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11.6kw Solar Roof, but only one Inverter?

ericl

Member
Aug 19, 2021
68
25
florida
So I decided to just stop asking Tesla for the extra 3.8. I figure a 1:1 dc/ac ratio is going to decrease due to inefficiencies because the smallest one is 3.8. It just makes me crazy when I see a 8kw array with 7kw inverter in the same area as me generating more kw.
 

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h2ofun

Active Member
Aug 11, 2020
3,028
658
auburn, ca
So I decided to just stop asking Tesla for the extra 3.8. I figure a 1:1 dc/ac ratio is going to decrease due to inefficiencies because the smallest one is 3.8. It just makes me crazy when I see a 8kw array with 7kw inverter in the same area as me generating more kw.
Why, I have two 11.4K inverters with about 15kw per inverter. I basically never see clipping.
 

ericl

Member
Aug 19, 2021
68
25
florida
27 Face South, 7 face East Don't know the exact angle but looks to be between 20-30 degrees. Traditional 1960's Floridia house with low pitch roof.

As of now you are generating close to 3kw/hr but I am at 2.3kw/hr at 8:50 so I think maybe the direction of my panels + location is giving me less overall. Its pretty cloudy here today. That site you shared actually is a great resource, once I hit PTO I am going to look at the data more closely.
 

Bitslizer

Member
Jun 16, 2021
237
82
IL
Are you on the power wall+ ? The project manager for power wall said for the power wall , clipping is when it keeps spiking down and not a flat line. I specifically asked about this. I don’t know if the power wall can continuously handle 7.6kw? I previously was under the assumption it plateaus which is aligned with you.
It can handle continuous 7.7kw I have seen it occasionally spike to 7.8kw

Clipping is when the production curve plateau. You need a sunny cloudless day to truly see that as cloud edge effect can cause spikes
 

Bitslizer

Member
Jun 16, 2021
237
82
IL
As of now you are generating close to 3kw/hr but I am at 2.3kw/hr at 8:50 so I think maybe the direction of my panels + location is giving me less overall. Its pretty cloudy here today. That site you shared actually is a great resource, once I hit PTO I am going to look at the data more closely.

any update? Do you have a full cloudless sunny day smooth production curve yet? (no spikes?) I have a friend in a similar boat during the ordering process. trying to see how much clipping lost for a similar system
 

ericl

Member
Aug 19, 2021
68
25
florida
any update? Do you have a full cloudless sunny day smooth production curve yet? (no spikes?) I have a friend in a similar boat during the ordering process. trying to see how much clipping lost for a similar system
Lack of PTO means my production just stops as a certain point. So my data is not great. I am at peace of mind knowing my setup will generate the same as year 1 as year 10 and year 20 with the oversize even if there is clipping.

Also I have yet to have a smooth curve because its never not cloudy here haha. I definitely do see some plateauing at 7.6 as it hits that pretty easily at noon on a sunny day.

With only 12 days of data I am approximately.
Rainy days = ~30kw
Cloudy days = ~40kw
Semi-Cloudy = ~50kw

Highest I have gotten is 55kw.
Lowest I have gotten is 29kw.

Again data is kinda screwed up because of PTO and I am having other renovations being done. I deplete my powerwall to 10% at night and then in the morning set my AC to always on and sometimes my powerwall still hits 100% before the end of day. I work at home too.
 

OY1836

New Member
Dec 30, 2016
4
0
Boynton Beach, FL
Getting the Tesla Solar Roof installed right now. They upsized my system from 7.5kw to 11.6kw (limit for Tier 1 in Florida). I currently only have one Powerwall+ that will be installed. I thought I was going to get two because they promised a free one, but apparently the free one is the one I am already getting.

My question is, will a single inverter inside my sole Powerwall+ handle the a full load? I live in Central Florida so there are definitely days where its sunny and the majority of panels are all south facing with no shading at any time. Is it possible to get another inverter but not another Powerwall+? Or just get another Powerwall+? I just thought of this today, my project took only 1 month from contract to install so this didn't even cross my mind in the last month.

Edit - Apparently the Powerwall+ can kick into Overdrive to 12kw as just responded from my Tesla Advisor. This is done through software. Adding another inverter is not ideal as it will cause energy loss because the inverters themselves consume energy. Anyone have real world examples?
Live in FL also. My solar system is 9.52 kw. I have 3 powerwalls including one powerwall+ Have my system for about a month. NEVER get over 7.7 kw. Don't think we are getting the correct info! By the way was your project advisor Joel?
 

ericl

Member
Aug 19, 2021
68
25
florida
Live in FL also. My solar system is 9.52 kw. I have 3 powerwalls including one powerwall+ Have my system for about a month. NEVER get over 7.7 kw. Don't think we are getting the correct info! By the way was your project advisor Joel?
Eric = Powerwall Manager.
Sean = Roofing Manager.

I'm guessing you have one 7.6 too? I just cap at 7.7 and plateau for 3 hours. Inverter also has to restart for about 10 min always a little past 1pm.
 

jboy210

Supporting Member
Supporting Member
Dec 2, 2016
5,471
3,468
Northern California
Live in FL also. My solar system is 9.52 kw. I have 3 powerwalls including one powerwall+ Have my system for about a month. NEVER get over 7.7 kw. Don't think we are getting the correct info! By the way was your project advisor Joel?
Are all your panels facing due South with no shading? A 7.7 kW peak for a 9.5kW system is not bad. Also, the peak time of year for solar production is June 21, the summer solstice. Before or after that it then it will likely be less.
 

SageBrush

REJECT Fascism
May 7, 2015
12,563
16,589
New Mexico
I'm guessing a lot of that is due to ambient and panel temperatures being cooler during the day for those seasons, thus much less temperature derating, esp in New Mexico.

That is part of it; the other part is related to panel inclination. Flat roofs enjoy the sun at 75 degrees during the solar window in the summer but generation drops in the shoulder seasons when the sun is at ~ 50 degrees during the solar window, and of course generation collapses in the winter when the sun is at 30 degrees. A panel angle closer to latitude in the sun belt is best positioned for shoulder seasons.
 
Last edited:

wwhitney

Member
Nov 2, 2017
979
1,340
Berkeley, CA
That is part of it; the other part is related to panel inclination.
For ground mount solar at a fixed angle, the optimal (maximum energy production) inclination angle will be below the optimal angle on the solstice, as the rest of the year the sun will be lower in the sky. And the optimal angle on the solstice itself will be lower than the noon elevation angle of the sun, as the rest of the day the sun will be lower in the sky.

For roof mount solar, panel inclination is typically dictated by roof slope, so it's a toss up on what day the optimal panel angle for that day will most closely match the roof slope. Although for low slope roofs in the mid to upper latitudes, the panel inclination angle will likely be quite a bit lower than optimal, so then the solstice would be closest to optimal.

Cheers, Wayne
 

tdawg67

Member
Sep 21, 2021
5
0
colorado
Getting the Tesla Solar Roof installed right now. They upsized my system from 7.5kw to 11.6kw (limit for Tier 1 in Florida). I currently only have one Powerwall+ that will be installed. I thought I was going to get two because they promised a free one, but apparently the free one is the one I am already getting.

My question is, will a single inverter inside my sole Powerwall+ handle the a full load? I live in Central Florida so there are definitely days where its sunny and the majority of panels are all south facing with no shading at any time. Is it possible to get another inverter but not another Powerwall+? Or just get another Powerwall+? I just thought of this today, my project took only 1 month from contract to install so this didn't even cross my mind in the last month.

Edit - Apparently the Powerwall+ can kick into Overdrive to 12kw as just responded from my Tesla Advisor. This is done through software. Adding another inverter is not ideal as it will cause energy loss because the inverters themselves consume energy. Anyone have real world examples?
What happened in the end here? Is there really an overdrive that allows you to take in your full 11.6kw? I"m in the same boat, just installed a 12kw solar array, have 1 powerwallplus, which spec sheet says supports 7.6kw, and it is written on top of the system. My system hasn't been officially turned on but i did run it for one day to charge batteries. Solar power clipped at 7.6kW for 4 hours and this is end of september. Unless there is a hidden overdrive that is enabled, it doesn't seem like the system supports > 7.6kw.. Given i'm not approved to operate i don't know if the system is in a state that limits any potential overdrive.. Given the graph i have, i'm guessing right now i'm missing ~10-15kwH/day, and probably 20-30kwh/day in the summer if this is correct. What was the final outcome after your system was approved
 

Bitslizer

Member
Jun 16, 2021
237
82
IL
What happened in the end here? Is there really an overdrive that allows you to take in your full 11.6kw? I"m in the same boat, just installed a 12kw solar array, have 1 powerwallplus, which spec sheet says supports 7.6kw, and it is written on top of the system. My system hasn't been officially turned on but i did run it for one day to charge batteries. Solar power clipped at 7.6kW for 4 hours and this is end of september. Unless there is a hidden overdrive that is enabled, it doesn't seem like the system supports > 7.6kw.. Given i'm not approved to operate i don't know if the system is in a state that limits any potential overdrive.. Given the graph i have, i'm guessing right now i'm missing ~10-15kwH/day, and probably 20-30kwh/day in the summer if this is correct. What was the final outcome after your system was approved
No overdrive.... They would need to increase your wiring awg size and breaker size to handle the higher output, if they never did that during install....

Where are you located? All your panels face the same direction and which direction?
 

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