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Powerwall % Degradation
- Thread starter KHYE
- Start date
Five years, 2 PW outside, TOU from 100% to 20% every day... and still have 13.4kWh capacity in each! Less than 1% degradation.
You can try the powerwall companion app or the netzero.
2x PW2s installed Summer 2020 and 1x PW2 installed Spring 2021. Currently reporting capacity at: 101% / 100% / 101%. This is about a 1-2% drop in each. I seem to remember Tesla changed how they calculate capacity 1-2 years ago so the KWs reported were a little higher.
FWIW, summer-time PWs are set at 25-50% reserve, and winter time 50-90%.
FWIW, summer-time PWs are set at 25-50% reserve, and winter time 50-90%.
aesculus
Still Trying to Figure This All Out
3 year old PW2s. One 13.1 and one 13.2 kWh. General daily charge state is 50-80% during winter months and 20-100% during the rest of the year.
My newly installed PW2 charges full to 15,140 Wh. Maybe its just a question of watching that and working out the degradation over time because I would assume that it will start to lower the max it can charge over time. This value is coming from Home Assistant which uses the API to get this as opposed to just the %, which the Tesla app shows.
Matt-FL
Member
Couple of things to note on PW degradation. From Tesla's warranty perspective, the 'starting' kWh is 13.5 (or 13.2, depending on region). Also, the jury is still out on what counts as 'in warranty' versus out, for things like VPP and other items outside of 'Solar self-consumption/backup only', as stated in the warranty.
Anything outside that potentially falls into the second category with aggregate limitations. And, of course, there are a few discussions around what 'aggregate' means
. In 1.5 years, I've already sent or pulled 28MWh from my powerwalls, divide by 4 and that's 7MWh each battery. That means I'd potentially reach 37.8MWh in 8.1 years. I'm definitely in the first category, so I don't have any concerns, but for those that are using outside the first bucket, something to keep in mind.
I've got 4 PWs that are set to 20% reserve all year (except for occasional storms/concerns where I manually increase to 50 or 60%. Appox 1.5 years in and I'm at 107% warrantied capacity as per Powerwall Companion.
Powerwall Dashboard lists each individual PW capacity.
HTH!
Anything outside that potentially falls into the second category with aggregate limitations. And, of course, there are a few discussions around what 'aggregate' means
. In 1.5 years, I've already sent or pulled 28MWh from my powerwalls, divide by 4 and that's 7MWh each battery. That means I'd potentially reach 37.8MWh in 8.1 years. I'm definitely in the first category, so I don't have any concerns, but for those that are using outside the first bucket, something to keep in mind.I've got 4 PWs that are set to 20% reserve all year (except for occasional storms/concerns where I manually increase to 50 or 60%. Appox 1.5 years in and I'm at 107% warrantied capacity as per Powerwall Companion.
Powerwall Dashboard lists each individual PW capacity.
HTH!
Attachments
I am coming up on 6 years of Powerwall 2.0 usage and my two units report the following from system_status:
PW #1:
PW #1:
"nominal_full_pack_energy":13228
"energy_charged":9452910
"energy_discharged":8078863
PW #2:"nominal_full_pack_energy":13291
"energy_charged":9618418
"energy_discharged":8146049
Matt-FL
Member
So roughly 17kWh each batter aggregate. I'm curious if you have your batteries set to drain daily or do you set a high reserve?
I don't know what your 17kWh refers to. Did you mean 27kWh?
My Powerwalls supply all my house consumption from 3pm to midnight (everything except Off-Peak) and recharge to 100% every day. However, I've only started doing that this Winter. Previous years I didn't have Grid Charge enabled and my solar had limited generating capacity, so I kept raising the Reserve to leave only the best possible daily solar generation as headroom. If you have limited solar, there's no point to bouncing off a low Reserve - you might as well bounce off a high Reserve as long as you capture all the solar in the battery during Off-Peak. Having energy available for a Winter power outage is important to me.
Bottom line, my system discharges 10 to 15kWh per day from two Powerwalls.
[Edit] Actually, if you take the "energy_discharged" sum of both batteries and divide by the number of days since installation, it's only about 7.5kWh/day. Those 5 Winters really pull down the average and I don't have huge Summer loads.
He taking each battery's total input (about 9kwh charged) plus total output (about 8kwh discharged) and adding them "in aggregate" (9+8 = 17kwh), for the purposes of defining "aggregate throughput" for the threshold of the degradation warranty - though I think that should be 17 Mwh, not 17kwh.
Who knows what Tesla's actual definition is, it'll only become clear if someone actually tries to exercise a degradation warranty, but I would interpret "aggregate throughput" slightly differently than the sum of input and output. By analogy, if we were talking about say a network switch, where the bits that go in also go out immediately, then the "throughput" is basically the same as the "input" or the "output", assuming 100% of the data gets passed and nothing is discarded.
So the Powerwall battery is storing the energy, but you can also think of it as basically passing it "through" from the input (*charging") to the output ("discharging") with a long storage time delay. There is some losses, but basically the "throughput" is the lesser "output" that successfully makes it way in and out of the battery.
An imperfect analogy, sure, but "throughput" seems like a really odd word to use for a battery in the first place....
From system status: 10584 nominal full pack energy. About four years from installation. The battery did sit for thirteen months after the manufacture date, if that makes any difference. I've been keeping track for about a year and a half and it hasn't changed much. It's a small system like @miimura had so I keep the reserve high enough to capture and release any solar production from the day.
CrazyRabbit
Active Member
PW2 has 948 cells, and 21700 cells and if 20wh per cell that is 18,960wh per powerwall. 13,500/18,960=70%, so looks like tesla pw charges to 80% and discharges to 10%.
Seems reasonable to me.
Seems reasonable to me.
Matt-FL
Member
As Tesla's warranty states 'aggregate' (and I assume Tesla would interpret in which way works best for them), I read it as incoming + outgoing. Unless someone has received something specific from Tesla on the contrary, it's the way I would expect it to go. Once again, this would only affect those using PWs outside of the first category.
Yes, I meant 17mWh, thank you for catching that.
SoundDaTrumpet
Member
I installed the NetZero app yesterday to discover 26% & 25% degradation! I’m 4 months away from reaching the (ITC-related) 5 year mark where I plan to enable grid charging to maximize cost savings.
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