The role of bypass diodes in the failure of solar battery charging stations in Thailand

Abstract

This paper focuses on the failure of bypass diodes in solar battery charging stations (SBCS) in Thailand. The Thai government has installed over 1000 SBCS in unelectrified villages to be used to charge 12-V batteries for household lights and small appliances. The unnecessary inclusion of bypass diodes in these systems created an unexpected failure mode when villagers misconnected their batteries with reverse polarity. In a survey of 31 stations, 18 stations were disabled by burnt-out bypass diodes. The electrical engineering theory of this failure mode is analyzed. In addition, we discuss how the bypass diode failures have been compounded by lack of end-user feedback to the implementing agencies.