Nature Power 40015 18-Watt Solar Powered 12-Volt Battery Charger 18-Watt solar panel to keep your 12-volt batteries charged; charge controller is sold separately High quality amorphous solar material will work in all light conditions even on overcast days Weatherproof for outdoor use Battery clamp, and flat or tilted mounting hardware included Provides up to 18-watt or 1.2-amp per hour of sunlight