r/Powerwall

Sorry for the long post, just want to provide full context. tl;dr is I’m wondering if I can mitigate voltage drop on long undersized mains with a battery system like a PowerWall.

Okay, so I’ve got a farm property that was built in the late 70’s and the house is about 1000 feet from the meter. The mains are direct buried aluminum that are a bit undersized (appear to be about 4/0 or 250 MCM.) The house was set up for 100 amp service but rarely saw anywhere near that as it had propane for heat, hot water, and cooking appliances. Well we upgraded the water heater to a hybrid unit and installed an induction range and electric oven. We also put in a four head mini-split system and charge an EV as our primary vehicle. Suffice to say we are at times pulling significantly more amperage than before. I’ve got a Sense energy monitor and have noticed that fairly regularly we’ll see each leg’s voltage drop down to about 110v from its average of closer to 120v (220v across the legs.) I’ve verified this with a quality Fluke multimeter.

So what to do about this situation?

A) Fixing this by trenching and putting in properly sized new mains is exorbitantly expensive (my electrician estimated it would be north of $100k in copper alone before materials and labor.)

B) I’ve spoken to PG&E and running a new poles and meters would be I think $40k-60k or more though they are cagey on the numbers until after they complete engineering, which requires a few thousand dollar non-refundable deposit.

C) One electrician suggested a step up transformer near the meter and matched step down close to the house. Raising the voltage and thereby lowering the amperage would either require smaller replacement mains or we might be able to get by with our current ones. It looks like the transformers aren’t that expensive (maybe $15k in parts) but there is some inefficiency and ongoing energy loss by using them.

D) Here’s the creative one I’m wondering about. The voltage drop happens due to high amperage going through the mains. So what if I could shave off the peaks in that demand and average the amperage out to a lower level. Looks like the PowerWall 3 handles up to 11.5 kW of discharge so a couple of those could cover my peaks. If the house is drawing those down then my thought is that directly reduces the amperage pulled through the mains. They recharge at about 20-30 amps and so would effectively shave the peak usage and spread it over a longer period of time which would limit the voltage drop. Plus I’d have the benefits of battery storage and time shifting electricity usage, which PG&E seems to be incentivizing with its latest rate structures. And at a price point that would likely be similar to the transformers.

I’m on a 15 acre avocado farm with essentially limitless space for more solar panels (currently I have a dated system from about 20 years ago that outputs a peak 2.5 kW but I plan to add more.)

All thoughts and discussion welcome. Anyone seen a setup like I’m describing work or am I missing something obvious?

Hi all

Odd issue struggling to resolve. Around a week ago I had a new solar system installed adding an additional 11kW system to the existing 3.6. I have 1 Powerwall with x2 expansions for a total of 40kW storage.

Electricity tariff is Octopus cosy with import off peaks at 10p, mid peaks at 28p and peak at 40p. Export is fixed at 12p.

Back-up reserve is at 20% in TBC mode. Export is limited to 6.5kW

What I am finding is that the Powerwall will charge to 100% during the off peak rates, leaving no space for additional solar during the day. In theory the Powerwall should be trying to get most of its charge from the solar instead of the grid.

Instead it fills the battery, and then clips any solar that cannot be exported or used by the house.

While self powered mode could resolve this, it would require monitoring in case I use too much electric and it starts topping up the batterybwith the grid during higher rate slots.

I do make use of Netzero which can automate most of what I need but the TBC mode should be automating this itself I thought.

Any ideas or help at all please?

Sorry for formatting, made on mobile

TLDR - Filling battery to 100% from grid and clipping solar.

Thank you

Thank you! During these 15 minutes the powerwalls did not power the home at all. The home was powered by solar+grid.

Wondering if anyone is on IOG and their powerwall exports battery to the grid before the off-peak period kicks in.

My system only charges from the grid during the off-peak period. I often have about 90% before the off-grid kicks in so plenty to export to the grid. I've had to manually manipulate the tariff to encourage export.

Part of the selling point for a powerwall for me was the AI functionality that handles energy arbitrage.

I live in San Diego county. Our electric rates are ridiculous and I’ve been considering a powerwall for some time now. Trying to make sure my math is mathing and if this would be a worthwhile decision.

For the powerwall itself it seems like the lease option is actually coming up a bit cheaper than the finance option? Is that correct?

Lease
~$100/mo starting payment
3% annual escalator
~$8.6k buyout after year 5
Total paid after 5 years + buyout ≈ ~$15k
Cash/finance
~$16.6k upfront financed/purchased

Current SDGE billing plan TOU-DR1
~Super off peak 39¢/kWh
~Off peak 48¢/kWh
~On peak 70¢/kWh

Ideal plan (EV-TOU5)
~Super off peak 12¢/kWh
~Off peak 51¢/kWh
~On peak 80¢/kWh

Am in the process of purchasing an PHEV to be able to get the EV-TOU5 plan for the lower super off peak pricing. We have central A/C but all our appliances (currently) run off natural gas. I’m thinking a power-wall+expansion pack under lease for 5 years and then buyout at the 5 year mark and eventually converting the water heater and dryer to electric. We currently use around 10-16kWh per day. Sometimes more. Haven’t gotten to experience summer AC costs yet as we just moved into this house this winter.

Just using the powerwall, no expansion pack, say we utilize the entire capacity (13.5kWh) every day by charging at night and utilizing during off peak and on peak. Break even would be around 5-6 years assuming SDGE doesn’t change the super off peak rate drastically. Is this worthwhile ?

Is the installation included with the lease? Does the installer help navigate the HOA / permits? Any other advice or recommendations? Was originally looking at solar + powerwall but it seems like such a waste with NEM 3.0 and this seems like a much better “solution”.

Is Tesla legally allowed to disable a powerwall if they ‘think’ it is not installed by a ‘Tesla’ certified installer?

UPDATE:

NEM 2.0 status will be retained! In writing from Tesla, much more professional and thorough than the previous email. I posted a screenshot of the email in the comments below.

Powerwall+ one unit remotely disabled, both slated to be replaced May 7, these things have been shipped. Yet no one at SCE or Tesla can definitively tell me what is going on.

I’ve looked at having these powerwalls be derated from 11.5 kw output to 5.0 to match the Powerwall+ or disable exporting to grid from Powerwall completely (I use Powerwall for load shifting/high use periods/reserves bc of rolling blackouts in summer / occasional outages, etc)

Generation/battery capacity is identical, if power output on pw3’s match pw+’s this could be a simple warranty replacement like for like swap with an interconnection modification submitted, not a new application.

I just got an email from Tesla and their interconnection department saying I’d lose NEM 2.0 status. Here’s the actual quote, it’s insane.

“Findings-  you will lose the NEM 2 once the Powerwall is replaced from Powerwall + to Powerwall 3.

Resolution-  you can call Edison and ask them to enroll you on NEM 2 again after the new Powerwall 3 is installed. “

Oh yea I’ll just ask them to re enroll in a program that no longer exists, that I was grandfathered into, I’m sure that’ll work.

Tesla’s upper management at the Powerwall support seems to think they can derate and possibly keep my NEM status but whoever is filling out this application over at the interconnection dept (interconnection dept has NO customer facing side, you cannot talk to them directly) has plainly stated they’re gonna fill this out wrong and screw me.

Anybody have any experience here? SCE utility, Tesla directly is the contractor.

(Solar panels and a Powerwall 2.)
I know that if connectivity to Tesla's servers is lost, the PW will carry on working with the current settings; but as I understand it, there would then be limited monitoring and no way to change any settings.

Q1: Is that correct? (Especially regarding changing the settings)

Q2: Has anyone done any work on being able to control the PW without access to Tesla's servers? Aside from the (I hope remote) possibility of Tesla going bust and the servers being shut down, I'm in the UK and rather sensitive to possible trans-Atlantic diplomatic disruption.

I’ve been testing PW3 export behaviour and it appears the decision logic ignores solar generation, instead focusing on whether future import prices are lower than the current export price.

Test setup:

Solar generation continuously >4kW throughout the test
Export price set to £0 for Peak (P) and Super Off Peak (SOP)

Tariffs:
Export: £1/kWh from 11:30–13:00 (MP)
Import: £5/kWh during export window (MP)
Import: £10/kWh from 13:00–18:00 (P)
Import: £0/kWh from 18:00–20:30 (SOP)
Import: £10/kWh from 20:30–24:00 (P)

Observed behaviour:
At 11:45, PW3 decided to export from the battery.

Then I changed only one thing:
Changed 18:00–20:30 import price from £0 (SOP) to £10 (P)

Result:
PW3 almost immediately stopped exporting from the battery and switched to charging instead.

What’s interesting is that solar generation remained >4kW the entire time, so the export decision seems driven by future import pricing ignoring anticipated free solar availability (13:00 onwards).

Additional context:
System has been running Self-Powered for the last 3 days
No grid imports during that period
Battery (PW3+1) was at 100% at the start.
Overnight usage supplied from solar-charged battery

Hi all! As the title says, we are looking for a way to implement solar-only charging for our setup. We understand solar only charging would be available if we had a Tesla EV (controlled from the EV side) but that's not an option at the moment. We are only a few months in, but here is our setup:

Enphase brand inverters/solar system

Tesla Powerwall 3 + gateway

Tesla Wall Universal Wall Connector

Chevy Equinox EV

We have plenty of excess solar and would love to be able to charge the EV with it but not pull from the battery and drain it immediately. We also don't want to pull from the grid during the most expensive time-of-day rate where we live (no net metering here). Unfortunately the Chevy EV app is very limited and useless in this regard. Any suggestions for a solution -- something we already have under our noses but are overlooking, apps that work well to manage, etc? Swapping out the EV charger for one that allows solar only charging could be an option as well, so suggestions there are welcome too.

Just wanted to thank everyone here who responded to my earlier post about my Tesla solar lease buyout situation.

After weeks of no replies and frustration, Tesla finally responded and sent me a formal buyout quote. Your suggestions, encouragement, and shared experiences really helped me stay persistent.

Really appreciate this community taking the time to help a stranger on the internet. Thank you all!

Hello all. I’m looking at getting solar and a battery. I want a Powerwall 3. I was getting quotes a year ago but didn’t do anything at the time. One of the companies contacted me back today and suggested a solis intelihome battery instead of the Powerwall.

I emailed back and said I would like a Powerwall. He seemed quite angry and wanted to know why. He said that there was a firmware update recently and now everyone who has a Powerwall is having problems with it and it won’t charge fully depending on temperature and now they are basically rubbish. He reluctantly gave me a price for one.

Is this a thing with the Powerwall now then? Or is he just talking rubbish and wanting to sell me something else instead?

Thanks

Hi all,

I’m trying to buy out my Tesla solar lease (installed ~2019, now past 5 years), but I’m getting zero response from Tesla.
Sent initial request email

Sent 3 follow-ups

Tried calling — can’t reach anyone

No reply, no acknowledgment, nothing.

Has anyone recently completed a buyout? Any working contact or escalation path?

I’m in California (PG&E area). Really frustrated at this point.

Thanks for any help.

I've got a ~13kW system with a single PowerWall 3 and a Gateway 3. I do not have TOU metering, so I've basically did a "set battery to 80% reserve" and leave the system alone. I'm trying to determine if there would be any value-add to running a network cable to my PW3 and connecting it my home network.

I have toyed with NetZero, but as near as I can tell, unless I'm fine-tuning my system to control TOU, I wouldn't get a lot of value from NetZero.

Am I missing anything? Is there value in setting up the physical connection when I don't have TOU metering?