CATL's new Tener Stack energy storage system breakthrough can supply electricity from renewables to the average home for up to six years, in the first five of which it will undergo zero capacity degradation. It can also charge 150 electric vehicles before its batteries run out.https://www.notebookcheck.net/World-s-first-9-MWh-battery-storage-system-by-CATL-can-power-a-house-for-5-years-with-zero-degradation.1013696.0.html
I didn't see a price for the system.
The real question isn't how much degradation you have during first 5 years but what is the degradation curve and what is it like in 20 years?
Thing is, batteries are often times over-provisioned, 100% is closer to 90%. So your first 5 years of degradation could simply be the provision so it seems like 0, the drops.
If they give out a warranty then it is likely to retain 80% capacity during the 20 year warranty period. Even first LFP batteries had a very good longevity. They could easily last > 10 years if managed correctly. So this is not out of the ordinary for updated tech.
Cost product and install cost and diy ability?
This can be a big move into energy storage, where supply can be temporarily installed, removed to another site, or trains transporting the storage to site of usage?