Told by Tesla I can't run AC on Powerwalls

[d21mike]

They did for mind in late 2019. However, they were having troubles getting it working and after the third guy came out he fixed it quickly. Something about reversed wiring by the other installer but I am not sure.

 

[SMAlset]

Tesla supplied ours, but the installed gave us a warning that they do not work with all AC units. Ours was within the unit's capacity, but just barely. We have tried it once, and it did start. However, the drain on the PWs was large. Made me wish I bought 3 Powerwalls instead of 2.

Given how power hungry AC units can be, while waiting for our install I became concerned about not having enough battery power to last for a prolonged several day outage if temps were high and I wanted to run the AC (we can be in the 100+ range and for a week or so as experienced recently). Increased our order from 2 to 3 a few months back. Also wanted our system to support our old AC unit with the high LRA.

Have to say these current wildfires during high temps have given pause that while you think your system will easily charge the next morning/afternoon to provide a fresh charge for AC use the next day, the smoke clouds have made a serious dent in people’s recharging of their systems. The last few years we have lived with setting our AC to a higher temp so as to reduce our bill, but when smoke levels stay at unhealthy levels for many days and it’s hot, you really do want to have AC on and windows closed. Something to consider depending on locale. However I suppose you could just as easily have a slow moving hurricane/storm affect your next day charging ability even if wildfire concerns aren’t likely where you live. Having lived back east high temps and humidity can be equally oppressive.

If battery backup is a concern, I’d recommend adding as many PWs as you can justify. It will help get you more comfortably through outages while enabling you to live more off the grid the rest of the year.

 

[BGbreeder]

Given how power hungry AC units can be, while waiting for our install I became concerned about not having enough battery power to last for a prolonged several day outage if temps were high and I wanted to run the AC (we can be in the 100+ range and for a week or so as experienced recently). Increased our order from 2 to 3 a few months back. Also wanted our system to support our old AC unit with the high LRA.

Have to say these current wildfires during high temps have given pause that while you think your system will easily charge the next morning/afternoon to provide a fresh charge for AC use the next day, the smoke clouds have made a serious dent in people’s recharging of their systems. The last few years we have lived with setting our AC to a higher temp so as to reduce our bill, but when smoke levels stay at unhealthy levels for many days and it’s hot, you really do want to have AC on and windows closed. Something to consider depending on locale. However I suppose you could just as easily have a slow moving hurricane/storm affect your next day charging ability even if wildfire concerns aren’t likely where you live. Having lived back east high temps and humidity can be equally oppressive.

If battery backup is a concern, I’d recommend adding as many PWs as you can justify. It will help get you more comfortably through outages while enabling you to live more off the grid the rest of the year.

I agree. Thanks for all your informative posts by the way.

The fires and smoke did cause me to think through what we needed, and ended up reinforcing my belief that generators were a necessary part of the solution. I just wish that there was a way to use a generator to top up powerwalls during adverse events.(Smoke/ash/extended cloud cover/winter insolation)

All the best,

BG

 

[Vines]

I agree. Thanks for all your informative posts by the way.

The fires and smoke did cause me to think through what we needed, and ended up reinforcing my belief that generators were a necessary part of the solution. I just wish that there was a way to use a generator to top up powerwalls during adverse events.(Smoke/ash/extended cloud cover/winter insolation)

All the best,

BG

I think this is enough of an edge case, that I am not sure Tesla is really looking deep into it.

Assuming you have a proper main lockout circuit per code you could hack together a high quality inverter/generator to pretend to be a PV source, assuming it had designated "PV meters" on the generator feed. I know others are working on a DIY solution to this same problem. Biggest issue would be when the PW started getting to capacity, if the generator was still backfeeding then I do not know how the generator or powerwall would respond to the frequency shifting.

Tesla doesn't want you to do that, and it and would likely void warranty.

Really they need a hardware box that is essentially a TEG monitored 2 position transfer switch with interlock. When the switch is set to grid, all 1941 standards and safeguards are in place so backfeed to grid is controlled. Minor short term disturbances would only trigger the automatic disconnect inside the TEG. The generator circuit remains open.

For a long term outage, the switch is set to generator and the circuit closes to an ICE source, the TEG switches to off grid settings, and uses the generator exactly as an off grid setup would work. This allows the wider voltage and frequency ranges of a generator to still work to charge the Powerwalls. The TEG will not close its contractors again until it knows the generator ones are open, and 1741 grid safeguards are back in place.

Fingers crossed this is something that Tesla also realizes is worthwhile to implement.

 

[cridinger82]

would be nice to have that type of hardware in place, even for people during say a hurricane where you could roll out say a 12k portable generator and plug it into a rv style plug, and that could be used in case pv wasn't providing enough juice and the soc of the powerwalls fell to a certain state, the generator rolled out plugged in and used... i really dont have space to invest in a whole house genny and tank.

 

[BGbreeder]

Great idea. I would install it in a heart beat.

All the best,

BG

 

[jboy210]

Given how power hungry AC units can be, while waiting for our install I became concerned about not having enough battery power to last for a prolonged several day outage if temps were high and I wanted to run the AC (we can be in the 100+ range and for a week or so as experienced recently). Increased our order from 2 to 3 a few months back. Also wanted our system to support our old AC unit with the high LRA.

Have to say these current wildfires during high temps have given pause that while you think your system will easily charge the next morning/afternoon to provide a fresh charge for AC use the next day, the smoke clouds have made a serious dent in people’s recharging of their systems. The last few years we have lived with setting our AC to a higher temp so as to reduce our bill, but when smoke levels stay at unhealthy levels for many days and it’s hot, you really do want to have AC on and windows closed. Something to consider depending on locale. However I suppose you could just as easily have a slow moving hurricane/storm affect your next day charging ability even if wildfire concerns aren’t likely where you live. Having lived back east high temps and humidity can be equally oppressive.

If battery backup is a concern, I’d recommend adding as many PWs as you can justify. It will help get you more comfortably through outages while enabling you to live more off the grid the rest of the year.

I am in the Tri-Valley area, so we use a bit of A/C. The one good thing about the fires is they turned on StormWatch for a few really bad periods. This let me use the app to enable or disable PowerWall charging from the grid by toggling on and off StormWatch. I did this in the mornings on the bad days. I also, set the A/C low in the morning to cool the house, and let the grid charge the powerwalls and run the A/C. Then in the late afternoon, I turned off Power Watch, and A/C, and coasted through the peak evening periods using only the Powerwalls. I after 10 PM or so I enabled Stormwatch and let the Powerwalls get filled and A/C run from grid power.

 

[zƬesla]

@jboy210 – if StormWatch is on for your area and you have it off in the app, how long does it take to start charging from the grid once you enable it in the app?

 

[miimura]

@jboy210 – if StormWatch is on for your area and you have it off in the app, how long does it take to start charging from the grid once you enable it in the app?

In my experience it has been between 5 seconds and one minute. I manually turned it on during SW events 6 or 7 times in the last month.

 

[jboy210]

In my experience it has been between 5 seconds and one minute. I manually turned it on during SW events 6 or 7 times in the last month.

That was also my experience. It was a few minutes max.

 

[charlesj]

...

Examples of just how badly we've been robbed:

1. Submitted and city-approved building plans called for 8 tons of cooling capacity. They installed 6 tons. (We actually have it better than some; a neighbor's city-approved plans require 9 tons; she also got 6 tons.)

2. Swapped the locations of the air handlers--5-ton unit where the 3-ton is supposed to be, and vice-versa. (But they actually installed 4- and 2-ton units. Perhaps the HVAC installer had a boat payment coming due?)

3. Ducting plans: thrown out the window. With the swap of the air handlers, the Manual D Ducting Plan they submitted for approval was ignored; they seemingly made up the ducting plan up as they went along, or so it appears. And there are missing returns and registers as well.

4. Furnace constantly "short cycles" since it has far too little airflow; safety overheat system kicks it off-line as temps exceed 160F just aft of the plenum . . .

5. Is anyone surprised that the HVAC systems can't cool the home properly? Yes! The builder (and HVAC contractor, both scum) report that it's our fault we have all these issues. They're all due to the Nest Thermostats we installed(!) and because of our insufficient window coverings and lack of furniture! (The home remains vacant because it's uninhabitable: too friggin' hot, and it turns out the trusses are "fake" as what's installed doesn't match the PE-stamped paperwork Oooops. The City of Phoenix is on a recorded telcon advising that the "home should never have passed inspection." So it also has a fraudulent Cert of Occupancy, but they won't help us in any way. Nor will they visit any other home in the neighborhood to inspect theirs now either, despite promising to do so.)

It's been an ongoing 3-year nightmare with an expensive, brand new home, but we've had verbal estimates of some $40k to rip out these incorrect systems and install the proper equipment. If we have to do that, we may as well get units that will work with Powerwalls . . . .

Long Story Complete.

I know this was a month ago but just been reading your story. Is the A/C contractor and builder still in business? If they did other houses in your neighborhood, have you thought of getting together a group and do a class action law suit against the city and the builder.
This is criminal in reality.