Should we add extra batteries

[huminga1]

Hello ,
We have a
Solar PV system 4.35kw with 11.52 kw of battery
1master and 3 Slaves ( I think !)
We charge the batteries overnight using the low ish Octopus Flux Tarrif . They run out during the day and I charge them again an hour or so before the higher rate kicks in between 4pm and 7 pm . It’s definitely seems cheaper to live off the batteries . I could add 3 more batteries to bring it up to 20 kwhrs . Should I do this ?
We don’t produce much solar input at the moment due to the time of year .
The batteries charge up pretty quickly especially since I put the insulation around them as described in another post.
Any advice gratefully received
Thanks
Belinda

[Will]

Adding batteries while you can is normally a good way to reduce your energy costs and increase your ROI of your investment. It's hard to tell you 100% how long the pay back will be as you need to compare how many kWh you're dipping into during peak rate.
Having more capacity if you can budget for it is normally only a good thing.