Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • The final cut of the 9th episode of the Tesla Motors Club Podcast, featuring Balazs Biro, of the prominent Hungarian EV channel Villanyautósok, is now available. You can watch it now on YouTube or listen to it on all major podcast networks.

Sudden drop of production on sunny day

hi folks, there are occasional times across multiple days where there is very low production while it is sunny and no cloud at all. My 6,12kw system should produce more than 3kw at 10am. But this morning it shows only 1.5kw while there are absolutely no cloud or fog at all. This happened also a couple of times in the morning around the same time on some other days (not all days though) and at noon sometimes. Would Tesla be able to run some troubleshooting remotely to make sure all panels are functioning properly?
 
It would probably be helpful to post screenshots from the app to help visualize the issue. Is this a new install where this has been happening, or one that was working as expected for a time and just began having this issue?

With the size of the system, I am guessing it is only one inverter. What kind of inverter is it? It sounds like the problem could be consistent with one string (or one inverter, if multiple) having an issue - either with it not working or with its generation not being reported to the app.

I would definitely contact Tesla as soon as you confirm there is an issue. Unfortunately, their support can be very slow, especially if it turns out they need to come on site for repairs, so it makes sense to get in line. If it ends up being something they or somebody on this forum can figure out how to fix without a visit, then that is just a bonus.
 
It would probably be helpful to post screenshots from the app to help visualize the issue. Is this a new install where this has been happening, or one that was working as expected for a time and just began having this issue?

With the size of the system, I am guessing it is only one inverter. What kind of inverter is it? It sounds like the problem could be consistent with one string (or one inverter, if multiple) having an issue - either with it not working or with its generation not being reported to the app.

I would definitely contact Tesla as soon as you confirm there is an issue. Unfortunately, their support can be very slow, especially if it turns out they need to come on site for repairs, so it makes sense to get in line. If it ends up being something they or somebody on this forum can figure out how to fix without a visit, then that is just a bonus.
Thank you so much for your reply.
It is a new system that I had been monitoring for a couple of days.
It is a 6kw system. The inverter is in the white glass box. I have a spec attached.
 

Attachments

  • inverter.PNG
    inverter.PNG
    573.6 KB · Views: 74
Thank you so much for your reply.
It is a new system that I had been monitoring for a couple of days.
It is a 6kw system. The inverter is in the white glass box. I have a spec attached.
It looks like you have one of the new Tesla inverters. Unfortunately, if you look around these forums, you will see other reports of issues with these inverters, and that could explain what you are seeing. A screenshot of the app itself (showing the solar production for the day, with the dips) might help. But I would contact Tesla - if you have PTO you may need to go through support. If you do not yet have PTO, you might also try contacting your installer and/or Tesla advisor. However, you may be told that they won't investigate until you receive PTO.
 

MorrisonHiker

Well-Known Member
Moderator
Mar 8, 2015
10,547
10,570
Colorado
If things are as you stated, yes, something is not right. I just looked at my so called 4kW system producing 2.3kW at 10AM, sun finally fully out and shining.
It doesn't produce 4 kW all day, every day. Typically if you have 4 kW of panels, your system might produce 4 kW around solar noon during the longest days of the year. What is your system producing at solar noon? If you review past days, you should see that it produces more kWh per day as the days get longer and has higher peak kW production as well. Once days start getting shorter, your peak production kW will be less and the total kWh per day will decrease as well.

Also, depending on the orientation of the panels, it might never hit 4 kW or it could generate more than 4 kW. Our 20.5 kW system often hits 22 kW around solar noon if it's not too hot out but typically these days we are maxing out at 18 kW.
 
It doesn't produce 4 kW all day, every day. Typically if you have 4 kW of panels, your system might produce 4 kW around solar noon during the longest days of the year. What is your system producing at solar noon? If you review past days, you should see that it produces more kWh per day as the days get longer and has higher peak kW production as well. Once days start getting shorter, your peak production kW will be less and the total kWh per day will decrease as well.

Also, depending on the orientation of the panels, it might never hit 4 kW or it could generate more than 4 kW. Our 20.5 kW system often hits 22 kW around solar noon if it's not too hot out but typically these days we are maxing out at 18 kW.
Mine is 6kw and peak is about 5kw at 1:30pm. Right now only 2.5kw at 1pm. Hope it is the issue with inverter not the panel, making it easier for the maintenance folks to fix the problem.
 
It looks like you have one of the new Tesla inverters. Unfortunately, if you look around these forums, you will see other reports of issues with these inverters, and that could explain what you are seeing. A screenshot of the app itself (showing the solar production for the day, with the dips) might help. But I would contact Tesla - if you have PTO you may need to go through support. If you do not yet have PTO, you might also try contacting your installer and/or Tesla advisor. However, you may be told that they won't investigate until you receive PTO.
Thank you so much. I do not have pto yet although city has inspected it. Hope it is the inverter instead of the panels.
 

Attachments

  • Screenshot_20210407-125608_Tesla.jpg
    Screenshot_20210407-125608_Tesla.jpg
    64 KB · Views: 72
I called the service adviser and he told me since I do not have PTO and not officially turn on the system now, the reporting from the app may be wrong. He asked me to wait until PTO and check again. I guess I will have to wait until PTO. Not sure if PTO and some official activation will make a difference at all.
 
I called the service adviser and he told me since I do not have PTO and not officially turn on the system now, the reporting from the app may be wrong. He asked me to wait until PTO and check again. I guess I will have to wait until PTO. Not sure if PTO and some official activation will make a difference at all.
I have a similar issue, did yours get resolved?
 
I think I'm having the same problem. 8.16kW system installed last month with Tesla inverter and 2 Powerwalls on south facing roof, no shade or obsructions. Today no clouds, temp is 77F, at peak 12:30pm system maxed out at 3.8kW. Been maxing out at 3.8-4kW since beginning of month. Not enough power generation to fully charge PW every day.
 
I think I'm having the same problem. 8.16kW system installed last month with Tesla inverter and 2 Powerwalls on south facing roof, no shade or obsructions. Today no clouds, temp is 77F, at peak 12:30pm system maxed out at 3.8kW. Been maxing out at 3.8-4kW since beginning of month. Not enough power generation to fully charge PW every day.
How many % of PW you draw down every night? I assume you run AC off PW as well since you are in LA. It is hard to compare system since every house and location is different. I have a 6.5 kW East facing solar roof with 2 PWs, TEG2 and Tesla inverter. Got PTO end of March but system only turned on for a week, my best day was last Thursday which was sunny all day, I got 37.3 kWh from the roof and sent 15.2 kWh surplus to grid, would have sent more back to the grid if I did not charge my car. I have no AC and PW is drawn down 30% every night and usually charged up to 100% best time by 10:30am or worst time by 1:30pm. Best continuous output I’ve seen so far is 5.2 kW for at least 30 minutes, I’ve seen strange spikes of up ti 6.9 kW for a brief second or 2. What does PVWatts say your output would be for your roof?
 
Tesla estimated yearly production of 13,800kWh from install, PVWatts estimates 13,100kWh. Max daily production is only 27-29kWh rather than what should be daily avg of 38kWh for April.

I haven't run AC at all this year. PW draws down to about 50% every night, but solar can only recharge it to 90-95% before solar stops production, so over time PW drains daily overall. Add in a cloudy day and PW won't even get charged to 80% from solar.
 
Tesla inverter is installed inside garage, ambient temp 77F. Using an infrared thermometer, heatsink near fan on inverter shows temp of about 48-49C. Watercooler tubing temps vary 49-53C. The fan rarely turns on, when hot leg of tubing was at 53.5C, and when it does only for about 15 seconds.
 
Tesla estimated yearly production of 13,800kWh from install, PVWatts estimates 13,100kWh. Max daily production is only 27-29kWh rather than what should be daily avg of 38kWh for April.

I haven't run AC at all this year. PW draws down to about 50% every night, but solar can only recharge it to 90-95% before solar stops production, so over time PW drains daily overall. Add in a cloudy day and PW won't even get charged to 80% from solar.
I hope you can get Tesla to check on your system, it does sound kind of low especially on a clear sunny day. My worst day is 50% production of the best day but it was a cloudy foggy day all day. Have you looked at the individual strings output to see if there’s any clue on a bad string?
 
I think I'm having the same problem. 8.16kW system installed last month with Tesla inverter and 2 Powerwalls on south facing roof, no shade or obsructions. Today no clouds, temp is 77F, at peak 12:30pm system maxed out at 3.8kW. Been maxing out at 3.8-4kW since beginning of month. Not enough power generation to fully charge PW every day.
What size inverter/s how many? Normally you wouldn't see anything close to system rating until May, sun is higher and more solar energy. Unless, DC to Ac ratio is high, 1.3 or more?
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top