Overnight air conditioning on PowerWall

Since I got the PowerWall installed, I've used essentially no energy from the grid; I've only sold energy to my utility.  I've been dreading the time when I don't feel comfortable at night without air conditioning.   Thursday night, 5/23/19, was a bit uncomfortable with a low of about 78 deg.  So, I left the air conditioner on last night, 5/24/19.  It wasn't a good test because the low was about 76 deg.

The result: about 7:30 am I'm producing over 1kw.  The air conditioner pulls a peak of about 1300 watts but relatively briefly.  Average is 300-800 watts.  So, the PowerWall has hit it's minimum.  That is 12%.  The PW will revert to grid power at 10% in order to leave a little energy for a real power failure.  So, a near thing.  Especially for a not very demanding night.

It is silly for me to worry about pulling a little grid energy.  My cost would be around $.10 per kwh used.  For an hour or two in the early morning hours, that cost would likely be $.05 to $.15.  Insuring remaining off the grid would require a second PW battery.  Cost, around $8k.

I can continue to make the claim of having used no grid energy since the PowerWall install.  Let me look that date up.....1/26/19.
 https://wmckemie.blogspot.com/2019/01/powerwall-install.html
Four months tomorrow!  I may continue to forgo night time air conditioning for a while.  Though I'm sure now that a hot night will exhaust the PW battery.

I finish writing this about 7:50 and the PW is charging at a few hundred watts whenever the air conditioner is cycled off.  Charge level remains at 12%.  This is a cloudy morning, so far.  12 hour overnight air conditioner consumption was 3.91kwh.  The first hour consumed .62kwh due to the warmer conditions.

Sunday, 5/26/19
It looks like we are in for a string of mid 70s nights so I have suspended overnight air conditioning experiments.

Sunday, 6/9/19
I just went through the first night with air conditioning running all night.  My minimum charge level was about 13%.  I'll probably start running the air conditioner around the clock.

Saturday, 6/22/19
I've been through several nights running the air conditioner.  I've come close to hitting the reserve threshold of 3%; the lowest has been 6%, I believe.  Once the threshold is hit, grid power is used.  So, I have so far avoided using grid power even using overnight air conditioning.

I decided to buy a 6k btu window unit for the bedroom so I could avoid running the big unit overnight.  Last night was the first using only the small new unit.  The PW got down to 30% just before morning production  began.  So, a success!  This gives me confidence that I can sleep comfortably during a long term grid down situation.  A major step!



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