Batteries also allow you to offset your solar use. You can fill the battery during the day and use the energy at night. That’s the most common use. Having one during a power outage is handy but shifting use is the primary use case.
8.7kWh at a somewhat high EU price yields somewhere between $2 and $3 a day. If this thing is about $6k, it should pay for itself within a year (if you have excess solar energy production, most contracts around here either don't pay anything for this, or trade at some 90%-ish discount).
Did I miss anything? I thought it would be 6 years at ~$1k saved per year, so I'm kind of waiting for prices to come down a fair bit more myself - also in the knowledge that batteries are rapidly improving now thanks to all the new players.
Regardless of the time to get ahead: Battery would make a great difference if your goal is to eliminate grid reliance and also to power an EV by solar only.
Whilst in summer a 6.6/5 system can produce 40kWh in a day, during winter months in Australia there really isn't too much sun - and what we get tends to be patchy. So being able to feed it into the battery would be great for avoiding grid use overall, and not to let bursts of sunshine go to waste.
