power outage, the Sunny Island isolates itself from the grid and provides AC power to the emergency subpanel, drawing energy from the battery bank.

The grid-tie Sunny Boy inverter will shut down during a blackout but will turn back on (after a 5-minute period) when AC power from the Sunny Island is present. The Sunny Boy inverter(s) will supply AC power to the backup load panel and, if enough power is available, will be used by the Sunny Island to charge the batteries. If the batteries are full, and the PV system is producing more power than the loads require, the Sunny Island will communicate with the Sunny Boy inverter (not HFUS series) to decrease its power output. If there are no loads and the batteries are full, the Sunny Boy inverter will automatically shut off to prevent battery over-charging. The battery bank is recommended to have 100 Ahr of capacity for every 1 kW of PV power.

Off-Grid Power

In off-grid systems, the Sunny Island works with Sunny Boy inverters exactly as it does with grid-tie systems during a grid outage. A generator can be connected to the Sunny Island’s AC input to provide backup and battery charging. The battery bank can also be charged using a PV array with a standard PWM or MPPT charge controller, or by other power sources like microhydro and wind turbines.

Data Monitoring

The Sunny Island utilizes removable SD cards to store performance data from the integrated data logger and to perform firmware upgrades. State-of-charge metering helps with battery management to ensure maximum battery life. The Sunny Island works with the SMA Sunny WebBox and SensorBox monitoring accessories, but not Bluetooth.

The Sunny Island inverters are listed to UL 1741 for the U.S. and Canada and carry a 5-year warranty.

SMA Sunny Island Inverters
Model Continuous Output Battery Voltage AC out (volts/hertz) No load draw Charger output AC surge output
SI4548-US 4500W 48 VDC 120VAC/60Hz 25W 100A 11000W
SI6048-US 5750W 48 VDC 120VAC/60Hz 25W 100A 11000W

Additional information

Weight139 lbs
Dimensions24.1 × 9.3 × 18.4 in

5 years


Listed to UL 1741 for the U.S. and Canada