Solar panel assemblies herein are configured to couple to a boat trailer in order to charge a battery in a boat secured on top of the trailer. The solar panel assemblies can be configured to have means for 360 rotation to allow efficient sunlight capture and to allow for a more aerodynamic profile when the trailer is being towed. The assemblies herein include a solar panel housing that can include downwardly slanting sides to protect the one or more solar panels mounted within the housing from road debris.