Solar Panels Query

[River Song]

It still remains very difficult to get accurate information from the installers.

The proposing to install 12 panels on the roof.
Voltage they say around 400v DC
Into an inverter of some kind and then into the grid.
There is also an isolator for some reason.

I've been told that if the grid is down then i get nothing.

Ok so this is where I need some help.

I can't do it until after it is installed but I certainly dont want to wait until TU

so what can you suggest?

Possible some form of charge controller?? Going to 2 x deep cycle batts
running some form of 12v circuits in the house?

Any ideas? Can you point me to some authorative resources I can read?

Cheers