This improved performance enables the plant operator to make a higher profit during in-feed into the medium-voltage system. 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 transformer-less 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 energised or de-energised 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.

About Siemens Southern Africa:

Siemens has had a presence in South Africa since 1860 when the company installed the first telegraph line linking Cape Town and Simon’s Town. Today, Siemens offers a balanced portfolio of technologies focusing on the Industry, Energy and Healthcare sectors, together with the cross-sector business of Siemens IT Solutions and Services. The unique ability to offer horizontal, customised, end-to-end technology solutions enables Siemens to keep its customers one-step ahead. As a committed corporate citizen, Siemens has active corporate social investment programmes as well as a comprehensive approach to local content, manpower development, skills and training. Further information is available on the Internet at www.siemens.co.za

About Siemens Energy:

The Siemens Energy Sector is the world’s leading supplier of a complete spectrum of products, services and solutions for the generation, transmission and distribution of power and for the extraction, conversion and transport of oil and gas. In fiscal 2008 (ended September 30), the Energy Sector had revenues of approximately EUR22.6 billion and received new orders totaling approximately EUR33.4 billion and posted a profit of EUR1.4 billion. On September 30, 2008, the Energy Sector had a work force of approximately 83,500. Further information is available at: www.siemens.com/energy