SDGE - Time Of Use (TOU) Rates. Good or bad for Net Metering?

sensij · 07-15-2017, 01:06 PM

If you overproduce your consumption, the charge for all plans will show as ~$120 dollars.

When I get some time this weekend I'll post a real life example for a typical light A/C, non-EV, PV sized less than 100% scenario. It appeared DR-SES was better for that person, even though the billed usage was closer to example 1 above than example 2. Definitely wouldn't mind peer review of the results, though.

At one point, I did in fact model *every* one of the tou plans offered by SDG&E (along with most from SCE and PG&E). I don't have actual bills to validate against for the less commonly discussed plans though, so ymmv.

J.P.M. · 07-15-2017, 12:36 PM

Originally posted by cebury

Sensij knows what hes talking about.
A lot of folks mixup NEM and their rate plan, they are separate. Your report shows you should be on DRSES which has very solar favorable time periods, as stated, but some people dont care much about 13-14 bucks month. Two to three drinks at Dutch brothers nowadays. Id switch now and review it each year as the pricing and periods start chsnging.

IMHO, one great thing the cpuc has done has pressured the utilities to provide these reports to accurately and easily inform us as customers which plan is the most economical, assuming we behave with the same lifestyle (electrical profile) we chose during the past 12 month period it analyzed. Prior to this, only the most technically proficient could calculate alternative plans without blind guessing.

Sensij pretty much seems to know what he's talking about.

But I've got some problems with the info SDG & E put out on that sheet. The one I got shows the current cost/yr. as equal to my billing year to date charge - for all plans. That's not cost /yr. and even if it was, that's useless for comparison purposes for me. I doubt it's accuracy and therefore its usefulness.

I'd be real careful about taking the blurb's information at face value and also be careful about the assumptions made when reading it.

Furthermore, the blurb says DR-SES will be the best plan choice for oversized systems. While that may be true, it's unfortunately more complicated than that.

If a system is oversized on tiered rates, for the same annual use, it'll be equally oversized from the standpoint of generation exceeding the use. But, such a system will either be over or under sized with respect to any balance due the POCO or overgeneration payment received from the POCO at trueup, depending on the time of that same usage.

Some examples:

Example 1: If, for example (and it's admittedly maybe a bad example because 500 kWh/billing period in summer w/A/C is not likely to occur around here, at least inland), you are billed for 500 kWh/billing period in summer. On a tiered schedule (DR), it'll cost ~ $97/billing period. The same use on DR -SES ( for users with a PV system) will cost somewhere between ~ $113.60 (all billed @$0.22721/kWh , that is, all at off peak time), to ~ $253.15 ($0.50629/kWh at all on peak time). Actual T.O.U. billing will be somewhere in between, but still higher than the tiered bill.

Example 2: A customer is billed for 1,500 kWh/billing period in summer and inland (and probably a bit more likely). On tiered schedule, that'll cost ~ $549 - $558/billing period depending on your # of billing days. On the same T.O.U. schedule as example one (DR-SES), it'll set you back somewhere between $341/month and $759/month, again, depending on times of use of that 1,500 billed kWh/biling period. Use it all between 10 P.M. and 6 A.,M and the lower figure will apply. Use it all between 11 A.M and 6 P.M. M-F and the higher figure will apply. So, at current peak times, if some discipline is possible to lower use by time shifting loads off the 35 hrs./week for ~ 26 weeks of peak summer rates (~ 910 hrs./yr.), T.O.U. may save money., particularly if it's sunny.

Example 3 : A customer is billed for 2,500 kWh/billing period in summer and inland. On tiered schedule, that'll cost ~ $980 - $990/month ( Gulp !). Same amount billed on T.O.U. will set you back between $568 and $1,256/billing period, depending on when the power is used, same as the other examples, and it'll take less discipline (but still some) to get the bill down to the same total as under a tiered tariff.

Now, as if all that isn't somewhat confusing looking (but not as conceptually difficult as it may look, and reasonably amenable to a spreadheet to make things a lot more manageable, honest), there are a some flies in ointment:

1.) The T.O.U. times are shifting. At this time, some of the PV summer generation occurs during peak billing (and so peak offset for PV), maybe ~~ 5 hrs. per weekday or 25 hrs./week out of maybe 7 or 8hrs./day or 49 to 56 hrs./week total PV generation time, so ~~ 50 % of the time. That's the current sweet spot for PV on T.O.U. However, once those peak hours shift to later in the day, say to after 4 P.M - and they will - most, maybe all of the PV generation will no longer be at peak times and a lot of the peak time benefit will be gone as far as far as billing, use and PV generation are concerned.
2.) Right now, shifting to T.O.U for solar customers will probably lock in the earlier in the day rates for 5 years. After that, for all anyone (including the POCO) knows, there may be no tiered rate to go back to. That may be the gotcha'.
3.) Other non PV system T.O.U. tariffs are available. At this time anyway, those other tariffs appear to be an amalgamation of T.O.U. times and tiered rates. I'm working on logic to figure them out for a spreadsheet, but haven't gotten around to it yet. If Sensij has already cracked that nut, I'd be happy.

Spreadsheets are a powerful tool, but not my strong point or favorite thing to do - more of a necessary evil. Having said that, I've found that while creating a spreadsheet with 24 X 4 X 365 = 35,040 rows sounds daunting, the task is made about and at least 1/26 times less daunting by the fact that only 2 schedules, one for summer weeks and one for winter weeks are needed and then copied, with 5 of the 7 (week)days for each of those weeks identical, as are Sat. and Sun. Holidays are same weekend schedule and will change 5 days max. to weekend schedule. The finished template can then have POCO and/or array generation data added along with various tariff prices and T.O.U. times made changeable, and Voila' - a useful tool. Mine works great and after adjustinmg for some some B.S. taxes on the bill, usually gets me to the penny or thereabouts. I'm on MEM 1.0 and so are the neighbor's systems I monitor, so I don't have a way to confirm how NBC's are accounted for, but I believe I've got them correct. However, and as a bit of an aside, Escondido Charlie's billing anomalies with respect to what are probably NBC billing are a source of confusion, and an example of why I think SDG & E could be more forthcoming and helpful as to explantions and examples of how they bill stuff.

IMO, and FWIW only - and no more than that - the idea of trying to make an informed decision about what to do with respect to a tariff to chose is made very much more difficult than it need be by the POCO's general lack of clear explanation and examples of what the implications and consequences of various choices as to options might entail. Equally at fault is the consumers' actions of not taking the time to learn about how they actually pay for what they seem to spend a lot of time bitching about.

Seems to me that the bitching time could be better spent as tariff education time, and the POCO's might improve their image a bit with better information that's easier to understand. One of the mandates of AB 327 was to make things easier to understand. seems to me that not only has that mandate not yet been met, but the waters are a bit muddier than before.

cebury · 07-14-2017, 07:07 PM

Sensij knows what hes talking about.
A lot of folks mixup NEM and their rate plan, they are separate. Your report shows you should be on DRSES which has very solar favorable time periods, as stated, but some people dont care much about 13-14 bucks month. Two to three drinks at Dutch brothers nowadays. Id switch now and review it each year as the pricing and periods start chsnging.

IMHO, one great thing the cpuc has done has pressured the utilities to provide these reports to accurately and easily inform us as customers which plan is the most economical, assuming we behave with the same lifestyle (electrical profile) we chose during the past 12 month period it analyzed. Prior to this, only the most technically proficient could calculate alternative plans without blind guessing.

sensij · 07-14-2017, 12:44 PM

Net metering and TOU are separate. No matter what rate plan you are on (TOU or tiered), you are still under the terms of net metering 1.0.

The rate plan comparison that you are looking at shows what your bill would be like under the *current* terms of the existing TOU plans. It appears that DR-SES would save you some money. The peak hours of the *current* plan are 11 am-6 pm during the week, which aligns more favorably with solar production hours than the 3pm-9pm change which was just approved.

If you elect onto a TOU plan before July 28, you will keep the favorable peak hours for 5 years. If you wait until after then, you should re-run the price comparison tool and see how the TOU plan compares to the tiered plan under the new hours, or you can build a spreadsheet to figure that out now, if you'd like.

Many NEM 1.0 customers can benefit from the TOU plans... at my old house, I was producing only 70% of the energy I consumed, but fully zero-ing out my bill (except for the monthly minimum which cannot be avoided).

SDGE - Time Of Use (TOU) Rates. Good or bad for Net Metering?

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