The amount of your home that can be backed up by your Generac generator depends on the size you select. There are generators like the 17KW -20KW Guardian Series that can cover the whole house including the A/C units. The best way to determine the appropriate size for your need is to think about what you would like to have when the power goes out. Most people think of things like bathroom and bedroom lighting, heat, A/C, refrigeration and other appliances, and general rooms of lighting and power. It is important to think about those things that don’t first come to mind as well. These may be garage door openers, health and safety equipment (oxygen tanks, smoke and carbon monoxide detectors), pet needs (fish tanks), and more. But, the best way to determine the size of generator is to schedule a free estimate and walk through your home with a Penco Electric certified technician.