Power management control for off-grid solar hydrogen production and utilisation system

Climate change concerns, increasing global energy demand, coupled with pending peak supply of fossil fuels, calls for development of new power source. The rapid price drops for solar technologies and combined with international and national policy changes makes solar energy more affordable and accessible for widespread adoption. Solar energy also contributes towards the reduction of greenhouse gas emissions. The combination of electrolysis of water and fuel cells, which use hydrogen as an energy carrier extends the utility of the solar energy. For an integrated solar powered hydrogen production, storage and utilisation system, one of the elements that needs to be designed carefully is the power management system. Power management strategy has a complex function in this type of solar hydrogen system. This paper presents a power management strategy based on fuzzy logic technology to address the problems. The target of this power management strategy is to use the solar power to meet the power demand, then utilise any addition power to maximise the hydrogen production, and minimise the usage of battery at the same time. Therefore, the overall system's efficiency will be increased and lifetime of the battery pack will be extended. The numerical results based on real solar data for a one year period shown that the proposed fuzzy logic controller can direct the power flow wisely between different elements such as load, electrolyser, fuel cell and battery, it is capable of meeting the daily power demand of an office block and using the excess solar power to produce hydrogen as far as possible while maintaining the battery's state of charge in a desired region in order to extend the lifespan of the battery. Copyright (c) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.