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Disappointing Power Generation, and I need help with analysis of pypowerwall output please!

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Regarding PVwatts,

It is really useful. Note a couple of things:

  1. You can set the STC watts -- just multiply the number of panels in the string * 400 watts/panel (in your case.)
  2. Default PVwatts shows average generation each month for your location/azimuth/inclination but you can change the setting to get *by the hour*. It is a lot of data, so have your spreadsheet skills handy.
Thanks, I see the "Hourly" button now, I will def download and plot this out.
 
Thanks, I see the "Hourly" button now, I will def download and plot this out.

Have fun. I say this sincerely -- I enjoy spreadsheets.
Pivot tables and the AVG function are your friend. Trying to graph without them is going to give you very noisy data.

One other point to know:
Inverters have a cut-off voltage for each channel. It varies by manufacturer but somewhere in the range of 50 - 150v rings a bell. Don't be surprised if your NW and NE panels are shut-off for most hours of the day. I'm disappointed in Tesla for not sharing reasonable generation expectations for the panel setup they designed.
 
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FWIW I have a 10.5 kW system and all panels are basically S with 2.5 kW NW. 45 kWh is about as good as it gets. Last June I did have 3 days that got 48, but that was rare.

While the NW panels do better obviously during the summer months, they heat just about negates their input. My peak production is around 6 kW and I don't think I have every seen it at above 7, and that is not often. I have three inverters so I have no clipping.

So if you have clipping then I suspect they could move some panels around at bit to other inverters, but it kind of sounds like with your orientation, you are getting what you should get.
both yours and OP generation seem low to me.
I have 11.8 kW system. Little over half face E, the rest W. I've been above 70 kWh every day this month except for days with clouds. The past 5 days have been 100+ and I'm still above 70 kWh. It was 101 yesterday and I produced 72 kWh. My best day in May was 74
 
...

As for optimal performance, the Bay Area’s current heat wave is not the best for solar. I believe ambient temperatures ideally should be 60-70 degrees (as poster above said), as rooftop temperatures are another +20 degrees. Basically the weather now is too hot for peak efficiency, but that only loses a few percentage points.
I have Micros so I can monitor inverter/panel temps. Right now, Ambient is about 18C and inverter/panel is at 41C. I have seen 50C on warmer days but need to check again when ambient 30C
 
both yours and OP generation seem low to me.
I have 11.8 kW system. Little over half face E, the rest W. I've been above 70 kWh every day this month except for days with clouds. The past 5 days have been 100+ and I'm still above 70 kWh. It was 101 yesterday and I produced 72 kWh. My best day in May was 74
Wow. That is impressive. I have three independent systems done years apart and they mostly put out about the same power per square foot, with the exception of the one that has some panels NW.

Now I am jealous. :(
 
FWIW I have a 10.5 kW system and all panels are basically S with 2.5 kW NW. 45 kWh is about as good as it gets. Last June I did have 3 days that got 48, but that was rare.
Perhaps you are correct but that is far below what I get on a 9.5kW system. Granted, all my panels are facing South / Southeast but last Friday I produced 70+ kWh and I regularly get into the high 60s this time of the year (Northern Calif.)
 
They fubar’d your panel wiring.
The standalone inverter is 3.8kW; the Powerwall Plus inverter is 7.6kW. This is all Tesla equipment (I thought they didn't use microinverters?).

10 panels are north east facing
4 panels are north west facing
5 panels are south east facing
5 panels are south west facing

The only shaded panels would be the 4 north west panels. These are on the garage roof, which is shaded by the second floor in the afternoon. There is no shading from trees or adjacent structures

By eyeballing the roofline, I would guess all panels are 40 degrees from horizontal.
I would assume 37 degrees, 10/12 pitch.

They fubar’d your array wiring design. All four arrays should be on individual mppt controller. Between mppt and inverter is a buck/boost circuit as voltage needs to be equal from all four arrays before going to the inverter. Ideally everything is same azimuth and pitch, and each string is equal panels; then buck/boost circuit has nothing to do. There will be very minor losses due to heavy buck/boost.

This is why I like micro inverters, designers and installers can’t screw it up.
 
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..
Did you take a look at the string information I printed in the original post, does it look normal? I am really curious what string A's status means when it says "Connected: false". Does this mean there is no string there, and it's an unused input?
Correct, not connected.

A single string should be 10 amp and around 37-40 volt/panel at optimal mppt voltage. There is an indicator pypowerwall output if a input is bonded together, the inverter can detect that. So you should post full output.
 
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Open a chat session and ask for the plans again. I had mine in my account before the chat session was even over.
I'd love to chat with Tesla, but the chat button doesn't appear in my account (?!?). When logged into the website in a browser and I find a chat link, it brings me to the Tesla home page. Also int he app, the "Request Support" button does not appear. I've loaded the app on both Android and IOS phones, and it is the same; however, my coworker has what appears to be the same version of the app (latest), and the "Request Support" button appears on his app. Not sure what's going on, but it's frustrating getting support.
 
both yours and OP generation seem low to me.
I have 11.8 kW system. Little over half face E, the rest W. I've been above 70 kWh every day this month except for days with clouds. The past 5 days have been 100+ and I'm still above 70 kWh. It was 101 yesterday and I produced 72 kWh. My best day in May was 74
That is my feeling as well, although my only detailed data point is my coworker. He has a 8.8kW system also in the Bay Area, and for most of this month he is producing ~65kWh per day. When we compare our arrays side by side on our apps, mine is ~45kWh on days when his is ~65kWh. It's nice to get more data points, much appreciated!
 
The standalone inverter is 3.8kW; the Powerwall Plus inverter is 7.6kW. This is all Tesla equipment (I thought they didn't use microinverters?).

10 panels are north east facing
4 panels are north west facing
5 panels are south east facing
5 panels are south west facing

The only shaded panels would be the 4 north west panels. These are on the garage roof, which is shaded by the second floor in the afternoon. There is no shading from trees or adjacent structures

By eyeballing the roofline, I would guess all panels are 40 degrees from horizontal.
It's all about expectation, not saying nothing wrong with your system. What did Tesla quote you for estimated annual production? Sometimes if your roof is not ideal or perfect for solar then you would get a less optimal system to get the energy you ask for. I have a small system of 6.5 kW because my annual consumption is under 7000 kWh and Tesla told me the system they designed for me would be good for that. My solar cells are all East facing (Azimuth 80) because my all 4 planes of roof are East/West facing, there are quite a few 60 ft tall pine trees 20 ft away staring down my South and West facing roof so Tesla said it is better to have everything facing East to maximize my production. My one year production since PTO is above Tesla estimate but a little below PWwatts estimate, but PWwatts only deal with historical data within an area, they have no clue about shades. So as Tesla told me, as long as my annual production is at or above what they told me the system is fine. I know, some people may say I could have gotten more and paid less, probably true but I signed up for what I was promised. I also come to believe that 85% output (sustain output for at least 30 minutes, not spikes, because I get minutes of spikes for over 7.2 kW) of my system in kW is about as good as it gets with my location and weather, of course I also heard people from this forum they get 100% output all the time, good for them, maybe they live in a lab.

Having said that, I think it is kind of strange that Tesla would give you the additional 3.8 kW inverter as the 7.6 kW inverter should be good enough for your system. Insist on getting your line diagram and find out how many strings they have on the roof and going down to your 2 inverters and work with them. They are slow but not as evil as some people think. I mentioned to Tesla on chat about inverter slow starting up in the morning after a night of drizzle for 4 occasions over a 16 months period, they contacted me numerous times and actually came out to my house 3 times to check.
 
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They fubar’d your panel wiring.

I would assume 37 degrees, 10/12 pitch.

They fubar’d your array wiring design. All four arrays should be on individual mppt controller. Between mppt and inverter is a buck/boost circuit as voltage needs to be equal from all four arrays before going to the inverter. Ideally everything is same azimuth and pitch, and each string is equal panels; then buck/boost circuit has nothing to do. There will be very minor losses due to heavy buck/boost.

This is why I like micro inverters, designers and installers can’t screw it up.
Thanks for the information. I'll correct my pvwatts input and rerun the numbers. Also, I didn't mean to imply that that I have four arrays (the installers mentioned I had two). I am not sure how many are really up there (I'd like to see the schematics), but my previous post was meant to convey that my panels are not all facing the same direction.

Responding to your other response (re: string data), just to clarify, you're saying that String A data should not show 0 current and low voltage, and showing "Connected: False" is an indicator that it is not connected properly? Sorry to belabor the point, but when I talk to Tesla next time I want to make sure I understand what's gong on. Thanks!
 
Perhaps you are correct but that is far below what I get on a 9.5kW system. Granted, all my panels are facing South / Southeast but last Friday I produced 70+ kWh and I regularly get into the high 60s this time of the year (Northern Calif.)
3/4 of mine are solar roofs. I wonder if they are not as efficient as panels? Also one is on a 45* roof which is worse during the prime production months.

Oh well. I am sure the quality of my power is better. 🙂
 
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It's all about expectation, not saying nothing wrong with your system. What did Tesla quote you for estimated annual production? Sometimes if your roof is not ideal or perfect for solar then you would get a less optimal system to get the energy you ask for. I have a small system of 6.5 kW because my annual consumption is under 7000 kWh and Tesla told me the system they designed for me would be good for that. My solar cells are all East facing (Azimuth 80) because my all 4 planes of roof are East/West facing, there are quite a few 60 ft tall pine trees 20 ft away staring down my South and West facing roof so Tesla said it is better to have everything facing East to maximize my production. My one year production since PTO is above Tesla estimate but a little below PWwatts estimate, but PWwatts only deal with historical data within an area, they have no clue about shades. So as Tesla told me, as long as my annual production is at or above what they told me the system is fine. I know, some people may say I could have gotten more and paid less, probably true but I signed up for what I was promised. I also come to believe that 85% output (sustain output for at least 30 minutes, not spikes, because I get minutes of spikes for over 7.2 kW) of my system in kW is about as good as it gets with my location and weather, of course I also heard people from this forum they get 100% output all the time, good for them, maybe they live in a lab.

Having said that, I think it is kind of strange that Tesla would give you the additional 3.8 kW inverter as the 7.6 kW inverter should be good enough for your system. Insist on getting your line diagram and find out how many strings they have on the roof and going down to your 2 inverters and work with them. They are slow but not as evil as some people think. I mentioned to Tesla on chat about inverter slow staring up in the morning after a night of drizzle for 4 occasions over a 16 months period, they contacted me numerous times and actually came out to my house 3 times to check.
I realize it is about expectation, but I am also worried that it wasn't installed properly. Some backstory: on the last day the installers were on-site, the foreman said he was finished at 1PM, then the whole team proceeded to hang around for an additional 1.5 hours, crawling all over the roofs again, checking this and that. It turns out that the panels weren't outputting what he expected (he didn't give me a number he was expecting though) and they couldn't figure out why. He said he would return on a very sunny day and retest - but he never returned, there was never another visit scheduled to check this out. Next came commissioning, then inspection, then PTO. So I've been thinking that there could be something wrong with the installation since then. Since Tesla won't help check it out at this point, I'm trying to determine on my own (with the help of all the folks here) whether or not there is indeed something that is installed incorrectly, which could bite me in the a$$ later. If it turns out that everything is installed properly, and 45kW per day is the best I can expect, then I will be satisfied.

Having said all that, the only "promise" I can find in my docs is the Interconnection Agreement, which states 12774 kWh. I'm pretty sure this is a conservative number, but I guess this is the minimum they promise. The last customer service person I spoke to told me that they expected my arrays to produce 1500 kWh in June. It looks like it won't reach it.

I am not sure about the inverters either, all of this is new to me.

Thanks for your help!
 
I realize it is about expectation, but I am also worried that it wasn't installed properly. Some backstory: on the last day the installers were on-site, the foreman said he was finished at 1PM, then the whole team proceeded to hang around for an additional 1.5 hours, crawling all over the roofs again, checking this and that. It turns out that the panels weren't outputting what he expected (he didn't give me a number he was expecting though) and they couldn't figure out why. He said he would return on a very sunny day and retest - but he never returned, there was never another visit scheduled to check this out. Next came commissioning, then inspection, then PTO. So I've been thinking that there could be something wrong with the installation since then. Since Tesla won't help check it out at this point, I'm trying to determine on my own (with the help of all the folks here) whether or not there is indeed something that is installed incorrectly, which could bite me in the a$$ later. If it turns out that everything is installed properly, and 45kW per day is the best I can expect, then I will be satisfied.

Having said all that, the only "promise" I can find in my docs is the Interconnection Agreement, which states 12774 kWh. I'm pretty sure this is a conservative number, but I guess this is the minimum they promise. The last customer service person I spoke to told me that they expected my arrays to produce 1500 kWh in June. It looks like it won't reach it.

I am not sure about the inverters either, all of this is new to me.

Thanks for your help!
As I said, wait till you get your line diagram to spot anything obvious, though I find it strange with your extra 3.8 kW inverter. June is not a good benchmark for the Bay Area because of the heatwave, my May production looks to be better than June. It is worrisome but you do not have to resolve all the problems now as Tesla will probably tell you to call them back after a year if you do not get 12774 kWh in a year. Your production sounds kind of low to me but that is not knowing all the details, your roof planes do not seem to be optimal for solar either, without seeing them. Your NE and SE seem to contribute to your peak production from 10am to 2pm this time of the year if it is not too hot in the valley, the rest may extend your production in the afternoon but would not contribute to the peak.
 
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Thanks for the information. I'll correct my pvwatts input and rerun the numbers. Also, I didn't mean to imply that that I have four arrays (the installers mentioned I had two). I am not sure how many are really up there (I'd like to see the schematics), but my previous post was meant to convey that my panels are not all facing the same direction.

Responding to your other response (re: string data), just to clarify, you're saying that String A data should not show 0 current and low voltage, and showing "Connected: False" is an indicator that it is not connected properly? Sorry to belabor the point, but when I talk to Tesla next time I want to make sure I understand what's gong on. Thanks!
You have panels of four azimuths, Each azimuth should be separate array on individual mppt. I don’t know how to be more clear.

Come on man!