New transformerless solar inverters by Siemens achieve 98 percent efficiency

In addition, system costs can also be reduced with the option of a voltage window increased from 900 to 1000 volts. In this case, for example, a number of photovoltaic (PV) modules are linked together as in a chain and fewer generator terminal boxes and smaller conductor areas are needed. The new inverter series also includes units with graduated ratings of 500, 1000 and 1500 kilowatts and also 2 megawatts, which is the most powerful transformerless inverter currently on the market. The new Sinvert inverters are suitable for applications in medium and large-scale PV power plants.

The new central inverter units satisfy the currently effective medium-voltage regulations and can be used either as a stand-alone solution or in combination. The master-slave principle with “rotating master”—introduced on the market by Siemens over ten years ago—is above all an advantage in the event of changing intensities of solar radiation in the course of the day or in case of cloudiness. Depending on the degree of radiation, the necessary inverters are energized or de-energized by means of an ingenious process. This increases the efficiency of the PV plant, especially in partial-load operation. Only the required number of inverters is operated subject to light intensity. The connection of as many as four inverters in the form of a master-slave system enables the plant to start already at low levels of solar radiation and to achieve very high efficiencies even in the low output range. The rotating master contributes to the long useful life of the system, for the inverter unit with the lowest operating hours is always controlled as master and therefore the operating time distributed uniformly among the inverters.

Siemens is a global powerhouse in electrical engineering and electronics. The company has around 400,000 employees working to develop and manufacture products, design and install complex systems and projects, and tailor a wide range of services for individual requirements. Siemens provides innovative technologies and comprehensive know-how to benefit customers in 190 countries. Founded 161 years ago, the company focuses on the sectors of Industry, Energy and Healthcare. In the fiscal year 2007/2008 (ended 30 September 2008), Siemens had sales of €77.3 billion and net income of €1.9 billion.
Siemens resumed the operations of its subsidiary in the Czech Republic in 1990. Currently, with 12,500 employees, Siemens belongs among the largest employers in the Czech Republic. In the fiscal year 2007/2008 (ended 30 September 2008), Siemens Czech Republic reported a turnover of CZK 44 bn.
Further information is available at www.siemens.com and www.siemens.cz.