[ziga]

I agree about home batteries being too expensive, hopefully prices will come down with scale.

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...

[bboygravity]

There's a reason why Tesla picks 10 years (8 years for car batteries) as a warranty period. Ask yourself: why 8 years and not 10 for cars? Why 10 years and not 15 or 20 years for home batteries? It's not arbitrary.

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.

[LUmBULtERA]

Tesla and other car makers set their warranties at the mandatory minimums. Why would they offer more when they don't have to and consumers find them long enough and/or other car makers aren't competing on warranty length? That doesn't tell you anything about battery longevity.

Edit: Does my MacBook Pro die after 1 year when it's applecare warranty is over?