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The Archive section contains a library of publications produced by the IEA Photovoltaic Power Systems Programme (PVPS) since its inception in 1995. These documents are organized by type, activity, year, country and task. For a hint to find specific documents please read the "How to Find Documents in the Archive" link.
|Title:||Testing of batteries used in stand-alone PV power supply systems: Test procedures and examples of test results|
|Description:||In stand-alone PV systems special attention must be paid to the battery bank, which is often said to be the weakest component of the system and the highest contributor to its life cycle cost. For this reason, designers, project managers are very concerned by the evaluation of the battery lifetime. This document makes an analysis of cycling test procedures for batteries used in stand alone photovoltaic power systems. The main objective of a cycling test procedure is to evaluate the battery lifetime, expressed in terms of reduced capacity, by reproducing a typical use of the battery in the field. This document presents an overview of frequently used battery test procedures. A description of seven cycling test procedures is made and the performance of more than 40 batteries of various types is presented. The test procedures induce ageing of the battery by accelerating the degradation (sulphation, corrosion, stratification and softening) of the battery grid and the active mass. The analysis of the results shows that most of the cycling procedures lead to significant battery sulphation, but almost none of them accelerate battery corrosion. In fact, there is no test procedure where the four degradation mechanisms lead to a significantly high level of degradation. It is therefore advisable for project managers to select several methods in order to ascertain the most likely battery degradation pattern for a given application and then be able to choose the right battery. In terms of battery technology, the results show that there is a wide range of efficiency and lifetime values for various batteries of the same technology. This is due to differences in the type of grid alloy, the active mass composition, the manufacturing process or the cell geometry. In addition, the longer and better service of tubular batteries was confirmed by the analysis. The behaviour of tubular batteries is, in general, not very dependent on the selected test procedure, as this kind of battery is more sensitive to sulphation than to softening and corrosion. However, flat plate solar batteries are sensitive to all types of degradation and their cycling life is much more dependent on the test procedure. Nevertheless the present results show that there is still a lot of work to do on the topic of accelerated battery cycling life evaluation. There is a strong need for a deeper international collaboration (Round Robin tests) to focus on a limited number of cycling procedures, gather more results on battery tests, search for other means to accelerate the tests (key parameters, modelling studies) and lead to the standardization of these cycling tests.|
|Creator / Publisher:||Olivier Bach Hervé Colin Daniel Desmettre .. / IEA PVPS|