Three weeks post Install Questions

[skiingj]

Hi All - Great forum. I've learned so much.

My install was three weeks ago and I'm currently waiting for Tesla to re-submit permit as they moved the Inverter and Gateway. I've been running pre-PTO, other than the obvious my local city utility being upset. Any advice or secrets to run pre-PTO?

I have a 8.14kw system with 2 PWs (2.1). It normally takes most of the day to charge the Powerwall's. I have a 2900sf house with pool pump and AC set to 79 day and 82 night. We have full sun all day, 21 panels are SW facing, 3 SE facing. Its normally 100 degrees each day. I generate ~56 kwh a day. Powerwall's are normally drained each night even though AC only comes on once or twice for 5-10 minutes. Pool pump only runs during the day. I remember Tesla said two Powerwall's would give me six days whole home backup. Is that just powering one lightbulb for six days? I can't get thru one night.

Appreciate the feedback! Thanks

 

[Zabe]

What is your reserve set at? NVM you said they are drained. Two PW's have 27 kWH of power. Your home is using 30/kW while your solar is generating or about 3 kW/hour. If your AC and pool pump are not running much at night you should not be draining your PW's. Check your utility hourly meter values pre install to get an idea of how much power you used to use each hour off peak. Check your tesla app for how much power you are using each hour off-peak. Find whatever is running that is consuming a couple of kW/H and turn it off

 

[jjrandorin]

Hi All - Great forum. I've learned so much.

My install was three weeks ago and I'm currently waiting for Tesla to re-submit permit as they moved the Inverter and Gateway. I've been running pre-PTO, other than the obvious my local city utility being upset. Any advice or secrets to run pre-PTO?

I have a 8.14kw system with 2 PWs (2.1). It normally takes most of the day to charge the Powerwall's. I have a 2900sf house with pool pump and AC set to 79 day and 82 night. We have full sun all day, 21 panels are SW facing, 3 SE facing. Its normally 100 degrees each day. I generate ~56 kwh a day. Powerwall's are normally drained each night even though AC only comes on once or twice for 5-10 minutes. Pool pump only runs during the day. I remember Tesla said two Powerwall's would give me six days whole home backup. Is that just powering one lightbulb for six days? I can't get thru one night.

Appreciate the feedback! Thanks

There is ZERO chance 2 powerwalls would run pool pumps and AC for 6 days.

You can figure out your usage by looking at your daily electricity usage (or hourly). There is also very (very) little chance that in 100 degree heat, if your AC is set to 79 degrees, it comes on "once or twice for 5-10 minutes". If you look in the tesla app you will find thats not the case, you will clearly see the spikes in usage that correspond to your AC / pool pumps coming on and cycling off.

 

[getakey]

What mode are you operating in? Balanced, Cost Saving, etc?
I think it is unusual for PWs to take most of the day to be charged unless you are in Self Powered mode

 

[Electrph]

as @jjrandorin pointed out you may be underestimating how much power central AC consumes ..
as example i have 2 power walls .. has been 100 -104 most days here .. modern home (built 2018) w/ single central AC on 2800sf single story ...runs my two batteris down to their higher summer 60 % reserve from 100% daily by about 2am (run self powered mode)

by ac coming on once or twice for 10 min do you mean every hour? that sounds more reasonable

the tesla number of days is marketing .. way way too many variables to make blanket statement about how long 2 powerwalls will support home .. i can run forever on two powerwalls and zero grid power if i am carefull with use of AC ... charging model 3 .. etc etc but we would likely be uncomfortable (heat) at certain times of some days

 

[getakey]

I think OP was saying once or twice at night with thermostat at 83

I live close to Roseville and we actually turn our ACs off at night, but we have a whole house fan

 

[EVRider-FL]

My solar/Powerwall system was completed on Friday, so I don’t have much data yet. 10.56 kw solar (non-Tesla) with 2 Powerwalls, installed by a Tesla certified installer. Comparable house to OP (including pool). 90’s here in southeast FL. Panels on the east facing roof.

I have the Powerwalls set to 50% reserve. I find they charge from 50 to 100% in about 4 hours every morning. Solar is generating between 50-60kwh daily. Powerwalls start sending energy to the house in the late afternoon, and appear to run down to 50% at around midnight at which point the grid kicks in. Don’t know if that’s typical, but I’m pretty happy with the performance so far.

Note that unlike the OP, I turn the AC temp down overnight, so I’m using more electricity for that.

 

[Electrph]

My solar/Powerwall system was completed on Friday, so I don’t have much data yet. 10.56 kw solar (non-Tesla) with 2 Powerwalls, installed by a Tesla certified installer. Comparable house to OP (including pool). 90’s here in southeast FL. Panels on the east facing roof.

I have the Powerwalls set to 50% reserve. I find they charge from 50 to 100% in about 4 hours every morning. Solar is generating between 50-60kwh daily. Powerwalls start sending energy to the house in the late afternoon, and appear to run down to 50% at around midnight at which point the grid kicks in. Don’t know if that’s typical, but I’m pretty happy with the performance so far.

Note that unlike the OP, I turn the AC temp down overnight, so I’m using more electricity for that.

this is exactly what i do ac down at night / mostly off in day time since nobody home
i see system switch over to grid anywhere from 10pm to 2am depending on night temp set / temp outside (more detail than my above general post )

 

[h2ofun]

this is exactly what i do ac down at night / mostly off in day time since nobody home
i see system switch over to grid anywhere from 10pm to 2am depending on night temp set / temp outside (more detail than my above general post )

I leave 5 of my mini split heads on AC 24 hours a day. 3 set at 72, 1 set at 74, and one set at 66. I use maybe 40kwh per day unless its the 110 and uses more. I love it being "cold" in my entire large home when its 100 outside right now

 

[skiingj]

Thanks everyone for the responses. I will try to answer and provide some Tesla App screenshots.

Reserve is set to 5%. Self-power mode.

1-2 times a night AC comes on. I just realized by looking at app details the Powerwall’s are starting to drain late afternoon when production starts to drop.

These screenshots are from yesterday. I did charge my EV for an hour around 3pm and it pulled most if it from the grid.

Any pre-PTO secrets to stay out of trouble?

 

[jjrandorin]

Just as a note, you can see the spikes going all day long of your AC, and you can also see when you charged your car. You can also see that when you (likely) plugged in your car, your powerwalls switched from charging to discharging. Your car did not charge only from the grid, it charged from both stored energy in your powerwall and the grid.

In self powered mode this is normal.

You can also see that your daily usage for the time period you show is 63.5kWh. Each powerwall is 13.5 for a total of 27. At your current run rate, your powerwalls would provide 1/3 to 1/2 of a days worth of energy, not counting solar.

your powerwalls were being drained starting at all those spikes you see starting at 4pm, so your AC (or pool pump) is not running for 5-10 minutes, each one of those spikes is likely either your pool pump or your AC. I am going to guess AC since they stop around 8pm when you say you turn your AC temp down (higher). Those spikes look like they are up to around 5kWh or so.

Your usage is all normal looking, but it doesnt match what you mentioned in your first post. One thing getting this data does is let someone see what their home is actually doing, not what they think its doing. Your AC is using quite a bit of power, which is normal.

TL ; DR, with your current home usage, if you didnt have solar filling your powerwalls, you would around 10-12 hours or so of power.

 

[getakey]

To the OP, I'm surprised you have your reserve set so low being in PG&E land.

 

[h2ofun]

To the OP, I'm surprised you have your reserve set so low being in PG&E land.

My reserve is set at 10% and yep, in PGE land

 

[getakey]

My reserve is set at 10% and yep, in PGE land

Do you know what your annual true up will be?

 

[solarAddict]

My reserve is set at 10% and yep, in PGE land

10% reserve... But you have five PWs.

I'm actually surprised by 5% reserve too. Even I live in the area where power outages are very uncommon I still keep my reserve at 20% (2 PWs system).

 

[h2ofun]

Do you know what your annual true up will be?

Since with all my changes, I keep getting more true ups.

So for the first 15K of solar, keeping house 60 in winter, I ended up with $1100 generation, so only got $100 based on wholesale cost. This was 12 months.

Then right after, the battery install made another true up, and changed my plan. So, everything is still in flux, so PGE cannot tell me what is going on.

And now I just got PTO for another 15K of panels, so waiting to see if this makes another true up, like 3 in 4 months.

But, I do know this, I will continue to have a zero ENERGY bill, since I am all electric. My AC is running 24/7 set at 72. (My downstairs exercise room is at 66) Next winter I also will have my heating running 24/7 running at 72 degrees, no more freezing. I still have a feeling I might still be generating more than I use, which is why I might offer free EV charging to friends.

My output is limited by the inverter outputs, which together are 22.8 kw. I have seen 22.4kw once. Lots of my panels are north facing so will do nothing in the winter.

 

[h2ofun]

10% reserve... But you have five PWs.

I'm actually surprised by 5% reserve too. Even I live in the area where power outages are very uncommon I still keep my reserve at 20% (2 PWs system).

I have 2 on my house, and lowest I have seen is like 50%. But, my other 3 are on the AC, and when it got to 110 outside, they drained to like 15%. So, I use a l of energy with my big house before the solar kicks in. During those days, batteries stopped being used and grid powered the AC.

 

[getakey]

If you are a large net generator on an annual basis, I see no reason to set your reserve so low. You are risking an unplanned outage with very little backup

 

[h2ofun]

If you are a large net generator on an annual basis, I see no reason to set your reserve so low. You are risking an unplanned outage with very little backup

Nah, least of my worries. If I did have an outage, and batteries drain, I just turn on the generator. As you know, so easy to change stuff. Now, my comments are for the summer type months. In the winter, with limited solar, yep, would kick the reserve up some.

 

[skiingj]

Thanks jjrandorin Great Info, much appreciated.