Was sceptical initially but thought the price point warranted testing. It is hooked up to a 110aH leisure battery connected to an energizer for an electric fence. I mounted it on an 8ft scaffold pole and good news, it "does" keep the battery fully charged which is exactly what I hoped it would do. Low wind periods see the battery voltage drop and then after a decent couple of days of decent wind the battery is back at full voltage. Can't complain.