I didn’t mean they only last 2 years but battery degradation is a pretty common and known thing.

By a quick search I didn’t find any claim of storage battery lifetimes outside of 10-15 years, so there doesn’t seem to be a breakthrough in tech I wasn’t aware of. 15 years is hardly the lifetime of a house, so you certainly don’t “buy only once”.

Solar panels also don’t work indefinitely but their efficiency degradation is more on par with the lifetime of major parts of the building, like the roof itself.