New Powerwall Advanced Options [Toggles for charging from and discharging to grid from powerwalls]

[YRide]

YRide,

I posted a while back, nothing definitive but similar to your topic: Link.

My understanding on the number of power walls is that the PG&E NEM tariff treats systems with larger capacity differently. Over 10kW, they require special metering or non-export controls, while systems under 10kW can use the "estimation methodology". (Special Condition 9, c, 2, ii). I gather this is all to minimize TOU arbitrage, grid charging off peak and exporting on-peak, by limiting export to the amount of solar production, either measured or estimated. Larger systems make larger export possible, so they want better data, it seems. Early on at least, Tesla seemed to be helping PG&E enforce their rules, but more recently some folks with 3 and more PW have reported that they can Export Everything.

In my case, with only one PW and no ITC taken, I am flying below the radar. Still, against my installer's advice, I did, opt to tell PG&E I was enlarging my solar array so that they would calculate a larger export limit, even though this meant I lost my NEM1 grandfathering.

Anyway, on both your ITC and the multi PW questions, there still does not seem to be much clarity. Oh, and the new NEM3 tariffs have not been published yet, so uncertainty reigns, I fear.

SW

Ok, so when you say over 10kW you are referring to the sizing of the PV system (PV panel output X number of panels, ie wtat you see in the Tesla configurator)? So not the sizing of the ESS/PW (I guess even one PW is exceeding that)?

I am currently designed for a 10.8kW system (27 panels X 400W), so it looks like I might run into this issue. But it sounds like PW qty should not have an impact?

 

[swedge]

Ok, so when you say over 10kW you are referring to the sizing of the PV system (PV panel output X number of panels, ie wtat you see in the Tesla configurator)? So not the sizing of the ESS/PW (I guess even one PW is exceeding that)?

I am currently designed for a 10.8kW system (27 panels X 400W), so it looks like I might run into this issue. But it sounds like PW qty should not have an impact?

Sorry, I should have said that. It is the nameplate rating of 10kW output from the battery. Each PW is 5kW max continuous, so 2 is the limit.

I have heard from two people with 3 PWs that PG&E waived the metering requirement for them.

We love our PW. Export Everything is giving us extra leverage on our solar by shifting export to peak period on EV2-A rate. Expecting ~$100 trueup even with charging our Model Y. Sharing wifi and cellphone charging with neighbors during psps extended outage was icing on the cake.

 

[YRide]

Sorry, I should have said that. It is the nameplate rating of 10kW output from the battery. Each PW is 5kW max continuous, so 2 is the limit.

I have heard from two people with 3 PWs that PG&E waived the metering requirement for them.

We love our PW. Export Everything is giving us extra leverage on our solar by shifting export to peak period on EV2-A rate. Expecting ~$100 trueup even with charging our Model Y. Sharing wifi and cellphone charging with neighbors during psps extended outage was icing on the cake.

Ok, thx for the clarification, that makes more sense now.

Btw, isn’t the PW+ actually 7kW continuous (and 9.6kW continuous under full sun)?

So a PW+ and any other PW, or two PW+ (as I need to have 7 MPPT’s for my 10.8kW PV design!) will actually exceed the threshold as we understand for EE turn-on?

And yeah, just got another Y…looking forward to not having a $1k/mo bill!

 

[jjrandorin]

Ok, thx for the clarification, that makes more sense now.

Btw, isn’t the PW+ actually 7kW continuous (and 9.6kW continuous under full sun)?

So a PW+ and any other PW, or two PW+ (as I need to have 7 MPPT’s for my 10.8kW PV design!) will actually exceed the threshold as we understand for EE turn-on?

And yeah, just got another Y…looking forward to not having a $1k/mo bill!

The only difference between a powerwall+ and a powerwall 2 is that the powerwall+ has a solar inverter attached to it. I am virtually certain that neither are "7kW continuous" devices. The newest ones might allow a burst mode of 7kW for something like starting up an HVAC system (so a soft start device may not be needed) but its not 7kW continuous, I am 99.9999999999% sure.

 

[sunwarriors]

Did the IRS ever provide clarity on void/clawback of the ITC credit if one were to charge constantly from grid super-off peak, then export or self consume during on-peak?

 

[YRide]

The only difference between a powerwall+ and a powerwall 2 is that the powerwall+ has a solar inverter attached to it. I am virtually certain that neither are "7kW continuous" devices. The newest ones might allow a burst mode of 7kW for something like starting up an HVAC system (so a soft start device may not be needed) but its not 7kW continuous, I am 99.9999999999% sure.

Hmmm. Just trying to understand these “specs”.

PW+ shows 9.6kW / 7kW continuous…

Whereas the PW doesn’t say on website, but then spec sheet https://tesla-cdn.thron.com/deliver...f7/bvlatuR/WEB/powerwall-2-ac-datasheet-en-na does indicate 5kW continuous.

 

[YRide]

The only difference between a powerwall+ and a powerwall 2 is that the powerwall+ has a solar inverter attached to it. I am virtually certain that neither are "7kW continuous" devices. The newest ones might allow a burst mode of 7kW for something like starting up an HVAC system (so a soft start device may not be needed) but its not 7kW continuous, I am 99.9999999999% sure.

For HVAC startup you should more focus on the LRA spec right? Not the continuous or peak power (you need to consider these too, but specifically for startup I believe it’s just Locked Rotor Amps you care about).

I’ll disclaim that I am no expert here…

 

[jjrandorin]

For HVAC startup you should more focus on the LRA spec right? Not the continuous or peak power (you need to consider these too, but specifically for startup I believe it’s just Locked Rotor Amps you care about).

I’ll disclaim that I am now expert here…

I believe those specs for powerwall+ might assume "full sun" (I cant see what the subnote is that is indicated there). Any backup power spec that would require full sun be shining to hit the continuous number does not count as "continuous" to me, but perhaps it might as a spec on a spec sheet?

LRA is the number to look at for HVAC startup as you mention, but I am not an expert on that subject either. I just know that starting up HVAC units can be an issue for some, but if you are planning 4 powerwalls that wouldnt be an issue for you.

Given we dont know what triggers tesla to enable export everything (that just became available this year), I dont believe I would include that in my financial calculations myself.

 

[YRide]

Did the IRS ever provide clarity on void/clawback of the ITC credit if one were to charge constantly from grid super-off peak, then export or self consume during on-peak?

My understanding is it’s unclear, not yet tested or clarified by IRS. Prob since we’re just coming into the window of reality now, literally today.

What does seem to be clarified is that an ESS-only system installed after Dec 31, 2022 (today!) is eligible for the full ITC (30% until the new phaseout date) without requiring 100% solar/PV production. This would imply you can grid charge both an ESS-only as well as an ESS+PV system, assuming they are installed after today. That is from an ITC (so federal gov’t / IRS perspective).

Unclear if your utility allows the grid charging though…

 

[swedge]

Unclear if your utility allows the grid charging though…

My original interest in grid charging was that on some cloudy winter days, our solar production was not sufficient to fully charge the PW.

Typically, we would solar charge up to 100% by mid day. Then at 3pm when off-peak ended, the battery would cover our loads, draining down to around 50% by midnight when off-peak began again. On those cloudy days, we could get down to our 20% reserve setting before midnight, and have to draw from the grid at peak pricing, much to my chagrin. But when I looked at how few days that actually was, I calculated that it cost me less than $100 per year. Still it is nice now to have Grid Charging to solve that annoyance.

But now that Export Everything is also available, Grid Charging becomes even more helpful. We start peak period every day at 100%, and use roughly 50% for the house. This leaves 30% more to export with 20% in reserve. That is roughly 4kWh with 41¢ credit for which we paid 22¢ or less depending on solar contribution. So it is at least $0.76 per day, $23/mo. More during the summer due to higher peak credit and solar providing all of the charging. It works out to several hundred per year to help offset the cost of charging the car.

In your case, with maybe 3 or 4 PowerWalls, this could affect the economics substantially. If this is crucial to your decision, I would suggest getting clarity from PG&E and Tesla on both exporting and grid charging. If you can... Your installer should know these rules too, but likely does not, sigh. ( Especially since they have to fill out the interconnection request correctly! )

 

[YRide]

My original interest in grid charging was that on some cloudy winter days, our solar production was not sufficient to fully charge the PW.

Typically, we would solar charge up to 100% by mid day. Then at 3pm when off-peak ended, the battery would cover our loads, draining down to around 50% by midnight when off-peak began again. On those cloudy days, we could get down to our 20% reserve setting before midnight, and have to draw from the grid at peak pricing, much to my chagrin. But when I looked at how few days that actually was, I calculated that it cost me less than $100 per year. Still it is nice now to have Grid Charging to solve that annoyance.

But now that Export Everything is also available, Grid Charging becomes even more helpful. We start peak period every day at 100%, and use roughly 50% for the house. This leaves 30% more to export with 20% in reserve. That is roughly 4kWh with 41¢ credit for which we paid 22¢ or less depending on solar contribution. So it is at least $0.76 per day, $23/mo. More during the summer due to higher peak credit and solar providing all of the charging. It works out to several hundred per year to help offset the cost of charging the car.

In your case, with maybe 3 or 4 PowerWalls, this could affect the economics substantially. If this is crucial to your decision, I would suggest getting clarity from PG&E and Tesla on both exporting and grid charging. If you can... Your installer should know these rules too, but likely does not, sigh. ( Especially since they have to fill out the interconnection request correctly! )

Ha ha ha…I’ve been over this so many times with the Tesla energy team. They really don’t seem to know (and it’s ever changing situation). So they data coming from you and others here is way more useful.

The good thing is it looks like from both NEM3 and ITC/IRA, you can add ESS later without causing problems (like moving from NEM2 to NEM3). Btw, prob shouldn’t call it NEM3, it is Net Billing.

But also kinda a hassle to install others later after the fact.

With two (currently 3 but need to offload quickly!) Y’s…and the potential to switch stove, water, heating over to electric…and fam growing…and rates rising, it might. E worth having the headroom now.

But I’m now back to the original question which kicked off this flurry…does PGE have an official unit on how much ESS you can have to enable them to authorize Tesla to enable EE as an option (and i guess grid charging too).

It will be interesting indeed!

 

[h2ofun]

Ha ha ha…I’ve been over this so many times with the Tesla energy team. They really don’t seem to know (and it’s ever changing situation). So they data coming from you and others here is way more useful.

The good thing is it looks like from both NEM3 and ITC/IRA, you can add ESS later without causing problems (like moving from NEM2 to NEM3). Btw, prob shouldn’t call it NEM3, it is Net Billing.

But also kinda a hassle to install others later after the fact.

With two (currently 3 but need to offload quickly!) Y’s…and the potential to switch stove, water, heating over to electric…and fam growing…and rates rising, it might. E worth having the headroom now.

But I’m now back to the original question which kicked off this flurry…does PGE have an official unit on how much ESS you can have to enable them to authorize Tesla to enable EE as an option (and i guess grid charging too).

It will be interesting indeed!

Personally, IMO, adding batteries for this game make no sense. Now if one just have money to spend to play, great. The last 2 batteries I
installed made ZERO sense. I have yet to even have a power outage since I got all this stuff, and this have been years. Working with my sister in law to install a whole house generator, makes much more sense than batteries and or solar.

 

[Zsoldier]

This seems to be an outdated policy for powerwalls strictly enforced by Tesla. I tried contact Tesla to enable grid charging on my batteries installed in 2023 and they refused stating that my batteries were marked as "ITC". Basically because it was part of my entire solar system project, so that only qualifies them to charge from solar ONLY.

Correct me if I'm wrong here, but as of 2023, even standalone powerwalls qualify for ITC in the US.
Energy Incentives | Powerwall Support
By this same logic, those standalone powerwalls would qualify for ITC therefore be limited to charging from a non-existent solar system? (I think I made the chat's person head explode when I told them this)

Tried going through support, but they just wouldn't budge. I'm guessing they simply haven't updated their policies. I mean, the arbitrary block for nontechnical reasons, to charge from the grid is extremely frustrating. Anyone had any luck w/ this?

 

[sunwarriors]

Asking a Tesla support person for ITC tax guidance seems unwise. Low level support folks tend to just follow a script and until there is case law or higher ups say otherwise, I don't think it's ever been clear about solar, batteries and grid charging off hours for folks who did solar/storage under the ITC.


I think the ITC charge rule is just not in a clear place anymore with the new IRA laws and the IRS hasn't come clean on this point. With the old ITC law, it could probably be argued from the IRS that storm watch should not be allowed neither and you need to prorate that out from the ITC, but it's unlikely the IRS will ever do anything since they are so short staffed as it is.

New House just tried to abolish the IRS and income tax completely, but that's all noise really with divided Congress/Prez veto.

It would be nice if this was given clear guidance, but you may have utilities now lobby against that. Someone here ran the numbers for San Diego and there was decent ROI to just discharge during on-peak, charge during super off-peak already due to an extremely high difference between those rates here.

 

[Zsoldier]

Asking a Tesla support person for ITC tax guidance seems unwise. Low level support folks tend to just follow a script and until there is case law or higher ups say otherwise, I don't think it's ever been clear about solar, batteries and grid charging off hours for folks who did solar/storage under the ITC.


I think the ITC charge rule is just not in a clear place anymore with the new IRA laws and the IRS hasn't come clean on this point. With the old ITC law, it could probably be argued from the IRS that storm watch should not be allowed neither and you need to prorate that out from the ITC, but it's unlikely the IRS will ever do anything since they are so short staffed as it is.

New House just tried to abolish the IRS and income tax completely, but that's all noise really with divided Congress/Prez veto.

It would be nice if this was given clear guidance, but you may have utilities now lobby against that. Someone here ran the numbers for San Diego and there was decent ROI to just discharge during on-peak, charge during super off-peak already due to an extremely high difference between those rates here.

It’s rather ridiculous considering enphase batteries don’t have this limitation. It’s really frustrating that Tesla is imposing a really moronic thing at this point.

 

[lensovet]

I am virtually certain that neither are "7kW continuous" devices

sorry this is wrong. PW+ will supply about 7 kW continuous in off-grid mode (either manually triggered or due to an outage) with no sun and will only supply 5.8 kVA (about 5.6 kW) when grid-connected with no sun. i know this because i've seen it firsthand on my installation. This is also explicitly called out in the comparison chart on How Powerwall Works | Powerwall Support.

This seems to be an outdated policy for powerwalls strictly enforced by Tesla. I tried contact Tesla to enable grid charging on my batteries installed in 2023 and they refused stating that my batteries were marked as "ITC". Basically because it was part of my entire solar system project, so that only qualifies them to charge from solar ONLY.

it's worth nothing that there are utility limitations too, so this might be a utility issue. the new rules only went into effect less than three weeks ago, I would not expect Tesla to be on top of this. just look at what happened with their car prices.

 

[Zsoldier]

sorry this is wrong. PW+ will supply about 7 kW continuous in off-grid mode (either manually triggered or due to an outage) with no sun and will only supply 5.8 kVA (about 5.6 kW) when grid-connected with no sun. i know this because i've seen it firsthand on my installation. This is also explicitly called out in the comparison chart on How Powerwall Works | Powerwall Support.


it's worth nothing that there are utility limitations too, so this might be a utility issue. the new rules only went into effect less than three weeks ago, I would not expect Tesla to be on top of this. just look at what happened with their car prices.

I double checked utility limitations for Georgia power, but could find none. Those I know that have enphase or other batteries on GA power don’t have this limitation.

 

[jjrandorin]

sorry this is wrong. PW+ will supply about 7 kW continuous in off-grid mode (either manually triggered or due to an outage) with no sun and will only supply 5.8 kVA (about 5.6 kW) when grid-connected with no sun. i know this because i've seen it firsthand on my installation. This is also explicitly called out in the comparison chart on How Powerwall Works | Powerwall Support.


it's worth nothing that there are utility limitations too, so this might be a utility issue. the new rules only went into effect less than three weeks ago, I would not expect Tesla to be on top of this. just look at what happened with their car prices.

You say "with no sun" so you turned off the solar inverter on your powerwall+ and in an off grid situation saw 7kW ? Its called out "full sun" for 7kW continuous in the chart you linked.

EDIT:... I may be looking at the chart incorrectly as well.

 

[wwhitney]

sorry this is wrong. PW+ will supply about 7 kW continuous in off-grid mode (either manually triggered or due to an outage) with no sun and will only supply 5.8 kVA (about 5.6 kW) when grid-connected with no sun.

I agree, the data sheet says the same thing.

I wonder how they do that, since the bottom is just a PW, and its inverter is rated for only 5.8 kVA continuous either on grid or off grid. It seems like that would mean that they are leverage the PV inverter somehow in off-grid mode. But I thought the integration between the upper PV inverter/PW controller and the lower PW was minimal. I.e. no DC conductors from the battery, which would be required to utilize the upper inverter in a no-sun, off grid mode.

Cheers, Wayne

 

[lensovet]

You say "with no sun" so you turned off the solar inverter on your powerwall+ and in an off grid situation saw 7kW

Lol no, I went off grid via the app when the sun was down and saw the PW supply a hair over 7 kW to the house. Never tested the “full sun” spec but that’s not of any particular interest to me since I would basically never need it in a real life scenario.