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Roof Removal & Prep: 3/8, Roof Install: 3/22, Powerwall Install: 3/24

GoGoGoMach5

Member
Mar 11, 2020
17
4
Southern California
When we put down our deposit on February 17, 2020, we didn't think it would take more than a year to get an install date. After upgrading our electrical service to 200 amp and installing a requisite main panel to go with it, we had to endure Permit Volleyball between Tesla and our city. Once that match was over, the last kicker (for now) was to see our roof replacement costs more than quadruple after the pre-install site visit.

Having been through all that, I do know it's going to happen. Why? They actually dropped off material like flashing and underlayment at the house a week ahead of time. And in keeping with the way this project has been going, the early forecast has rain for two days during roof removal. Still excited, but damn I'm tired. I'll try to update this thread as the installation proceeds.

IMG_4802.jpg Tesla_layout.jpg
 
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Mar 1, 2021
117
31
San Diego, CA
When we put down our deposit on February 17, 2020, we didn't think it would take more than a year to get an install date. After upgrading our electrical service to 200 amp and installing a requisite main panel to go with it, we had to endure Permit Volleyball between Tesla and our city. Once that match was over, the last kicker (for now) was to see our roof replacement costs more than quadruple after the pre-install site visit.

Having been through all that, I do know it's going to happen. Why? They actually dropped off material like flashing and underlayment at the house a week ahead of time. And in keeping with the way this project has been going, the early forecast has rain for two days during roof removal. Still excited, but damn I'm tired. I'll try to update this thread as the installation proceeds.

View attachment 641692 View attachment 641694
Exciting! Our permit came through in 2 weeks, plan on tear off and install taking 3-4 times longer than advertised.
 

GoGoGoMach5

Member
Mar 11, 2020
17
4
Southern California
Quick update: The title of this thread is no longer relevant. Our project is currently on hold because of .475. That number is the fraction of a kilowatt that our solar roof (as presently designed) is short of to support 2 Powerwalls.

Tesla resubmitted our design to our AHJ to include the new Tesla inverter. Our city took another look and discovered (very late in the game) that our solar roof was too small to support 2 Powerwalls. At this point, we either subtract one battery or increase the number of tiles.

Talking to Tesla, they felt reducing the number of Powerwalls was the easier route because our design was already at the 110% cap that the AHJ enforces. I was disappointed by Tesla's reaction and short-sightedness. They did not realize the cap figure was based on 2019 usage (we signed our initial contract in May 2020).

I made a plea to the city if we could have Tesla increase the PV capability based on our 2020 usage (800kWh more, additional freezer and planning to buy an EV charger). The city replied an hour later approving the increase. I'm now trying to confirm with Tesla the next steps.

Regardless of the route we took (less battery or more tiles), we would still have to submit a new plan and re-apply for a new permit. It's supposed to rain the next two days so I'm not disappointed they couldn't start the roof tear-off. More updates to come!
 

Electrph

Member
Aug 29, 2019
273
157
Central California
Well sounds like you have an abundance of the key trait needed to do business with Tesla energy ... patience
I would 100% agree with you and not give up a power wall and have the limitations of just one
Good luck with your install
 
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wjgjr

Active Member
May 11, 2020
1,064
803
Silver Spring, MD
Quick update: The title of this thread is no longer relevant. Our project is currently on hold because of .475. That number is the fraction of a kilowatt that our solar roof (as presently designed) is short of to support 2 Powerwalls.

Tesla resubmitted our design to our AHJ to include the new Tesla inverter. Our city took another look and discovered (very late in the game) that our solar roof was too small to support 2 Powerwalls. At this point, we either subtract one battery or increase the number of tiles.
Is this a CA/AHJ rule, or related to qualifying for an incentive? I just find it unexpected, because from a technical perspective it doesn't seem like there is really a minimum number - it just means it will take longer to re-fill the PWs. But, in any case, I completely agree with your approach of adding more solar. Adding 8-9 more shingles is much closer to the original plan you approved than taking away one PW (which is a huge change, including changing what can be backed up, as with 1 PW, you are definitely limited in what can be included.) And, since it sounds like the limiting factor was usage and not roof space, it should be easy for Tesla to slot in those extra shingles. Either way, it seems like Tesla will need to update their diagrams and the permits.
 

GoGoGoMach5

Member
Mar 11, 2020
17
4
Southern California
Is this a CA/AHJ rule, or related to qualifying for an incentive? I just find it unexpected, because from a technical perspective it doesn't seem like there is really a minimum number - it just means it will take longer to re-fill the PWs. But, in any case, I completely agree with your approach of adding more solar. Adding 8-9 more shingles is much closer to the original plan you approved than taking away one PW (which is a huge change, including changing what can be backed up, as with 1 PW, you are definitely limited in what can be included.) And, since it sounds like the limiting factor was usage and not roof space, it should be easy for Tesla to slot in those extra shingles. Either way, it seems like Tesla will need to update their diagrams and the permits.
This was an AHJ rule. This is taken from the rejection letter:

The maximum battery size is determined by both the discharge (kW) and the capacity (kWh). The discharge (kW) is limited to 150% of the PV generating capability. In this case, the proposed PV system has a CEC-AC rating of 6.35 kW, so the battery discharge cannot exceed 9.525 kW. With (2) battery units, they discharge 10 kW total. Please reduced the battery units to one.

I've made a request with Tesla to only increase the solar enough so we can have 2 PWs. As much as we'd love to max out the roof, there are additional pre-construction costs looming that also need to be finalized. That's another story I can save for later.
 

wjgjr

Active Member
May 11, 2020
1,064
803
Silver Spring, MD
This was an AHJ rule. This is taken from the rejection letter:

The maximum battery size is determined by both the discharge (kW) and the capacity (kWh). The discharge (kW) is limited to 150% of the PV generating capability. In this case, the proposed PV system has a CEC-AC rating of 6.35 kW, so the battery discharge cannot exceed 9.525 kW. With (2) battery units, they discharge 10 kW total. Please reduced the battery units to one.

I've made a request with Tesla to only increase the solar enough so we can have 2 PWs. As much as we'd love to max out the roof, there are additional pre-construction costs looming that also need to be finalized. That's another story I can save for later.
The rule makes it seem like it might be even easier to meet since you do not need to add 0.475 kW, but only 2/3 of that, so potentially even fewer than the 8-9 shingles I was guessing before, depending on where they can fit it orientation-wise. You would think this would be simple for Tesla since it seems like there is room left, and they will, of course, charge you more for the extra shingles.
 
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GoGoGoMach5

Member
Mar 11, 2020
17
4
Southern California
The rule makes it seem like it might be even easier to meet since you do not need to add 0.475 kW, but only 2/3 of that, so potentially even fewer than the 8-9 shingles I was guessing before, depending on where they can fit it orientation-wise. You would think this would be simple for Tesla since it seems like there is room left, and they will, of course, charge you more for the extra shingles.
From your post to God's ears, the next time Tesla reduces the price of our project will be the first (and probably the only time). ;)
 
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