Solar/Battery quote feedback

Hi all,

Diving into a potential Solar/Battery setup for my property (Rural New England area of northern NSW). I am a novice when it comes to solar/battery infrastructure so hoping for some feedback on this quote compared to our situation.

We have 4 buildings (main house, 2 granny flats, workshop) feeding from the one meter (single phase). We are basically an extended family with our own homes on the same land.

We have a power pole where the meterbox is terminated with a smart meter
We also have a 20kVA diesel generator that is wired in to a manual changeover isolator in the meterbox.
Each building has its own 63A circuit from the main meterbox to each buildings' respective subpanel.

Solar panels to be installed on the main house, but we are hoping to have the system utilised by all buildings on the property (and potentially have the generator fed into the solar gateway so we can charge the battery's during extended power outages)

Combined yearly power usage for the last 12 months is ~26000kW (ranging from 1500kW in May 2025 to 3400kW in Dec 2025. Our power for the last 12 months has cost us ~$10k

Our grid is a bit flakey, we have multiple outages throughout the year (a couple of hours per outage) which is where our generator comes in handy. Our longest outage was ~50 hours.

Ideally looking to cut power costs where possible, while also being able to stay online as long as possible (within reason) during extended outages. We will still continue to use the generator in a hybrid approach where needed.

We received the following quote from Freedom Energy who came highly recommended by a colleague who recently had some SigStor batteries installed at his place, so reached out for a quote

18.525kW SOlar (Trina Solar Vertex S+)
48.36kWH Sigenergy SigenStore BAT 8.0
Sigenergy Sigen Hybrid Inverter 12kW

I do run home automation (Home Assistant) and was looking at integrating with Amber Energy and setting up some automations to export during peak FIT times.

We don't have any EVs, but do heavily use our split system AC's in all buildings during the summer heat.

From the numbers I've crunched, we are looking at a potential 90% reduction on our bill, 90% self-sufficiency, while being able to potentially export 7000kWh throughout the year.

No comparison quotes as yet, but open to other quotes if this seems unreasonable?
Appreciate any feedback and recommendations you can offer!

Thanks in advance!