SMA Sunny Island 4248 Watts 48 Volts Power Inverter

Manufacturer Part Number: 4248U

The Sunny Islands offer you first class possibilities in the installation of self-sufficient energy systems. In conjunction with a battery pack the devices form a self-sufficient AC voltage grid, which meets with the highest of quality standards.

In the Sunny Island System, electricity generators and consumers are integrated in equal measure. PV and wind energy systems, diesel devices, water or CHP (Combined Heat and Power) can be coupled on the AC side just as conventional 230 Volt consumers.

Thus the Sunny Islands offer you two decisive advantages: at system planning and layout you can enjoy the highest degree of flexibility, during installation the complex DC cabling is not required.

Sunny Island 3324 and 4248: Making stand-alone grids easier than ever

Easy installation, safe operation and an outstanding price-performance ratio make the SMA Sunny Island 3324 and 4248 battery inverters especially suitable for small and mid-sized stand-alone grids. The Sunny Island 4248-US model is available for countries with voltage systems compatible with the U.S. standard. The inverters guarantee a reliable and high-quality power supply. Due to their outstanding overload capabilities and that they are designed to withstand high ambient temperatures, this line can be used under extreme weather conditions.

Features

Simple

• For systems from 2 to 5 kW
• AC and DC coupling
• Simple installation

Efficient

• High efficiency
• Excellent price-performance ratio

Durable

• Extreme overload capability
• 5-year warranty

Specifications

Detailed Description

Overview

Over twenty years of inverter manufacturing experience has gone into the design of the Sunny Island 4248U. As a result, the Sunny Island 4248U represents state-of-the-art technology, high reliability and overall ease of use, all the things you’ve come to expect from SMA, the industry leader in inverter manufacturing. Some of the features included are:

• Optimized for high ambient temperature operation
• Very high efficiency
• Integrated DC breaker
• Near silent operation
• Non-volatile memory
• Compatible with all Sunny Boy and SMA Control products
• Advanced battery management system
• Sealed electronics compartment
• Generator overload protection
• Generator reactive power compensation

Code Compliance

The Sunny Island 4248U has been tested and listed by ETL to meet the requirements of UL 1741 Static Inverters and Charge Controllers for use in Photovoltaic Power Systems. The Sunny Island 4248U also meets all RFI/EMI requirements of FCC Part 15, part b.

Safety

Features

The Sunny Island 4248U is equipped with several safety related components. Some of the safety features included are:

• Built in DC disconnect
• AC input current limiting to protect generator
• Automatic fan control
• Over and under-voltage monitoring of both AC and DC voltages
• Input and output AC frequency monitoring
• Generator relay failure detection
• Over-temperature protection

Note: The Sunny Island 4248U is not a grid interactive inverter and therefore does not provide any active anti-islanding features. It will however, allow power generated by grid interactive inverters such as the Sunny Boy, to be passed through it to the grid via its grid-isolation relay. The Sunny Island 4248U will not supply power to the grid from its batteries and therefore can not create and island on the utility grid.

System Configuration

There are several different configuration options for the Sunny Island.

Off-Grid / Stand Alone Systems

By definition, off-grid or stand alone systems are systems where electrical power is generated and stored without assistance from the utility grid. These systems typically consist of one or more power generation sources such as a PV array, a wind generator, a hydro-electric generator or a gas powered generator.

Typically, there is a need to store the power that is generated. Without a storage method, power would only be available when one or more of the generating devices were active (i.e. when the sun was shining for a PV array, or when the wind was blowing for a wind generator). Batteries are the most common device used for power storage. The size and type of batteries used depends greatly on the system power requirements.

Because many of the loads that will be powered by the system require AC power as opposed to DC power, an inverter is needed to change the DC voltage to an AC voltage that can be used by the AC loads. This is exactly what the Sunny Island 4248U was designed to do. The Sunny Island 4248U can also function as a battery charger for charging the battery bank. This mode operates by connecting an AC power source to the inverter’s AC power input. The AC power source could be a gas powered generator or even the utility grid, if available at the system’s location. The power generated by the external source can be used to power AC loads via the Sunny Island 4248U while the batteries are being charged at the same time. The Sunny Island 4248U watches the battery voltage and only applies the amount of power necessary to bring the batteries up to a full state of charge after all power required by the loads is supplied.

Frequency Shift Power Control (FSPC) for Off-Grid Applications Only

When the Sunny Island 4248U is coupled to Sunny Boy inverters on the AC output, it requires a method in which to control the power output of the Sunny Boys. To do this, it employs a type of control referred to as Frequency Shift Power Control (FSPC). Using the FSPC feature, the Sunny Island 4248U is able to increase the frequency of its AC output. This increase in frequency causes the Sunny Boys to decrease their power output.

Although the Sunny Island 4248U increases its output frequency during these periods, it keeps track of how much frequency shifting has taken place. Shortly afterwards, the inverter will automatically compensate for the frequency shifting and bring any appliances such as electric clocks back to normal. In this way, users don’t have to worry about any inaccuracies in their electronic equipment.

The activation of the FSPC feature is controlled by the “SunnyBoys” parameter in the Sunny Island 4248U. When this parameter is set to “Yes”, the FSPC feature is enabled.

When the FSPC feature is enabled and the generator in the system is operating, the generator becomes the frequency reference and the Sunny Boys will respond to any shifts in frequency by the output of the generator. Typically, generators run at 60Hz when loaded and therefore, in most cases, the Sunny Boys will be allowed to run at full power when the generator is operating.

Back-Up Systems

A back-up system is configured differently from an off-grid system. The purpose of a back-up system is to supply power when the primary source of electrical power, such as the utility grid, fails for some reason. When used as a back-up system, the Sunny Island 4248U is designed to begin providing AC power automatically whenever the primary source of AC power shuts down.

In a back-up configuration, the Sunny Island 4248U still requires a source for its power. This is accomplished through the use of a large battery bank. Again, the size and type of batteries used will be determined by the intended operation of the system.

When using the Sunny Island 4248U in a back-up system configuration, the utility grid needs to be connected to the grid isolation relay in the inverter via the AC input terminals.

During times of normal operation where the primary source of AC power is active, the Sunny Island 4248U maintains the charge of the battery bank so that they are ready in the event of an outage. The Sunny Island 4248U applies a sophisticated charging algorithm to ensure that full charge capacity is maintained and that the life of the battery bank is maximized. Once the batteries are fully charged, the Sunny Island 4248U will automatically enter “Silent Mode”. Silent Mode is a standby mode during which most of the electronics in the inverter are turned off to reduce power loss during periods of inactivity. The metering functions of the inverter are still active so the inverter will “wake up” and charge the batteries if needed. It will also respond immediately to a grid failure. When the inverter is in Silent Mode, it is indicated on the display by “Silent“.

The Sunny Island 4248U also has the ability to connect external sources of power, such as a gas powered generator to assist in powering the loads and charging the battery bank during extended outages.

Control of Sunny Boy Inverters in a Grid-Tied Configuration

In grid-tied applications frequency shifting alone cannot be used because it would require that the Sunny Boy inverters allow changes in frequency to occur which exceed UL safety limits for grid-tied inverters. Therefore, in grid-tied applications, primary control of the Sunny Boys is accomplished through the use of the RS-485 communication line. The Sunny Island sends commands via the RS-485 bus to the Sunny Boys that limits the output of the Sunny Boys when required to prevent overcharging the batteries.