USAutomatic 020335 Medium 300 Solar Charged Automatic Gate Opener Double Gate Basic Kit The solar option for charging allows for remote installations and qualifies for a 30% federal tax credit. The Sentry is designed to be installed on farm gates up to 20 feet in length, ornamental iron gates up to 12 feet in length and chain link up to 14 feet in length. Made in the USA and powered by a 12 vdc battery which is charged by the included solar panel kit or AC transformer. The Sentry's energy efficient design makes it the first truly solar charged gate opener that eliminates the need for AC power to charge battery and will provide 8 weeks of operation with no sun. Sentry Plug N Go wiring harness eliminates the need for wiring and makes installation simple and quick, typically less than 2 hours.