This paper reports progress in the development of a miniature, monolithic AlGaAs/GaAs photovoltaic solar cell array, used in combination with scintillating fibers, and its application to recharging batteries of unattended ground sensors. Improvements in the design and processing of these photovoltaic arrays resulted in significant increases in both voltage and current. Moreover, new polycarbonate scintillating fibers that are more durable and flexible than polystyrene ones were tested. Output electric power density as high as 73 mW/cm2 for total area and 105 mW/cm2 for active area was measured outdoors for a 6-cell array integrated with a 1 foot long fiber bundle.