Usually part of it. Most installs back up a selected group of circuits rather than the whole house, and you choose which circuits those are at design stage.

The thing that catches people out is what sets the limit. It isn’t the size of your battery. Storage capacity decides how long your backup lasts. Power output decides how much you can run at the same time. A bigger battery gives you more hours, not more appliances.

That’s why the heavy loads are the ones usually left out: ducted air conditioning, electric cooking, EV charging. A fridge, lights, power points, internet and phone charging are the typical starting set.

Whole-home backup is possible, though the system has to be sized to handle your home’s peak demand, not just its daily usage. Work out which circuits genuinely matter to you first, then have your installer size around those.