System Technology for the Next Generation Village Energy Supply
According to the newest IEA World Energy Outlook, 1.2 billion people do not have access to electricity. Most of them live in remote areas where a connection to the public grid is not economically feasible. On the other hand, almost all of these areas are located within the “Sun Belt” region around the equator and have high solar resources. Offgrid solar energy systems have always been an interesting option for these remote areas and the continuing drop of solar panel prices as well as the low carbon emission of photovoltaic (PV) electricity makes them an even more attractive option. So far, in the field of remote PV energy systems, only low power components are available on the market. In order to supply larger consumers, different kinds of technical solutions allow parallelizing multiple small inverters or battery chargers in the range of a few kilowatts (kW) to reach a few hundreds of kW. Although this is a well-proven approach, it makes PV off-grid systems more complex and foremost more expensive. The Fraunhofer Institute for Solar Energy Systems has developed, in the frame of a research project funded by the German Ministry for Environment (BMU), the architecture and framework of the next generation village energy supply system (BMU key number 0325121). In this paper the focus is on the power electronic components developed within the project. Firstly the common system topology for PV-based off-grid applications is presented. Then a very advanced 125 kVA off-grid inverter, which is designed to challenge large diesel generators in their well-established market, is introduced. In a second part the associated highly innovative high voltage PV battery charger with its hybrid lead-acid (Pb) and lithium-ion (Li) battery will be presented. Also the energy management system and the used communication architecture will be introduced.
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