I hope you have a good electrician to wire that all up. Also you have to keep in mind that the vessels lose heat as well. I have a 3000 watt induction burner and it struggles to keep 10 gallons boiling.
9000w at 210volts is 42amps normal in home service is 150amps here in the US, so that would use all your home usage assuming 9000 per kettle.
You would have to upgrade your service, that is a pretty penny.