Zythryn
Posts: 1021
Joined: Fri Jun 04, 2010 4:49 am

Re: Tesla Powerwall

Sat Feb 03, 2018 12:00 pm

Interesting, thanks for posting.
Referring back to an earlier discussion on heat pumps...
We have now been through two January’s, which are generally the worst month for heating.
At normal temps (72) without any additional energy saving techniques, we used about 17kWh per day on HVAC.

The heat pumps themselves use about 2 1/2 kWh per day. The condensers, air ventilation and such used another 14 1/2 kWh per day.

In the event of a power outage, the set temp would immediately go down, lowering the energy requirements. If we knew it maybe an extended outage, we would basically shut down the heat, and just keep the domestic hot water on to prevent pipes from freezing. The PowerWalls should work, in our case, for a couple of weeks, or even in the worst conditions, a full week (we would find temporary shelter elsewhere after the first day of no sunshine).

On the more interesting side, our PowerWalls are currently being installed! Swould be ups and running by the end of the week. :o
Previous owner of Prius, Volt, Leaf & Model S
Current owner of Model 3
http://www.netzeromn.com

SageBrush
Posts: 2481
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: Tesla Powerwall

Sat Feb 03, 2018 1:41 pm

Zythryn wrote: (we would find temporary shelter elsewhere after the first day of no sunshine).

Typo ?

I've forgotten ... are you off-grid ? I'm unsure why you would buy powerwalls.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Car is now enjoying an easy life in Colorado
3/2018: 58 Ahr, 28k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

User avatar
RegGuheert
Posts: 6228
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Tesla Powerwall

Sat Feb 03, 2018 2:27 pm

Zythryn, I just watched the videos of your home and I have to say it is an absolutely marvel! Great job!
Zythryn wrote:The heat pumps themselves use about 2 1/2 kWh per day. The condensers, air ventilation and such used another 14 1/2 kWh per day.
What about the pumps for the well loop(s) and the loop through the air handler? Is that included in the 2.5 kWh/day number? I will assume that the COP for the geothermal heat pump is based solely on the 2.5 kWh/day number and that the 6X larger number is NOT. That's what I found when I was looking into this option for my sister's off-grid home. The electrical energy requirements for geothermal really added up and made it a non-starter for them.
Zythryn wrote:On the more interesting side, our PowerWalls are currently being installed! Should be up and running by the end of the week. :o
I gathered from your blog that you are installing three PowerWalls. And I'm going to guess that the inverter that is in the basement that connects to them is being fed by the PV modules on the garage, which appear to be 6820 Wp total. Is that correct? So where do the PowerWalls go and are they stacked or side-by-side?

Also, I see you have a bunch of (3?) load centers down there. How do things work in a grid-out situation? Is only one of those three powered by the PowerWall? Can you run the geothermal system or is that purely grid connected? (I'm guessing it is grid only.)

Also:

- $0.08/kWh * 22,000 kWh/year * 10 years = $17,600.00 -- Very nice bonus!
- Please post something about your heat-pump dryer in the Off-topic section. I've never heard of such a thing!
- I would expect that there would be a bit of an urban heat island effect from the stone mulch around the plantings. I suppose that's not such a bad thing in Minnesota, but I'm wondering if the shrubs found in there are expected to grow up to a point where they will shade much of the stone?
- No-mow fescue that is drought tolerant? Is that for real?
- Please tell your contractors that they appeared to be VERY knowledgeable in the video. (I'm sure you already have!) The heat-pump room was extremely well laid-out. We tried to hire a contractor for some solar thermal in my sister's home and it was a major disaster. We had to take over the job when they started to take up ALL of the storage area for piping, etc. They really didn't know the first thing about what they were selling. It was sad...
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

Zythryn
Posts: 1021
Joined: Fri Jun 04, 2010 4:49 am

Re: Tesla Powerwall

Sat Feb 03, 2018 3:44 pm

SageBrush wrote:
Zythryn wrote: (we would find temporary shelter elsewhere after the first day of no sunshine).

Typo ?

I've forgotten ... are you off-grid ? I'm unsure why you would buy powerwalls.


No, we are grid tied.
The PowerWalls are primarily there for backup and efficiency if the grid goes down.
In the worst conditions (30 below zero, no sun, grid down for more than a day), we would turn the temp down to 40 degrees and find a friend, hotel, or just sleep in the car.

Because of utility red tape, we have one PowerWall paired with each inverter. So we will be using some of the capacity for backup reserve, and some to minimized our grid use. In the summer, spring and fall, we will not worry about backup power and not use grid power at all (fingers crossed).


RegGuheert wrote:Zythryn, I just watched the videos of your home and I have to say it is an absolutely marvel! Great job!

Thank you so much! Most of the kudos goes to our great team :)

[quote=“RegGuheert”]
Zythryn wrote:The heat pumps themselves use about 2 1/2 kWh per day. The condensers, air ventilation and such used another 14 1/2 kWh per day.
What about the pumps for the well loop(s) and the loop through the air handler? Is that included in the 2.5 kWh/day number? I will assume that the COP for the geothermal heat pump is based solely on the 2.5 kWh/day number and that the 6X larger number is NOT. That's what I found when I was looking into this option for my sister's off-grid home. The electrical energy requirements for geothermal really added up and made it a non-starter for them.[/quote]

That I can’t tell you. The system is very integrated, but I would expect some parts are included, but not the whole 17kWh. So some of that 17kWh goes towards heating the domestic hot water, some the infloor heat and some the heating for forced air, when used (rare).


[quote=“RegGuheert”]
Zythryn wrote:On the more interesting side, our PowerWalls are currently being installed! Should be up and running by the end of the week. :o
I gathered from your blog that you are installing three PowerWalls. And I'm going to guess that the inverter that is in the basement that connects to them is being fed by the PV modules on the garage, which appear to be 6820 Wp total. Is that correct? So where do the PowerWalls go and are they stacked or side-by-side?[/quote]
Actually, when we designed the house, the first PowerWall had just been announced and we had minimal details about it. What little info we had was that the backup PowerWall required being within feet of the inverter.
With delays, redesign of the PowerWall, hurricanes, 100MW battery installation bets and installer issues, we moved to the second gen PowerWalls. These are all mounted in the garage on the wall. As I recall, we have a 7500 and 6500(?) inverters. The second gen PW has its own inverter built in. So the PW’s proximity with the inverter is less of an issue.


[quote=“RegGuheert”]Also, I see you have a bunch of (3?) load centers down there. How do things work in a grid-out situation? Is only one of those three powered by the PowerWall? Can you run the geothermal system or is that purely grid connected? (I'm guessing it is grid only.)
[/quote]

The original idea was one panel would be our backup panel. We actually eliminated one panel to make room for some of the PW setup needed. On our original backup panel we had the geothermal system, a couple of outlets and a small fridge. We have added the garage (more logistics than anything) our main fridge (removing the small fridge),master bedroom lights and outlets, and a few other miscellaneous draws.

The main purpose of the original concept was to have heat in the event of an extended power outage in the winter.



[quote=“RegGuheert”]Also:

- $0.08/kWh * 22,000 kWh/year * 10 years = $17,600.00 -- Very nice bonus!
- Please post something about your heat-pump dryer in the Off-topic section. I've never heard of such a thing!
- I would expect that there would be a bit of an urban heat island effect from the stone mulch around the plantings. I suppose that's not such a bad thing in Minnesota, but I'm wondering if the shrubs found in there are expected to grow up to a point where they will shade much of the stone?
- No-mow fescue that is drought tolerant? Is that for real?
- Please tell your contractors that they appeared to be VERY knowledgeable in the video. (I'm sure you already have!) The heat-pump room was extremely well laid-out. We tried to hire a contractor for some solar thermal in my sister's home and it was a major disaster. We had to take over the job when they started to take up ALL of the storage area for piping, etc. They really didn't know the first thing about what they were selling. It was sad...[/quote]

— Yes, it is a great incentive. Xcel owns the RECs for that production, so they get something out of it. But it helps the payback immensely.
— will do
—Mulch is wood, although the stone steppingstones and granite boulders definitely absorb some of that heat. In MN that is a wonderful thing:). We will get some more shading during the summers as the vegetation grows.
—Sort of for real ;) If you don’t mind it growing to about 8 inches, my understanding is it is basically ‘no-mow’. While it is getting established we are mowing it, about once every 2-3 weeks depending upon how much it rains. After the first 9 months, we don’t irrigate it. Haven’t had a good drought here, but it is much more tolerant to low water.
— Thank you, and yes, I have. Our highest priority was getting a good crew together that could all work well together.
Previous owner of Prius, Volt, Leaf & Model S
Current owner of Model 3
http://www.netzeromn.com

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