Only during a power outage. He doesn't even need the AC to be a backed up load in order to power with the PWs walls as long as the grid is on.
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Powerwall 2 and Central Air question
- Thread starter jurmanji
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Only during a power outage. He doesn't even need the AC to be a backed up load in order to power with the PWs walls as long as the grid is on.
That's assuming his installer knew to put CT's upstream to meter the non-backup loads.
Out of personal experience, many installers would not do that type of upstream metering because it is a weird concept for them. I wouldn't assume that 100% of homes with partial backup solutions also have powerwalls deploying energy throughout the home when the utility was operational.
Tesla was my installer and they did that for me without asking. How else would you load shift your non backed up loads? That's kind of the entire point. If your installer doesn't install all the required CTs, then the install is incomplete.
No joke, when I was on the phone with Tesla to request the feature that you describe as a no-brainer, they said it couldn't be done.
The guy on the phone said, if the load isn't backed up, it cannot get power from the batteries regardless if the utility was online or not. If you want the battery power to get to the load, it has to be on the backup side no matter what even if the power company was operating as normal.
For proof, here is the first ever post I made here. Back then prior to signing up for TMC, I had been "educated" by like over 5 ESS installers that what Tesla did without you asking was actually impossible or would damage the Powerwalls.
Advice on whether this installation is possible
First time poster here - I'm trying to get new PV and Powerwall partial backup installed in my home in Northern California. If you have a partial backup system, can you help me understand if my goal is possible? My goals for the PV + partial backup: 1) When the Utility is working fine, I...
teslamotorsclub.com
PS, Vines and wwhitney is amazeballs. If they weren't on this forum, I guarantee you I'd have a partial home backup solution right now with only like 5 loads getting energy from my Powerwalls during peak time (even when the utility was operational).
No joke, when I was on the phone with Tesla to request the feature that you describe as a no-brainer, they said it couldn't be done.
The guy on the phone said, if the load isn't backed up, it cannot get power from the batteries regardless if the utility was online or not. If you want the battery power to get to the load, it has to be on the backup side no matter what even if the power company was operating as normal.
For proof, here is the first ever post I made here. Back then prior to signing up for TMC, I had been "educated" by like over 5 ESS installers that what Tesla did without you asking was actually impossible or would damage the Powerwalls.
Advice on whether this installation is possible
First time poster here - I'm trying to get new PV and Powerwall partial backup installed in my home in Northern California. If you have a partial backup system, can you help me understand if my goal is possible? My goals for the PV + partial backup: 1) When the Utility is working fine, I...
PS, Vines and wwhitney is amazeballs. If they weren't on this forum, I guarantee you I'd have a partial home backup solution right now with only like 5 loads getting energy from my Powerwalls during peak time (even when the utility was operational).
That's just WOW!
BTW, it doesn't escape me that you could take that Neurio that is installed in the upstream main panel which talks to the TEG wirelessly and move it somewhere else and feed it a fake signal to trick the powerwalls into dumping to the grid at peak time.
You are a magnet for bad replies from solar people. My Tesla install with two PWs has an unbacked up A/C compressor plus two other circuits that I stupidly said they they didn't need to move to the new backed-up panel. The CTs there were installed had issues, but after two service calls I finally got the configuration straightened out so that the unbacked up loads are reported in the Tesla app and the PWs feed power to them when needed.
The last service tech couldn't quite get it right when comparing the load in the house to the smartmeter reading, so when the A/C kicks in and is drawing 6-7kW about 0.3kW is being fed back to the grid. It is negligible amount that you might see in a 5 minute reading, but that export will be unnoticeable in a 1 hour reading. If there was a grid outage and the TEG isolates the house then nothing will go to my unbacked up loads or the grid.
Yeah what you're describing was the exact thing I wanted when I went out for bids in early 2020. I gave people that PRD of what happens when the utility was online and when the utility was offline. 5 separate installers told me I was insane and barking up the wrong tree. They were either selling me 1 Powerwall that was backing up 4/5 critical loads (no upstream metering), or selling me a whole home backup (Tesla wouldn't do partial home due to my MSP). I was getting so frustrated; so glad I found TMC.
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Yeah, there's a thread on TMC where someone was going to rig up a CT to read a home load "incorrectly". Like put it on a 10w LED light bulb circuit or something. Then spoof the CT into reading that load to be like 600x more than it really is. So that 10w becomes a 6000w reading, and the Powerwalls try to push out 25A to fill that booger with energy.
I guess he'd have to find a way to smooth out the CT reading... so it doesn't spike all over and confuse the PWs hah. Either way it's too much effort for me lol.
I'm just hoping Elon releases some code so that if I see tomorrow is a cloudy day on the forecast, I can off-peak charge my Powerwalls between midnight and 6am to get some energy ready for the following day's peak time even though I wouldn't get much solar.
Hi, just found out that the Powerwall 2s have a update going to them to boost power to 7.5kw. So that should handle the A/C start up without any issue. I have 2 PW and have the whole house except for my stove, microwave, washer & dryer on the solar system. So if my grid goes down, only way to know is the stove won't work.
breakers don't immediately trip from a momentary excursion above their nominal amperage. As long as the inverter can support the surge, it would work fine.
We have 2 Powerwalls which back up 10 circuits in our home, excluding the 3.5ton Ruud package a/c unit.
Each day, the batteries will run the entire home, including the a/c, between 4-9pm.
On really hot 100 degree days, the batteries might get down to 40% remaining with the thermostat set at 78. Most days, with the a/c running between 1pm and 10pm at 76-78, they will deplete to between 50-60% remaining.
I installed a $300 soft start on the a/c myself (it is very easy and most definitely not rocket science) but the batteries were handling the a/c without it quite well without tripping any breakers.
Each day, the batteries will run the entire home, including the a/c, between 4-9pm.
On really hot 100 degree days, the batteries might get down to 40% remaining with the thermostat set at 78. Most days, with the a/c running between 1pm and 10pm at 76-78, they will deplete to between 50-60% remaining.
I installed a $300 soft start on the a/c myself (it is very easy and most definitely not rocket science) but the batteries were handling the a/c without it quite well without tripping any breakers.
I'm an HVAC contractor and M3 driver - I regret the confusion in our industry between hard start and soft start kit accessories.
To anyone considering trying to operate a whole house HVAC system with an off-grid / grid down electrical backup system I strongly recommend looking into a true variable capacity heat pump / AC system such as Trane XV, Carrier Greenspeed or Lennox XP25. Those systems use inverters / DC drives for their compressors and thus totally bypass the notorious inrush / Locked Rotor Amp draw of conventional compressors that is so hostile to non-grid electric systems.
Soft start kits can help, purportedly reducing inrush by 65% to conventional systems, but I'm willing to bet that 95-99% of HVAC contractors haven't the foggiest notion as to how soft starts work and how they are different from hard start kits.
To anyone considering trying to operate a whole house HVAC system with an off-grid / grid down electrical backup system I strongly recommend looking into a true variable capacity heat pump / AC system such as Trane XV, Carrier Greenspeed or Lennox XP25. Those systems use inverters / DC drives for their compressors and thus totally bypass the notorious inrush / Locked Rotor Amp draw of conventional compressors that is so hostile to non-grid electric systems.
Soft start kits can help, purportedly reducing inrush by 65% to conventional systems, but I'm willing to bet that 95-99% of HVAC contractors haven't the foggiest notion as to how soft starts work and how they are different from hard start kits.
RKCRLR
Active Member
I have a Carrier Infinity system with a 2 stage reverse run Bristol compressor. The Hyper Engineering soft start is not compatible with reverse run compressors. Are you aware of any soft start devices that will work with a reverse run compressor? My understanding is the reverse run confuses the learning microprocessor controlled soft start devices. It seems like a standard soft start switch that requires manually setting the start ramp would work.
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