Let's be optimistic, and assume the battery lasts 10 years - 3000 cycles from full-empty.
This is perhaps optimistic.
I am using the numbers for my electricity costs.
These are $.28 or so.
If it's 10kWh, and lasts 3000 cycles, that's 30000kWh.
Or close on $10K worth of electricity stored.
Even with free electricity - it will never break even against grid cost.
Actually having to buy solar panels makes the numbers much worse.
Is it great for off-grid - perhaps. It's a _lot_ more expensive than even spendy lead-acid batteries.