John - thank you so much.
I got a quote from Skylar Solar - just over 17K. Eye waterring but maybe this is what it costs now.
This is for 17x 410w Hyundai panels, Growatt SPH6000, 2x Growat batteries GBLI6531 and a few Tigo optimisers. Panels will be on both sides of the house (orientation: South & West) so additional cost with scaffolding. Anyway they only do Growatt systems these days. After quick research I got loads of negative reviews so was initially quite aprehensive.
What is your experience with that system? If you had opportunity to choose again would you go for the same?
My main objective is to charge batteries from solar and in winter months from grid. The system needs to work well with Zappi & Eddi and in near-future with air-to-air heat pump.
If I find I'm not happy with the inverter can Growatt batteries be used with another brand? Can I add more batteries in the future? (Growatt says only 1-2 allowed; but my installed claims they sometimes install eg 4 batteries without need for second inverter so I'm not sure who is right).