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Powerwalls + Air Conditioning
- Thread starter cr0ntab
- Start date
Brovane
Member
Sounds like you had the same issue that I had with 2xPowerwall's. Everything appears ok but you cannot draw above 5kw for any length. This indicates a issue with one of the Powerwall's.
I would say going forward for anyone doing 2xPowerwall installs or more that before they sign-off on the install that a test is done to verify that the system can handle doing continuous draws above 5kw.
Do you have anymore info on this? This would be great for my pool here in California
I would request they charge the design to include the AC, especially with 4 Powerwalls.
With Peak rates as high as $0.53 from 4-9 I'm really glad we put the whole house, including AC, behind the Powerwalls. We want all the solar produced during that time to go to the grid, for max net metering credit.
As I type this (5:49pm), I baking dinner in the oven and the AC is running from the Powerwalls, while 2kW of solar goes to the grid
Even if your AC units are on the other side of the gateway you can still run them from the Powerwalls when the grid is up. But if the grid goes down and you are running the house in backup mode they wouldn't be able to run. (At least that is my understanding.)
Really! If it is true, that will be great. Let me check with Tesla.
Can any current PW owner confirm too?
TIA
Can any current PW owner confirm too?
TIA
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The Powerwall runs in one of two modes:
Island mode (the grid is out). Only loads on the Powerwall side of the Backup Gateway can get power. The CTs are not involved in how the Powerwall works in this mode, its inverter just provides a stable reference voltage and provides or accepts power as required to balance the microgrid, instantaneously.
Grid-tie mode. Absent CT info, the Powerwall would never discharge in this mode. With self-powered mode or advanced time control, and CTs monitoring household consumption, the Powerwall can choose to discharge to offset the measured consumption. But this doesn't necessarily happen in instantaneous balance, and it doesn't have to, as the grid is providing the stable voltage reference and will make up or absorb any discrepancy.
So the upshot is that when the grid is up, if the CTs are configured to measure the HVAC usage, or any other load on the grid side of the Backup Gateway, the Powerwall will recognize the consumption and can discharge to offset it if its algorithm decides to do so.
Cheers, Wayne
Island mode (the grid is out). Only loads on the Powerwall side of the Backup Gateway can get power. The CTs are not involved in how the Powerwall works in this mode, its inverter just provides a stable reference voltage and provides or accepts power as required to balance the microgrid, instantaneously.
Grid-tie mode. Absent CT info, the Powerwall would never discharge in this mode. With self-powered mode or advanced time control, and CTs monitoring household consumption, the Powerwall can choose to discharge to offset the measured consumption. But this doesn't necessarily happen in instantaneous balance, and it doesn't have to, as the grid is providing the stable voltage reference and will make up or absorb any discrepancy.
So the upshot is that when the grid is up, if the CTs are configured to measure the HVAC usage, or any other load on the grid side of the Backup Gateway, the Powerwall will recognize the consumption and can discharge to offset it if its algorithm decides to do so.
Cheers, Wayne
Thanks. This is exactly as I planned to use it. I wouldn't want PW2 to backup my AC units in case of power outage but I do want it to discharge when needed during peak hours when the grid is present.
Come to think of it, it does make sense as my solar array is running the AC during the day time even though the AC load is on the other side. Got confused by my installer.
Come to think of it, it does make sense as my solar array is running the AC during the day time even though the AC load is on the other side. Got confused by my installer.
So SCE is doing maintenance in the area today and I took the opportunity to do some more digging on why my setup can't fire up the AC condenser. And I made a little discovery....
The home has 10.89kW DC of solar on a 7.6kW AC inverter.
When the home is off the grid the power walls with adjust the frequency higher when the have a full charge to signal the solar inverter to shut off.
When the power level on the battery drops down, it brings the frequency back in line and the inverter fires up and recharges the battery.
Works quite well actually.
Now, the development is this: I noticed that when the solar was on and charging the battery if I turned on the AC there was enough power available such that the voltage didn't drop and the condenser could fire up.
I'm currently running the AC (and pool actually) off of solar and batteries with no issue, it just needs to be timed.
So this points me in the direction of the power walls being at fault somewhere.
The home has 10.89kW DC of solar on a 7.6kW AC inverter.
When the home is off the grid the power walls with adjust the frequency higher when the have a full charge to signal the solar inverter to shut off.
When the power level on the battery drops down, it brings the frequency back in line and the inverter fires up and recharges the battery.
Works quite well actually.
Now, the development is this: I noticed that when the solar was on and charging the battery if I turned on the AC there was enough power available such that the voltage didn't drop and the condenser could fire up.
I'm currently running the AC (and pool actually) off of solar and batteries with no issue, it just needs to be timed.
So this points me in the direction of the power walls being at fault somewhere.
Attachments
Sounds like the two Powerwalls alone don't have enough surge power capacity (14 kW) to start your AC, but that once you add in 7.6 kW of solar power, you get enough available power to start the AC.
Cheers, Wayne
Cheers, Wayne
Agree'd
What's the best (re: most accurate for a reasonable sum of money) to measure the startup current of the AC?
My cheap clamp on multimeter isn't fast enough, that's what I originally used to measure it.
It should be on the AC nameplate as LRA (locked rotor amps). Very hard to measure without a scope and shunt as it lasts only a few cycles.
I do have the name plate rating, but I also have a soft starter attached to the condenser.
Hyper Engineering | Single Phase
I need to measure ahead of the soft starter to get an accurate reading.
I guess that makes sense in terms of most accurate measurement, I'll borrow a scope and buy a shunt to see what I can measure.
Most of the big name US systems need a lot of amps to start up, but still run at full speed. These multisplit systems, like the Fujistsu in the pic in the thread can start off as low as 5A and then gradually scale up to full speed as needed, and are much more efficient too.
If you want to drive AC from PW's and are doing a new build or replacing AC, take a look at the Mitsubishi, Daikan or Fujitsu gear. A better fit for PW's.
thx
mike
If you want to drive AC from PW's and are doing a new build or replacing AC, take a look at the Mitsubishi, Daikan or Fujitsu gear. A better fit for PW's.
thx
mike
Oh I have looked into it, I got a few quotes to re-do the house with mini splits or a more efficient conventional setup.
The quotes ranged from $18k - $24k not anywhere remotely in the cards right now. Especially considering the current AC setup works great, it just draws a lot of power.
Is it possible that your soft start device is defective or mis-wired? Or under sized?
