Glenn Miller showed me to his backyard, where a discrete plastic box sits a few feet away from the propane tank. Inside is a small motor patiently waiting for the power to go out. It’s a Kohler generator. “Within 10 seconds of the power going out, the generator kicks on. When it detects that the grid is stable it goes back into standby.” Miller has sold and maintained generators for about 30 years, but the windstorm of 2011 really got him into the business. Powerlines were down all over town and no one had electricity for days. These days he deals primarily with machines built by Honda and Kohler due to the quality of their parts. “A generator is an investment that adds value to…