Grid Charge Powerwall with Solar

[h2ofun]

why is your obligation different than everyone else with PWs?

If one gets their PW's om the ER program, this is a requirement One I cannot get ITC since one gets 100% money back from SGIP.

For folks who get their PW's under what I think is called the step program, and take the ITC, I am not aware of any reporting requirements.

Here is the info on cycling

V9 of SGIP handbook, page 49

Residential systems are required to discharge a minimum of 52 full discharges per year. A “full discharge”
is the equivalent of discharging the SGIP-incentivized energy capacity, whether it is during a single or
multiple discharges.57

 

[h2ofun]

The ITC requirement is to charge from solar only, not the grid. There are no cycle requirements (charge or discharge) for the ITC.

Yep, cycling has zero to do with ITC. Its a SGIP requirement of the 100% ER program. With that said, I am still confused and have not been able to get a clear answer between the well and medical baseline qualifications. Seems one would always want to keep the well batteries at 100% charge. I have continued to ask about the cycling requirements but have yet to get a clear answer. Guess I will find out if I get the batteries. One reason charging from grid in winter for me would help me meet these possible requirements.

 

[Ampster]

The ITC requirement is to charge from solar only, not the grid

I have seen various interpretations that are not that rigid. One said charge from solar 75% and I know Tesla allows it for storm situations and in California for PSPS. I don't have a Powerwall but my inverter has logs so I know I have documentation if I ever get audited.

 

[Ampster]

I am not aware of any reporting requirements.

You are correct, I have not heard of any reporting requirements. With a Powerwall presumably, if audited, one would just have to point out Tesla policy for proof.

 

[Ampster]

I have continued to ask about the cycling requirements but have yet to get a clear answer.

Calling it a cycling requirement may imply that there are requirements around charging, when there are not. Also if one picked a strategy to have the battery at 100% that would reduce the probability of quickly meeting the SGIP discharge requirements. To me the optimal strategy would be to pick a reserve based on the needs of a well or medical device. There is comfort in the case of the PSPS (Public Safety Power Shutoffs) that Tesla has allowed Powerwalls to be charged from the grid during the time that those shutoffs are anticipated.

 

[getakey]

here's what I see on Tesla web site:
The goal of the SGIP program is to reduce load on the grid and reduce greenhouse gas usage. In order to participate in the program, SGIP requires you to use Powerwall to help the program meet this goal. Powerwall must meet a ‘cycling’ requirement where Powerwall will need to fully charge and discharge at least 52 times, or 687 kWh, per year.

687 kWh/year is an ave of <2 kWh/day. That is trivial. Yesterday I had my reserve set at 80% because of the storm and I still discharged 6.6 kWh from 3 PWs.

 

[Ampster]

Yes, I see the requirement for number of discharges to be easily accomplished in California by beginning of summer with conservative reserve settings.

 

[wjgjr]

I have seen various interpretations that are not that rigid. One said charge from solar 75% and I know Tesla allows it for storm situations and in California for PSPS. I don't have a Powerwall but my inverter has logs so I know I have documentation if I ever get audited.

I would be interested to see any sources that state this as it applies to the residential credit. The only 75% rule of which I am aware applies to the commercial credit. As a summary, from Energy Storage Tax Credits Explained | EnergySage

Eligibility for residential properties
If you are installing energy storage on a residential property, it is eligible for a credit under the ITC – as long as the battery is only charged by an on-site renewable energy system like solar. If you don't have solar panels, and plan on charging the battery with electricity from the grid, it isn't eligible for the 26 percent solar tax credit.

Eligibility for commercial properties
If you are installing energy storage on a commercial property, it is eligible for a credit under the ITC as long as the battery is charged by a renewable energy system more than 75 percent of the time. The exact value of the federal tax credit for batteries depends on how frequently the battery is charged by a renewable energy system. To claim the full value, the battery needs to be charged by renewable energy 100 percent of the time. Otherwise, the credit is based on the portion of renewable energy it receives.

 

[Ampster]

I would be interested to see any sources that state this as it applies to the residential credit

I did not find anything either. I did discover that if one falls below 100% then the percentage charged from solar is the percentage of the credit that one can take. Thanks for the clarification.

 

[Blup85]

I'm curious if anyone here has just used a 14 pin relay to flip the CT's on a Time of day basis to charge the PW at night during off-peak. (I don't know how to write code, but I'm guessing people have found a way to fake a storm event too through some type of API interface)

 

[wjgjr]

I did not find anything either. I did discover that if one falls below 100% then the percentage charged from solar is the percentage of the credit that one can take. Thanks for the clarification.

It is very confusing because there are a lot of similarities between the residential (section 25) and commercial (section 48) credits, but there are some key differences. This includes the 75% rule and the "safe harbor" rule which allows projects to start with a small expense to secure the higher credit amount, both of which apply only to the commercial credit. Despite this, some - particularly unscrupulous - companies will try to advise residential clients they can apply these rules.

Additionally, the 100% rule is technically only a private-letter ruling, so there is no official policy that is the rule, or that PWs even qualify for the credit at all. (Though it seems very likely the 100% rule and that PWs qualify are the rules, but the IRS is not explicit on this point in official guidance.)

 

[h2ofun]

I'm curious if anyone here has just used a 14 pin relay to flip the CT's on a Time of day basis to charge the PW at night during off-peak. (I don't know how to write code, but I'm guessing people have found a way to fake a storm event too through some type of API interface)

interesting idea

 

[Ampster]

New I'm curious if anyone here has just used a 14 pin relay to flip the CT's

Probably not that hard with a Neurio. I don't know enough about the new gateway and inverter to even guess about CT access or location..

 

[HankLloydRight]

I'm curious if anyone here has just used a 14 pin relay to flip the CT's on a Time of day basis to charge the PW at night during off-peak. (I don't know how to write code, but I'm guessing people have found a way to fake a storm event too through some type of API interface)

Would be a piece of cake with an Arduino. Why 14 pins? How many CTs do you need to switch?

 

[RKCRLR]

With regards to the 52 times cycling requirement if you get a SGIP incentive, there used to be something on Tesla's website (maybe in the FAQs) about Tesla monitoring the battery cycles during the year and commanding the powerwalls to discharge if it looks like they are going to come up short. It is probably still there but I haven't looked.

 

[Ribeyesteak]

I can't imagine Sempra in California allowing a pw2 to charge from the grid even if SGIP/ITC was rejected but I will contact them and let you guys know...

 

[garyhooper]

New to both Powerwall (with solar) and the conversation. Is it not in the best interest of PG&E and other utilities to allow overnight charging from the grid to the Powerwall? This would make it more likely that power would be available during peak times, especially in winter, and help balance their generation over each 24-hour period. PG&E?

 

[RKCRLR]

New to both Powerwall (with solar) and the conversation. Is it not in the best interest of PG&E and other utilities to allow overnight charging from the grid to the Powerwall? This would make it more likely that power would be available during peak times, especially in winter, and help balance their generation over each 24-hour period. PG&E?

Its not in the best interest of PG&E and other investor owned utilities to allow feeding battery power back to the grid during peak hours since they are for-profit corporations. However, it is in the best interest of consumers to allow this to happen.

 

[Vines]

New to both Powerwall (with solar) and the conversation. Is it not in the best interest of PG&E and other utilities to allow overnight charging from the grid to the Powerwall? This would make it more likely that power would be available during peak times, especially in winter, and help balance their generation over each 24-hour period. PG&E?

There are 3 major players:
Tesla will only warranty your ESS for unlimited cycles over 10 years when charged from renewable sources. Tesla will not enable grid charging with a PV system on site.

IOU wants to make money off you, so whatever you do that threatens the bottom line they do not like.

The consumer wants to use their tech the most advantageous way to save money and the environment in some proportion.

 

[Ampster]

Is it not in the best interest of PG&E and other utilities to allow overnight charging from the grid to the Powerwall?

Yes, as far as the revenue from that charging is concerned. However, as discussed earlier in the thread, a fourth player in this drama is the IRS who has rules about the ITC and a requirement to charge from solar in order to qualify for ITC.. It is not a simple issue. To add further complexity there may be SGIP grant rules for some.