OPzV Batteries in a Standalone Solar Hybrid Telecom Application: Key Design and Operation Issues Investigated by Accelerated Lifetime Testing

OPzV batteries' ageing is investigated based on a case study for a real hybrid telecom application. In this framework, four different manufacturer's OPZV batteries were subjected to several accelerated lifetime tests in order to tackle the impact of different design and operational parameters (e.g. DOD, charging algorithms). Results showed that sulfation is the critical degradation mechanisms leading to accelerated battery degradation. The operational behaviour under severe sulfation considerably affects the strategies for a proper battery selection and sizing. Thereby, recommended design and operation strategies are discussed, particularly focusing on batteries working in standalone installations with restricted charging capabilities. The relevance of the findings showed that dedicated lifetime tests at laboratory level are essential to ensure that the expected performance and lifetime requirements can be met in real field operation.