Tektrum 30A 12V/24V Solar Panel Charge Controller - 30% Power Boost Under voltage protection Rated Voltage: 12V / 24V ( Auto Switch ); Overload protection (automatic restoration); Short circuit protection (automatic restoration) Thunder protection; Reverse discharge protection; Reverse polarity connection protection (automatic restoration) Rated Current : 30A; Efficiency: 95% ~ 97%; Open Voltage of Solar Panel : ? 20V (12V battery ) , ? 40V (24V battery ); Over-charging Protection : 13.7V / ( 27.4V ) Low Voltage Disconnection / LVD: 10.7V / ( 21.4V ); Low Voltage Reconnected / LVR: 12.5 V / ( 25V ); Dimensions: 7.5 x 4.25 x 2 in; Weight : 20 ounces