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Powerwall in Texas Storm

jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
6,497
4,447
Northern California
A better test might be to see how Powerwalls are performing in the NorthEast or Colorado. Also, mounting inside or at least in a garage can make a difference. The Texas event was not nearly as extreme as conditions further north. My daughter says it is 70 at their place in Austin today and getting even hotter the rest of the week.
 

bob_p

Active Member
Apr 5, 2012
3,738
2,947
In Houston, while the storm conditions weren't as bad as locations north of us - the area isn't prepared to handle freezing temperatures for several days or temperatures dropping to around 10 degrees overnight.

Everything is designed primarily for warm weather - not as well protected from freezing temperatures - especially if the temperatures don't go above freezing during the day.

When planning for our 15.4KW solar/4 PowerWall system - planning was focused on operation after a hurricane, when temperatures are warm and it's likely we'll get a lot of sun after the storm passes.

Preparing for a winter storm is different - less or no sun for days - need to run heat periodically - and to keep the pool lines and pumps for freezing.

At least we had our PowerWalls installed inside our garage - so they weren't exposed to the very cold temperatures. And we had enough time before we did lose power (for only a few hours) to prepare to reduce power consumption drastically, just in case the outage lasted days (many people lost power for more than 3 days).

A week ago, we were recovering from overnight temperatures around 10. This week - highs are back in the 70's...
 

brkaus

Well-Known Member
Jul 8, 2014
8,503
7,130
Austin, TX
A better test might be to see how Powerwalls are performing in the NorthEast or Colorado. Also, mounting inside or at least in a garage can make a difference. The Texas event was not nearly as extreme as conditions further north. My daughter says it is 70 at their place in Austin today and getting even hotter the rest of the week.

One difference is Texas isn’t built for cold. We use way more energy than a Colorado house on a 5 degree day. Our house couldn’t even maintain 62 with heat running non-stop. It got worse as the week progressed and the exposed slab cooled.

But yes, there are likely more learnings available from colder climates on PW operation.
 
on the coldest night, when temps outside were near 0F, my garage was in the low 30s. I have 2 PWs in my garage, and I noticed them pulling some grid power even when they were supposedly at 100% from storm watch. I assume this was some kind of preconditioning or heating. The app SOC never showed less than 100% so I can’t be sure of any loss due to the cold. Also never lost grid so can’t comment on their performance during the low temps.
 

MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,546
10,569
Colorado
A better test might be to see how Powerwalls are performing in the NorthEast or Colorado. Also, mounting inside or at least in a garage can make a difference. The Texas event was not nearly as extreme as conditions further north. My daughter says it is 70 at their place in Austin today and getting even hotter the rest of the week.
Our Powerwalls in Colorado have gotten us through several unplanned multi-day outages over the past 2 years. During the first multi-day outage, our Powerwalls got down to 5% and shut-down. While it was sunny out on the second day of the outage, the Powerwalls kept raising the frequency which kept causing the solar to turn off. Tesla has made several software updates since then and also adjusted our inverters so we shouldn't have that problem again. Tesla posted this which has some useful information: Best Practices During Power Outages | Tesla Support

Last year, Tesla released the feature to slow or stop vehicle charging during outages. This is a great new feature and can help prevent your Powerwalls from being drained if your cars are charging and the grid goes down. During a second multi-day grid outage last year, we had absolutely no problems and everything ran as expected, including the reduced amps for car charging.

We did 8 days off-grid test with our solar and Powerwalls in 2019. We even had a good snow storm but everything worked fine. I do use a snow rake to clear a few panels. Usually I clear off about 14 of our 63 panels. If I have more time or some help, I can clear off 23 or even 35 of our panels. We're looking into possibly adding some heating tape to help clear the snow off the less-accessible panels that are higher up.

 

jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
6,497
4,447
Northern California
One difference is Texas isn’t built for cold. We use way more energy than a Colorado house on a 5 degree day. Our house couldn’t even maintain 62 with heat running non-stop. It got worse as the week progressed and the exposed slab cooled.

But yes, there are likely more learnings available from colder climates on PW operation.
Strange the houses and systems do so poorly. Where I am in Northern California (SF East Bay Valley) it does not get that cold, maybe 30 and gets up to 105 a few days a year. But, we usually do not run the heat more than a few hours a day and A/C no more than 1/2 the hottest summer day. We have forced air gas heating which keeps us nice and toasty. Also, we have been adding insulation as we remodel and tear open walls. We are on a concrete slab.
 
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bob_p

Active Member
Apr 5, 2012
3,738
2,947
When we purchased our custom home, we committed to the purchase while it was still in frame, with no interior walls.

Our builder gave us the option to get sprayed foam insulation in the exterior walls and the underside of the roof - something we hadn't considered - and we are so glad that we purchased that upgrade. The foam seals almost all of the air gaps - and insulates much better than normal insulation. When the exterior temperatures are very high (100's) or very low (below freezing), the inside of the house, including the attic stays close to 70-80 degrees throughout the house. Even our garage where the PowerWalls are located didn't get that cold during the freeze this year.

For anyone planning to build a home, based on our experience, we'd strongly recommend going with sprayed foam insulation - plus solar panels and battery storage...
 

jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
6,497
4,447
Northern California
Just heard from family in Austin. Apparently, it is starting to get cold already. I hope they do not have a repeat of the snow event from last winter.

I was there in Spring, and as @garrett5688 says these homes are not built for the cold. I was in the attic checking the A/C drainage and could see the outside at the ends of the eaves. And not just through some wired attic vent. But rather from a 5 foot by 1-foot gap in installing the facia boards. This is for a 10-year old house in an upper end subdivision.
 

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