By Edgardo Villalobos Calculations to find what voltage and current the solar cells need to provide to charge the battery in 8 hours. Table of Contents Voltage Battery  Solar Panels need to be able to charge a 12-Volt, 7-Ah (10-Ah) battery Rule of thumb  Rule of thumb: Solar Panel Voltage = Battery Voltage x 1.5 … Continue reading Solar Panel Voltage Calculations