(for Australia it is 5, for other countries it might be 8)

Once you get to that "nice to have" problem of what to do about the remaining 3% of power needs it would probably make most sense to synthesize and store gas (methane/hydrogen) from electricity when solar and wind is overproducing. Gas can be stored cheaply for long durations. The roundtrip efficiency is poor but it's still cheaper than nuclear power on the windiest sunniest day.

The nuclear + carbon lobbies would of course prefer to model green energy transitions by pretending that the wind and sun simultaneously turn off for 2 weeks at a time every year and that electricity can only be stored in very expensive batteries. This is not realistic.