All year power supply with off-grid photovoltaic system and clean seasonal power storage

The objective of the project is an all-year secure supply of alternating current based on a solar energy island grid consisting of serial components and seasonal energy storage. Photovoltaic modules, inverters, electrolysers, batteries, hydrogen stores and fuel cells form the basis of the independent power supply system. For this, selected load profiles were analysed and evaluated in theory and practice. The analysis is based on the results of the test runs of the system and the simulations, in which the combined hydrogen-battery-system is compared to the battery system. It was revealed that it is sensible to complement an island grid operating on lead batteries for shortterm energy supply with hydrogen as a long-term store. This ensures a year-round supply security based on solar energy and the extension of the life span of the batteries required for hydrogen-based power stores. The systems based purely on batteries can not provide perfect supply security during long periods of low solar radiation since they do not possess energy stores which allow long-term energy storage. Hence a seasonal energy store, such as hydrogen, is required to guarantee reliable power supply for every day of the year. Autonomous power supply systems with long-term energy stores operate independently from the public grid system and can be implemented without elaborate intelligent energy management. For this, however, the costs of the serial components must be reduced and the efficiency of the system must be improved. (C) 2011 Elsevier Ltd. All rights reserved.