I used both. It seems like the bucks came to the pipe gravity feeders better. My spin cast all run on AA batteries. It sucked changing batteries. I may invest in the solar panels this summer. It would get expensive using nothing but gravity feeders even with out low deer density. I set my spin cast to go off at 845 am and 405pm. I rarely hunted over them but hunted trails 300 yds away and that seemed to be the ticket.