Wind Energy

Modular PV and hybrid system technology for intelligent system control in decentralised electrical supply systems

The aim of the project is to create and disseminate technical principles for setting up modular energy supply systems fed by photovoltaics (PV) and other energy converters. By modularising these energy supply systems, it is impossible to improve efficiency while simultaneously increasing supply reliability.



Globally, it is hugely important to set up a supply for potential decentralised consumers of low quantities of electrical power who cannot be connected to an existing network. This is an application that is ideally suited to the use of photovoltaic energy supply systems. Previous experience has clearly shown that these systems should have a modular design in the power range from 2 to 30 kW, so that they can subsequently be expanded and easily and efficiently combined with other energy systems, such as diesel units and wind power plants.

The aim of the research project was to develop a modular, expandable system technology for intelligent and optimised feed control for PV and other energy systems (PV hybrid system technology). It has to be suitable for uncomplicated use both in grid connected and autarkic power supply systems.

The central component of this technology is the battery current inverter. It must ensure constant network figures on the AC voltage side, and uses the battery as a buffer to achieve this.


  • Five current inverters making up a network were operated in parallel with no communication cable and successfully tested for different operating conditions.
  • Parallel operation as a network or in conjunction with diesel units was possible with no problems.
  • The battery management system developed delivers a significantly longer battery life and improved system efficiency.
  • A model was developed for more accurate calculation of the thermal load on semiconductor components in current inverters. This enables the systems to be utilised more effectively.
  • Because of the easy installation and coordinated components, a significant reduction in the susceptibility to faults is anticipated.
  • There is still major potential for optimisation, which would ensure further significant cost reductions in PV hybrid systems.

Project Participants

Implementing Institution

University of Kassel

Technology providers

SMA Solar Technology AG

More Project Informations

Project number:  0329833

Project period:  1998 - 2001

Project region:  Germany (Hesse), Austria

Project contact:

Herr Dr.-Ing. habil. Zacharias

View Publication

Source:German National Library of Science and Technology Hannover (TIB)