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Told by Tesla I can't run AC on Powerwalls
- Thread starter stevemc
- Start date
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- air conditioner Powerwall
We just had out roof and PWs installed. Tesla also installed a soft-start.
Come to think of it I did not test to see if the A/C still works. Guess I should do that!
After the system has been installed, strongly recommend doing an off-grid/full load test:
- Charge the PowerWall(s) to 100%
- Under full sun (with solar power being generated), disconnect the grid power (which may be as easy as throwing the breaker inside the Tesla Gateway panel)
- Using the Tesla app, verify you are off grid, power coming from the PowerWalls and solar power has been shut off
- Verify devices inside the house are working, particularly UPS boxes
- If UPS boxes aren't working, it's likely your solar cutoff frequency is too high (default is 65%) and will require Tesla to lower to 63Hz or below
- Turn on all major devices that would typically be running when you're away from home (air conditioners, pool pumps, ...) and verify they all work
- If air conditioners don't come on, you'll likely need a soft start upgrade to the outside HVAC equipment to eliminate the power surge when the compressors start up
- If your PowerWalls don't have enough power to cover equipment that would likely be running when you are away from home, you may want to look at options to prevent that from happening
- Not as concerned about heavy power usage when we're at home (such as running electric ovens) - since we can manually turn those devices off during a power outage
- When PowerWall charge level drops below 95%, within a few minutes, the solar power should turn back on, powering the house and recharging the PowerWall(s)
- Turn the grid power back on. It will take a few minutes before the Gateway will switch back to grid power, and resume normal operation.
Our smaller HVAC system uses around 2 KW when running; the two larger systems use around 4KW. Now that we have the hard start upgrades to eliminate the surge when starting the A/C, in theory we'd be able to operate any of these systems off a single PowerWall (though with a single PowerWall, you'd be limited in what else might be running, since it can only provide 5KW of continuous power).
With 4 PowerWalls, we've verified we can run all 3 air conditioners and our pool pumps plus what we would typically be using inside the house. Our electric ovens appear to use 4-5 KW each when they are heating up, so we would likely avoid using those if we are off-grid.
With 4 PowerWalls, we've verified we can run all 3 air conditioners and our pool pumps plus what we would typically be using inside the house. Our electric ovens appear to use 4-5 KW each when they are heating up, so we would likely avoid using those if we are off-grid.
Comment #43 by bob_p is very good. I'd add that you should try the same thing at night, when there's no solar power. I did the bob_p test and things worked. Then I did a similar test at night and found that my larger A/C unit would not start properly. It seems that my two PW's plus solar were enough to start the A/C, but the PW's alone couldn't do it properly -- they needed the extra boost from solar, which is roughly equivalent to having a 3rd PW in terms of kw output. I'm going to get a soft start to fix that, but this was the first indication I'd need one.
If you run the off-grid test during the day with the PowerWalls fully charged, the Tesla Gateway will set the powerline frequency high to turn off solar power - which would be the same as doing a nighttime test (without any sun).
And if the PowerWalls aren't fully charged, if your system has breakers for the solar panels, you can throw those breakers to disconnect the solar panels from the rest of the system to ensure the off-grid test is relying 100% on PowerWall power.
And if the PowerWalls aren't fully charged, if your system has breakers for the solar panels, you can throw those breakers to disconnect the solar panels from the rest of the system to ensure the off-grid test is relying 100% on PowerWall power.
Good point. I did my testing with PW's around 90%, so I was getting solar. With full PW's, the 65hz output told my a/c compressor to shut off, so I couldn't test that way. I've since had it dropped to 62hz, so I'll try again. Good idea.
Part of the reason for purchasing our system was to operate off grid after a hurricane. Doing the off-grid testing now ensures that should we ever have an actual emergency, we won't have problems with the system.
And since the system was installed, we've had several short periods when we lost grid power, and other than a brief flicker of the lights, we haven't noticed any differences inside the house - everything (electronics, HVAC, ...) has kept running until the grid came back on.
And since the system was installed, we've had several short periods when we lost grid power, and other than a brief flicker of the lights, we haven't noticed any differences inside the house - everything (electronics, HVAC, ...) has kept running until the grid came back on.
Dukeybootie
Member
@bob_p
Post #43 is an excellent summary and should be its own sticky on this forum page. Can't emphasize it enough. Thank you!
As a side note, my Powerwall installer (LA Solar Group) did their best to install a SureStart on my HVAC as well. It worked initially but ended up crippling the compressor to the point of being nonfunctional later on. I called my HVAC service folks and everything worked fine once the SureStart was removed. They ended up installing their own device (which they called a "hard start"...go figure) and now everything works as intended.
Post #43 is an excellent summary and should be its own sticky on this forum page. Can't emphasize it enough. Thank you!
As a side note, my Powerwall installer (LA Solar Group) did their best to install a SureStart on my HVAC as well. It worked initially but ended up crippling the compressor to the point of being nonfunctional later on. I called my HVAC service folks and everything worked fine once the SureStart was removed. They ended up installing their own device (which they called a "hard start"...go figure) and now everything works as intended.
Chancellor32
Member
Dukeybootie
Member
Very unlikely. Every mini-split I've seen uses variable drive that has very low LRA.
