hill
Well-known member
. . . . . and why / why not?
Grid Tied PV Members: TOU? ... or Not
- Thread starter hill
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garygid
Well-known member
Not TOU because:
1. SDG&E billing (with PV over-generation in some time slots)
has not been explained.
2. Likely that one gets "credited" little for over-gen, and gets charged
more for even Super Off-Peak usage.
3. With Net metering, I can charge any time,
and from any socket that is convenient.
4. No need for an expensive install of a 2nd meter.
5. There does not APPEAR to be any significant advantage to using TOU.
1. SDG&E billing (with PV over-generation in some time slots)
has not been explained.
2. Likely that one gets "credited" little for over-gen, and gets charged
more for even Super Off-Peak usage.
3. With Net metering, I can charge any time,
and from any socket that is convenient.
4. No need for an expensive install of a 2nd meter.
5. There does not APPEAR to be any significant advantage to using TOU.
thankyouOB
Well-known member
at LADWP, there is significant advantage to TOU.
There is no loss of banked funds at the end of the year, only when you move.
With TOU, you produce in the four summer months at 22 cents a kWh and consume at 11 cents.
In the darker months, the ratio is closer but still advantages the daytime versus nighttime.
You dont need a second meter, unless you want to go on the EV rate, which allows you to save 2.5 cents on every kWh used to power the car, but it also requires a second service fee. I dont see any advantage to that.
There is no loss of banked funds at the end of the year, only when you move.
With TOU, you produce in the four summer months at 22 cents a kWh and consume at 11 cents.
In the darker months, the ratio is closer but still advantages the daytime versus nighttime.
You dont need a second meter, unless you want to go on the EV rate, which allows you to save 2.5 cents on every kWh used to power the car, but it also requires a second service fee. I dont see any advantage to that.
Boomer23
Well-known member
YES! So Cal Edison TOU-D-TEV rate uses the single household meter so no second meter install needed. Summer On-Peak solar production credits your account at 55 cents in Tier 2 (where you'd most likely be) and EV charging midnite to 6 am (Super Off Peak) is billed at 16 cents per kWh. Overall, if you overproduce PV power and you don't use up a lot of On-Peak power with air conditioning or electric cooking or laundry, you can offset your costs of EV charging to the point that you can get EV charging at zero cost for more kWh than you produce with your PV system!
EricH
Well-known member
Yes.
The California Public Utilities Commission sets rates for PG&E, SCE, and SDG&E customers (not for LADWP, SMUD, and numerous other smaller muni's including Pasadena, Azusa, Anaheim, etc.). My discussion here probably doesn't apply to municipal utilities.
All CPUC residential rates are now set using five "tiers" that vary with your baseline allocation (which is set using statistical analysis of recorded usage data from all customers in your climate zone). Each tier costs more than the last, so that high-usage customers like me hit Tier 5, which is very costly. So your cost to charge on the regular domestic rate depends heavily on what "tier" your usage will hit with your Leaf plugged in.
All of the above utilities offer (or will have to shortly) a whole-house, single-meter TOU rate for EV owners -- this is the "TOU-D-TEV" rate for SoCalEdison customers. I believe it has 2 tiers at present and those may be short-lived (i.e. it will change later this year to a simple on/mid/off-peak TOU rate with at least 8 hours of off-peak time to fully charge your EV).
In SCE's case, you may return from a TOU rate to the regular "D" (non-TOU) rate at any time, but you are then pinned to the "D" rate for at least 12 months - this is a reasonable way to prevent people from hopping off the TOU rate for summer and back on in the winter
I don't know where you live, but the CPUC enforces some comparability among its regulated utilities, so SDG&E and PG&E terms are likely similar.
SCE also offers a TOU-EV-1 rate for domestic usage that is dedicated to EV charging, but this requires an investment in a second meter panel, which has been discussed in other thread(s) on this forum. SCE ran an analysis using my historical usage, my estimated on/off-peak ratios and forecast LEAF mileage, and it appeared that I would spend $525/year to charge the Leaf on the 2nd meter rate, but $650 extra ($125 "delta") for the single-meter rate. My payback is then $10/month vs. $1,500-$2,500 for a second panel, so the TEV rate was a no-brainer.
PS: Staying on the regular "D" rate would cost over $1,300/year because all of my charging would be at the Tier 5 rate, so moving to TEV cuts that by more than half. If you live near the coast and use little A/C, you may be a Tier 1 customer so your savings from moving to TEV could be far more modest than mine; this is why they offer the customized analysis.
The California Public Utilities Commission sets rates for PG&E, SCE, and SDG&E customers (not for LADWP, SMUD, and numerous other smaller muni's including Pasadena, Azusa, Anaheim, etc.). My discussion here probably doesn't apply to municipal utilities.
All CPUC residential rates are now set using five "tiers" that vary with your baseline allocation (which is set using statistical analysis of recorded usage data from all customers in your climate zone). Each tier costs more than the last, so that high-usage customers like me hit Tier 5, which is very costly. So your cost to charge on the regular domestic rate depends heavily on what "tier" your usage will hit with your Leaf plugged in.
All of the above utilities offer (or will have to shortly) a whole-house, single-meter TOU rate for EV owners -- this is the "TOU-D-TEV" rate for SoCalEdison customers. I believe it has 2 tiers at present and those may be short-lived (i.e. it will change later this year to a simple on/mid/off-peak TOU rate with at least 8 hours of off-peak time to fully charge your EV).
In SCE's case, you may return from a TOU rate to the regular "D" (non-TOU) rate at any time, but you are then pinned to the "D" rate for at least 12 months - this is a reasonable way to prevent people from hopping off the TOU rate for summer and back on in the winter
I don't know where you live, but the CPUC enforces some comparability among its regulated utilities, so SDG&E and PG&E terms are likely similar.SCE also offers a TOU-EV-1 rate for domestic usage that is dedicated to EV charging, but this requires an investment in a second meter panel, which has been discussed in other thread(s) on this forum. SCE ran an analysis using my historical usage, my estimated on/off-peak ratios and forecast LEAF mileage, and it appeared that I would spend $525/year to charge the Leaf on the 2nd meter rate, but $650 extra ($125 "delta") for the single-meter rate. My payback is then $10/month vs. $1,500-$2,500 for a second panel, so the TEV rate was a no-brainer.
PS: Staying on the regular "D" rate would cost over $1,300/year because all of my charging would be at the Tier 5 rate, so moving to TEV cuts that by more than half. If you live near the coast and use little A/C, you may be a Tier 1 customer so your savings from moving to TEV could be far more modest than mine; this is why they offer the customized analysis.
lonndoggie
Well-known member
garygid said:
Gary, are you talking TOU for just the EV, or the whole house (DR-SES), or a mix of both? Seems like some of both.
PV over-generation is a DR-SES issue. I'm a little nervous about this, too, but this statement can be found on SDG&E's site about DR-SES:
Given that, 2 kWhs of over-gen at peak offsets 3 kWhs of usage off-peak, give-or-take. Except that the generation charge (or whatever the other per-kWh component is) might also be charged for actual off-peak usage, but not credited for on-peak generation.
Anyone else using SDG&E DR-SES? Good, bad?
For the separate EV TOU, I'm doing that, as it's not costing me anything to install, I'll be charging at night to get the low-low rates, and--most importantly--our PV system doesn't generate enough to cover our usage plus the car (or even enough to keep us in tier 1 or 2 with the car).
I really think this is a YMMV deal; sounds like it doesn't make sense for you, whereas I think it will make sense for me.
LEAFfan
Well-known member
thankyouOB said:
Here in AZ, our PU only pays .04/kwh for any extra and that includes on peak. They charge .34 for on-peak use (3PM-6PM weekdays). Since there is no difference, we're switching to the 'Basic' plan. I've banked over a half megawatt so far since Jan.
garygid
Well-known member
Since I am not in EVProject territory, I pay for any install work needed to get ready for a 2nd meter. So, I have only one meter, and it is not TOU.
The CPUC does not set rates, it approves them, or not, as submitted (differently) by each different PU. So, each PU will, in general, have different rates and billing structure.
The new head of the CPUC is apparently very much an EV and PV fan, interested in having one-meter rates that are good for house, EV, and PV. So, apparently the CPUC is requiring PUs to submit such a tariff for approval.
The CPUC might also require some REASONABLE PV "credit" system, including credits & payments for over-generation.
If GOOD payments/credits emerge for over-generation in a TOU tariff (get more credit for a kWh at Peak than a kWh costs Off-Peak), I will consider switching from simple tierred Net, to TOU.
The CPUC does not set rates, it approves them, or not, as submitted (differently) by each different PU. So, each PU will, in general, have different rates and billing structure.
The new head of the CPUC is apparently very much an EV and PV fan, interested in having one-meter rates that are good for house, EV, and PV. So, apparently the CPUC is requiring PUs to submit such a tariff for approval.
The CPUC might also require some REASONABLE PV "credit" system, including credits & payments for over-generation.
If GOOD payments/credits emerge for over-generation in a TOU tariff (get more credit for a kWh at Peak than a kWh costs Off-Peak), I will consider switching from simple tierred Net, to TOU.
planet4ever
Well-known member
This thread is about grid-tied PV, i.e. solar panels. I certainly hope that no one with solar panels is hitting tier 5.EricH said:
Ray
planet4ever
Well-known member
In PG&E territory the answer is definitely yes to some form of TOU. Let's say, for example, that your LEAF brings you up to tier 3 on the E1 (non-TOU) schedule, and compare that with the E6 (TOU for PV) schedule.
With E1 the marginal rate for charging your LEAF will be $0.28/kWh, though part of the charging would be at $0.14/kWh if you were down in the middle of tier 2 before. Your PV system is going to be paying you exactly the same rate as you are paying to charge the car.
With E6, assuming you are charging at night, your marginal rate will be $0.25 for charging, but your solar panels will often be paying you peak ($0.47) or partial peak ($0.311 summer) rates. As with E1, if you are selling PV power at off-peak rates you will be getting exactly the same rate for the PV as you are paying to charge the car.
Specifically, in summer your peak PV hours, 10 AM to 4 PM, will be half at PG&E peak rates and half at partial peak rates on weekdays, all off-peak on weekends. Since off-peak is a wash, you come out ahead roughly:
1/42 * (15 * ($0.47 - $0.25) + 15 * ($0.31 -$0.25)) = $0.10
for each kWh you generate and use in the car, May through Oct.
Note 1: 1/42 because I'm looking at 42 hours/week of solar generation.
Note 2: You can only count the lesser of PV generation and EV usage.
Since winter PV generation is virtually all off-peak, that is a wash. I haven't counted the summer weekday hours from 4 PM to 7 PM. These also have the peak rate advantage, but your solar output is lower. Including a bit for that, and assuming 2,000 kWh going to the car in 6 months (with more from the PV) you should be ahead more than $200/year by using E6. The special EV rates, E9a and E9b, could be better or worse than E6 depending on your situation.
To summarize, TOU is an almost certain win, can't lose, proposition in PG&E territory. No second meter need be involved; and PG&E does not deduct transmission charges from the solar credit.
Ray
With E1 the marginal rate for charging your LEAF will be $0.28/kWh, though part of the charging would be at $0.14/kWh if you were down in the middle of tier 2 before. Your PV system is going to be paying you exactly the same rate as you are paying to charge the car.
With E6, assuming you are charging at night, your marginal rate will be $0.25 for charging, but your solar panels will often be paying you peak ($0.47) or partial peak ($0.311 summer) rates. As with E1, if you are selling PV power at off-peak rates you will be getting exactly the same rate for the PV as you are paying to charge the car.
Specifically, in summer your peak PV hours, 10 AM to 4 PM, will be half at PG&E peak rates and half at partial peak rates on weekdays, all off-peak on weekends. Since off-peak is a wash, you come out ahead roughly:
1/42 * (15 * ($0.47 - $0.25) + 15 * ($0.31 -$0.25)) = $0.10
for each kWh you generate and use in the car, May through Oct.
Note 1: 1/42 because I'm looking at 42 hours/week of solar generation.
Note 2: You can only count the lesser of PV generation and EV usage.
Since winter PV generation is virtually all off-peak, that is a wash. I haven't counted the summer weekday hours from 4 PM to 7 PM. These also have the peak rate advantage, but your solar output is lower. Including a bit for that, and assuming 2,000 kWh going to the car in 6 months (with more from the PV) you should be ahead more than $200/year by using E6. The special EV rates, E9a and E9b, could be better or worse than E6 depending on your situation.
To summarize, TOU is an almost certain win, can't lose, proposition in PG&E territory. No second meter need be involved; and PG&E does not deduct transmission charges from the solar credit.
Ray
thankyouOB
Well-known member
garygid said:
lonndoggie
Well-known member
thankyouOB said:
See http://www.mynissanleaf.com/viewtopic.php?p=66928#p66928
As with that, EVProject will install the EVSE and the "hole" for the second meter, SDG&E will provide the meter and install it--all for free (my install is straightforward enough).
YMMV, based on your conditions.
davewill
Well-known member
In SDG&E territory (and others?), SDG&E is working with Ecotality to get second meters installed so they can do a pricing/usage study. Ecotality's contractor will be installing the second meter socket, and SDG&E will be installing the meter, both at no cost to me.thankyouOB said:
Randmac
Active member
Yes, TOU. I switched to SCE TOU-D-T in January in preparation for EV charging because I believe it will save me money. I am NOT planning to use the TOU-EV rate at this time because a significant portion of my consumption is between 6pm and midnight. I am not interested separate meter EV billing at this time because of cost and complication that do not appear to have a reasonable pay back, for me.
I'm able to net generate M-F 10am-6pm because this is very very low consumption period, for me.
I plan to L1 charge between 7pm and 8am. (Also, my employer will make an outlet available for me to L1 charge M-F 9am-6pm).
The nature of TOU billing allows consumption of more kWh's off-peak than net generated on-peak. This is what saves money in my situation.
My PV system was sized at 2.3kW AC to eliminate all tier 3 and most tier 2 consumption. I've generated over 31MWh since Sep. 2003 (about 4160 kWh / year); about 70% of my pre-EV electric usage. After I have a years worth of EV charging and TOU-D-T experience I will re-evaluate my SCE rate plan and the economics of additional solar generation capacity.
I'm able to net generate M-F 10am-6pm because this is very very low consumption period, for me.
I plan to L1 charge between 7pm and 8am. (Also, my employer will make an outlet available for me to L1 charge M-F 9am-6pm).
The nature of TOU billing allows consumption of more kWh's off-peak than net generated on-peak. This is what saves money in my situation.
My PV system was sized at 2.3kW AC to eliminate all tier 3 and most tier 2 consumption. I've generated over 31MWh since Sep. 2003 (about 4160 kWh / year); about 70% of my pre-EV electric usage. After I have a years worth of EV charging and TOU-D-T experience I will re-evaluate my SCE rate plan and the economics of additional solar generation capacity.
DaveinOlyWA
Well-known member
not TOU here in WA. have Puget Sound Energy which bills on volume. you have to be less than a hermit to qualify for tier one which is something like under 300 Kwh for a month or something like that. only one person i know can make that and that is Joe who has a ton of solar on his roof. he creates a surplus in the summer which he uses occasionally in the winter to keep at tier one.
Jimmydreams
Well-known member
I think it all depends on expected use vs your solar production. My solar production covers 99% of electric bill annually. We also have a 'tiered' billing system. I drive my leaf 1500+ miles a month, so my electrical usages is in the neighborhood of 500+kWh/month. That would put me into tier 2 or higher, so having a separate TOU meter for the EV is cheaper.
If I was driving the Leaf less, (and would stay in tier 1 territory), then having a separate meter will actually cost you more....
It all depends on your numbers....
If I was driving the Leaf less, (and would stay in tier 1 territory), then having a separate meter will actually cost you more....
It all depends on your numbers....
walterbays
Well-known member
True. And the utility's numbers too. My PV meets just over 100% of my house needs. If after studying the results of the EV Project, SDG&E picks a rate structure that is advantageous to night time EV charging, then two meters will be best for me. If I recall correctly one of the rates goes as low as 6.7 cents. At those rates it wouldn't pay to install more PV to essentially "buy" back the power from myself at the marginal feed-in tariff rate expected to be something like 5.0 cents, barely lower than the SDG&E rate without any capital outlay.Jimmydreams said:
But if SDG&E picks a bad rate structure, then one meter with additional PV is the way to go. The existing EV rate is 14.1 cents at the lowest off-peak, and the tier 2 DR rate is even worse. Then I wouldn't worry about when I recharged since my cost would be the same marginal rate of 5.0 cents (annual reimbursement forgone by using the electricity myself, regardless of when produced and when used).
TomT
Well-known member
Not, because what I would save would be more than eaten up by the installation cost of the second TOU meter for the Leaf here in LADWP land. A single TOU main meter is also not an option because my wife and I are often home during the day peek which would nullify any TOU savings..
hill said:
TomT
Well-known member
The EVProject folks emphatically said no to installing a second meter as part of my EVProject install even though it would have been relatively simple. It may be different outside of the LADWP fiefdom.
lonndoggie said:
Azrich
Well-known member
We signed up for TOU in anticipation of the LEAF and then got the solar panels. The summer months schedule seems to work out better for solar production and crediting kWh, than the winter schedule.
Off Peak rates (LEAF charging) : winter: $ 0.0651 - 10 a - 5 p and 9 p -6a, and all day on weekends
summer: $ 0.062953 - 8pm - noon and all day on weekends
On peak rates: winter: $ 0.1138 rest of the week day
summer: $ 0.150144 2pm to 6pm
In the summer, there is a Shoulder-peak time too at about $0.086
Whatever time the solar system produces the kWh is at what rate they are credited to us. We have about 1000 kWh at off peak rates credited to us now. There is no second meter for LEAF in Tucson.
Off Peak rates (LEAF charging) : winter: $ 0.0651 - 10 a - 5 p and 9 p -6a, and all day on weekends
summer: $ 0.062953 - 8pm - noon and all day on weekends
On peak rates: winter: $ 0.1138 rest of the week day
summer: $ 0.150144 2pm to 6pm
In the summer, there is a Shoulder-peak time too at about $0.086
Whatever time the solar system produces the kWh is at what rate they are credited to us. We have about 1000 kWh at off peak rates credited to us now. There is no second meter for LEAF in Tucson.