Help with SCE Rate Plan Selection

[cambyses]

Ok. We now have our solar system operating and I want to decide which SCE rate we should go with.

Prior to solar, we were on TOU-D-B plan. But it has a fixed $0.53/day basic charge, which translates to about $16 in fixed monthly charge.

I am am trying to decide if we should switch to TOU-D-A, or TOU-D-T, or even just the non-TOU tiered domestic rate.

I searched on the forum here and there is a couple of good threads with a lot of analysis and spreadsheet on this topic. I am hoping you guys can help me make a quick but informed decision without having to spend hours and fully understanding all the complexities associated with how SCE does our bill.

FYI, we are on SCE NEM 1.0 and our system is designed to cover 100% of our current usage, and hopefully still close to 100% once we add an EV.

Our panels are facing SE and so most of our production will be during the morning hours, with the peak production currently occurring around ~11am.

Given that whatever rate we change to, according to SCE, we will be stuck with it for 12 months, I would greatly appreciate any input and advice you guys may provide so I could make a quick decision without having to do a full spreadsheet analysis of my own!

Thanks...

[sensij]

TOU-D-A comes out ahead in almost every scenario I've seen. TOU-D-T is sometimes close, or slightly better. Based on what you've written, I would choose one of those.

[cambyses]

TOU-D-A comes out ahead in almost every scenario I've seen. TOU-D-T is sometimes close, or slightly better. Based on what you've written, I would choose one of those.

Thank you... Yes, without any detailed analysis, I do see why TOU-D-A or TOU-D-T could come out ahead. And among the two, and given the direction of our panels, I have a feeling that TOU-D-T could probably be a bit better since the peak hours for TOU-D-T (12-6pm) would have a larger overlap with our peak production times when compared with the peak hours for TOU-D-A (2-8pm).

But this is all just based on quick and rough analysis. And once we add an EV, the equation could change as we could use more of the EV charging energy during the off-peak hours for TOU-D-A (10pm-8am) as opposed to the longer off-peak hours for TOU-D-T (6pm-6am).

[sensij]

If you are a net generator in the morning, the higher credit paid by TOU-D-A from 8-12 tends to offset the lower credit from 12-2, and the higher cost of electricity from 6pm-8pm. Your panel orientation might actually favor -A, but they are probably close.

[maximizese]

I think you'll have to provide more information. It really depends on how much energy you're using during 12pm-9:59pm compared to 10:01pm-11:59am. The EV will likely change things; it was a big game changer for us. We don't have solar yet, don't use much energy throughout the day, and lived like resource-misers for the last 8 years. We use to average 12kWh per day before the EV. Since my wife got an EV and started driving 45 miles to work each day, we switched to TOU-A we're using about 27kWh per day (we've also added radiant heaters during the winter). 80% of our energy usage is during super off-peak (10pm-8am). I started using the delay timer on both the EV and electric clothes dryer to finish before super-off peak ends. During the summer months, I plan to use my old 5-ton central AC to cool the house earlier in the day, use my whole house fan to cool the house in the evening, then slowly lower temps with the AC during off peak/super off-peak. I've got a Nest, so I'll set the temps to take advantage of lower energy rates.

[J.P.M.]

I think you'll have to provide more information. It really depends on how much energy you're using during 12pm-9:59pm compared to 10:01pm-11:59am. The EV will likely change things; it was a big game changer for us. We don't have solar yet, don't use much energy throughout the day, and lived like resource-misers for the last 8 years. We use to average 12kWh per day before the EV. Since my wife got an EV and started driving 45 miles to work each day, we switched to TOU-A we're using about 27kWh per day (we've also added radiant heaters during the winter). 80% of our energy usage is during super off-peak (10pm-8am). I started using the delay timer on both the EV and electric clothes dryer to finish before super-off peak ends. During the summer months, I plan to use my old 5-ton central AC to cool the house earlier in the day, use my whole house fan to cool the house in the evening, then slowly lower temps with the AC during off peak/super off-peak. I've got a Nest, so I'll set the temps to take advantage of lower energy rates.

Smart ways to game the system. Biggest hassle/temptation for me would be to resist A/C use until peak time ends in the evening. Precooling with A/C while walking around with a sweater on before peak time starts would also be an ironic PITA for me in hot weather.

[maximizese]

Smart ways to game the system. Biggest hassle/temptation for me would be to resist A/C use until peak time ends in the evening. Precooling with A/C while walking around with a sweater on before peak time starts would also be an ironic PITA for me in hot weather.

Imagine what I would do with a 10kWh battery

[cambyses]

Here are three typical hourly profiles I got from SCE website. One is a typical hot day in the last summer. One is from earlier this month prior to our solar installation. And one is during a sunny day after our solar installation. The first three peaks you see are due to our multi-speed pool pump running at high speed. I can, of course, change the schedule for our pool pump operation, and move those peaks around. And as I mentioned, we may also add an EV during the next year, and so I want to keep that in mind as well, in deciding which rate plan I should switch to.

[J.P.M.]

Imagine what I would do with a 10kWh battery

OK. Among other things, run a 5 ton A/C unit for about 1.5+ hrs. or so sooner than the end of or during peak rate time. Continued full exhaustion might be tough on the equipment however. Also, I suspect you'd need to ensure that the recharge capabilities will be sufficient to accomplish that recharge task during super off peak times.

Just a back of envelope thought: If used and exhausted every day, at a cost differential of, say, $0.35/kWh (peak - super off peak) price advantage, a savings of ~ ($0.35)*365 = $128/yr. per kWh of useable battery capacity, or ~ $1,204/yr. for a 10kWh battery. How much is a 10kWh battery worth these days ? And how long might it be expected to last performing that duty ? If the battery will sustain, say, 10,000 complete charge/discharge cycles, which seems a lot to expect, it'll save ~ $0.35*10 *10,000 = $35,000 at $0.35 price diff. At 1,000 complete cycles of 10 kWh each, $3,500. Electricity rates will change, and this moron analysis takes no account of the time value of money or other factors, but it may be something to consider as a starting point, even if overly simplistic.

[maximizese]

OK. Among other things, run a 5 ton A/C unit for about 1.5+ hrs. or so sooner than the end of or during peak rate time. Continued full exhaustion might be tough on the equipment however. Also, I suspect you'd need to ensure that the recharge capabilities will be sufficient to accomplish that recharge task during super off peak times.

Just a back of envelope thought: If used and exhausted every day, at a cost differential of, say, $0.35/kWh (peak - super off peak) price advantage, a savings of ~ ($0.35)*365 = $128/yr. per kWh of useable battery capacity, or ~ $1,204/yr. for a 10kWh battery. How much is a 10kWh battery worth these days ? And how long might it be expected to last performing that duty ? If the battery will sustain, say, 10,000 complete charge/discharge cycles, which seems a lot to expect, it'll save ~ $0.35*10 *10,000 = $35,000 at $0.35 price diff. At 1,000 complete cycles of 10 kWh each, $3,500. Electricity rates will change, and this moron analysis takes no account of the time value of money or other factors, but it may be something to consider as a starting point, even if overly simplistic.

I'm not sure what happened to the rest of my previous post; it was a joke, but I guess the joke is on me.

Back to the OP's electricity usage, I would schedule the pool pump to take a break during the peak rate period. It also didn't seem cost advantageous to be on TOU (as shown in your second graph) during hot summer days as your usage between 10am-8pm is substantially higher than 8pm-8am. Those solar panels are going to help you a lot this summer.