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Will PGE okay charging batteries from grid with solar?

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,471
2,539
Northern California
I presume it would take a modification of the NEM agreement. What form did that CPUC ruling take. A new tariff?
I don't think it's gotten that far yet. Just that it was an acceptable mode.

I don't know why it would take a new tarriff. We are allowed to sell our energy back that we generated. Does the current one limit you to just when you create it?
 
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Ampster

Active Member
Oct 5, 2012
1,780
477
Kenwood, California
Does the current one limit you to just when you create it?
I am not sure what my NEM agreement says. I can not believe the IOUs let that one slip by. I am an advocate for discharging into the grid when the grid is stressed and it has been implemented in several states. Tesla is coordinating some of those programs. Things are evolving. For people who got SGIP funds they are subject to restrictions and my understanding is they are monitored in terms of the amount feeding into the grid.
 

Ampster

Active Member
Oct 5, 2012
1,780
477
Kenwood, California
Does the current one limit you to just when you create it?
I realize I did not convey my philosophy in my earlier response. I believe the grid in California can be helped if battery systems were able to charge during the belly of the duck curve and discharge during the neck of the curve. I am hopeful that Tesla and other aggregators can implement that in California in the near future.
Currently I am on NEM 2.0 and pay NBCs of about $10 per month, which are not offset by generation credits. Most of that is because I charge two Tesla's at off peak. I have a self installed hybrid inverter with lots of batteries. My economic model is now to self consume as much energy as possible with the excess going to the grid at peak rates to be consumed by EV charging at off peak rates.

Also I may be in a grey area with regard to my NEM agreement and whether my hybrid inverter is actually "connected" or its transfer switch is just passing through the energy produced by the GT system. That explains why I have not persued a more definitive answer to your question. We are in a significant transition and as I move through this transition, my strategy is to find ways to hedge the cost of energy.
 
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swedge

Member
May 12, 2020
81
66
Oakland, CA
PG&E and CPUC tariffs explicitly allow charging from the gird. They do not allow discharging a battery to the grid, hence no "arbitrage". But you can charge from solar or the gird, and consume solar, battery or grid, according to the tariffs. I have the text from the tariffs somewhere, or you can look it up.
 
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pilotSteve

Active Member
Jul 14, 2012
1,486
1,365
Prescott Az
Then under some circumstances your power company might be able to detect if you were discharging your batteries to the grid. As @swedge mentioned they probably would have not problem if you charged them from the grid. It is the IRS that cares about that if you took the ITC.
thanks, that does make sense. Its just weird to have three meters…. I think one is solar production, one is battery in/out and one the bidirectional utility meter.
 

swedge

Member
May 12, 2020
81
66
Oakland, CA
It is the IRS that cares about that if you took the ITC.
NERL says here (https://www.nrel.gov/docs/fy18osti/70384.pdf) that if storage is 75 - 99% charged from solar (or wind), the ITC can be claimed to the same percentage. It references an IRS personal letter ruling (https://www.irs.gov/pub/irs-wd/1208035.pdf) as support. If this is all true, IRS does not actually require 100% solar charging. In my case, I am not taking the ITC, so by both PG&E and IRS, I can grid charge as much as I wish. Tesla does not make it easy, but in another thread I have explained how I do so when I need to. Tesla Powerwalls are sometimes installed without solar, in which case Tesla does, of course, allow grid charging.

SW
 
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wjgjr

Active Member
May 11, 2020
1,254
998
Silver Spring, MD
NERL says here (https://www.nrel.gov/docs/fy18osti/70384.pdf) that if storage is 75 - 99% charged from solar (or wind), the ITC can be claimed to the same percentage. It references an IRS personal letter ruling (https://www.irs.gov/pub/irs-wd/1208035.pdf) as support. If this is all true, IRS does not actually require 100% solar charging. In my case, I am not taking the ITC, so by both PG&E and IRS, I can grid charge as much as I wish. Tesla does not make it easy, but in another thread I have explained how I do so when I need to. Tesla Powerwalls are sometimes installed without solar, in which case Tesla does, of course, allow grid charging.

SW
All of this applies to section 48, which is the commercial credit, and not section 25D, which is the residential credit. In fact, the IRS form even includes a note warning about this:

Section 48 guidance inapplicable. Costs, later, clarifies that guidance published under section 48 does not apply to the residential energy credits
 

swedge

Member
May 12, 2020
81
66
Oakland, CA
All of this applies to section 48, which is the commercial credit, and not section 25D, which is the residential credit. In fact, the IRS form even includes a note warning about this:

Wow, good point! As Rosanne Rosanadana said, Never Mind.

I think I found where the 100% solar interpretation came from, an IRS ruling on this issue here: https://www.irs.gov/pub/irs-wd/201809003.pdf

Some further amateur musings on this topic:

Interestingly, that case involved a storage system which was described as only using solar to charge, and so is not really relevant to grid charging. And, the IRS relied on the absence of wording in the code to determine the congressional intent. As is normal, the ruling explicitly states it can not be used as precedent.

Since PowerWalls actually do grid charge when in Storm Watch, and hence are not 100% solar charged, they would not qualify for ITC if this ruling is actually binding. I think the ruling is wrong anyway, because grid charging is done only when solar production is inadequate, and grid charging is simply an additional free function of the AC coupled system. Equivalently, one could put lights over the solar panels, run the lights from the grid, and charge the battery with that "solar" energy. Not very efficient, but it would not defeat the purpose of capturing solar energy when it is available.

I'm glad I did not take the ITC, so I don't have to argue it with the IRS, but it would be nice if someone would. As far as I can tell, there is nothing in the code which actually says what IRS does. They essentially made it up by assuming water heating (which inherently includes storage) is the same as solar, storage for which was impractical when the code was written.
 

wjgjr

Active Member
May 11, 2020
1,254
998
Silver Spring, MD
Wow, good point! As Rosanne Rosanadana said, Never Mind.

I think I found where the 100% solar interpretation came from, an IRS ruling on this issue here: https://www.irs.gov/pub/irs-wd/201809003.pdf

Some further amateur musings on this topic:

Interestingly, that case involved a storage system which was described as only using solar to charge, and so is not really relevant to grid charging. And, the IRS relied on the absence of wording in the code to determine the congressional intent. As is normal, the ruling explicitly states it can not be used as precedent.

Since PowerWalls actually do grid charge when in Storm Watch, and hence are not 100% solar charged, they would not qualify for ITC if this ruling is actually binding. I think the ruling is wrong anyway, because grid charging is done only when solar production is inadequate, and grid charging is simply an additional free function of the AC coupled system. Equivalently, one could put lights over the solar panels, run the lights from the grid, and charge the battery with that "solar" energy. Not very efficient, but it would not defeat the purpose of capturing solar energy when it is available.

I'm glad I did not take the ITC, so I don't have to argue it with the IRS, but it would be nice if someone would. As far as I can tell, there is nothing in the code which actually says what IRS does. They essentially made it up by assuming water heating (which inherently includes storage) is the same as solar, storage for which was impractical when the code was written.
There has been more detailed discussion in the tax thread and elsewhere, but you are correct on the private letter ruling link being the one cited to justify PWs. And, while it might be interesting for somebody to try and challenge the IRS further on the interpretation, I consider it fortunate they did not decide to disallow battery deductions completely as they aren't really integral to producing solar. The real solution is updated legislation which has been proposed that would explicitly address batteries, hopefully removing any ambiguity and providing more flexibility in how the battery is used

As to storm watch, I have similarly noted that it is a bit of a gray area, particularly in places that are subject to frequent warnings. But I would guess that the unpredictable, emergency nature of the charging is probably just enough for the IRS to let it slide. But, again, hopefully updated legislation will remove the potential uncertainty.
 

h2ofun

Active Member
Aug 11, 2020
2,672
490
auburn, ca
PG&E and CPUC tariffs explicitly allow charging from the gird. They do not allow discharging a battery to the grid, hence no "arbitrage". But you can charge from solar or the gird, and consume solar, battery or grid, according to the tariffs. I have the text from the tariffs somewhere, or you can look it up.
Yep, I sent this stuff to Tesla and they basically blew me off
 

Ampster

Active Member
Oct 5, 2012
1,780
477
Kenwood, California
Yep, I sent this stuff to Tesla and they basically blew me off
Why did you even bother? Most people have known the answer for years. I had a reservation for two Powerwalls Three years ago and cancelled because I did not want those restrictions. You got subsidized Powerwalls and that subsidy included more restrictions than the IRS. It is no surprise they blew you off. Have you looked at the SGIP application you signed? There is no such thing as a free lunch.
 
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h2ofun

Active Member
Aug 11, 2020
2,672
490
auburn, ca
Why did you even bother? Most people have known the answer for years. I had a reservation for two Powerwalls Three years ago and cancelled because I did not want those restrictions. You got subsidized Powerwalls and that subsidy included more restrictions than the IRS. It is no surprise they blew you off. Have you looked at the SGIP application you signed? There is no such thing as a free lunch.
the sgip application i signed says its fine which i included to tesla. i bothered because i am covering my butt legally with all this stuff. they blew me off for same reason on how they treated folks with signed contracts for solar roofs
 

Redhill_qik

Member
Aug 16, 2020
305
216
South SF Bay, California
I was browsing my CCA's, Silicon Valley Clean Energy, website today and came across this press release for Lights On Silicon Valley that provides up to $1,250 rebate if you install Sunrun + ESS and agree to export your battery when the grid needs it.

What is Lights On Silicon Valley?

It’s a program from Silicon Valley Clean Energy (SVCE) to develop a network of storage devices. These systems will also help its customers maintain power during grid outages. Eligible homeowners who install solar and storage with Sunrun can get a $1,250 rebate if they sign up for this program.
When your battery is enrolled in Lights On Silicon Valley, it joins a local network of storage devices to provide some power to the grid when it needs it the most. You benefit by selling your excess energy at the highest peak rate possible. By utilizing a little energy from all of these devices, we can help the grid avoid turning on natural gas power plants at these times and keep emissions low. You get a discount on your solar and storage system, backup power to use in case of an outage, and the grid gets even cleaner. It’s a win-win-win
There is nothing that I read that indicates that there is ability to charge the ESS during off peak, but this is definitely an approved export program.

 

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