Any solar panel that is rated 12 watts or higher requires the use of a solar charge controller. The Nature Power 30-Amp Solar Charge Controller regulates the current and voltage going to the battery and prevent over-charging.• Pre-set charging modes available for most common battery types• Automatic recognition of 12V/24V battery system• Provides multiple load control mode options• Industrial-grade design with reverse polarity protection• 5V 1A USB outlet provides charging for mobile devices• APP ChargePro for mobile phone monitoring and operation (available at iOS App Store and Google Play Store)SPECIFICATIONS Charge Controller Type: Pulse Width Modulation (PWM)DC Input Max Solar Input Voltage: