I run a large 18650 powerwall at 121kwh. Thus, I'm very interested in how long my powerwall will be effective and even more interested in what 'failure' will look like.
But I'm not seeing any way to relate 50K / 100K miles to solar powerwalks. What do you folks think - extrapolate energy consumed per mile from the EV batteries and relate that to energy consumed from the powerwall by the inverters?
Let's try that.....
100K miles at 0.346kwh/mile (
https://ecocostsavings.com/average-electric-car-kwh-per-mile/ ) = 34,600kwh from an EV battery for 100K miles and 6-10% degradation. So far my inverters have consumed ~85,000kwh from the powerwall over 1,957 cycles. That's 2.46 times the 100K energy - so I should see 2.5 times the degradation? - e.g. 6% * 2.5 = 15% degradation??
Don't believe I'm seeing that much degradation but I didn't start with all 9 batteries in the powerwall at once. This is the powerwall makeup over the 85,000kwh consumed to date. Lifetime average of 35.8% DOD.
Perhaps the newer batteries in parallel with battery #1 are propping it up and hiding 15% degradation to battery #1 so it's more like 4% overall spread among all 9 batteries in parallel in proportion to their age/cycles.
I am tracking ah/v of energy provided during 0 PV times - e.g. straight battery -> inverter. This is not apples to apples from year to year because of the new batteries added but soon I'll be 'static' (no more batteries) and I'm hoping that ah/v will eventually give a peek into degradation over the next 5-10 years.