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Last year we had only a few days of ryu (<5) if I remembered right. So unless in a tie breaker it should not be your main consideration. If you expect lots of excess production in the day and eventually be close to net zero, ev-tou2 should be your best bet, because it's the only plan with the huge factor between day and night.
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I agree the RYU should not be the deciding factor unless it is close. I'm not so sure about EV-2 though, the TOU-DR plan will have $0.46/kWH summer peak and $0.13/kWh off-peak, if the baseline credit works the way I hope. I've emailed SDG&E for more info.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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FWIW on Rates:
1.) T.O.U. is not as easy to analyze as tiered rates (a big no "kidding" on that - applause, etc. - thank you all !).
2.) One way I've found that helps me to make more sense of things is to think of a PV system as a revenue producer and completely delink it from energy use - at least initially.
3.) I put each of the 8,760 hourly rates per a T.O.U. schedule on a spreadsheet. Sounds like a PITA, but not as bad as it seems. For different T.O.U. rate schedules, use additional columns.
4.) For a fixed roof, plug in the hourly output/kW of the chosen equipment from PVWatts, SAM etc. into the spreadsheet.
5.) Multiply each hourly $$ rate (in this case revenue) by each hourly per kW system output for each T.O.U. schedule under consideration. Sum over 8,760 hours.
6.) What you'll have at this point is raw data to see how much revenue each or any T.O.U. plan produces for each installed nameplate kW of system size. In the case of multiple schedules, which schedule produces the most (or least) revenue. That's good, but not complete information.
7.) Depending on how much of your annual load you choose to offset, and assuming the system output is reasonably proportional to system size, divide that annual load by the annual per kW system kWh/yr. output to get a system size. Multiply that system size by the revenue per kW to get annual system revenue. More good info, but still not enough. (An aside: If you have a way to accurately calc. a tiered rate bill for the same usage, that's more nice info, but I'm not sure what use it might be except as an interesting comparison at this point).
8.) Now the fun begins. Fun in the sarcastic sense because perhaps the biggest uncertainty in all this besides, and maybe even more than weather variability, is getting a reasonable guess on hourly use patterns. For simpler T.O.U. rate schedules like T.O.U.- SES, multiply each hourly use by the hourly rate (in this case now a cost) from the T.O.U - SES tariff. Sum over 8,760 hours. This will be your annual bill.
9.) Sticking with the simpler T.O.U.- SES for now, subtract the annual electric bill from the annual system revenue. If a negative #, increase the system size by the appropriate amount. OR, adjust the use pattern (time shift usage) in ways to reduce the cost as possible, as deemed useful or desirable, OR both. If the subtraction results in a positive #, reduce the system size, or splurge on more A/C, EV, etc.
10.) For more complicated T.O.U. schedules that include some consideration(s) of monthly allowances and tiers as will as times of use, a mix of the tiered rate schemes overlaid on T.O.U. pricing is necessary. I'm still working on that one, but something similar to the above with some mod. of the tiered rate schemes will work.
11.) Caveat: All this takes no account of what the results of rate reform will have on rates, or any future rate/tariff changes for that matter.
To sum up: I've found separating system revenue from the electric bill, at least initially, gives me a bit more information and helps me see things a bit more clearly. This is a work in progress.
Take what you want of the above. Scrap the rest.Comment
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I know what you're thinking/hoping, but I think the baseline adjustment credit applies to all three TOU periods. Plus I thought for the solar customers, the only choices are the normal DR, DR-SES and EV-TOU2. Other plans are for non-solar customers. But you should verify.16xLG300N1C+SE6000[url]http://tiny.cc/ojmxyx[/url]Comment
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You will find out more about sizing and benefit of little larger solar when you start driving EVs. I start to like Solaredge inverter especially go larger unit with easier expansion feature on mutiple roofs. It seems oversizing the inverter has no affect to the performance unlike other string inverters
If you do driving 15k miles per year, you soon will learn your 3.12kW system is way too small even with TOU....Comment
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I'm generally with you however charging nightly on TOU is cheap even if you don't have enough solar, at least 2x cheaper than paying for gas. Better pay the difference than end up with extra unneeded solar if somehow you need to part with the EV due to it not working for your needs.Comment
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Thanks for the comments. I like the revenue approach, and am guessing that the successor to net metering may eventually require submetering the generation. I find that for some of the more complicated rate plans, the net approach keeps the analysis cleaner than the revenue approach. It is hard for me to grasp when consumption moves into a higher tier and then the generation pulls it back out again, or vice versa in the negative direction. If the net consumption stays solidly in the baseline allocation, a lot of the other problems go away.
No... AB327 more or less prohibits restricting plans to non-solar customers. There are only a few special conditions that can prevent net metering eligibility, but for customers on any of the normal residential plans, net metering is available. You can read more about the net metering terms here if you'd like to understand it better. The TOU-DR and TOU-DR-P plans were just released in February for the first time, so there doesn't seem to be much experience out there with them. SDG&E already knows I have solar, and those plans are available for me to select online.
The catch with SDG&E rate plans is that once you switch, you are locked in for 1 year. They have "bill protection" so that if the previous rate plan (DR for me) would have worked out better, you can pay that bill instead. However, compared to the standard DR plan, I think any TOU plan will be better, and there is nothing that protects me if I pick a suboptimal one from the available choices.
With regard to the baseline allocation, it would work best for me if the entire net monthly usage was summed and evaluated against the baseline, and not each individual TOU period. The net consumption is likely to be a positive number, and should benefit from the credit. If the allocation is split up among TOU periods (as SCE does), some periods will be negative and others positive and the effect of the credit will be more mixed.
Yeah, no, there is no such thing as too small. 15k mi at 28 kWh / 100 mi is 4200 kWh. That almost exactly doubles my consumption. Even under the DR rate, my net consumption should be Tier 1, but I am thinking that a TOU plan will push my average energy cost even lower than that. As anyone who looks closely at the numbers will say, it is very hard to justify solar to replace energy that costs $0.15 / kWh. *Maybe* I will consider adding a couple panels (DIY) at the end of the year if the justification makes sense, while I can still grandfather the net metering, but I suspect that a TOU plan will, in some form or another, take care of things. I don't *want* 100% offset... if a minimum bill is likely to be the direction the CPUC approves, at least for the next few years, then I might as well pay for some energy with that money instead of just giving it to them.
Yes! Even if I pay for charging at night, the TOU plans have favorable rates, which look to have some legs. Just need to work through the analysis and figure out which TOU plan will be best. Having no A/C makes it easier, since my daytime usage should almost always be net negative, even with shifting peak hours.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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Good to know they weren't available when I signed up last year. There were just 3 choices before, which made my decision much easier. So according to the document you linked.
The value of generation and consumption are calculated at the billing cycle (every month). So with TOU-DR most likely you will be inside the baseline. The baseline rate reduction should apply to all 3 TOU periods.Baseline Rates: If the customer is a net consumer over a billing period, the net kWh consumed shall
be billed at the applicable baseline rates up to the billing period’s baseline allowance, with any
excess kWh consumed billed at the applicable non-baseline rates charged other customers in the
rate class.
If the customer is a net generator over a billing period, the net kWh generated shall be valued at the
applicable baseline rates up to the billing period’s baseline allowance, with any excess kWh
generated valued at the applicable non-baseline rates charged other customers in the rate class.
If I understand it correctly, the interesting thing with this plan is that if for some reason (eg. vacation out of town for a month in the summer) you net generated more than the baseline, you will be credited at none-baseline rate which is much higher.16xLG300N1C+SE6000[url]http://tiny.cc/ojmxyx[/url]Comment
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OK, let's try to run with this... let's say in a month with 300 kWh baseline, I'm charging 20 kWh per night, for 20 nights out of the month. That is 400 kWh in the off-peak TOU. Let's say my net for the peak TOU period was -250 kWh. How do you think the bill would be calculated?
One possibility
(-250 * peak price) + (400 * off-peak price) + (150 * baseline credit, which is a negative number)
Does this sound right to you?
Another scenario, same 300 kWh baseline, but lots of sun.
400 kWh off peak consumption
-400 kWh net peak
(-400 * peak price) + (400 * off-peak price) + (0 * baseline credit)
One more scenario, let's say I was on vacation and didn't drive the car for two weeks
200 kWh off-peak consumption
-250 kWh net peak
(-250 * peak price) + (200 * off-peak price) + (-50 * baseline credit)
In this scenario, the baseline credit ends up working against me.
If the above is correct, I think it means that the minimum average energy price would occur if the off-peak kWh consumption exceeds the on peak net generation by exactly the baseline allocation. Haven't heard back from SDG&E yet, I'll try them again later today.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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New tariffs released today... my spreadsheets are already out of date!CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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I spoke with an SDG&E rep. She more or less confirmed the interpretation above. She also said that after the first bill, I can change back to my previous plan, or select a different one. I would not be able to go back to the cancelled plan for 12 mo after that.
I think that is enough to do some modeling this weekend... we'll see which one comes out on top.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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