Yes, STC rebates are available where you have a Fronius SCERT inverter coupled with a Selectronic SP Pro micro-grid. This is a standard solution we offer.
The cost to go off-grid will depend on your expected/anticipated energy demand. With knowledge of your energy demand we can then help you size your battery storage, solar PV, generator, microgrid inverter, etc.
It is worth noting that connecting a new block to the power grid can cost between $15,000 and $50,000 depending on the situation. And a typical energy bill for the average household is around $3000-$4000 per year (or higher in colder areas). Given the cost of grid connection and supply, a well maintained and high quality off-grid system is likely to be cheaper in the long run (20 years +), depending on your particular situation (if grid connection is >$30,000 you can pretty much assume off-grid will be cheaper).
You want as large a rooftop solar PV system as you can fit on your roof to reduce the amount of time you need to rely on your backup generator that may be required for periods during winter periods or times of low solar radiation (i.e. multiple cloudy days).
We generally recommend a minimum 10kW solar PV system, but the final size will depend on your anticipated load/demand. We can help you work this out by using our load profile sheet as part of our comprehensive quoting process.
Your solar system should cover your power needs 95% + of the time, however we highly recommend a good quality, automatic start generator to ensure you have energy security and full power capacity throughout the worst days of winter.