Design and implementation of a 5 kW photovoltaic system with li-ion battery and additional DC-DC converter

The integration of photovoltaic (PV) generators in the gird is still an ongoing topic. The peak efficiency of today's power electronics is already above 98 %, therefore innovative aspects can grow from new ways of grid integration. This paper focuses on the combination of a 5 kW PV-generator with a li-ion battery. The temporal decoupling of the generation and injection of energy into the European low voltage grid is presented. Compared to a classic PV system, an additional bidirectional DC/DC-converter is required to ensure the charge and discharge of the battery. The power management of the system can be controlled by the grid operator or according to the best profit defined in a feed-in tariff law for renewable energy. Special attention has to be paid to the efficiency of this DC/DC-converter, due to the bidirectional energy passing before a grid injection is possible in case of energy buffering. After a brief introduction and system overview, this paper focuses on the DC/DC-Converter.