Help with understanding PowerWall 2 available energy hours ?

[P@dge]

I am totally with you on this one. And if these devices are not defective (seriously doubt they are) then this exercise is significant for me to never consider mini-splits, not that I was thinking about it.

My decades old, super inefficient, standard forced air heat pumps use less energy than this during colder outside air in a 4k sq foot house with tons of windows. And I thought the whole value of mini splits was that you could have different temps per system so you were not heating spaces you were not occupying.

OP says they have them set to 68F in a 1100 sq foot loft but did not note the main living space setting.

Home is 24' x 40' with open loft and open living area supported by (2) splits; (2) 10'x7' Br's below the loft, each with
their own split . ALL set to 68F.

 

[charlesj]

Hey Charlesj, The water pump is from Deep Well (country boy here) and I never turn that off. I just posted that usage below
which is nothing for the 1 minute period it would run... There should all but NEVER be a need for that to turn on thru the
night unless I had some sort of water leak .

Thanks. That is what I thought it could be. I bet you have a storage tank that gets filled, pressurized and when you need water in the house
it turns on again. Had one of those once, a long time ago, in Florida to water yard only.

 

[charlesj]

... 4k sq foot house with tons of windows. ...

Oh, you measure by weight?

 

[charlesj]

For someone planning a system would 3 Powerwalls be enough for 70kWh a day? Should 4 PW be given any consideration.

Let me add that obviously there are other important factors like system size in kW, geographic location (solar production), roof direction/angle, utility rates and rules (is system kW size limited to qualify for net metering as it is in Georgia), budget, etc.

Yes, lots of consideration including length of possible outages. Texas comes to mind.
But with that kind of daily use, I'd think 4 PW if system size can also charge them most of the time.

 

[h2ofun]

Hey JJ... I'm just trying to see which devices are the "drivers" of our overnight usage by turning on for that test period of time overnight.
Like, tonight , I'm planning on adding my Water Heater to the mix and see total usage when that's on for the time, then Freezer Chest next night, Garage Fridge next, and finally the Mitsubishi units , which will be ALL of the units for the test... I think h2o has it right that it is probably going to be the (4) Split units driving my overnight use.... that will be a bummer for me :-( Made assumptions the design was created to cover ALL YEAR USE, not just Spring thru early Fall right ?

I just turned off my 5 mini split heads at 7 pm. Got up to a 60 degree home. I still have them off. I want to see what my usage is without them so I know exactly what they are costing, which I still believe is about 2kwh set at 64.

 

[h2ofun]

Yes, lots of consideration including length of possible outages. Texas comes to mind.
But with that kind of daily use, I'd think 4 PW if system size can also charge them most of the time.

At some poiint, IMO, the generator has to be added. PW's are NOT cheap. My generator does not care about sun or temperatures.

 

[aesculus]

Oh, you measure by weight?

One set of units is as good as another, as long as you have a conversation table.

 

[h2ofun]

Hello all ! I am new to this forum group and randomly picked jboy210 as the "participant", hope that's ok ?

I am new to Solar Energy coupled with (2) Tesla Powerwall 2 battery backups .
I'm not an electrician but I'm trying to understand the Powerwall 2's energy usages.
I am experiencing poor feedback from Tesla Support in my opinion, maybe from my own ignorance ?
1.I've noticed my (2) Powerwall 2's seem to run down from 100% full to my %10 Reserve in less than 10 hours ?
2.I've run a test this week where I set Energy Consumption to BACKUP ONLY so I would have 100% battery
available when turning on the Battery support at night.
3.I turned every energy consuming device OFF in my home the night of the test this week.
4.I turned ON the Battery backup for use at approximately 8m Eastern at %100.
5.I set my sleep timer for 6:00am Eastern to see where we were , Battery % .
6.I reviewed the Consumption rate from the Tesla Mobile App with the majority of those 10 hours being
below 3kW with a single 7.xx kW spike around 2:00am or so that may have lasted 15min. graph wise ?
7.My Battery %remaining shown by the Tesla Mobile App was 11% at 6:00am .
So,.. basically I am showing I've used 89% of (2) Tesla Powerwall 2's in 10hours at 3kw home use or less ?
Tesla Support told me it looked at the last 5 days of data and the Batteries were running perfectly ????
I told them to only use my data from 8:00pm to 6:00am.... and they said even that shows my batteries
working correctly ????
Does anyone have any information / ideas on what I'm looking at here ? I absolutely feel I am NOT getting
the energy promises I see online by others ( days without grid and only 2 powerwall 2's also ) and I'm only
talking about a 10 hour period ?
Thanks for any support you can offer,
Padge

I just did a test. I have been running about 2.4 kwh during the night with 5 mini split heads running. 4 at 64 and 1 at 61.
I then turned them all completely off and my usage went to .53. So my guess of 2 kwh was pretty close for me.

 

[P@dge]

OK,... Here we go..... Ran EVERYTHING last night except the Mini Splits . 8:00pm - 7:00am @ 46F .
Took the Mobile App data (130) 5-min entries, totaled them and divided by 130, giving me
the average kW's as 0.436923 kW per hour, for those 11 hours. Take the average and multiply * 11 hours and
it comes out to 4.806154 kW's consumption as I see it (virtually nada consumption) ! ??
GET READY Mitsubishi's !!!! If they are sucking up more than 20 kW's over that same period (11hrs),
I'm going to be beside myself with the initial , 3rd Party Installer, design right ? !!!!!
NOTE: I will not be running a test tonight because we are to be in the 20's overnight and I actually DO have
(2) non-household units that I know are heavy users that I have shut off for these tests.
I'll be back after the next test of ALL Household units, temperature willing

 

[P@dge]

I just did a test. I have been running about 2.4 kwh during the night with 5 mini split heads running. 4 at 64 and 1 at 61.
I then turned them all completely off and my usage went to .53. So my guess of 2 kwh was pretty close for me.

So,... 2kW over 10 hours or so would all but use up the 27kW (2)Powerwalls right ?

 

[h2ofun]

So,... 2kW over 10 hours or so would all but use up the 27kW (2)Powerwalls right ?

That about 2kwh, over 24 hours, is like 40kwh per day or yep, 27kw per 10 hours. I will have 3 pw's but it would be tight to use just them.
I have to admit, am surprised they use this much, but if cold, well, .. I turned them all off now and am running my whole house fan trying to get the 64 degree air into my house. But it got cold enough last night I got up at 1:30am and turned them on. I still may have plenty of solar to no care, but do not have that data yet.

 

[Gwgan]

GET READY Mitsubishi's !!!! If they are sucking up more than 20 kW's over that same period (11hrs)

Have they been serviced, cleaned, vacuumed?

 

[P@dge]

Have they been serviced, cleaned, vacuumed?

Hey GW..... I vacuum/clean them every couple of months.... they aren't but 15 months old ... I have not swapped
out the nano-filters... they have cleaned nicely..... the small carbon and other front filter(s) look great too .

 

[getakey]

seems like you guys need more insulation in your homes
I have a gas furnace for half my home and heat pump for the other half
My house is on a hill and the 2 stories go down rather than up. Top floor is street level and has gas furnace. Lower level is heat pump
We set upper at 74 and lower at 72. We turn off both at night ~10pm. House rarely cools lower than 68. We probably have somewhat milder temps than you, but even when low was close to freezing, house only got down to 66, maybe 65

 

[h2ofun]

seems like you guys need more insulation in your homes
I have a gas furnace for half my home and heat pump for the other half
My house is on a hill and the 2 stories go down rather than up. Top floor is street level and has gas furnace. Lower level is heat pump
We set upper at 74 and lower at 72. We turn off both at night ~10pm. House rarely cools lower than 68. We probably have somewhat milder temps than you, but even when low was close to freezing, house only got down to 66, maybe 65

yep, gets cold at 1500 feet

 

[aesculus]

yep, gets cold at 1500 feet

The other weird thing are these microclimates. I can be 10 degrees warmer than a neighbor just down the road at roughly the same elevation. But we are on a slight hill while they are in a slight dip.

 

[getakey]

yep, gets cold at 1500 feet

I'm at 900 feet

 

[charlesj]

I'm at 900 feet

Hell of a lot better that at 9000 ft.

We are about 600 ft and no kidding about the micro climates.
Too bad the jurors didn't accept that evidence on the OJ case.