SMA Sunny Island
Off-Grid Solar Inverter
Model 4248U

The Sunny Island is an inverter with built-in battery charger.  The primary function of the Sunny Island is Back Up Power in the event of a power failure on the Grid.  It is connected to a 48 vdc battery bank up to 6000 AH in size.  The output is 120 vac. Two Sunny Islands can be used in series for 240 vac output.  The Sunny Island can use AC input from the grid to charge batteries.  There are two AC connections in the Sunny Island, AC IN and AC OUT.  AC IN is connected to the utility grid or a generator.  AC OUT is connected to the "Optional Standby" load center.

Product Features:

• Compatible with the Sunny Family of products
• Optimized for high ambient temperatures
• Very high overload capability
• High efficiency
• Integrated DC breaker
• Intuitive user interface
• Output load shedding
• DC and AC coupling of energy sources
• Nearly silent operation
• Automatic generator start
• Battery protection
• Insect proof
• Easy installation and commissioning
• Non volatile parameter settings

Product Benefits:

• Perfect sine wave off-grid electricity
• High efficiency, robust power and outstanding reliability
• Simple to install and use
• loaded with powerful and advanced features
• designed to meet the needs of off-grid as well as back-up power system applications

Product Applications:

• An inverter is required when you want to power AC devices.
• The inverter converts the DC power from the PV array/batteries into AC power.

The Sunny Island inverter doesn’t require anti-islanding protection, but it is is not "Grid Interactive". It cannot sell power back to the grid.  The Sunny Island inverter will not operate without batteries and requires a 48Vdc connection.

There is a 56A rated transfer relay inside the Sunny Island 4248U. When the grid or a generator is present on the AC INPUT of the Sunny Island the relay is CLOSED, so the grid or generator is powering the AC loads in the "Optional Standby" load center. The Sunny Island 4248U works as a Charger in this situation.

When used with Sunny Boy inverters the Sunny Island is in a standby mode maintaining batteries. The Sunny Boys are selling PV power to the grid. If there are Sunny Boy inverters connected they will be on the AC OUT side, in the "Optional Standby" load center. If the utility grid fails, the transfer relay inside the Sunny Island 4248U opens, disconnecting the "Optional Standby" load center and the Sunny Boys from the grid. At this moment the Sunny Island switches from a charger to an inverter, in about 0.2 seconds. Now the AC loads in the "Optional Standby" load center are being powered by the Sunny Island 4248U.

If there are Sunny Boys connected in the "Optional Standby" load center, they will also see the 120/240Vac output from the Sunny Island. The Sunny Boys will see this voltage as the "grid" and re-connect to the Sunny Island grid, and continue to make power. This power will go directly to the AC loads or to charge the batteries When Grid Power is restored the Sunny Island will transfer the loads to grid and begin battery charging from the grid. The Sunny Boys will reference the grid and begin selling PV power again.

Product Specifications:

The Sunny Island 4248U provides a continuous power output of 4200 watts at 25°C and 3400 watts even at scorching temperatures up to 45°C. That's enough power to comfortably energize most household appliances with power to spare. Large critical loads such as water pumps and refrigerators can be easily powered by the Sunny Island 4248U.

This inverter operates silently and can be powered from multiple sources: wind, utility grid [for back-up power], hydro, solar electric and is even compatible with fuel cells.

A number of communication options provide flexible remote system monitoring. The optional SMA "GenMan"  [Generator Management Box] provides advanced control of even the most basic generators. The Sunny Island 4248U also works in conjunction with grid tied Sunny Boy solar systems to provide a powerful and efficient back up power solution.

The internal battery charger can supply up to 100A to the battery when in charge mode. Transition from charge to invert mode is a lightning fast 20ms, so even your computers will stay on-line. A pass-through relay with a rating of 60A at 120V is also included. Two Sunny Island 4248's may be paralleled to support 240VAC split-phase load centers. Once installed, the Sunny Island 4248U will run with basically no maintenance for years to come. With its state-of-the-art software and non-volatile memory, just set it and forget it.

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Product Manufacturer: SMA America, Inc.