That pricing seems way over the top,
A 5k5 hybrid inverter can be had for 13,000bht.
No need for ATS, the inverters switch themselves, I use a breaker/fuse box that cost under 1,000bht.
Mountings can be made with little effort from 2x1 box steel (400bht for 6m)
Cables can be made from household 2.4mm twin, one 25m reel should do at about 1,500bht.
20kWhr batteries, (2 x 12kWhr NMC) @ 50,000bht each = 100,000bht.
Use your existing home grounding.
No need to have every electrical item in your house running from solar, pick and choose.
My home is 80% solar from 1x 5K5 hybrid inverter, 9x 340W panels, and a 50,000bjt LifePo battery.
Total cost was under 100,000bht.
Aircon/shower heaters and electric cooker powered direct from grid.
Rest of house runs from the Inverter, which switches to grid if batteries/sun run out.