I've been using the Mighty Mule 500 on Mom's 16' single gate for years now. Just have to shovel a little snow now and then because the gate opener hates pushing the heavy wet stuff. Use a battery box, a lawnmower battery and a 5-10 watt solar panel aimed south. Replaced the battery once in 12 years. Have a couple of the wireless keypads mounted on pieces of conduit pounded into the ground(one inside the fence to get out, one outside to get in), for when folks without transmitters come around. Works great even if the wireless range is kinda short. Tractor supply and Murdoch's have them in stock usually.