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Sunny Island SI5048-US

The Sunny Island 5048-US is a bi-directional battery-based inverter/charger that can be used completely off-grid, or for battery backup in grid-tie systems with Sunny Boy grid-tie inverters. The Sunny Island is a complete high efficiency power center all in a compact wall-mounted package. It includes 5kW of sine wave output power, low idle losses, and a 100A battery charger, and offers an integrated data monitoring system with battery disconnect.

Grid-Tie System Backup

The Sunny Island can back up critical loads during utility grid blackouts. Combine it with a Sunny Boy grid-tie inverter system and a bank of batteries, and the Sunny Island will enable the PV array to power loads and charge the batteries. This is done as an "AC-Coupled" system, where the AC output of Sunny Boy grid-tie inverters 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. AC power from the Sunny Boy inverter(s) can be used by the Sunny Island(s) to charge the batteries. If the batteries are full, and the PV system is producing more power than the loads require, the Sunny Island(s) will communicate with the Sunny Boy inverter to decrease its power output. If there are no loads and the batteries are full the Sunny Boy inverter(s) will automatically shut off to prevent the battery over-charging.

Off-Grid Power

In off-grid systems, the Sunny Island works with Sunny Boy inverters exactly as it does with grid-tie systemsduring a grid outage. Rather than act exclusively as a back-up, the system operates as if there were a permanent grid outage, and the critical loads panel becomes the main panel. A generator can be connected to the Sunny Island's AC input to provide back-up 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 sources like micro-hydro and wind turbines.

Data monitoring

The Sunny Island utilizes removable SD cards to store performance data from the integrated data logger and allow easy firmware upgrades. State-of-charge metering helps with battery management to ensure maximum battery life. The SI5048-US works with the SMA Sunny WebBox and SensorBox monitoring accessories (pg. 73).

The Sunny Island SI5048-US is UL Listed to UL 1741 for the U.S. and Canada. 5-year warranty.

MCB-12U Multi-Cluster Box for the Sunny Island 5048U

The Multi-cluster Box for the Sunny Island 5048-US is the ideal solution for the easy installation of three-phase hybrid systems. Connect up to four parallel three-phase clusters, each consisting of three Sunny Island battery inverters, for 30kW, 45kW, or 60 kW of inverter capacity. The Multi-Cluster Box is pre-wired with 300A main disconnect breakers for the grid or generator connections, loads, Sunny Boy inverters, plus 70A AC input breakers for up to 12 Sunny Island battery inverters. There is also a load shedding contactor. Includes required communication cables.

NEMA 12 enclosure standard: NEMA 4 or 4X available. Size: 65"H x 48"W x 14"D. Weight: 485 lbs. Listed to UL 508A. 5-year warranty.



Battery voltage

AC out volts/hertz

No load draw

Charger amps

AC surge output

Weight (lbs)

Item code



48 VDC

120 VAC / 60HZ

25 watts


8400 W




SMA Multi-Cluster Box, three-phase only, up to 60kW




SMA Multi-Cluster Piggy Back Board - CAN and RS-485 bus, one required for each cluster


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