Time of Use Power Shifting for Powerwall 2

[Doctor X]

Hello everyone,
I would like some guidance from this group please. I’m in Canada and I’ve earned a PW through the referral program (or alternatively a Tesla credit). I already have a natural gas generator in my house for the rare outages we may get, but my sump pump HAS to work in order to avoid flooding my basement when we get a good storm. Were I live we have a TOU rate on electricity and I do not have any solar at all. So if I were to choose the install a PW it would be to charge it at night (7pm to 7am) when the rates are low and discharge it to run the house power during the higher electricity rate (7am to 7pm). The price difference between the two rates is 6.5 cents at night versus 13.2 cents per kWh during the day. Does it make sense? Is this doable? I appreciate any comments or suggestions.

 

[MorrisonHiker]

Hello everyone,
I would like some guidance from this group please. I’m in Canada and I’ve earned a PW through the referral program (or alternatively a Tesla credit). I already have a natural gas generator in my house for the rare outages we may get, but my sump pump HAS to work in order to avoid flooding my basement when we get a good storm. Were I live we have a TOU rate on electricity and I do not have any solar at all. So if I were to choose the install a PW it would be to charge it at night (7pm to 7am) when the rates are low and discharge it to run the house power during the higher electricity rate (7am to 7pm). The price difference between the two rates is 6.5 cents at night versus 13.2 cents per kWh during the day. Does it make sense? Is this doable? I appreciate any comments or suggestions.

Yes, you could use a Powerwall with TOU exactly as you describe. Buying a Powerwall to handle that wouldn't have a very good return on investment but since you earned one in the referral program, it makes it much more affordable. If you only have one Powerwall, you wouldn't be able to back up the entire house but you could cover specific circuits, such as the sump pump and a few others.

 

[cwied]

So if I were to choose the install a PW it would be to charge it at night (7pm to 7am) when the rates are low and discharge it to run the house power during the higher electricity rate (7am to 7pm). The price difference between the two rates is 6.5 cents at night versus 13.2 cents per kWh during the day. Does it make sense? Is this doable? I appreciate any comments or suggestions.

The Powerwall is intended to handle your situation. The question is whether your power company would allow you to use it that way and whether (and when) Tesla will enable the time-based control feature in your area. The last I heard, the feature is currently not available everywhere, but indications are that they do plan to roll it out universally.

 

[Ed Hart]

The Powerwall is intended to handle your situation. The question is whether your power company would allow you to use it that way and whether (and when) Tesla will enable the time-based control feature in your area. The last I heard, the feature is currently not available everywhere, but indications are that they do plan to roll it out universally.

Here in California, in order to qualify for a rebate under the Self-Generation Incentive Plan (SGIP), a user cannot take power at night and either use it during the day or send it to the grid; batteries must be charged from solar, only.
Here is how my system manage load yesterday:
Car charging and pool pump running at night
Solar first charging Powerwalls.
Once Powerwalls fully charge, juice then sent to grid.
100F+ temperatures and afternoon home activities all three AC units running heavy in late afternoon.
Powerwall dropped out at its reserve level of 20% around 9:15 PM
Car charging started again at 10:00 PM
Working as planned.

 

[cwied]

Here in California, in order to qualify for a rebate under the Self-Generation Incentive Plan (SGIP), a user cannot take power at night and either use it during the day or send it to the grid. Batteries must be charged from solar, only.

Doctor X is in Toronto, though, and also doesn't have solar. TBC without solar does do grid charging (and I believe would also have been SGIP eligible - I think you're thinking of the ITC).

 

[bkp_duke]

Here in California, in order to qualify for a rebate under the Self-Generation Incentive Plan (SGIP), a user cannot take power at night and either use it during the day or send it to the grid. Batteries must be charged from solar, only.

I would be nice if they (Tesla) would let us export that solar energy back to the grid during peak non-sunlight hours. Doesn't have to be all of it, but it would help counter the TOU rate game that the utilities play.

 

[cwied]

I would be nice if they (Tesla) would let us export that solar energy back to the grid during peak non-sunlight hours. Doesn't have to be all of it, but it would help counter the TOU rate game that the utilities play.

I don't think the right "they" is Tesla. It's the utilities that don't let you export from the batteries currently. At least that's the case with PG&E. I'm guessing SDG&E is no different.

 

[liuping]

I would be nice if they (Tesla) would let us export that solar energy back to the grid during peak non-sunlight hours. Doesn't have to be all of it, but it would help counter the TOU rate game that the utilities play.

You cannot export it, but you can use it to power you house, then all solar that comes in during the peak rates can go to the grid.

For example, most days during the summer, I export 8kwh of solar to the grid from 4-9pm (at $0.54 per kWh), even with the AC running, and dinner in the oven. Since I now have EVTOU-5 rates, the super off peak is $0.094 per kWh, so that 8kWh of peak rate exporting covers up to 45kWh of EV charging after midnight.

 

[bkp_duke]

SDG&E has to get you somewhere. I notice that the minimum bill on EV-TOU5 is $16. Bastards.

 

[liuping]

SDG&E has to get you somewhere. I notice that the minimum bill on EV-TOU5 is $16. Bastards.

SDG&E gave EV owners $500 in credit per registered EV this year.

We have 2 Tesla and a Volt, so they credited my account $1500. I think that more than covers the $16 a month for a while

 

[GenSao]

SDG&E gave EV owners $500 in credit per registered EV this year.

We have 2 Tesla and a Volt, so they credited my account $1500. I think that more than covers the $16 a month for a while

I believe all the California utilities have a similar rebate program.

• $500 for PG&E
• $450 for SCE

 

[miimura]

I believe all the California utilities have a similar rebate program.

• $500 for PG&E
• $450 for SCE

The big difference is that PG&E and SCE give those rebates once per VIN while SDG&E divides up their LCFS funds every year and divides it among those that register for it. I have no idea how PG&E and SCE will reconcile their LCFS balances over multiple years when LCFS credits are varying in value. They have an obligation to disburse those funds to EV drivers. SDG&E's scheme makes a lot more sense to me.

 

[wwhitney]

Here in California, in order to qualify for a rebate under the Self-Generation Incentive Plan (SGIP), a user cannot take power at night and either use it during the day or send it to the grid; batteries must be charged from solar, only.

That is not a requirement of the SGIP, it is only a requirement of the ITC.

Cheers, Wayne

 

[wwhitney]

It's the utilities that don't let you export from the batteries currently. At least that's the case with PG&E. I'm guessing SDG&E is no different.

My reading of the PG&E tariffs is If you have solar and Powerwalls, the only restriction is that your annual total export not exceed your annual (estimated) solar production. So solar production time shifting is not prohibited.

Cheers, Wayne

 

[markb1]

The big difference is that PG&E and SCE give those rebates once per VIN while SDG&E divides up their LCFS funds every year and divides it among those that register for it. I have no idea how PG&E and SCE will reconcile their LCFS balances over multiple years when LCFS credits are varying in value. They have an obligation to disburse those funds to EV drivers. SDG&E's scheme makes a lot more sense to me.

Right. I made $700 so far on my one car, I think. It's funny how people complained when SDG&E originally announced the rebate would be a minimum of $50.

 

[cwied]

My reading of the PG&E tariffs is If you have solar and Powerwalls, the only restriction is that your annual total export not exceed your annual (estimated) solar production. So solar production time shifting is not prohibited.

Cheers, Wayne

The reason I don't think it's allowed is because my interconnect agreement is for a "non-Net Metering eligible power storage device." If the Powerwall is not Net Metering eligible, then I don't think that exporting to the grid from the batteries would be allowed. Of course I don't know whether they have the ability to enforce that.

 

[Ed Hart]

That is not a requirement of the SGIP, it is only a requirement of the ITC.

Cheers, Wayne

Thanks for the feedback, Wayne. This is how it was presented to me:

May I use my energy storage system solely as a source of backup power?

No. The SGIP rules prohibit energy storage systems from being used solely for backup purposes. The system must “cycle” – charge and discharge on a regular basis – to meet some of your onsite electrical needs.

Will I still get to benefit from the Investment Tax Credit (ITC)?

If Powerwall is installed at the same time or retrofitted onto existing solar panels, Powerwall is eligible for the 30% Federal ITC. You can receive both the California SGIP incentive as well as the Federal ITC for your Powerwall if you are meeting both program requirements.

What are the requirements to receive SGIP?

1. As your applicant, your contractor must first file all the SGIP paperwork.
   
   
2. After your installation is complete, and utility permission to operate is provided, the contractor will submit more
   
   SGIP paperwork. Then, after they review, an SGIP administrator may inspect your system to
   
   confirm it is operating properly.
   
   
3. Then you will receive your cash rebate, approximately 30 to 60 days from the SGIP approval.
   
   
4. Over the next five years you’ll need to meet SGIP’s minimum requirement to support the grid infrastructure. For each Powerwall installed, this means discharging 687 kWh of Powerwall’s capacity to meet your home’s energy needs every 12 months. This is intended to ensure that the Powerwall reduces strain on the grid by reducing the amount of power you are drawing from the system during peak periods.

Of interest, it looks like our first month discharge from two Powerwall units will be about 600 kWh, meaning meeting the annual goal of 1,374 kWh should be duck soup.

 

[miimura]

You can install a Powerwall on SGIP without solar and use it with Time Based Control and TOU metering to avoid Peak period usage and charge it overnight. IIRC, the SGIP parlance is "Paired Storage" and "Non-Paired Storage". Paired meaning paired with on-site generation like solar. You just can't get SGIP if you use it purely for backup, sitting there waiting for an outage. You also typically can't use the battery to export energy, you can only offset what you're using.

 

[Ed Hart]

You can install a Powerwall on SGIP without solar and use it with Time Based Control and TOU metering to avoid Peak period usage and charge it overnight. IIRC, the SGIP parlance is "Paired Storage" and "Non-Paired Storage". Paired meaning paired with on-site generation like solar. You just can't get SGIP if you use it purely for backup, sitting there waiting for an outage. You also typically can't use the battery to export energy, you can only offset what you're using.

Thanks. You seem to know the details. The above is all I got.

 

[NuShrike]

Here in California, in order to qualify for a rebate under the Self-Generation Incentive Plan (SGIP), a user cannot take power at night and either use it during the day or send it to the grid; batteries must be charged from solar, only.
View attachment 322534

Halfway-false. SGIP requires minimum 75% charging from solar only when a battery install is paired with solar. ITC requires minimum 100% solar charging.

SGIP does support standalone installations unpaired to on-site solar that charges directly from the grid. Not taking the ITC rebate means you're not subject to additional solar-charging requirements.

This is an installation configuration many installers are hiding from you, as well as Tesla, probably because it's complicated to support especially with how to deal with "multiple sources" of on-site power. However, it's a fully legal configuration that qualifies for the SGIP rebate.

Unpaired standalone has been directly confirmed in written text with the SCE SGIP administrator.