@ShaulaEvans like all good answers, it depends. Partly on what you mean by solar generator. Mostly on what you consider critical. If you're in a place that gets significant sun, that probably means refrigeration and air conditioning which are unfortunately not ideal loads for a solar inverter due to the reactance of inductive loads. 10-12kw is enough for a normal sized home to run everything as if nothing has changed. Battery size is much more so based on your actual usage, number of solar panel