We install Honeywell and generac whole house generators. 14kw generators for a household with 100-150 amp circuit breaker panel is typical. Also depending on load in the home. If there is multiple refrigerators, a/c condensers then a larger generator may be needed. With an automatic transfer switch the generator will turn on within 30 seconds of sensing power is lost from utility company.
Below is a smaller home with a 100 amp panel. A 10kw is installed. Oversizing unit for house load is not recommended.
Below is a 14kw generator. This home has a 150 amp panel with a much higher load,(more electrical appliances, larger a/c unit and ductless units). Another factor in sizing a generator is having your gas provider upsize your gas meter. Check rating plate for listed maximum but’s required to run generator under full load capacity (yes this will happen if unit running whole house). On average a generator rated above 14kw will need an upsized gas meter. Residential gas are usually 275-350k btu’s rated. A 14kw for example requires 256k btu’s at full load. So depending on gas appliances in home you may exceed gas meter output.