No batteries I know of will make economical sense though. Batteries are expensive, wear down and/or require maintenance. After x years / cycles your batteries will be dead and will need to be replaced.
Storing your "free" energy in a battery will end up costing more than just buying the energy when you need it.
Expensive energy storage is a big part of the reason why "green" energy countries like Germany have some of the highest energy prices in the world. And also some of the highest CO2 emissions per kWh in the EU (they need coal and gas powered plants as backups for when there's no wind and solar, because batteries don't make economical sense).
But the part about battery degradation is not true. Tesla Powerwall has a 10 year warranty[1] with 70% capacity retention. This means that Tesla has data showing that the battery will have higher capacity than 70% after those years. That's a lot of cycles and a lot of renewable energy that the battery will provide in its lifetime.
[1] https://energylibrary.tesla.com/docs/Public/EnergyStorage/Po...
Battery degradation is not linear. It's not like: 10 years = 70%, 20 years = 40%. It's probably closer to 20 years = 20 % capacity left. The decay becomes exponential-like after a relatively linear period of roughly 10 years.
If you want to get an idea, this is what the decay of battery capacity roughly looks like: https://www.researchgate.net/profile/Simon-Montoya-Bedoya-2/...
The Tesla warranty will fall under "first life" in the image in the link above.
So batteries (even Tesla Powerwalls) do degrade and do degrade to the point where you need to replace them a bunch of times during lifetime of a house.
Edit: Does my MacBook Pro die after 1 year when it's applecare warranty is over?
The fact that other car makers aren't competing on warranty length seems to me to prove my point, but you seem to think it doesn't? What I mean is: if battery degradation for cars isn't that bad after 8 years, then why are other brands not offering significantly longer warranties to compete with the Tesla one? Not sure about the competition argument anyway, since Tesla didn't have any competition initially and arguably still doesn't have real competition (depending on what features of the car you value most).
Edit: Does my MacBook Pro die after 1 year when it's applecare warranty is over? --> Pretty close yes IMO. My personal experience is that my laptop and phone battery capacities degrade very fast after 1 year and need to be replace after about 2 years, 3 years if you really really push it and are OK with constantly charging.
RE: MacBook Pro dying close to a year right after it's warranty it over --> well now you're just trolling. My iPhone 15 pro battery still maintains 100% battery health a year after its manufacturing date. It obviously won't need replacing in 1-2 more years even if I "really really push it and are OK with constantly charging". I used an iPhone XS until last year after it was about 5 years old, 5x longer than your supposed device-dead date. I don't think this is unusual.
Not sure why you consider them to be "green" given the facts you brought up. Germany has never been particularly green energy wise. It's a big population and lots of heavy industry with relatively little energy resources like hydro.
The are building solar and wind quickly now. Maybe that's why you got the impression that they are "green".
Set https://app.electricitymaps.com/ to the yearly view and see the CO₂ figures.
(This is incomprehensible to Anglosphere FPTP two-party systems)
Fully integrated consumer battery prices haven't (yet) followed the decline in cell price, probably because there's lot of demand for this kind of product.
Dutch example: 0,12 EUR / kWh assuming 5000 cycles with 0 degradation. Example source: https://www.otovo.nl/blog/kennisbank/lfp-batterijen/
The real number is likely still significantly higher than 0,12 EUR / kWh due to battery capacity (and charge discharge efficiency) going down due to wear over time.
It does look like when the price of integrated storage products goes down more, it could become interesting for countries who have had very expensive energy policies (Denmark, Germany, Netherlands etc).
As for cycling the industry standard is give the number of cycles to 80% capacity remaining so the battery is far from dead at 5000 cycles. The simple division I used is conservative.
Small integrated battery:
3.5 kWh
Starting at about € 2.100,-
The price of cells is not directly relevant, since you can't actually buy cells and just throw them at your house to magically start charging/discharging when you desire.
BTW because I'm lazy to expand my system I just ordered 14 kWh of fully packaged LFP battery (box, BMS, cells, breaker) for $1800, $130/kWh, $0.026/kWh cycled.
Note how ridiculously fast the battery rollout in Texas and California has been recently.
If you've not got some local regulation that stops early adoptors from being left high and dry when the market changes, then you're in head to head competition for that cheap nighttime energy with big corporations building out grid scale batteries.