Buy just the unit here with built in battery and you can add your own 12 volt solar panel or get one from us. Our standard Outback-Mate500 package comes with a 50 watt solar panel, but you may also choose to connect a 100 watt solar panel which will speed up the total solar charge time to approximately 3 hours, cutting it in half! Pick up one of our 10" energy efficient DC fans and/or some LED lights and lamp cords, and you'll have a custom portable solar power dynamo!