TOU for SCE in Southern California analysis

[silversaver]

Except I already have it (the TOU-EV1) and it has certain benefits like the 11c/kWh off-peak rate from 9pm to noon and lower on-peak rates than TOU-D-A, so I would like to keep it. I just want to clarify how the Baseline Allocation Credit is calculated in terms of meters. And btw, my understanding is that SCE will credit you 10c less per kWh you produce in excess of what you consume up to your monthly baseline allocation.

When you are a net consumer for the month (i.e., you consume more electricity from SCE than you export to the grid), a portion of your energy charges will be lowered through the baseline credit applied monthly on a $per kWh basis. For example:
• If a customer has a Baseline Allocation of 500 kWh/month and their net kWh (consumption from SCE minus exported generation) for the month is 750 kWh, the customer will receive 10 cents per kWh credit up to the 500 kWh Baseline amount, equal to a $50 credit.
• If a customer has a Baseline Allocation of 500 kWh/month and their net kWh for the month is 250 kWh, the customer will receive 10 cents per kWh credit up to the net 250 kWh, equal to a $25 credit.
Net Generator of Electricity
When you are a net generator for the month (i.e., you export more electricity than you consume from SCE that month), the Baseline Credit will appear as a monthly charge since you are multiplying a negative kWh amount by a negative billing factor. This is necessary to ensure that you receive the same rate for the exported kWh that you would have received if you had consumed that same kWh from SCE.
For example, if a customer has a Baseline Allocation of 500 kWh/month, and their net kWh for the month is -100 kWh (exported generation is greater than consumption from SCE), the customer’s bill will reflect a 10 cents per kWh charge up to the net -100 kWh of generation, which results in a $10 charge.


the calculation were done at end of each statement on net consumption. Orange County is region 8, I believe winter 9.2kWh/day Summer 10.1kWh/day baseline.

[gvl]

Thanks, I think I understand how the Baseline Allocation Credit in general. The uncertainty is around having some of the electricity consumed and billed through a second meter that is on a completely different rate plan that has no Baseline Allocation Credit (and no solar attached to it). Here is an example:

Monthly solar generation is 1500kWh.
Monthly usage on the main TOU-D-A meter is 1000kWh
Monthly usage on the EV TO-EV-1 meter is 600kWh
Total usage for 2 meters is 1600kWh

Looks like I'm a net consumer for this month, however unless SCE ignores the fact the 2 meters are separate for the purpose of the Baseline Allocation Credit calculation I think what is going to happen is that they will give a credit for 500kWh of production (more than half of which will have the 10c BAC "penalty") that will be applied towards the TO-EV-1 usage, so assuming baseline allocation of 300kWh, in this month a 2-meter setup would be $40 more expensive than a single domestic TOU-D-A plan for both the home and EV charging?

EDIT:

I think I found the answer in the NEM aggregation FAQ:

The electrical consumption of kilowatt-hours (kWh) registered on each aggregated account’s meter will be reduced, for NEM billing purposes, by a proportional allocation, at the 15-minute interval level, of the electricity generated by the REGF that is exported to our grid. The proportional allocation is determined per billing period based on the cumulative consumption of each aggregated account compared to the cumulative consumption of your NEM Aggregation arrangement since the start of the relevant period, and the cumulative generation exported from the REGF since the start of the relevant period.

A %-age of generation will be allocated to the EV meter for the purposes of NEM credit calculation, so for the above example EV usage is 37.5% and 62.% is household, the EV account will get 562.5kWH generation and the main will get 937.5kWh, so there will be a ~$6 BA credit, while there is also a $5 charge for account aggregation it is not as bad as $40 I originally thought. There is however a bigger problem, I think the EV meter will "steal" some of the higher-priced generated energy due to differences in rates.

[silversaver]

Thanks, I think I understand how the Baseline Allocation Credit in general. The uncertainty is around having some of the electricity consumed and billed through a second meter that is on a completely different rate plan that has no Baseline Allocation Credit (and no solar attached to it). Here is an example:

Monthly solar generation is 1500kWh.
Monthly usage on the main TOU-D-A meter is 1000kWh
Monthly usage on the EV TO-EV-1 meter is 600kWh
Total usage for 2 meters is 1600kWh

Looks like I'm a net consumer for this month, however unless SCE ignores the fact the 2 meters are separate for the purpose of the Baseline Allocation Credit calculation I think what is going to happen is that they will give a credit for 500kWh of production (more than half of which will have the 10c BAC "penalty") that will be applied towards the TO-EV-1 usage, so assuming baseline allocation of 300kWh, in this month a 2-meter setup would be $40 more expensive than a single domestic TOU-D-A plan for both the home and EV charging?

EDIT:

I think I found the answer in the NEM aggregation FAQ:



A %-age of generation will be allocated to the EV meter for the purposes of NEM credit calculation, so for the above example EV usage is 37.5% and 62.% is household, the EV account will get 562.5kWH generation and the main will get 937.5kWh, so there will be a ~$6 BA credit, while there is also a $5 charge for account aggregation it is not as bad as $40 I originally thought. There is however a bigger problem, I think the EV meter will "steal" some of the higher-priced generated energy due to differences in rates.

Please keep it simple. Switch back to 1 meter TOU-D-A plan. There is no need to keep 2 meter plan when you have solar.

[gvl]

Please keep it simple. Switch back to 1 meter TOU-D-A plan. There is no need to keep 2 meter plan when you have solar.

I thought there was, but now see there is no real benefit and it actually makes things worse. Now I wonder if they would let me to put both meters on the TOU-D-A plan just to avoid electrical work and some $$. I have a nice 100A dedicated line tapped into the service just before the main panel for current and future EV needs, it will have to be abandoned which is a bummer.

[silversaver]

I thought there was, but now see there is no real benefit and it actually makes things worse. Now I wonder if they would let me to put both meters on the TOU-D-A plan just to avoid electrical work and some $$. I have a nice 100A dedicated line tapped into the service just before the main panel for current and future EV needs, it will have to be abandoned which is a bummer.

Call SCE see if they allow you to combine both meters. I don't think they will allow that to happen since TOU-D-A is 1 meter.

[gvl]

Call SCE see if they allow you to combine both meters. I don't think they will allow that to happen since TOU-D-A is 1 meter.

Just spoke with SCE, while they admitted they are still getting familiar with all the new aggregation rules they said most likely they won't allow to have 2 TOU-D-A meters. I don't know why they care as it is just the way the monthly bill is calculated, perhaps there are assumptions built into their accounting system. They couldn't definitely confirm if the excess energy exported will be split into 2 parts and credited to my account under TOU-D-A and TOU-EV-1 rates separately, but I don't see how else it is going to work. They promised to get back to me next week with more details.

[gvl]

Slightly OT, but considering the steadily growing solar install base I'd like to hear some opinions on how likely SCE is to change the TOU plans over time to minimize the cost gap between the on-peak and off-peak rates.

[J.P.M.]

Slightly OT, but considering the steadily growing solar install base I'd like to hear some opinions on how likely SCE is to change the TOU plans over time to minimize the cost gap between the on-peak and off-peak rates.

Very likely, but probably not as a gesture of good will or humanitarianism. One big reason TOU rates exist is to help the POCOs manage peak loads. They often refer to time variant pricing such as T.O.U as a way of "sending rate signals" to the users to disincentivize/discourage using power at peak times such as weekdays, mid to late afternoon. Initially, the idea itself had little to do with solar production, and actually still doesn't.

T.O.U. plans will continue to change as they have in the past in response to changes in load patterns. It may be that in the future, POCOs will uncouple T.O.U. use pattern pricing from Solar time variant generation reimbursement. There's not much reasoning I can think of why they MUST be joined at the hip. Even now, peak solar generation and peak load are out of sync by a few hrs. in CA, and probably other sunny markets with peak load occurring about 2-3 hrs. later, which BTW is probably why peak T.O.U. hrs. for CA POCO's have been shifting later for the has couple/3 years or so - that change adding some backup to the belief that T.O.U. rate policies and purposes are mostly about load management.

[gvl]

Very likely, but probably not as a gesture of good will or humanitarianism. One big reason TOU rates exist is to help the POCOs manage peak loads. They often refer to time variant pricing such as T.O.U as a way of "sending rate signals" to the users to disincentivize/discourage using power at peak times such as weekdays, mid to late afternoon. Initially, the idea itself had little to do with solar production, and actually still doesn't.

T.O.U. plans will continue to change as they have in the past in response to changes in load patterns. It may be that in the future, POCOs will uncouple T.O.U. use pattern pricing from Solar time variant generation reimbursement. There's not much reasoning I can think of why they MUST be joined at the hip. Even now, peak solar generation and peak load are out of sync by a few hrs. in CA, and probably other sunny markets with peak load occurring about 2-3 hrs. later, which BTW is probably why peak T.O.U. hrs. for CA POCO's have been shifting later for the has couple/3 years or so - that change adding some backup to the belief that T.O.U. rate policies and purposes are mostly about load management.

I'm basically thinking along the same lines and it makes me believe that sizing your solar system to the today's TOU realities is not the right approach and it may bite you back some time down the road as higher bills. Adding more panels may become more difficult in the future, amongst other things it will likely nullify your grandfathered net-metering agreement that guarantees the same price for usage/export.

[J.P.M.]

I'm basically thinking along the same lines and it makes me believe that sizing your solar system to the today's TOU realities is not the right approach and it may bite you back some time down the road as higher bills. Adding more panels may become more difficult in the future, amongst other things it will likely nullify your grandfathered net-metering agreement that guarantees the same price for usage/export.

In the bigger scheme of things, the less electricity used, the less the bill. I'll put more effort into load reduction within the limits of a lifestyle than worrying about the future direction of POCO rates, using the logic I'll work on things I may have some measure of control over.

Since things will change in the future in ways that are unpredictable, and for me uncontrolable - as in $4.00/gal. 12 months ago to ~ $2.50/gal a few months back, to about $3.00/gal. now - T.O.U. rates may or may not be attractive in the future. Example: Someone may solve the energy storage situation in a scalable way for both residential up to district and utility considerations, perhaps making residential utility hookup an anachronism. I'm not betting the farm on that happening in my lifetime, but the lower the load (something I can do something about) the less POCO and rate payer shenanigans can affect me, and that's about as much future planning about where rates are going as I deem worthy of thinking about.

Thought about in a certain way, T.O.U. pricing MAY be best used in the planning stages of any residential solar project, both for system sizing and array orientation, but my guess is that will best work with a pretty hard load/use profile as f(time). It may be that an array can be oriented to best maximize revenue according to a current T.O.U. time schedule and rates, with the full knowledge that the time schedule and rate(s) used will change - that's life - so take your best shot. That sizing can then be matched to the expense side - what is used, how much and when after gerrymandering the load profile to minimize expense by attention to both how much and when power is used as seen fit. Basically, size and orient the system to match the expense of the electricity, after getting that expense as low as possible by managing when and how much electricity is used.

[gvl]

... Basically, size and orient the system to match the expense of the electricity, after getting that expense as low as possible by managing when and how much electricity is used.

It is the right strategy I suppose. I'm currently facing a dilemma whether or not to do what you say or delay the payback period for a year or so and get a larger system that should give me more comfort and flexibility in the long run. About the only sensible approach to minimize my usage right now is to install a variable speed pool pump which will cost about $1000 after rebates, then a 8kW solar should be enough to 0-out or close my monthly bill under the current TOU rate schedule. Or I can install 10kW solar for $5k more before the tax credit and not worry about the pump for the moment with the same effect on my monthly bill. So the pump becomes a ballast I can throw out in the future should my solar install out become insufficient for whatever reason be it rate changes, degradation, or buying an EV. Would you say that getting a 10kW system is unwise in this situation?

[SunEagle]

In the bigger scheme of things, the less electricity used, the less the bill. I'll put more effort into load reduction within the limits of a lifestyle that worrying about the future direction of POCO rates, using the logic I'll work on things I may have some measure of control over.

Since things will change in the future in ways that are unpredictable, and for me uncontrolable - as in $4.00/gal. 12 months ago to ~ $2.50/gal a few months back, to about $3.00/gal. now - T.O.U. rates may or may not be attractive in the future. Example: Someone may solve the energy storage situation in a scalable way for both residential up to district and utility considerations, perhaps making residential utility hookup an anachronism. I'm not betting the farm on that happening in my lifetime, but the lower the load (something I can do something about) the less POCO and rate payer shenanigans can affect me, and that's about as much future planning about where rates are going as I deem worthy of thinking about.

Thought about in a certain way, T.O.U. pricing MAY be best used in the planning stages of any residential solar project, both for system sizing and array orientation, but my guess is that will best work with a pretty hard load/use profile as f(time). It may be that an array can be oriented to best maximize revenue according to a current T.O.U. time schedule and rates, with the full knowledge that the time schedule and rate(s) used will change - that's life - so take your best shot. That sizing can then be matched to the expense side - what is used, how much and when after gerrymandered the load profile to minimize expense by attention to both how much and when power is used as seen fit. Basically, size and orient the system to match the expense of the electricity, after getting that expense as low as possible by managing when and how much electricity is used.

Good advice. Keep it simple. If you want to spend less on your electric bill find ways to use less. Conservation first is my motto.

[J.P.M.]

It is the right strategy I suppose. I'm currently facing a dilemma whether or not to do what you say or delay the payback period for a year or so and get a larger system that should give me more comfort and flexibility in the long run. About the only sensible approach to minimize my usage right now is to install a variable speed pool pump which will cost about $1000 after rebates, then a 8kW solar should be enough to 0-out or close my monthly bill under the current TOU rate schedule. Or I can install 10kW solar for $5k more before the tax credit and not worry about the pump for the moment with the same effect on my monthly bill. So the pump becomes a ballast I can throw out in the future should my solar install out become insufficient for whatever reason be it rate changes, degradation, or buying an EV. Would you say that getting a 10kW system is unwise in this situation?

Since you ask:

Right strategy ? - Who knows, opinions vary. Just one of many. Unwise : ?? Not a word I'd choose.

This being a free country the short answer is it depends on what you want and how you see your options.

If it was me, I'd do the most cost effective stuff first, if not done already, change the pool pumping schedule to only operate at super off peak times , and see what effect that has on the bill. Changing out a pump may not save that much more elec. vs. simply changing the # of hrs. the pump runs and when. Is it possible to only run it only at super off peak times ? Use your head first instead of your wallet if/when at all possible. That's called the smart money way. See what a schedule change does, and then get a new pump if you figure that will add to the savings over the current pump when both are operated only at super off peak, while at the same time paying for itself sooner than some other use reduction/bill reduction (solar) measure.

The 2 kW reduction in array size will reduce annual output by VERY ~ 3,000 kWh/yr, +/- some, and reduce array cost by ~~ $4,500 after tax credit. So, what's the marginal cost of the last 3,000 kWh of power you buy at say, 1/3,1/3,1/3, peak, off peak, super off, while keeping one corner of one eye on the best SWAG of what costs are likely to do in the future (as in who knows ? - but being too pessimistic can be as bad as too optimistic).

[bcroe]

Good advice. Keep it simple. If you want to spend less on your electric
bill find ways to use less. Conservation first is my motto.

Energy conservation is FIRST here too, its been pursued & improved here for years. But
it is a game you can't win, because zero is never attained.

So then there is SECOND. Here that means find an energy source that eliminates
that frustration of never reaching zero, perhaps at a more comfortable level. With
solar, its a lot easier to build big first, than to try and find a way to expand later.

Another approach used here on many things, is try something small scale first, get
real world experience, then use that background to get a powerful solution.

Obviously these ideas will not appeal to all. Bruce Roe

[J.P.M.]

Energy conservation is FIRST here too, its been pursued & improved here for years. But
it is a game you can't win, because zero is never attained.

So then there is SECOND. Here that means find an energy source that eliminates
that frustration of never reaching zero, perhaps at a more comfortable level. With
solar, its a lot easier to build big first, than to try and find a way to expand later.

Another approach used here on many things, is try something small scale first, get
real world experience, then use that background to get a powerful solution.

Obviously these ideas will not appeal to all. Bruce Roe

Hey Bruce: On getting to zero:

"Ah, but a man's reach should exceed his grasp, or what's a heaven for ?"

Robert Browning