If you don't have this already, do they install it for free?
How long are the cheaper night time rates guaranteed for?
The Octopus Go webpage says you need an EV to get the tariff, it doesn't mention home battery storage?
Yeah strictly speaking the go tariff is for Evs, many switched to it without even being asked
When your a customer there is also Go faster which is a newer version allowing 4 or 5 hours (you pick) and across more time bands (again you pick)
Right now Octopus certainly lead the way in offering better tariffs, but eventually the others will catchup else the whole market will want to switch to Octopus
Its certainly a gamble to install a battery first, best bet would be to move to octopus when that makes sense as a normal supplier then try to get on Go.
As someone said above most of the Ev systems are using apps now so you would set the parameters in your app
It gets used from my understanding as it supplies a slightly higher voltage so it takes precedence over grid supply.
Output is based on two things, battery and inverter (I think you can get built in inverter versions for battery only install).
Eg the battery I am looking at is 2x 5.8, giving 10.4 usable, one unit a master and the other a slave, can chain upto 3 slaves. As you add slaves as long as you add a higher capacity inverter you can go upto 10kw peak draw. 2 will give me 6kw peak draw in theory but I am having a hybrid inverter that will limit slightly below that as its a hybrid to control convert the AC/DC for the battery and the solar panels