sudden drop in production every day in the mid-afternoon

[squashmeister]

Hello,

I have a 15 kW system that was consistently producing 100-106 kWh daily in Phoenix. Last weekend I noticed a sudden instantaneous drop in the solar generation. Similar pattern has been repeated every day since then. Around mid afternoon, a little before 2 pm, there will be a sudden instantaneous drop in solar production. I have attached plots for 2 different days below.

System description: 14.96 kW system. 2 Tesla inverters (7.6 kW). Neurio installed in electrical panel.

Has anyone run into similar issues ? Would appreciate any tips to help figure out if this is a hardware issue, Neurio wiring issue or a software glitch in the app. The fact that it happens around the same time every afternoon seems highly suspicious. I have reached out to Tesla, but they cant come here until the end of the month.

 

[Mardak]

Suspiciously the kW reported amount drops at 2pm seems to be half of what it probably would normally display. That halving seems to continue until 4pm when it doubles back to the expected amount. Do you have access to both inverters during that time to see what they're reporting?

 

[Zabe]

Can you post screenshots of your usage from the grid? If your grid usage is spiking you probably have an inverter going out, if not you likely have a metering issue.

 

[squashmeister]

Suspiciously the kW reported amount drops at 2pm seems to be half of what it probably would normally display. That halving seems to continue until 4pm when it doubles back to the expected amount. Do you have access to both inverters during that time to see what they're reporting?

I have not tried logging into the inverter.. but thats probably a great idea. I will try that

 

[squashmeister]

Can you post screenshots of your usage from the grid? If your grid usage is spiking you probably have an inverter going out, if not you likely have a metering issue.

Here is the data from yesterday. The grid usage also appears to drop at the same time, so I am beginning to think it is a metering issue as you said.

 

[Zabe]

It looks to me like your pushing energy out to the grid and it drops when your production drops which would make sense if one inverter is shutting down. I would not expect your home usage to drop by half at the same time though, unless you have some load cycling off at the exact same time which is unlikely, NVM your in Phoenix your AC will be running full blast

 

[Zabe]

If you have hourly usage data posted by your utility check it, they will very likely not have a metering issue and you can compare it to some previous days and determine if your solar is dropping off or not.

 

[squashmeister]

If you have hourly usage data posted by your utility check it, they will very likely not have a metering issue and you can compare it to some previous days and determine if your solar is dropping off or not.

Great idea. checked the utility data.. their data also seems consistent with the fact that production drops off mid-afternoon. Have posted screenshots for 2 different days (one before the problem, and one after)

 

[jjrandorin]

Based on what some others have posted here, if I had to guess, it would be an inverter issue with one of your inverters overheating or something.

 

[Zabe]

Yup looks like an inverter is dropping off.

I don't have solar but I did stay in a holiday in express once

 

[scotsmanswan]

This may also be related the fires out to the East which will be reducing potential solar production. I have seen materially less production in afternoon for last week or so as a result but it’s less of a sharp decline on my end. Perhaps the smoke change that seems to happen early afternoon with the winds and high heat are causing inverter to shut down…

 

[squashmeister]

Thank you everyone for your helpful responses. I wanted to give an update on this issue :
The Tesla tech came today. Looked at my production data and called his superiors to escalate it to a Level 2 service call. They looked at the inverter logs and suspect it is a firmware issue with one of the inverters. They will be replacing the faulty inverter. Interestingly, the level 2 guy on the phone was familiar with this issue, i.e. he had seen other similar reports. So Tesla is apparently aware that there is a problem with their new inverters.