Tesla Powerwall

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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. :eek:
 
Zythryn said:
(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.
 
Zythryn, I just watched the videos of your home and I have to say it is an absolutely marvel! Great job!
Zythryn said:
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 said:
On the more interesting side, our PowerWalls are currently being installed! Should be up and running by the end of the week. :eek:
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...
 
SageBrush said:
Zythryn said:
(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 said:
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 :)

“RegGuheert” said:
Zythryn said:
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.

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).


“RegGuheert” said:
Zythryn said:
On the more interesting side, our PowerWalls are currently being installed! Should be up and running by the end of the week. :eek:
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?
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.


“RegGuheert” said:
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.)

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.



“RegGuheert” said:
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...

— 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.
 
Going with Powerwall or other battery storage solutions here in CA is quite tempting. SGIP is available in California and combined with the Federal ITC this should cover way over half the cost including install:

To encourage more residential storage deployments in California, the California Public Utilities Commission (CPUC) established the Self-Generation Incentive Program (SGIP). The program provides incentives to help reduce the costs of storage to consumers. Residential storage batteries, like Powerwall, reduce strain on the utility power grid and in turn help reduce the need to build expensive fossil fuel-fired power plants.

https://www.tesla.com/support/energ...rnia-self-generation-incentive-program--sgip-
 
Tesla website quotes $11,800 for 2 Powerwalls and $1,100 for supporting hardware for a "$12,900 total equipment cost".

The first quote I got today from a certified Powerwall installer was for $21,500 "gross system price". After Federal ITC (-$6,450) and the CA SGIP (-$6,960) they quote net cost to customer of $8,090. I asked the rep to explain how they came to such a high install price and he didn't have an answer. Although not overtly saying so, he suggested the Tesla website was not correct. :(

The Tesla website notes "typical installation cost ranges from $1,000 to $3,000. This does not include solar installation, electrical upgrades (if necessary), taxes, permit fees, or any retailer / connection charges that may apply."

Based on tax in my area we are talking about $1k and there are no upgrades needed. So the install costs are still way out of line with the Tesla website.

Waiting to hear back from another company.
 
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