PHOTON International The Photovoltaic Magazine

New stand-alone inverter from SMA

One year after the introduction of its first inverter for several module strings, the German company SMA Regelsysteme GmbH will present a smaller version of its transformerless device, the Sunny Boy Multistring 5000, in June.

	© SMA Regelsysteme GmbH
A well-known outfit: On the outside, the new Sunny Island 4500 battery inverter looks like its predecessor. But the new model, which has a higher nominal power, is suitable for use with 48 V batteries.

This specialized device is designed to function as the heart of a mini-grid in which AC wiring is used instead of DC wiring. In addition to the Sunny Island, other AC sources – such as diesel generators, PV modules via on-grid inverters, and wind or hydro power systems – can be connected to the AC bus. If the energy supply in the AC grid is higher than demand, the Sunny Island stores the surplus energy in batteries. In the case of an energy deficit in the AC network, the stored energy is delivered back into the grid.

The Sunny Island 4500 has a nominal power of 3.7 kW and is designed to replace its predecessor, the Sunny Island 3300. The device can transform the nominal battery voltage of 48 or 60 V DC into 230 V AC. By contrast, the earlier Sunny Island 3300 had a nominal power of 3.3 kW and was suitable for use only with 60 V batteries.

At ambient temperatures of 25 °C, the new inverter can perform at 4.5 kW for 30 minutes (P30), and even bear 6 kW for a minute (P1). By connecting up to three devices to one phase the inverters can work together to achieve levels of 13.5 kW. The devices can also be connected to form a three-phase power system. This allows the inverters to handle three-phase loads or electricity generators. Users can parallel connect up to three three-phase systems giving the inverters a maximum system power of 33.3 kW. A further improvement over the inverter's predecessor, says SMA product manager Michael Wollny, is the inverter's smooth starting control for difficult loads.

The Sunny Island 4500 basic model is offered worldwide at a retail price of around €6,200 ($6,926) before taxes.

In June SMA will begin offering four different product packages. In addition to the Sunny Island, the packages will contain batteries and diesel generators according to customer specifications. The company plans to introduce its new inverter at the Intersolar trade fair in Freiburg, Germany end of June.