Generac 22KW Generator. The 22 kW Guardian(TM) Series home standby generator is the largest air-cooled home standby generator on the market. Not only does it deliver all the features and functionality customers have come to expect from the market-leading brand of home standby generators, but with an MSRP that is the lowest cost per kilowatt of any air-cooled home standby generator. Provides whole house coverage for many homes.