Power consumption reporting differs when off grid

[brian954]

So I recently have been doing some off grid tests and noticed something strange.

my house idles at about .3-.5 kWh usage and when my AC kicks on it goes to about 2.9-3.3kwh. If I am in backup mode my max reported power draw is about 1.4kwh. That is with the AC running (and blowing cold). Running nothing but the AC should draw about 2.8kwh so something is going on here. I reported the issue to tesla and they don’t have a solution yet.

I was thinking maybe the c-clamps that measure power are misplaced somewhere?

any ideas?

 

[Davidja92]

Let’s get some more info. How many powerwalls do you have? is your a/c system backed up? and were your solar panels generating any solar?

 

[brian954]

Let’s get some more info. How many powerwalls do you have? is your a/c system backed up? and were your solar panels generating any solar?

I have two powerwalls, and yes my ac system is backed up. The solar panels were generating solar during the tests but intermittently as my powerwalls were full.

 

[Ampster]

Could it be that the solar was providing most of the power for your A/C. How could your PowerWalls be full if you were running a 3 kW load?

 

[Dan123]

So I recently have been doing some off grid tests and noticed something strange.

my house idles at about .3-.5 kWh usage and when my AC kicks on it goes to about 2.9-3.3kwh. If I am in backup mode my max reported power draw is about 1.4kwh. That is with the AC running (and blowing cold). Running nothing but the AC should draw about 2.8kwh so something is going on here. I reported the issue to tesla and they don’t have a solution yet.

I was thinking maybe the c-clamps that measure power are misplaced somewhere?

any ideas?

It is possible that your air-handler was running, and blowing cold air, but your AC compressor was not running. When the powerwall is near full, it increases the frequency, and some AC compressors do not like the increased frequency and shut down.

Without the AC, is your baseload off-grid still 0.3-0.5? Maybe turn off the AC, and run the experiments with your stove or some other appliance, to see if this is related to your AC, or is related to the way your app measures usage.

 

[brian954]

Could it be that the solar was providing most of the power for your A/C. How could your PowerWalls be full if you were running a 3 kW load?

the powerwalls were shutting down solar because the batteries were too full to accept more power.

It is possible that your air-handler was running, and blowing cold air, but your AC compressor was not running. When the powerwall is near full, it increases the frequency, and some AC compressors do not like the increased frequency and shut down.

Without the AC, is your baseload off-grid still 0.3-0.5? Maybe turn off the AC, and run the experiments with your stove or some other appliance, to see if this is related to your AC, or is related to the way your app measures usage.

I’m in south Florida and it was a hot day, my AC doesn’t blow cold without the compressor running. I will need to wait for a full charge and retest to try with some additional known loads to check the power consumption readings.

 

[Dan123]

the powerwalls were shutting down solar because the batteries were too full to accept more power.



I’m in south Florida and it was a hot day, my AC doesn’t blow cold without the compressor running. I will need to wait for a full charge and retest to try with some additional known loads to check the power consumption readings.

Try testing with a charge that is less than 90%.

Also, the AC will blow cold air for several minutes even without the compressor. Maybe you also have a variable speed AC that lowers its speed and consumption.