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Powerwall and high heat!!

holeydonut

Active Member
Supporting Member
Jun 27, 2020
2,381
1,723
East Bay NorCal
I went by my powerwalls and heard a lot of noise. I walk by them and the fans are blowing like crazy. It is at least 108 outside, and will be hotter this weekend.
I hope they do not fail.

You didn’t notice this in the previous heat wave?

Time to install more solar to power these around your batteries.

 

h2ofun

Active Member
Aug 11, 2020
3,108
685
auburn, ca

h2ofun

Active Member
Aug 11, 2020
3,108
685
auburn, ca
Sounds (no pun intended) like the system is doing what is supposed to do to keep the internal temps under control. Running the coolant pumps and using the fans to push air through the radiator. Better some noise than a shutdown powerwall.
Was not saying bad, just saying boy does this heat impact things. I have my garage door stick so I could not open it for a while
 

aesculus

Still Trying to Figure This All Out
May 31, 2015
4,566
2,618
Northern California
I am at the same elevation as Auburn, but just more south. My max temp yesterday was 109F. Noticed the fans were louder than normal but not as crazy as my MX supercharging on a hot day is. :)

I did think my Powerwall drain was higher than I was expecting. Obviously I used much more power during peak than normal and that accounts for most of it. But I suspect the overhead of running the fans more and cooling pumps trying to keep everything under control during times of high load and high temps has it's toll.

Overall I was pretty pleased. With some conservative inside temperature settings and moving my reserve down to 20% I only had to use peak grid power for 20 minutes yesterday. The rest of the time I was giving back (@ 54 cents a kWh). So I gave PG&E 22 kWh during peak and had to take 1 kWh back.
 
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h2ofun

Active Member
Aug 11, 2020
3,108
685
auburn, ca
I am at the same elevation as Auburn, but just more south. My max temp yesterday was 109F. Noticed the fans were louder than normal but not as crazy as my MX supercharging on a hot day is. :)

I did think my Powerwall drain was higher than I was expecting. Obviously I used much more power during peak than normal and that accounts for most of it. But I suspect the overhead of running the fans more and cooling pumps trying to keep everything under control during times of high load and high temps has it's toll.

Overall I was pretty pleased. With some conservative inside temperature settings and moving my reserve down to 20% I only had to use peak grid power for 20 minutes yesterday. The rest of the time I was giving back (@ 54 cents a kWh). So I gave PG&E 22 kWh during peak and had to take 1 kWh back.
And it is going to be hotter today and tomorrow. I will be in Santa Cruz Sunday morning racing. Will be a shocker to leave from the ocean back to the foothills in 110 degree weather.

Luckily I have enough PW's that I am 100% off grid now from 3 to 1am. But the grid kicked back on at 1am since it has learned how the charging goes. Luckily I am still sending back about 100kwh to PGE per day. I see my solar down at least 10% with the heat, and yep, I believe the PW's are not as efficient either. I just keep waiting for the power outages to really smile. :)
 
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Sounds (no pun intended) like the system is doing what is supposed to do to keep the internal temps under control. Running the coolant pumps and using the fans to push air through the radiator. Better some noise than a shutdown powerwall.
First time I actually heard fans from my powerwalls (in garage) few weeks ago I was a bit concerned as @h2ofun since my garage can briefly hit 100 F during 110 F days. Then I relaxed and took @jboy210 mindset … doing what they are supposed to be doing … maybe like me others are sensitive about our “babies” and their welfare 😆
 
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Now I'm curious what these fans sound like. My PW's are indoors and the garage got to 100F. But all I heard was the normal "wum wum wum" sound at 5pm.
i‘m sure acoustics make a diff (outdoors vs enclosed) ..to me they sound like …hmm you know sound of laptop suddenly blowing fan full force when you were not even sure it had a fan … just larger scale ? I dunno I suck at this game 🤣
Can def hear them throughout a 3 car garage as a new sound
 

h2ofun

Active Member
Aug 11, 2020
3,108
685
auburn, ca
i‘m sure acoustics make a diff (outdoors vs enclosed) ..to me they sound like …hmm you know sound of laptop suddenly blowing fan full force when you were not even sure it had a fan … just larger scale ? I dunno I suck at this game 🤣
Can def hear them throughout a 3 car garage as a new sound
I had never heard also. They were on real high speed, where before they were always low speed.
 

SMAlset

Well-Known Member
Mar 4, 2017
9,251
10,125
SF Bay Area
Now you guys have me curious as to the sound of ours during these really hot days. Our PWs are in our double garage on the opposite side of the outer stucco wall which is SW facing — so that wall really heats up in afternoon with little to no shade. Our electrical panels are on that wall (main on outside, whole house loads to two panels inside garage). Our NEMA 14-50 and Tesla charger are located inside the garage near the panels.

We paid extra to run the electrical from there to across garage ceiling to the other side wall (opposite side of interior bedroom btw) so that our 3 PWs, Gateway 2 and Solar Edge inverter could be installed on that wall, thinking cooler location for the electronics. The garage doors in our complex are those rather thin I think aluminum ones, no windows in garage. Wondering if adding garage door foam panel sections to our current garage door would help keep the garage cooler during summer (and warmer during the winter). Any thoughts on that?

Yesterday it got to 102-104 during the afternoon. Had our AC (old 10Seer 5-ton Carrier unit, split for 2-story) set to 76. Fully charged early on and we turned up to 77 around 10-11pm. PWs were at 44% after midnight and with it cooling down outside we opened windows although no real wind last night. Figured with it approaching 100+ after noon today wanted to be fully charged then. Woke to it still at 44%. In case Cal ISO orders cutbacks/blackouts this afternoon-evening want to have sufficient SOC to run some AC in addition to necessary loads which would be minor.

Lots of AC use yesterday:
CBBC4159-5810-4FFB-B1B8-DEDB3F9B8473.jpg
 
@SMAlset, wow, I’ve never seen so much cycling on and off on the a/c. Do you have some super strict tolerance applied to the control?
Mine is similar in hot weather. I think there is a 2 degree difference between it is too hot so turn on the A/C to it is cool enough so turn it off. I've never seen this value to be adjustable in any thermostat.
 
Mine is similar in hot weather. I think there is a 2 degree difference between it is too hot so turn on the A/C to it is cool enough so turn it off. I've never seen this value to be adjustable in any thermostat.
We have an older home automation thermostat that has settings like that, I think. Something like a deadband and some sensitivity settings. I’d be surprised if other higher end thermostats didn’t offer something similar.
 

wwhitney

Active Member
Nov 2, 2017
1,019
1,385
Berkeley, CA
Proper sizing procedure:

Conduct an ACCA Manual J calculation (likely using software) based on detailed information about the building's construction, number and orientation of windows, etc. to determine the cooling load at the 99.5% high outdoor temperature for the target indoor temperature (say 72F). Using that size, the system will run 100% of the time without cycling during those conditions; and 1 or 2 days a year (such as the current heat wave), the temperature will exceed the 99.5% high outdoor temperature, so it won't be able to maintain the 72F target temperature, and the indoor temperature will rise a bit higher while the system runs constantly.

Typical sizing procedure:

- Most houses in this area need about 1 ton per 750 sq ft. This house is 3000 sq ft, so let's put in a 4 ton unit. [Not an awful starting point if the rule of thumb is based on ACCA Manual J calculations, rather than historic oversizing.]

- Last time we put in a system sized by Manual J, the customer complained that when they got back from vacation and it was 85F inside, the system took six hours to cool the house down to 72F, and that was too long. So now we add another 50%.

- Bigger is always better. [Far from true.]

Cheers,
Wayne
 

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