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Need advice on PW storage vs NEM use

SVDNN

Member
Sep 23, 2018
45
22
SF Bay Area
Trying to let go of the reins of power control and from my addiction to the Tesla app (looking at 20+ times a day) for energy cost savings...but not so happy with current advance control mode. Asking for advice...

Have 20.4 Kw solar roof, PWv2 x 3, on PGE EV2A rate (nonpeak rates 12mn-3pm), but overall solar production est to be only 2/3 of annual demand (we are energy hogs). Priority was solar glass with new roof and aesthetics, to get rid of peak/part peak demand rates (by history was roughly 20% total energy use on same rate plan) and minimize total energy cost, and less of concern of power backup for outages in NoCal - SF Bay area (which now maybe a little more predictable) but want that when needed.

I have been switching between backup only mode to charge powerwalls to 90% during non-peak then have reserve to 20% to discharge during peak rates on Self powered mode. This eliminates all peak rates during the worst of winter months and used all of solar generated to home use and minimize grid use. But this is a daily switch process and active monitoring of when to switch back to self powered to not overcharge PW and depends on weather of day and est solar production.

NOW, trying to let go of control (kids complaining that I am looking at my phone too often)...
used Advanced TOU cost savings mode, BUT it seems to want to charge PWs to 100% then favors using solar excess to NEM during later non-peak time and peak 3p-5p (current sunset). I assume this will only continue to increase my NEM credits as we go into spring - summer production.

I get that I am loosing some power (10%) in conversion solar to PW to home use. But my concerns are:

1. I will accumulate NEM peak rate credits that I will never use in end annual true up and get terrible credit reimbursement (? $.03 / Kwh) when I could have just used them for at least other nonpeak use ($0.17/ Kwh - $0.017 /Kwh conversion loss).

2. MY conditioned mentality from Tesla EVs of not charging to 100% imparts the same worry of longevity to PWs auto charging to 100%

Seems like it would be nice to have more control parameters on Advanced mode, but wanted to know how people would currently do differently?

Thx (sorry for long post)
 

h2ofun

Active Member
Aug 11, 2020
2,159
334
auburn, ca
Trying to let go of the reins of power control and from my addiction to the Tesla app (looking at 20+ times a day) for energy cost savings...but not so happy with current advance control mode. Asking for advice...

Have 20.4 Kw solar roof, PWv2 x 3, on PGE EV2A rate (nonpeak rates 12mn-3pm), but overall solar production est to be only 2/3 of annual demand (we are energy hogs). Priority was solar glass with new roof and aesthetics, to get rid of peak/part peak demand rates (by history was roughly 20% total energy use on same rate plan) and minimize total energy cost, and less of concern of power backup for outages in NoCal - SF Bay area (which now maybe a little more predictable) but want that when needed.

I have been switching between backup only mode to charge powerwalls to 90% during non-peak then have reserve to 20% to discharge during peak rates on Self powered mode. This eliminates all peak rates during the worst of winter months and used all of solar generated to home use and minimize grid use. But this is a daily switch process and active monitoring of when to switch back to self powered to not overcharge PW and depends on weather of day and est solar production.

NOW, trying to let go of control (kids complaining that I am looking at my phone too often)...
used Advanced TOU cost savings mode, BUT it seems to want to charge PWs to 100% then favors using solar excess to NEM during later non-peak time and peak 3p-5p (current sunset). I assume this will only continue to increase my NEM credits as we go into spring - summer production.

I get that I am loosing some power (10%) in conversion solar to PW to home use. But my concerns are:

1. I will accumulate NEM peak rate credits that I will never use in end annual true up and get terrible credit reimbursement (? $.03 / Kwh) when I could have just used them for at least other nonpeak use ($0.17/ Kwh - $0.017 /Kwh conversion loss).

2. MY conditioned mentality from Tesla EVs of not charging to 100% imparts the same worry of longevity to PWs auto charging to 100%

Seems like it would be nice to have more control parameters on Advanced mode, but wanted to know how people would currently do differently?

Thx (sorry for long post)
looking forward to advice. WOw, 20kw and only 2/3rd use. And I thought I had a big house
 

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,383
2,486
Northern California
Trying to let go of the reins of power control and from my addiction to the Tesla app (looking at 20+ times a day) for energy cost savings...but not so happy with current advance control mode. Asking for advice...
First off don't worry about having your PWs charge to 100%. Its not the same as the car battery.

Second Cost Savings mode will try to "learn" your behavior. It can take a week or more. But when weather is variable that might be a problem.

Third you can force it to some unnatural things by adjusting your peak, off peak times. For example if you wanted it to send energy back when not at 100% you could set your peak time earlier.

And you may find that another mode might be better than Cost Savings. The advanced modes do have to learn you situation so give them a few days if you switch things around.
 
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arnolddeleon

Supporting Member
Jul 21, 2012
752
835
SF Bay Area
You should try something like "balanced" but you need to give the system a chance to learn. I would stop trying to change the controls for a few weeks before trying another mode.

Stop worrying about "overcharging" your powerwalls as already noted @aesculus .

I'm a little confused about the concern about energy credits that reimbursed at at low rate. In one part of your post you say the system will only produce 2/3rds of your need. The only way you end being reimbursed at wholesale rates (about $.03 kWh) is if you have excess production which you apparently won't reach because you said the system is 2/3rds of your usage.

Are you thinking that credits only offset like for like (peak for peak, off peak for off peak?). That's not the case, outside of Non-Bypassable Charges (NBCs) you get to off set most of your charges from the credits you get. That's key of idea of "Net Metering" for consumers.

Who is your energy provider? Do you have a Community Choice Energy provider like Silicon Valley Clean Energy? They tend to have better reimbursement rates for excess credits if this is a real concern.

You've mentioned some of your concerns. What are you goals? Are you trying to minimize your bill? Consume as much of your solar? How much reserved do you "need"?

If you're taking your Powerwalls down to 20% and they're starting at 90% (should be at 100) then I calculate that you are consuming an average 3.2kW from 3:00 pm to midnight. Is that right?
 

miimura

Well-Known Member
Aug 21, 2013
6,171
5,762
Los Altos, CA
My suggestion: Try Balanced Mode and leave it like that for two weeks. Watch it each day, but don't touch any settings. This will allow the adaptive algorithm to learn your generation and usage pattern. Start with the Peak/Part-Peak/Off-Peak settings in the app exactly like the EV2-A schedule. If you really don't like what it's doing, consider changing the Part-Peak hours to either Off-Peak or Peak, depending on what you don't like.

I understand the desire change the mode to Self-Powered for Peak hours to extend your running time by keeping your energy. However, you will probably come out ahead by letting the solar generated during Peak to earn you NEM credits at Peak rate. Your concern about the poor NEM reimbursement only comes into play if you generate more kWh than you consume. You said the solar will only cover 2/3 of your usage. It may be possible to have a dollar credit balance at true-up and still use more kWh than you generated. If you are not on a CCA, that dollar credit will be wiped out. It was just a product of bonus Peak TOU credits, so no biggie.
 

getakey

Active Member
Jan 28, 2020
1,130
368
95762
You should try something like "balanced" but you need to give the system a chance to learn. I would stop trying to change the controls for a few weeks before trying another mode.

Stop worrying about "overcharging" your powerwalls as already noted @aesculus .

I'm a little confused about the concern about energy credits that reimbursed at at low rate. In one part of your post you say the system will only produce 2/3rds of your need. The only way you end being reimbursed at wholesale rates (about $.03 kWh) is if you have excess production which you apparently won't reach because you said the system is 2/3rds of your usage.

Are you thinking that credits only offset like for like (peak for peak, off peak for off peak?). That's not the case, outside of Non-Bypassable Charges (NBCs) you get to off set most of your charges from the credits you get. That's key of idea of "Net Metering" for consumers.

Who is your energy provider? Do you have a Community Choice Energy provider like Silicon Valley Clean Energy? They tend to have better reimbursement rates for excess credits if this is a real concern.

You've mentioned some of your concerns. What are you goals? Are you trying to minimize your bill? Consume as much of your solar? How much reserved do you "need"?

If you're taking your Powerwalls down to 20% and they're starting at 90% (should be at 100) then I calculate that you are consuming an average 3.2kW from 3:00 pm to midnight. Is that right?

I'm confused too. If he produces less than he consumes, he should never be getting the $.03 credit. It will mostly be credits at Peak if he is using Cost Saving mode. I doubt his annual NEM will be negative
 

SVDNN

Member
Sep 23, 2018
45
22
SF Bay Area
Thanks for suggestions ...
Maybe my bad assumption was if I generate summer peak time credits in NEM but never use them during peak time grid use since peak is being covered with solar and PW year round. Then assumed that those peak credits would not be used at all (ie., like for like) and would be cashed out at the low reimbursement rate at annual true-up. But I guess, they will be used for non-peak grid time use at some point ... How / when does PGE make that decision prior to annual true-up?
(Again, sorry have not been thru that process as of yet.)

Our energy provider is Peninsula Clean Energy ...unclear to me how that impacts the energy costs from the grid now with the home solar, but glad to hear they may be more beneficial for NEM credits (??) than otherwise. Again assumed NEM was all processed from PGE and Peninsula CE was just were I was getting & paying for grid clean energy.

Otherwise as to app, I was using cost savings mode over balanced as priority was cost savings over backup energy storage...
Will just "let it go" for awhile and see how things go, and consider changing start of peak time to earlier.

As an aside then...what makes PW battery chemistry different to be able to handle 100% charge much better than EV battery chemistry...and why not have the EVs with the similar capability?
 

miimura

Well-Known Member
Aug 21, 2013
6,171
5,762
Los Altos, CA
The NEM credits are converted to dollars each month and added to your running total for the year. It doesn't matter which TOU period you earn credits or use credits. Since you are on the PCE CCA, they will have a separate true-up for the generation portion of your bill. If you end up with a credit over $100 at the end of the year, they will pay it all out. This is better than the PG&E Net Surplus Compensation because the PCE Off-Peak Generation rate is 4.4c/kWh. If you earned Peak credits, they are worth 12.6c/kWh on EV2-A

I just discovered that Peninsula Clean Energy also has a $1,250 rebate for solar+storage customers. It appears that they want some of your battery energy during Peak. I'm curious how that works.
Power On Peninsula: Homeowner
 

SVDNN

Member
Sep 23, 2018
45
22
SF Bay Area
The NEM credits are converted to dollars each month and added to your running total for the year. It doesn't matter which TOU period you earn credits or use credits. Since you are on the PCE CCA, they will have a separate true-up for the generation portion of your bill. If you end up with a credit over $100 at the end of the year, they will pay it all out. This is better than the PG&E Net Surplus Compensation because the PCE Off-Peak Generation rate is 4.4c/kWh. If you earned Peak credits, they are worth 12.6c/kWh on EV2-A

I just discovered that Peninsula Clean Energy also has a $1,250 rebate for solar+storage customers. It appears that they want some of your battery energy during Peak. I'm curious how that works.
Power On Peninsula: Homeowner

Thanks for the PGE & PCE NEM explanation...did not get that impression from the NEM info PGE hands out.
I also saw the PCE rebate info before but it seems intimately tied to Sunrun...did not pursue and fill out as no desire for another call list to be on from sales or other telemarketers. Hope someone here can prove otherwise.

Screen Shot 2021-02-22 at 11.47.26 AM.png
 

miimura

Well-Known Member
Aug 21, 2013
6,171
5,762
Los Altos, CA
Thanks for the PGE & PCE NEM explanation...did not get that impression from the NEM info PGE hands out.
I also saw the PCE rebate info before but it seems intimately tied to Sunrun...did not pursue and fill out as no desire for another call list to be on from sales or other telemarketers. Hope someone here can prove otherwise.
I would just call them at the contact number just below that form.

Learn more about potentially reducing your energy costs
with Power On Peninsula
Get in contact with a us at
(888) 605-9786
M-F 9 AM-5 PM PST
 

Patrick66

Member
Oct 27, 2019
62
39
Honolulu
My advice... get someone to do an energy audit or install a few IoTaWatt’s to give you a better idea of what is actually using energy rather than just living with it. I had mine installed on Thursday and have already figured out how to reduce loads by ~2-3kWh per day with a quick analysis. I also found a few things that I thought would help that are inconsequential.

Better monitoring can also help you find ways to use energy at the lowest cost point.
 
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SaveOurPlanet

Member
Jan 6, 2018
209
124
San Francisco
PCE has in the past provided real rebate for some EVs like PG&E (Tesla never included) but this battery rebate is all a promotion for Sunrun solar+battery purchase, I made the mistake of submitting before reading the whole thing and I got Sunrun calling me everyday for 2 weeks.
 

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