Help with understanding PowerWall 2 available energy hours ?

[P@dge]

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

 

[Laketime]

For reference one kW running for one hour is one kWh- this is the equivalent of running (10) 100 watt light bulbs for one hour. Your walls store 13.5kWh of energy each or 27kWh total. At 2.7kW of constant household usage they would last roughly 10 hours.

First- your energy usage seems a bit high if you turned off high consumption devices. For reference my 4700ft house uses roughly 900W to 1.6kW overnight (during the winter with no AC or pool/pond pump going). During the day I'm between 1.9kW and 3kW if we don't use the dryer etc.

Second- it seems you have less Powerwalls than your consumption dictates. They recommended I go with 4 walls but I decided on 3. 2 walls is really the bare minimum. What is your annual kWh consumption? (I'm 21,000 if memory serves)

 

[jhn_]

Each Powerwall is 13.5kwh. So in total you have 27kwh. If you are using about 3kw per hour in your house overnight for 10 hours, that is about 30kwh. So you batteries are using most of not all of their stored 27kwh. They are working as expected and you just use more power than they store.

3kw per hour for a rather dormant house is a lot in my opinion. Do you use electric heat? AC? Pool pumps running 24/7?

 

[jhn_]

Lake time beat me too it.

 

[Laketime]

Lake time beat me too it.

And we said basically the same thing. Great minds...

 

[getakey]

I agree, 3kW/h overnight is a lot unless they have electric heat. But what about that spike? That seems equally odd
Be good if OP could post pics of the consumption from the App

I have a heat pump for half of my house. Unless its less than 45 degrees out, it will spike my consumption to 3 kW at night until we go to bed and turn it off. Then the rest of the night is ~1kW draw. This is with 2 Refrigs and 1 big wine cooler. In the morning when the heat pump comes back on (and temp is pretty low), consumption spikes to ~5kW until outside temp warms up

 

[Vines]

I agree, 3kW/h overnight is a lot unless they have electric heat. But what about that spike? That seems equally odd
Be good if OP could post pics of the consumption from the App

I have a heat pump for half of my house. Unless its less than 45 degrees out, it will spike my consumption to 3 kW at night until we go to bed and turn it off. Then the rest of the night is ~1kW draw. This is with 2 Refrigs and 1 big wine cooler. In the morning when the heat pump comes back on (and temp is pretty low), consumption spikes to ~5kW until outside temp warms up

Spike is likely the hot water heater.

 

[charlesj]

I am wondering what was the expectation and design goals for the system?
It looks like system storage and generation was too small.

 

[jjrandorin]

Like others in this thread, the numbers look "correct" for that home run rate, but thats a pretty high run rate for a home overnight. There HAS to be some sort of pump / motor running overnight.

My 3300 square foot home with 2 fridges uses .6kWh (600 watts or, less than 1kWh) per hour during the night. If the home usage is roughly 3kWh per hour, simple math says it the powerwalls will be empty in less than 10 hours.

OP you say you "turned off high usage devices" but there is obviously something you are either unaware of, or cant turn off. There is no way you will get "days of usage" with that kind of usage. You also didnt say what size your PV was, but it sounds fairly obvious that you dont have enough powerwalls if your goal was "days of usage" and your usage overnight (when people are generally sleeping) is close to 3kWh per hour.

 

[gpez]

Spike is likely the hot water heater.

My dryer turns on occasionally at night if clothes are left in it, a feature to prevent wrinkles. Probably should turn that off...

Another thing to add for @P@dge is that the 13.5kwh usable per Powerwall is the initial capacity, doesn't include the small reserve the Powerwall keeps to allow it to restart during grid outages after running low, and doesn't include the 95% inverter efficiency factor. For practical purposes I consider my Powerwall to have 11kwh of usable power in a grid outage.

Also agreed that 3kw is high for overnight usage. Our average consumption at night is under 1kwh and I have a lot of networking/home automation/server equipment running 24/7.

 

[jboy210]

Like others in this thread, the numbers look "correct" for that home run rate, but thats a pretty high run rate for a home overnight. There HAS to be some sort of pump / motor running overnight.

My 3300 square foot home with 2 fridges uses .6kWh (600 wats or, less than 1kWh) per hour during the night. If the home usage is roughly 3kWh per hour, simple math says it the powerwalls will be empty in less than 10 hours.

OP you say you "turned off high usage devices" but there is obviously something you are either unaware of, or cant turn off. There is no way you will get "days of usage" with that kind of usage. You also didnt say what size your PV was, but it sounds fairly obvious that you dont have enough powerwalls if your goal was "days of usage" and your usage overnight (when people are generally sleeping) is close to 3kWh per hour.

We use about the same amount of power per hour as @jjrandorin most of the night. Around 0.6kW. We have gas heat. The only big electric use we have at night are heated floors in one bathroom and those can add up to 1.5kW for an hour or so.

Our home is around 3100 sq feet, so maybe the OPs house is larger, has electric heat, or has some other power-consuming items like a pool pump that run at night.

 

[Icebox_inel]

 

[h2ofun]

I agree, 3kW/h overnight is a lot unless they have electric heat. But what about that spike? That seems equally odd
Be good if OP could post pics of the consumption from the App

I have a heat pump for half of my house. Unless its less than 45 degrees out, it will spike my consumption to 3 kW at night until we go to bed and turn it off. Then the rest of the night is ~1kW draw. This is with 2 Refrigs and 1 big wine cooler. In the morning when the heat pump comes back on (and temp is pretty low), consumption spikes to ~5kW until outside temp warms up

I use about 2 kw/h during the night. I have 5 mini split heat pumps running 24/7. And my settings are at 64 degrees.

 

[aesculus]

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 ?

Thanks for any support you can offer,
Padge

As an experiment set your Powerwalls to 100% backup. Then let your house only consume grid energy overnight. Post the graph the next day so we can see what your Home load was overnight. It should overlay the grid graph. The PW graph should obviously be flat.

 

[P@dge]

You guys and gals are AWESOME !! Thanks so much... I'll respond here to everyone's analysis
NOTE: I misquoted in the original post... I didn't turn off ALL energy consuming devices !!
I turned of ALL lights, oven, washer, dryer, pc's, clocks, with exception to the devices found
below in item #2 .
RESPONSES:
1. YES, I need to get a better grip on what's actually consuming my energy if I'm using above 3kW overnight.
2. My energy uses overnight for my 1,100 sq.ft. , OPEN SECOND FLOOR LOFT (20' ceiling) are as follows:
a. (4) Mitsubishi Mini Splits running 24 hours with single compressor and distribution box in crawl space.
Set to 68deg.
b. (1) Whirpool Energy Efficient 25cu.ft. fridge.
c. (1) ancient RCA 20.6cu.ft. fridge in garage(attached, unheated).
d. (1) Rheem Energy Efficient 45gal. elec. water heater (no additional insulation wraps) in garage.
e. (1) Fridgidaire Energy Efficient 12.8cu.ft. chest freezer in garage (apocalypse ready)
f. (1) Standard, deep well, water pump (usually doesn't run during overnight) in garage.
g. (1) Rainsoft water filter (2 tanks), with Ultra-violet light attachment in garage.
3. We had just been in our new home for 5 months when the third party installer did the sizing based
on the Grid usage they reviewed from our provider... we added (2) Energy consuming devices
that we turn OFF during our testing now that would really skew any numbers for our consumption via
normal home device consumption. i.e. Greenhouse Heater this Winter (turn off for overnight testing),
and an Airstream Heat Pump on 19ft.er that would be turned OFF also , but run other times during
Solar hours, so we can't give true consumption rates with past data, only our "controlled" test data.

I think all of you have hit the nail on the head for us to find out each consumption rates, over and above,
staying warm, including turning off all of a. thru g. above for the overnight, turning on individual things
1 at a time over a period of 7 nights I guess... this actually sounds kinda cool.... getting controlled usage
by device, then devices and reviewing the Tesla Mobile App data for the given hours .
I certainly will be writing back with our plans for device usage and report back on consumption

 

[h2ofun]

You guys and gals are AWESOME !! Thanks so much... I'll respond here to everyone's analysis
NOTE: I misquoted in the original post... I didn't turn off ALL energy consuming devices !!
I turned of ALL lights, oven, washer, dryer, pc's, clocks, with exception to the devices found
below in item #2 .
RESPONSES:
1. YES, I need to get a better grip on what's actually consuming my energy if I'm using above 3kW overnight.
2. My energy uses overnight for my 1,100 sq.ft. , OPEN SECOND FLOOR LOFT (20' ceiling) are as follows:
a. (4) Mitsubishi Mini Splits running 24 hours with single compressor and distribution box in crawl space.
Set to 68deg.
b. (1) Whirpool Energy Efficient 25cu.ft. fridge.
c. (1) ancient RCA 20.6cu.ft. fridge in garage(attached, unheated).
d. (1) Rheem Energy Efficient 45gal. elec. water heater (no additional insulation wraps) in garage.
e. (1) Fridgidaire Energy Efficient 12.8cu.ft. chest freezer in garage (apocalypse ready)
f. (1) Standard, deep well, water pump (usually doesn't run during overnight) in garage.
g. (1) Rainsoft water filter (2 tanks), with Ultra-violet light attachment in garage.
3. We had just been in our new home for 5 months when the third party installer did the sizing based
on the Grid usage they reviewed from our provider... we added (2) Energy consuming devices
that we turn OFF during our testing now that would really skew any numbers for our consumption via
normal home device consumption. i.e. Greenhouse Heater this Winter (turn off for overnight testing),
and an Airstream Heat Pump on 19ft.er that would be turned OFF also , but run other times during
Solar hours, so we can't give true consumption rates with past data, only our "controlled" test data.

I think all of you have hit the nail on the head for us to find out each consumption rates, over and above,
staying warm, including turning off all of a. thru g. above for the overnight, turning on individual things
1 at a time over a period of 7 nights I guess... this actually sounds kinda cool.... getting controlled usage
by device, then devices and reviewing the Tesla Mobile App data for the given hours .
I certainly will be writing back with our plans for device usage and report back on consumption

yep, I bet a big part are the Mini splits, since that is what I am seeing.

 

[P@dge]

Well dang... and we were sold that the Mini's were the most energy efficient devices on the market,
including we purchased that "Hyper Heat" add-on, that guarantees the efficiencies down to -6 deg !!
These will be our next to last test with that ancient fridge as the last

 

[h2ofun]

Well dang... and we were sold that the Mini's were the most energy efficient devices on the market,
including we purchased that "Hyper Heat" add-on, that guarantees the efficiencies down to -6 deg !!
These will be our next to last test with that ancient fridge as the last

I believe I have the hyper heat unit for my upstairs.

Why do you not think these are the most efficient? I have 10 heads in my house on 3 compressors. I love them compared to the force gas multipack we used to have. 100% zoning.

 

[P@dge]

I believe I have the hyper heat unit for my upstairs.

Why do you not think these are the most efficient? I have 10 heads in my house on 3 compressors. I love them compared to the force gas multipack we used to have. 100% zoning.

I just meant most efficient of any Heat Pump devices out there, particularly for Split unit types I guess ...

 

[h2ofun]

I just meant most efficient of any Heat Pump devices out there, particularly for Split unit types I guess ...

Yep