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Possibly adding a 3rd Powerwall. Good idea?

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J

jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
7,920
5,425
Northern California
#1
Hi,

Our solarroof is putting out a lot of power and we are feeding back to the grid considerably more than we consume. To capture some of this I am thinking about adding a 3rd Powerwall. Is this a good idea? If so, what sort of issues does this create with PG&E, NEM, etc.? Also, has anyone heard about Powerwalls switching to LiFePo technology?
 
#2
jboy210 said:
Hi,

Our solarroof is putting out a lot of power and we are feeding back to the grid considerably more than we consume. To capture some of this I am thinking about adding a 3rd Powerwall. Is this a good idea? If so, what sort of issues does this create with PG&E, NEM, etc.? Also, has anyone heard about Powerwalls switching to LiFePo technology?
Click to expand...
IMO, waste of money. Use the PGE battery!!
 
#3
Capture toward what end? And the downside to you feeding more back to the grid is? I.e. why do you want to add one? Better support for your long power outages? Rate arbitrage?

Lotsof rumors out there. LiFePO would make sense from a cost and risk perspective, and model 3s in China are supposedly shipping with them. But I doubt Tesla would offer you a choice... Personally, I would expect Tesla to go there at some point, unless sodium ion batteries make it to market at scale, but that is all speculation and not near term.

All the best,

BG
 
#4
My experience: I had 2 Powerwalls and 10.56kW of solar panels installed on a new home in SE Florida last year (by a third-party Tesla certified installer). After using the system for a while, I determined that the 2 Powerwalls would not be able to provide quite enough backup power to get me through the night in the event of a grid outage, so I added a third Powerwall. That created a new issue: the 10.56kW wasn't producing enough to fully charge the 3 Powerwalls, so I ended up adding more panels for an additional 3.96kW. Now everything is working great, and I'm not using any grid power at this time of year (reserve set to 20%).

You have decide what's important to you. I wasn't concerned about the cost, so there were likely less expensive ways to accomplish the same thing. For me, having a full backup during any grid outage was an important goal.
 
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#5
EVRider-FL said:
My experience: I had 2 Powerwalls and 10.56kW of solar panels installed on a new home in SE Florida last year (by a third-party Tesla certified installer). After using the system for a while, I determined that the 2 Powerwalls would not be able to provide quite enough backup power to get me through the night in the event of a grid outage, so I added a third Powerwall. That created a new issue: the 10.56kW wasn't producing enough to fully charge the 3 Powerwalls, so I ended up adding more panels for an additional 3.96kW. Now everything is working great, and I'm not using any grid power at this time of year (reserve set to 20%).

You have decide what's important to you. I wasn't concerned about the cost, so there were likely less expensive ways to accomplish the same thing. For me, having a full backup during any grid outage was an important goal.
Click to expand...
Yep, if one has the money. Now since I have 5 ev charging stations ready, if I only could afford to buy 5 teslas :)
 
#7
My system is still pretty new and I don't even have PTO jut yet. But I could have easily been able to support 3 PW's with my 14.8kw system instead of 2. However, I think after I get a year of total use under my belt I may be close to a 'zero' energy bill once I can build up credits. Now if my goal were to survive the zombie apocalypse I should have gotten a 3rd PW. I understood I would not be able to get through a full night in a power outage on 2 PW's if I don't try to conserve. But if I shed loads I can get my essential loads through the night until production resumes. So in the case of a hurricane that shut down the local grid for 5-7 days I can get by, but I'd need to greatly reduce my AC usage over night. But over the span of a year my energy bill should/hopefully be near zero.
 
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#9
I wouldn't do it to capture some of the excess production, but it's more of a "where do I want to dump my $$" question. If $$ is no object and you just want to have 3 PWs, nothing else to buy, then get another.

Outside of lasting slightly longer in a long power outage (assuming 2 gets you through the night), I don't think 3 will make much difference.

The hassles alone would probably not be worth it for me unless like that other forum member, is able to get one for like $3k-$4k (was it?) or if I was starting to prep to go fully off grid (in my case, I'd get a generator, 2x more batteries, maybe wind turbine stuff and turn that into another project).

Too much hassle for 1 more...and I don't think it's LFP yet.
 
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#10
IMO, there are two factors working against adding a 3rd Powerwall.

1) Red tape: apparently getting 3x Powerwalls makes it so Tesla won't allow you to support the advanced features. And, PG&E will require a NEM2-MT agreement instead of NEM2-PS. All this red tape makes 3x Powerwalls unattractive.

2) ROI: it doesn't make much financial sense for now under the current TOU rates. If you're on E-TOU-C and your solar production is greater or equal than your annual consumption, a 3rd Powerwall won't help you much. I personally have a solar array that is too small, and I had to go to EV2-A per PG&E/SGIP* mandate. So the 3rd Powerwall is necessary for me to get through all of the super-long EV2-A shoulder+peak times. But my use case is very limited. Most people would rather just get more solar (I know, you can't due to your roof) to make it so their solar production was >= annual consumption. I'm just in the weird boat where I need to generate shoulder (or peak) credits to offset the undersized solar that PG&E capped me with.

* Note: Originally I only wanted 2x Powerwalls, but PG&E forced me to get a 3rd (which was funded by SGIP), or else they wouldn't approve my project.

If red tape and ROI were off the table, then more batteries is more better.
 
#11
h2ofun said:
Yep, if one has the money. Now since I have 5 ev charging stations ready, if I only could afford to buy 5 teslas :)
Click to expand...


Are you going to sign up on Plugshare?

1653668366444.png
 
#15
holeydonut said:
IMO, there are two factors working against adding a 3rd Powerwall.

1) Red tape: apparently getting 3x Powerwalls makes it so Tesla won't allow you to support the advanced features. And, PG&E will require a NEM2-MT agreement instead of NEM2-PS. All this red tape makes 3x Powerwalls unattractive.

2) ROI: it doesn't make much financial sense for now under the current TOU rates. If you're on E-TOU-C and your solar production is greater or equal than your annual consumption, a 3rd Powerwall won't help you much. I personally have a solar array that is too small, and I had to go to EV2-A per PG&E/SGIP* mandate. So the 3rd Powerwall is necessary for me to get through all of the super-long EV2-A shoulder+peak times. But my use case is very limited. Most people would rather just get more solar (I know, you can't due to your roof) to make it so their solar production was >= annual consumption. I'm just in the weird boat where I need to generate shoulder (or peak) credits to offset the undersized solar that PG&E capped me with.

* Note: Originally I only wanted 2x Powerwalls, but PG&E forced me to get a 3rd (which was funded by SGIP), or else they wouldn't approve my project.

If red tape and ROI were off the table, then more batteries is more better.
Click to expand...
Quick question. I purchased a home with 3 powerwalls. What advanced features am I missing out on?
 
#17
GolfProGiff said:
Quick question. I purchased a home with 3 powerwalls. What advanced features am I missing out on?
Click to expand...

Here's the thread discussing the new, advanced features. Basically it enables more control of the Powerwall to grid-charge and export stored energy generated from solar and/or sourced from the grid.

Experiences for who got access to the features is all over the place. Tesla told me on several occasions that my 3x Powerwall system was barred from the new features since 3 is bad, and 2 is good. But then @Vines has 5x Powerwalls (not the + kind) and he has the features. Maybe 2 is good, 3 is bad, 4 is ¯\_(ツ)_/¯, and 5 is good.

teslamotorsclub.com

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

With these new settings, we can now pretty much control all the modes for the PWs except put it in standby. Anyone know how to put the PWs in a standby mode? In either self-powered or TOU mode I don't see how I could do this, but would be nice if house load uses all available solar and any...
teslamotorsclub.com teslamotorsclub.com
 
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#18
holeydonut said:
Here's the thread discussing the new, advanced features. Basically it enables more control of the Powerwall to grid-charge and export stored energy generated from solar and/or sourced from the grid.

Experiences for who got access to the features is all over the place. Tesla told me on several occasions that my 3x Powerwall system was barred from the new features since 3 is bad, and 2 is good. But then @Vines has 5x Powerwalls (not the + kind) and he has the features. Maybe 2 is good, 3 is bad, 4 is ¯\_(ツ)_/¯, and 5 is good.

teslamotorsclub.com

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

With these new settings, we can now pretty much control all the modes for the PWs except put it in standby. Anyone know how to put the PWs in a standby mode? In either self-powered or TOU mode I don't see how I could do this, but would be nice if house load uses all available solar and any...
teslamotorsclub.com teslamotorsclub.com
Click to expand...
FWIW, I already have Export and charging from the grid options. I wonder if they take the charging option away?
 
Last edited:
#19
holeydonut said:
Here's the thread discussing the new, advanced features. Basically it enables more control of the Powerwall to grid-charge and export stored energy generated from solar and/or sourced from the grid.

Experiences for who got access to the features is all over the place. Tesla told me on several occasions that my 3x Powerwall system was barred from the new features since 3 is bad, and 2 is good. But then @Vines has 5x Powerwalls (not the + kind) and he has the features. Maybe 2 is good, 3 is bad, 4 is ¯\_(ツ)_/¯, and 5 is good.

teslamotorsclub.com

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

With these new settings, we can now pretty much control all the modes for the PWs except put it in standby. Anyone know how to put the PWs in a standby mode? In either self-powered or TOU mode I don't see how I could do this, but would be nice if house load uses all available solar and any...
teslamotorsclub.com teslamotorsclub.com
Click to expand...
Thank you. I have 3 (South Florida) and I do have these options available to me.
 
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