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1.PV Off-grid systems consist usually of a storage system, PV energy source and different loads connected to a charge controller to manage the energy flow.A look at the lifetime costs with the usually used lead acid batteries shows, that the storage system is the weak point concerning the costs on investment and maintenance.The lead acid battery with its limited amount of cycles reduces life time essential and if the storage has to be renewed life time costs going up.The positive aspect of this storage is, the low price comparing to other storage technologies and world wide availability.At the moment its the most used storage system in PV-Systems.To lower life time costs a combination of different storage technologies can be used.2.The paper shows, what a PV-system with a lead acid battery and a LiIo battery needs, to reach the goal of lowering life time costs and how such a system must be designed.On the technical side special safety features and an extended energy management have to be implemented.First simulation based results show, that the management algorithm has a big influence on the lifetime of the two storage systems.The algorithm is designed in that way, that the daily cycle is done by the LiIo battery and the long term cycle is done by the lead acid battery.With the right algorithm the lifetime of the lead acid battery can be more than doubled.In future LiIo batteries with more cycles and a decreasing in the price is expected.So the storage technology is in the way to make hybrid storage systems economical.