Yes but my battery capacity isn't unlimited, I can store 8.2KWH and my daily usage is about 16KWH, so with 4 hours covered under the Go rates, I need about 13KWH or so for the rest of the day.
If solar generation is absolutely 0, then I'll be taking 5KWH~ from the grid at peak rates this winter.
I've run some basic maths and I think a 2nd battery wouldn't make fiscal sense unless prices come down. There are a few reasons, but broadly:
1. Price per KWH on the battery is high.
2. On a good day, you won't need to add much charge to the batteries, so a lot of the time, the 2nd battery would be redundant.
3. Limited charge speed at 2.6KW on Givenergy with a single inverter, which means I can only charge 10.4KWH in the Go window (no I can't get onto Go Faster, also it's been removed from new switches as far as I can tell).
4. Even if I could charge both batteries fully, the additional capacity would only come into play on days when solar generation wasn't high enough. Current stats suggest that only recently has generation dropped low enough to really give me a shortfall.
I'd be looking at Nov - Feb as the only months where I really need the 2nd battery, for the rest of the year that extra expense isn't going to be adding much beyond peace of mind that I have more capacity to play with.