TOU for SCE in Southern California analysis

[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.

[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]

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]

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]

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]

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]

[ATTACH=CONFIG]6215[/ATTACH]

If you choose TOU-D-A, then you really don't need TOU-EV1 2 meters plan. Any plan you choose, SCE credit you the same way they charges you.

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.

[silversaver]

I have a somewhat less than common setup with 2 meters, one for the house one for the EV, no solar yet. SCE confirmed the 2 meters can be aggregated for the purpose of net-metering. Anyone can comment if under the TOU-D-A/net-metering the Baseline Allocation Credit is calculated for the "net" usage from 2 meters, or only the house one which is the solar will be connected to? The concern is that while I may be a net-consumer each month I can be a net-producer on the house meter and will miss out on the credit plus it will reduce the cost of the electricity that I sell. Abandoning the EV meter/rewiring the charger to the house panel would solve this issue but I'd like to avoid it.

If you choose TOU-D-A, then you really don't need TOU-EV1 2 meters plan. Any plan you choose, SCE credit you the same way they charges you.

[gvl]

I have a somewhat less than common setup with 2 meters, one for the house one for the EV, no solar yet. SCE confirmed the 2 meters can be aggregated for the purpose of net-metering. Anyone can comment if under the TOU-D-A/net-metering the Baseline Allocation Credit is calculated for the "net" usage from 2 meters, or only the house one which is the solar will be connected to? The concern is that while I may be a net-consumer each month I can be a net-producer on the house meter and will miss out on the credit plus it will reduce the cost of the electricity that I sell. Abandoning the EV meter/rewiring the charger to the house panel would solve this issue but I'd like to avoid it.

[silversaver]

Wait about 4 to 5 weeks later after you switch to TOU-D-A plan, SCE will give you the "net" consumption from "Green Botton" for last 13 months usage. Each hours break down to either "+" or "-" which make the calculation easy or difficult. For me, my solar is been up and running for 15 months, so I can get a real net consumption from "Green Botton". If your solar did not run more than 12 months, it will be a mix value which make your calculation difficult becasue you are getting mix of "net" and "consumption only" values.

[J.P.M.]

Couple more interesting graphs for TOU analysis.
Graph 1 (line) shows % usage by type for each of 12 months
Graph 2 (2 pies) shows % usage/gen by type averaged over 12 months

I think this type of graph helps convince one that TOU would be beneficial for them.

[ATTACH=CONFIG]6175[/ATTACH][ATTACH=CONFIG]6176[/ATTACH]

Slightly tongue in cheek: Keep this up and SCE will sue you for potentially reducing their bottom line. Thanx for the info and perhaps just as importantly the ideas.

[insaneoctane]

Couple more interesting graphs for TOU analysis.
Graph 1 (line) shows % usage by type for each of 12 months
Graph 2 (2 pies) shows % usage/gen by type averaged over 12 months

I think this type of graph helps convince one that TOU would be beneficial for them.

solar tou by type.JPGsolar tou pie.JPG

[J.P.M.]

I think I read TOU is a significant problem. The main issue would be properly setting a
24 hour timer to keep track of off peak time. I would just set the present thermostat to
the low temp threshold. Then attach an electronic sensor set at the high temperature,
to close a contactor in parallel with the original thermostat terminals, this only enabled
when the timer declared off peak time. Solid state is pretty reliable and the rest is
century old proven reliable. technology. I don't see any maintenance or reliability
issues. Guess this would be a custom job today, it ought to become an option on the left
coast pretty soon.

A production version might just shift the trip point of the thermostat
(mechanically or electrically) using an automatically set radio clock. Bruce Roe

Have you seen what a plain, old water heater thermostat looks like ? One step up from a snap switch and a piece of metal that expands/contracts w/ temp. I like your idea, but I I have my doubts the market will accept anything that's new, or costs money. Dumbed down argument that's hard to refute on the surface: It ain't broke - why fix it ?

[bcroe]

I'm sure there are a number of ways to handle the situation. While what you suggest is certainly logical and possible, given the current arrangement(s) and rather primitive controls in common use for DHW applications, I doubt if the added expense and complication with the attendant likelihood of increased maint. or other problems make it likely.

Most current thermostats for DHW applications are cheap and not very precise. However, they have the advantage of low cost, simplicity and because of the simplicity, some measure of reliability.

Before declaring something a problem, an understanding of what's happening (inside the tank for one example) and why may be helpful to see if a solution or a better mousetrap is needed.

Evolution has made DHW systems quite reliable and mostly stupid proof.

Current water heating tech. in the U.S. evolved when the cost of the energy was cheap - cheaper than more insulation or use reduction. Them days are gone and probably ain't coming back.

I think I read TOU is a significant problem. The main issue would be properly setting a
24 hour timer to keep track of off peak time. I would just set the present thermostat to
the low temp threshold. Then attach an electronic sensor set at the high temperature,
to close a contactor in parallel with the original thermostat terminals, this only enabled
when the timer declared off peak time. Solid state is pretty reliable and the rest is
century old proven reliable. technology. I don't see any maintenance or reliability
issues. Guess this would be a custom job today, it ought to become an option on the left
coast pretty soon.

A production version might just shift the trip point of the thermostat
(mechanically or electrically) using an automatically set radio clock. Bruce Roe

[SunEagle]

I'm sure there are a number of ways to handle the situation. While what you suggest is certainly logical and possible, given the current arrangement(s) and rather primitive controls in common use for DHW applications, I doubt if the added expense and complication with the attendant likelihood of increased maint. or other problems make it likely.

Most current thermostats for DHW applications are cheap and not very precise. However, they have the advantage of low cost, simplicity and because of the simplicity, some measure of reliability.

Before declaring something a problem, an understanding of what's happening (inside the tank for one example) and why may be helpful to see if a solution or a better mousetrap is needed.

Evolution has made DHW systems quite reliable and mostly stupid proof.

Current water heating tech. in the U.S. evolved when the cost of the energy was cheap - cheaper than more insulation or use reduction. Them days are gone and probably ain't coming back.

Maybe instant hot water units become more economical if they are tied to TOU rates. That would still cause a life style change for anyone wanting to take a hot shower during peak rates but late night for dish-washing or early morning for showers may show a cost savings.