Having had no power for 24 hours looking at generators, the one below is probably fairly typical of portable generators:-
"Sealey Petrol Generator 800w 2hp 2 Stroke Engine
Compact and lightweight unit capable of running small tools and lights etc. makes it ideal for roadside, building sites or leisure use. Powerful and reliable generator fitted with maintenance free brushless alternator. Fitted with 12V battery charging outlet and 230V 3-pin socket.
Model No: G950 Motor Power: 2hp Motor Type: 2-Stroke Output: 230V - 50Hz /12V DC Current Rating: 3A /8.1A Cont. Power Rating: 650W Max Power Rating: 800W"
Now, a fridge or freezer is only about 200W but I read this:- "
this whistled over my head with a big WHOOSH, anyone know if the example generator is likely to be powerful enough?