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New 6.78kW Solar Roof Installation in San Diego

Mar 1, 2021
118
32
San Diego, CA
Hi everyone. This forum has been a great resource as our installation occurred earlier this year.

We put in a 6.78kW solar roof, no power walls, with a delta M8 inverter.

The solar installation is complete, there are still some minor roof items that need to be cleaned up.

I am trying to figure out what kind of output I should be expecting from the system right now, I've never seen it get over 4.7kW at any given time.

This seems low to me. I have been watching the strings via the M Professional delta app, and they don't seem balanced in terms of voltage or current output.

One string is close to what I expected, the other two seem lower than I would have thought. I'm attaching a screen shot of a recent output.

Our roof was broken up into a lower section with 35 tiles, which I think is PV2, and an upper roof with 81 tiles that I expected to be a 40 and 41 tile string, PV1 and PV3. You can see that PV2 is beating the other 2 in max output by a lot, which doesn't make sense based on my assumption.

PV2 lower roof gets shade in the morning from our chimney and in the afternoon from the upper roof.
Screenshot_20210226-155214_M Professional.jpg


Has anyone else had this experience? I don't know what to do about it, I'd appreciate any advice you may have.
 

trautmane2

Member
Jul 13, 2019
226
153
Leesburg, VA
Sorry I don't have a useful suggestion to address your question - but I do have a question for you :).

Did you have to do anything special to get the string history charts to work in M Professional or with your inverter? I have a similar setup for my solar roof, but when I look at the string history in M Professional I just get empty charts. I can see realtime values on the main page and the overall inverter output charts for the current and previous days - but nothing for string history.
 
Mar 1, 2021
118
32
San Diego, CA
Sorry I don't have a useful suggestion to address your question - but I do have a question for you :).

Did you have to do anything special to get the string history charts to work in M Professional or with your inverter? I have a similar setup for my solar roof, but when I look at the string history in M Professional I just get empty charts. I can see realtime values on the main page and the overall inverter output charts for the current and previous days - but nothing for string history.

Good question! I activated the app using the "6532" code that was listed on another post, and also used that code to access my inverter every time. What access code are you using?

On my app I access it from Menu- Analysis- History- Last 10 days
Screenshot_20210301-155313_M Professional.jpg
Screenshot_20210301-155316_M Professional.jpg
Screenshot_20210301-155324_M Professional.jpg
 
  • Informative
Reactions: trautmane2

Barrygold

Member
Jun 20, 2019
421
460
Midwest
4.7 kWh seems to be within range for your system and technically it’s still winter.

Try the PV watts calculator and compare for this time of year

PVWatts Calculator


6.7 kWh is close to most most you’ll see in the summer so I’d say you’re doing well.
 

trautmane2

Member
Jul 13, 2019
226
153
Leesburg, VA
I activated the app using the "6532" code that was listed on another post, and also used that code to access my inverter every time. What access code are you using?

Ahhh - I had activated using "6532" within the app but was still using the code printed on my inverter to connect. Switching to "6532" to connect to the inverter did the trick. Thanks!
 
Mar 1, 2021
118
32
San Diego, CA
Hi everyone. This forum has been a great resource as our installation occurred earlier this year.

We put in a 6.78kW solar roof, no power walls, with a delta M8 inverter.

The solar installation is complete, there are still some minor roof items that need to be cleaned up.

I am trying to figure out what kind of output I should be expecting from the system right now, I've never seen it get over 4.7kW at any given time.

This seems low to me. I have been watching the strings via the M Professional delta app, and they don't seem balanced in terms of voltage or current output.

One string is close to what I expected, the other two seem lower than I would have thought. I'm attaching a screen shot of a recent output.

Our roof was broken up into a lower section with 35 tiles, which I think is PV2, and an upper roof with 81 tiles that I expected to be a 40 and 41 tile string, PV1 and PV3. You can see that PV2 is beating the other 2 in max output by a lot, which doesn't make sense based on my assumption.

PV2 lower roof gets shade in the morning from our chimney and in the afternoon from the upper roof.
View attachment 641064

Has anyone else had this experience? I don't know what to do about it, I'd appreciate any advice you may have.

So I got more information. Be sure to request the detailed design from Tesla before they submit it for permits.

In my detailed design, string length is limited to 36 tiles due to max Voc at min temp, so they ran two 35 tile strings into PV1 from both lower and upper roof, and then split the remaining 46 tiles across PV2 and PV3 (23 each).

Screenshot_20210301-214446_Drive.jpg

Screenshot_20210301-214351_Drive.jpg


I'm confused why they didn't run each of the 35 panel sets on their own strings, with the 23 tile strings in parallel. Max efficiency is above 380V, and the 35 tiles had Vmp of 384V, so having two strings of 35 would give me max efficiency on 2 of 3 strings, instead of just one.

Any ideas? Did everyone else get this detailed design before permits?
 
Last edited:

jboy210

Supporting Member
Dec 2, 2016
4,926
3,017
Northern California
Just ran it, it shows ~29.6kWh/ day estimate in March, I'm getting~25-28 kWh, so it's close.
That is impressive. We are getting close to 20kWh/day on our 12.75 KW SolarRoof. Right now we have shading issues (60-foot tree) that reduce power generation from 11 AM-1:30 PM. That should start disappearing in a couple of weeks. We generated over 90 kWh/day in June. I was plugging in cars, our or neighbors, to find a place to put power since we were pre-PTO.
 

jboy210

Supporting Member
Dec 2, 2016
4,926
3,017
Northern California
So I got more information. Be sure to request the detailed design from Tesla before they submit it for permits.

In my detailed design, string length is limited to 36 tiles due to max Voc at min temp, so they ran two 35 tile strings into PV1 from both lower and upper roof, and then split the remaining 46 tiles across PV2 and PV3 (23 each).

View attachment 641328
View attachment 641329

I'm confused why they didn't run each of the 35 panel sets on their own strings, with the 23 tile strings in parallel. Max efficiency is above 380V, and the 35 tiles had Vmp of 384V, so having two strings of 35 would give me max efficiency on 2 of 3 strings, instead of just one.

Any ideas? Did everyone else get this detailed design before permits?

Where did this diagram come from? We don't have anything like it and have 2 Delta inverters. I would really like to know which areas of tiles feed which inverter.
 

trautmane2

Member
Jul 13, 2019
226
153
Leesburg, VA
From my experience, there were at least 3 versions of that document (quoted labels are mine):

1. "Draft Plan": the site plan posted to my Tesla account within a couple weeks of my deposit that was specific enough to get initial building permits and the like, but which had small errors or omissions because it was done by someone in Vegas using Satellite imagery and the breaker box photos I sent.

2. "Inspection Plan": the site plan that was amended after Tesla came to my property and physically inspected and measured the site. It added jurisdiction notes, fixed locations of roof vents and equipment, and omitted an irrelevant alternate electrical tie-in methods page. I only received this after my install had started and I asked my install advisor if the plan had changed.

3. "Install Plan": the site plan the installers actually use. This is the one you want and I think what @SoCalSolarRoof has. It includes the detailed string information and also the specific PV tile layout for each roof face. I never received this one electronically, but I convinced one of the install leads to let me look at it and then took photos of each page.

Of course one danger of having the details and being annoyingly detail oriented is that you start to obsess over things not done exactly to plan:
Incorrectly Placed Solar Roof Tiles
 
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Reactions: SoCalSolarRoof

jboy210

Supporting Member
Dec 2, 2016
4,926
3,017
Northern California
From my experience, there were at least 3 versions of that document (quoted labels are mine):

1. "Draft Plan": the site plan posted to my Tesla account within a couple weeks of my deposit that was specific enough to get initial building permits and the like, but which had small errors or omissions because it was done by someone in Vegas using Satellite imagery and the breaker box photos I sent.

2. "Inspection Plan": the site plan that was amended after Tesla came to my property and physically inspected and measured the site. It added jurisdiction notes, fixed locations of roof vents and equipment, and omitted an irrelevant alternate electrical tie-in methods page. I only received this after my install had started and I asked my install advisor if the plan had changed.

3. "Install Plan": the site plan the installers actually use. This is the one you want and I think what @SoCalSolarRoof has. It includes the detailed string information and also the specific PV tile layout for each roof face. I never received this one electronically, but I convinced one of the install leads to let me look at it and then took photos of each page.

Of course one danger of having the details and being annoyingly detail oriented is that you start to obsess over things not done exactly to plan:
Incorrectly Placed Solar Roof Tiles

Thanks. I will contact Tesla and see if I can get a copy of the "Install Plan". Now that you mention it, I remember seeing it during the install. If only I would have been smart enough to take a picture. ;-<
 
Mar 1, 2021
118
32
San Diego, CA
That is impressive. We are getting close to 20kWh/day on our 12.75 KW SolarRoof. Right now we have shading issues (60-foot tree) that reduce power generation from 11 AM-1:30 PM. That should start disappearing in a couple of weeks. We generated over 90 kWh/day in June. I was plugging in cars, our or neighbors, to find a place to put power since we were pre-PTO.

Wow, that's a big swing! Good to know it fluctuates. I had tree shading, we ended up cutting them down, my wife wasn't sure about it but it really opened up our side yard, so everyone is happy now!
 
Mar 1, 2021
118
32
San Diego, CA
From my experience, there were at least 3 versions of that document (quoted labels are mine):

1. "Draft Plan": the site plan posted to my Tesla account within a couple weeks of my deposit that was specific enough to get initial building permits and the like, but which had small errors or omissions because it was done by someone in Vegas using Satellite imagery and the breaker box photos I sent.

2. "Inspection Plan": the site plan that was amended after Tesla came to my property and physically inspected and measured the site. It added jurisdiction notes, fixed locations of roof vents and equipment, and omitted an irrelevant alternate electrical tie-in methods page. I only received this after my install had started and I asked my install advisor if the plan had changed.

3. "Install Plan": the site plan the installers actually use. This is the one you want and I think what @SoCalSolarRoof has. It includes the detailed string information and also the specific PV tile layout for each roof face. I never received this one electronically, but I convinced one of the install leads to let me look at it and then took photos of each page.

Of course one danger of having the details and being annoyingly detail oriented is that you start to obsess over things not done exactly to plan:
Incorrectly Placed Solar Roof Tiles

I think you're right all the way around! I asked my project advisor for it and he was cool about sending it to me. Oddly enough he had to get it from the designers, he didn't have it in my file on his side.
 
Mar 1, 2021
118
32
San Diego, CA
Thanks. I will contact Tesla and see if I can get a copy of the "Install Plan". Now that you mention it, I remember seeing it during the install. If only I would have been smart enough to take a picture. ;-<

My install team had a more detailed roof layout than I've gotten, not sure who has that! I didn't get a copy either.
 

jboy210

Supporting Member
Dec 2, 2016
4,926
3,017
Northern California
Wow, that's a big swing! Good to know it fluctuates. I had tree shading, we ended up cutting them down, my wife wasn't sure about it but it really opened up our side yard, so everyone is happy now!
We cannot cut down most trees after a certain size in our city as part of their Heritage Tree rule. If you can't put your arms around the trunk, you can't cut it. This tree's trunk is 8 feet in diameter. The arborist guessed it was over 100 years old. When we get it trimmed every 7 years or so they put 4 or 5 guys with chainsaws up there in it at once. And charge us $5,000-$10,000. It is a beautiful old-growth oak, and it the focal point of the yard so it is not going anywhere. They just need to make more efficient solar panels that work without direct sunlight.
 
Mar 1, 2021
118
32
San Diego, CA
We cannot cut down most trees after a certain size in our city as part of their Heritage Tree rule. If you can't put your arms around the trunk, you can't cut it. This tree's trunk is 8 feet in diameter. The arborist guessed it was over 100 years old. When we get it trimmed every 7 years or so they put 4 or 5 guys with chainsaws up there in it at once. And charge us $5,000-$10,000. It is a beautiful old-growth oak, and it the focal point of the yard so it is not going anywhere. They just need to make more efficient solar panels that work without direct sunlight.
Fair enough, sounds like a great part of your property. Ours didn't fit the front yard theme anyways so made sense to remove.
 

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