I created a robotic boat that runs on a 12 volt 12 AH lead acid battery. I figured if this is sitting in the water with the sun beaming down on it, it would only make sense to use some of that energy. The boat has 12 volt motors and a 5 volt switching regulator for the Arduino, Xbee, and sensors. The battery is activated with a switch. What I am hoping for is to have a solar panel power the 5 volt electronics through the voltage regulator even if the battery is off or on. The idea here is so that if I leave this boat floating in a pool or lake for days that the solar panel will power the 5 volt stuff to transmit back sensor data. Of course there will be times I want to turn on the battery and drive it around too (Is drive the right word…? haha) So I need at least 200 mA on the 5 volt side and the regulator is at least 80% efficient. So my questions are can I connect a 12 volt solar panel in parallel with the battery system with out any other electronics? and can anyone recommended a solar panel that would be fitting for this project and be under $50?
Thank you for your time!