Stand-alone photovoltaic (PV) applications provide an enormous benefit to places where no grid is nearby and the cost of PV systems have to be compared with those of bringing the grid to that location, which could be up to several thousands of US dollars per kilometre. In many remote areas, they also compete with gasoline or diesel-powered generators that often use subsidised fuel and for which users are charged on a “pay-as-you-use” base [1]. Apart from the much higher environmental benefits compared to diesel generators or individual kerosene lamps, the large-scale dissemination of stand-alone PV systems heavily depends on the lifecycle cost of the systems, which are mainly driven by the cost and the frequency of exchanging the batteries. This is addressed here by proposing a new type of battery for solar PV application: Lithium-iron-phosphate, LiFePO4.
Lead acid batteries have been traditionally used for stand-alone systems, though they have many disadvantages, such as possible leakage of acid due to damage or spillage, noxious fumes given off during the charging process and their heavy weight [3]. Also the disposal of lead acid batteries often does not happen in a very environmentally friendly way, especially in remote areas, threatening the local people’s life for a long time. Another significant drawback of lead acid batteries is the fact that they age faster when kept in a low state of charge. Lead acid batteries need therefore to be frequently replaced due to this aging effect, which leads to additional system cost over time. Alternatively, in stand-alone system design, lead acid batteries can be over-sized compared to their nominal capacity, which then, however, increases the initial capital cost of the batteries significantly.
LiFePO4 batteries are widely used in electrical mobility applications, due to their advantages over other kinds of battery types: one key feature is its superior thermal and chemical stability, which provides better safety characteristics than lithium-ion batteries with other cathode materials [4]. Due to significantly stronger bonds between the oxygen atoms in the phosphate (compared to cobalt, for example), oxygen is not easily released and as a result, lithium iron phosphate cells are virtually incombustible in the event of mishandling, and can survive high temperatures up to 85°C without decomposing.
Post time: May-09-2022