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2xPowerwall whole house backup - HVAC sure start problem
- Thread starter af88
- Start date
I have 3 powerwall 2s and when my AC tries to turn on while the grid is out the powerwalls will shut off and the power goes out. The AC continues to try and start but can’t. Lights flicker on and off. I’m afraid this will damage something if im not home and the powerwalls are on. I was told 3 powerwalls were enough for my AC but I guess not.
I tried a soft starter and that worked for about a year but now the soft starter stopped working. Should I just get a hard start kit? I don’t want to get another powerwall. My other idea was to have the AC bypass the powerwalls and just have it directly connected to the grid but then I can’t run it when theres and outtage.
It’s hard to find any AC specialist that are familiar with this. None of them seem to want to install these soft starters.
I tried a soft starter and that worked for about a year but now the soft starter stopped working. Should I just get a hard start kit? I don’t want to get another powerwall. My other idea was to have the AC bypass the powerwalls and just have it directly connected to the grid but then I can’t run it when theres and outtage.
It’s hard to find any AC specialist that are familiar with this. None of them seem to want to install these soft starters.
Wow 3 PW and it can't support it. The funny thing is the solar company used a Tesla calculator which showed only 2 PW was enough to run the AC. Clearly that calculator is missing a lot of info about the type of compressor but as a consumer when I ask for whole house and AC and they tell me 2 PW will support it and it doesn't it makes for an awkward conversation to follow.
If the sure start quit working whats to say the next one won't suffer the same fate. In my opinion these companies including Tesla need to be clear about adding an AC compressor and proving more details on the specs to make it work. The only reason i got the PW is to have backup power for the house in the hot summers to have the AC working. This is less than ideal if it does not work.
With regards to AC specialists, I called 24 different HVAC specialist and only a handful had heard of a sure start and most were not familiar with adding Tesla and off grid setup. This is fairly new so i wouldn't expect to find many experts if any at all. It is bad enough the solar companies don't know enough about it where they are miss-wiring sure starts and causing damage but to get it working alone is another problem
If the sure start quit working whats to say the next one won't suffer the same fate. In my opinion these companies including Tesla need to be clear about adding an AC compressor and proving more details on the specs to make it work. The only reason i got the PW is to have backup power for the house in the hot summers to have the AC working. This is less than ideal if it does not work.
With regards to AC specialists, I called 24 different HVAC specialist and only a handful had heard of a sure start and most were not familiar with adding Tesla and off grid setup. This is fairly new so i wouldn't expect to find many experts if any at all. It is bad enough the solar companies don't know enough about it where they are miss-wiring sure starts and causing damage but to get it working alone is another problem
One route is to have the HVAC people add a 24V transformer to the grid side of the gateway and you that as a secondary enable for the AC units. Existing 24 control signal enables a relay that then connects the new grid based 24V to the AC control lines.
Large home with 3 HVAC systems. For the off grid stress test, I disconnected the grid. At the time, there was heavy cloud cover so no power from the solar panels - only from the PowerWalls - and then proceeded to set the thermostats on each HVAC system to 65 and confirmed all 3 of the units started running air conditioning.
4 PowerWalls may provide enough power to handle the surge from one compressor. Though if we were unlucky and more than one tried to start at exactly the same time, we might have problems. I will likely do another round of off grid tests next week, and more methodically validate startup and operation of the compressors.
We've had PTO for 10 days now, so we're still getting used to the system. And haven't lost grid power - yet...
How would that help with easing the inrush current on the batteries?
I'm wondering if it is worth it to try a sure start and make sure it is wired correctly as the Hard start kit made by Carrier didn't do it's job clearly and no specs what so ever are posted about it even from the mfg. At least with the surestart it gives you all the specs and says it reduces the LRA by 60%. Waiting to see what the solar company wants to do. They were supposed to contact Tesla to get some feedback.
The relay wouldn't help with inrush, but would allow you to disable the AC units without moving them to a non backed up panel.
Oh this sounds pretty good!
Okay so I could keep the AC unit in the main panel and also have another panel too? So I could have the breakers off on the main panel at all times in case the power goes out? But the second panel could be on all the time to run only when the grid is working?
One issue is my outdoor AC unit is pretty far from where the meter and the powerwall gateway is. It’s pretty much the complete other side of the house. Do you think they would be able to run a line that far? My main breaker is in the middle inside of the house away from the gateway and powerwalls.
Having a backed up panel and a non backed up panel is a common setup.
And anything is connectable if you write the request on the back of a large enough check
Using a 24V transformer on the grid side as an enable removes the need to extend the power lines all the way to the non backed up panel.
aesculus
Still Trying to Figure This All Out
I have the same issue. Two heat pumps would bury my two PWs in most scenarios. The HPs are three panels deep and about 200 feet away from the PWs and backup panel so they are always on. Also no way to run any control wires to the thermostats or heat pumps.
The Tesla installers told me that if they kicked on when in backup mode they would probably (certainly?) trip off the PWs. They would then wait a bit and attempt again. This would go on forever until I shut the HPs off (either via the breakers or turning off the thermostats).
So I am now looking into a way to monitor the grid state (via the PW API?) and sending a signal to a custom relay in the path of the thermostat On state. Still a work in progress. If this works then I won't have to worry about the conflict between the units, especially if I am not at home to deal with it. (Note some of this could be circumvented with network connected thermostats in theory but I am not excited about inviting any cloud based environmental control solution into my home).
All you have to do is put a relay in the wire that calls for cooling (or heating in the case of a heat pump) to the outdoor unit. I believe in the case of A/C it's usually a yellow wire. If you interrupt that, the air handler will run but the compressor will never start. This is the only smart thing that the old Generac load shedding devices do, interrupt the yellow wire to avoid A/C compressor loads.
This sounds perfect!
How does the relay know that they power is out and the Powerwalls are on? Do you know where I can get this relay from?
If you have a non-backed up panel, you can connect a 24V transformer to it (or even power the relay directly). Digikey would have any relay you needed.
It would be nice if the gateway had a direct signal, but I do not know if that exists.
aesculus
Still Trying to Figure This All Out
This is a great suggestion if you have the ability to drag wires.
I need to find a wireless way to do this as I cannot run wires from the non backed up panel to the heat pumps.
Looking for any suggestions.
Something like this:
iO HVAC Controls
might work for you.
Basically, set up the transmitter with the grid side 24V input. Use the receiver to enable the cooling control line.
aesculus
Still Trying to Figure This All Out
Wow. This may be exactly what I need. I will review and post my thoughts later.
One thing that did scare me was the range is only 100 feet which I am a bit over perhaps. But it you select wireless you see they have another longe range model.
iO HVAC Controls
Quick search of costs are about $160 for the regular and about $350 for the extended. I think these are for pairs but not 100% sure yet as I don't see the ability to order just the Tx or Rx modules.
EDIT: Update.These are much more complex than what I initially thought. These seem to relay the entire cable vs just one lead. Kind of like a cableless HVAC control system.
Still might work but well beyond just toggling the On lead (yellow).
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Yeah, the intended use is overkill for this application, but you can use it as a dumb signal extender.
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