Field performance of lead-acid batteries in photovoltaic rural electrification kits

A field survey was carried out in 83 rural communities within seven different states in Mexico, to assess the performance of photovoltaic (PV) rural electrification systems previously installed and to sense the degree of user satisfaction with PV technology. The present work reports on the performance of lead-acid batteries associated with domestic PV lighting kits. A sample of 555 batteries, from a total of 2512 PV kits installed in the region of study at the time of the survey, was randomly taken for analysis. Batteries were rated using a semiquantitative methodology developed at the Electrical Research Institute of Mexico (IIE). Results obtained from the survey are on the positive side, meaning that car-type batteries (representing 87% of the sample) perform reasonably well as part of PV lighting kits. However, there may be reasons for concern. A number of factors of technical, environmental and socio cultural nature, can negatively influence the performance of batteries in the field. Results from the survey show that undersized storage capacity is one of the main technical factors contributing to a rapid decrease in battery performance. However, improper operation and maintenance practices, derived from socio cultural factors and a lack of proper user training, are important recurring elements that may result in battery lifes shorter than anticipated, and the subsequent disappointment of the user with respect to PV rural electrification. Local availability of spare batteries at the rural community level is identified as one critical issue for the sustainability of massive PV rural electrification projects. Proper disposal of spent batteries is seen as a potential environmental problem requiring due consideration.