eml2
Member
What is the definition of NEM? I get paid for exporting energy, but it's only at a fraction of what I pay. Also, I have TOU rates for usage, but fixed rate for export. So, is this NEM?
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1.37.0
- Thread starter sashton
- Start date
I would not call that NEM. I would call that a Feed-In Tariff system.
With the NEM that is implemented in California, they total the net kWh for each TOU period and multiply it by the rate ($/kWh). They total the dollars for that billing period and add it to your annual true-up balance.
For example: (totally made up numbers)
Peak: -75kWh @ $0.32/kWh = -$24.00
Part-Peak: -200kWh @ $0.25/kWh = -$50.00
Off-Peak: 800kWh @ $0.12/kWh = $96.00
Total: $22.00
That is true net metering.
It’s odd because I’m on 1.34.2 / TBC / cost-saving and all my graphs look like your good graph, which is what I would call 100% self-powered by Powerwall during peak. (See my other thread on a bug in Tesla calc of this percentage, but the graphs and sum totals agree). And the only time I’ve seen off-peak discharge was the first day before TBC appeared. Now I hope I haven’t jinxed myself.
So, here's today's chart, with just the home and Powerwalls shown for clarity in the second chart.
Aside from a cloudy crummy solar day, pretty much the only problem I see is the discharge events I mentioned above at midnight and 4-7am. There were other tiny discharges around 8:30am and 1pm, but those are of little consequence.
One more mistake. The outage was on March 26th, not May 26th. So, scratch that explanation.
Actually, the Peak period behavior is unchanged. I would not call what it's doing during Peak "Self-Powered". I would call it "Discharge to export All Solar". The thing I was pointing out in my "good" chart on 1.37.0 was the behavior at the start of the Part-Peak period where it is discharging to zero out the grid before the solar ramped up above the household load. In the past, at best, it would put the Powerwalls in Standby at the start of Part-Peak until there was Surplus Solar, thereby reducing the grid contribution until it went to zero when the solar exceeded the household load.
New to NEM. Let's assume the $22 is a credit. If all other months total net zero, at the annual settlement period, you will NOT be issued a check for $22, correct? This is due to the fact that (at least in my area) you would instead be credited at the wholesale rate. The $22 represents the consumer rate.
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This is an area of nuance which depends on the state and the utility. My utility is PG&E in Northern California. If PG&E is also your energy provider (ie. you didn't sign up with a DA provider or CCA) then they will only issue a check if you are a net generator. That means that at the end of the year you exported more kWh to the grid than you consumed from the grid. It is possible to have a couple hundred dollar credit balance due to TOU differentials on retail energy prices and have it wiped out because you were not a net generator. The Net Surplus Compensation for net surplus kWh is "wholesale" at about 3.5c/kWh.
On the other hand, if you are on a CCA (Community Choice Aggregation) then they have their own policies for the generation portion of the bill that they handle. Most will actually cut you a check for credit balances based on retail generation rates whether you are a net surplus generator or not. PG&E will still wipe out your credit balance on the transmission and distribution part of your bill at true-up and of course you have to pay the minimum delivery charges of ~$10/mo every month as well.
Brovane
Member
I have been upgraded to 1.37.1 recently.
I am in SCE service area of CA. Rate Plan TOU-D-A.
I don't have any shoulder time configured under the price schedule in the App. My peak time is 2pm-8pm. I then have everything else off-peak. I used to have issues with the PW going into discharge status during shoulder time. After a call into Support it was recommended that I eliminate the shoulder time so I just have peak and off-peak time scheduled. This fixed the issue with my PW going into discharge status during shoulder time.
I noticed that after the update my PW is now discharging during off-peak times. Just today my PW discharged during the night while my EV was charging and in the morning at 5am I could see the unit still discharging.
Not sure exactly what is going on but I would rather my PW not discharge during off-peak times.
I can see that I am not the only one noticing some different behavior because of this latest update.
I am in SCE service area of CA. Rate Plan TOU-D-A.
I don't have any shoulder time configured under the price schedule in the App. My peak time is 2pm-8pm. I then have everything else off-peak. I used to have issues with the PW going into discharge status during shoulder time. After a call into Support it was recommended that I eliminate the shoulder time so I just have peak and off-peak time scheduled. This fixed the issue with my PW going into discharge status during shoulder time.
I noticed that after the update my PW is now discharging during off-peak times. Just today my PW discharged during the night while my EV was charging and in the morning at 5am I could see the unit still discharging.
Not sure exactly what is going on but I would rather my PW not discharge during off-peak times.
I can see that I am not the only one noticing some different behavior because of this latest update.
I'm same service, same rate, NEM2. Looks like I'm not missing anything with only 1.35.2. Sounds like only "self-powered" is predictable and usable.
I just use "self-powered" and Raspberry Pi to set my own arbitrary shoulder/super-off-peak times. Working wonderfully.
"shoulder" time 1, 7am to 8pm: PW charges only from excess solar in the morning -- otherwise discharges to zero grid-usage until 8pm, reserve at 78%. Then reserve is set to 100% to prevent any further discharge.
"shoulder" time 2, 11pm to 1am: PW discharges to cover night-time appliance usage such as dishwasher, washer, etc, reserve set to 75% to allow this extended usage, then back to reserve at 100%.
Rinse/repeat.
I think prior to 1.37, eliminating the shoulder period was the correct strategy. However, they have "fixed" the shoulder period starting 1.37 so that it usually runs like Self-Powered. The early discharge during shoulder is gone. However, my system has discharged during Off-Peak when the SOC was high, like over 80%. It never used to discharge during Off-Peak at all. I am running TBC-Balanced mode.
I would try putting the shoulder period back in your schedule and see how it does next week.
Thanks for the feedback.
Arbitrary numbers below conceptually reflecting actual bill at annual settlement. Are my calculations and conclusions correct?
TOU: Yes
Total @ consumer rate: -$500
Net Surplus: -2000 kWh (generation to grid)
Net Surplus Compensation @ 0.04: $80 (2000 * 0.04)
Monthly Mandatory Charge for 12 months @ $10/month: $120
- Total annual liability to my utility is $40 (120 - 80).
- Size of total consumer rate, if reflecting a credit, is irrelevant to my bottom line.
- Monthly mandatory charge is NOT offset by monthly net generation at consumer rate.
- Should target to have a Net Surplus to cover the mandatory charge.
- For simplicity, self-powered mode, is the "better" option given difference in consumer rate I pay and the surplus rate paid by my utility.
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Set your TBC to Cost Saving, not Balanced. I have the exact same setup as you do, and 1.37.1 discharged off-peak on the first day because I was still using Balanced. Changing TBC to Cost Savings stopped all off-peak discharge.
Generally, you've got it. One more nuance, or should I say nuisance? If you have a recent solar system on PG&E or SoCal Edison, you will be on NEM 2.0 which also has Non-Bypassable Charges. So, even if you have 2,000 kWh surplus generation, you will owe a small amount for every kWh that you take from the grid that cannot be offset by your generation. So, let's say you use about 500kWh/mo charging your car during overnight hours. You will owe about 1 cent/kWh (made up number, I've never been able to figure out the exact calculation) so you will owe about $5/mo more, in addition to the $10/mo minimum delivery charges.
So, if you are a Powerwall customer and you are truly a net surplus generator, arbitrage means nothing to your bottom line, so you will save the most by running in Self-Powered Mode to reduce your NBC's. You will also save more by charging directly from your solar as much as possible.
It's odd how some see discharging during off-peak. I've always used Balanced and have never seen my system discharge during off-peak. What do you have your reserve set to?
We typically have ours set to 30% and have a shoulder period set. Ours discharge predictably during the shoulder but never during off-peak. I might try eliminating the shoulder to see if they discharge during off-peak as you've seen.
NinjaVece
Member
While I'm under SCE and have Super-Offpeak, Offpeak and Peak (the new names for Off-Peak, Shoulder-Peak and Peak as far as SCE is concerned), I also have set my Reserve to 40% now that the Sun is tracking higher and there is more solar input time during Peak. I'm grandfathered under the old TOU-D-A regime.
Under my Cost Savings set-up, I only have the PW2 discharge under Peak, which is the most cost-effective due to my PPA charges for solar which almost match Off-Peak (the new Off-Peak) rates. My savings occurs during Peak for Winter and during Off-Peak and Peak for Summer...
I noticed my Powerwalls and solar appeared to shut off for a few minutes today. I checked and confirmed my firmware was just updated from 1.36.1 to 1.37.1 this morning.
There are actually release notes available for 1.37 now:
There are actually release notes available for 1.37 now:
I have been watching the app closely today since being upgraded to 1.37.1 this morning. It looks like they might've finally fixed discharging during the shoulder period before peak...or maybe things just reset and it will start over in a couple of days. While some people have reported seeing their Powerwalls discharge in off-peak, we've never had that issue. However, we've always seen our Powerwalls start discharging hours before peak period starts. For example, we have the peak period scheduled to start at 2 PM Monday - Friday. Since programming in peak, part-peak and off-peak, we've always seen the Powerwalls start to discharge hours early, sometimes 3 or 3 hours before peak. Today with 1.37.1, the Powerwalls were charged up from 32% to 100% by 11 am but they stayed at 100% until right at 2 PM. This is how I have expected things to work...but we'll see in the coming weeks if it stays that way!
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