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Decreased production since April - What happened?

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Hoping some of the experts can provide some insight here. I'm trying to include lots of information, as I see that often requested here. Happy to provide more info if needed, just let me know what I can do.

I've submitted a service request with Tesla, and it is an ongoing saga now going on second month. After 2 visits (detailed below), and a Tier 2 escalation, I was told that "everything is operating normally", which I refused to accept, petitioned, and it is being reviewed again.

System: 9.36kW solar roof with 2 Tesla PW. Tesla Inverter 7.6kW. Estimated year 1 production 11870kWh

Tesla Solar Roof Panel Layout.jpg


Tesla Solar Roof Permit - blacked out.jpg


The first picture is my production on April 3, the last day that the system was normal. It was peaking at 6.7kW on my 9.36kW system, with 46.5kwh total production which is consistent with what I had previously on clear days. This is a representative curve for the latter days in March where there was no cloud cover.
1654632853085.png


Starting April 4th, on clear sky days, there were sudden dips happening in the mid morning, with peak production subsequently maxing out around 5kw. This curve happened repeatedly for about a week.
1654632886106.png


When this was happening, I logged into the inverter and it said there were errors with String 3 not being online. Later, I was able to log in to the inverter again and find String 3 was online, but I dont know that numbers I'm supposed to be seeing. This is what it looked like today, at mid-day (highest peak production), still in a limited state.

Inverter june 6.jpg


The technician that stopped after my first service request by confirmed there was a problem with string 3 when he logged into the inverter, but he couldn’t get onto the roof by himself. He said he had to put in a request for a roof team to come by.

A few weeks later, the roof team showed up while I wasn't home, apparently not reading any case file or knowing what they were looking for. My wife at home simply told them production was low, and to call me. They apparently went on the roof, pulled some things up, and called and simply told me that production was low (but not "too" low) and they had to escalate it.

Clearly there is something wrong.

Since April 4, I have not had a day with total generation over 40kWH. Before this day, the norm in a clear day was mid 40 kWH, with this time of year increasing in production given my solar layout. In fact, my daily generation should be approaching 50kwh per day with the system peaking in the 60+kWh/day range.

On a clear day I am still only getting 38kwh
1654633299056.png



This is my historic production back in June last year when the system went online
1654633332199.png



The last contact I had from Tesla was that it was reviewed by a Tier 2 person and pushed back saying everything was working in order. Thats clearly not the case, and I argued with the Energy customer support person that it wasn't right, and she agreed to send it to another Tier 2 team. She said they would only expect to have a 0.5% decrease in production per year.

I'm hoping to better understand the problem so that I can continue to push to get this fixed if they come back saying things are still "OK"

Thanks so much in advance!
 
Certainly seems like there is an issue just by the peak power drop. I'm not too familiar with the solar roof but the currents and voltages you are reading also seem off to me too.

Can you post a higher resolution pic of your electrical plans? At the bottom it should show the expected currents and voltages at the max power point.
 
Are you still getting errors when you log into the inverter? Does the inverter keep track of production for each string independently? This would allow you to at least isolation string 3 as the cause of the production issue. They need to come out and fully test out string 3. I would demand they set up a timed appointment when you can be there.

I was very wary of solar roof for multiple reasons in my climate (mostly our propensity for ice dams in MN) but its also much more difficult to diagnosis and repair when you have issues with so many solar tiles in each string. With my microinverter system, I can see production from each panel so its much easier to diagnose production issues.
 
Outside of the screenshot I showed, Im unaware of additional information that I can extract from the Tesla Inverter when I log into it. I have not seen recurrence of the "String 3: Not Connected" on the random times I've checked since
 
So it looks like you have 5 total strings: a 40 tile and a 39 tile strings on your SE roof, a 27 tile string on your SW roof, and two 27 tile strings on your NE roof.

The wiring between the inverter and roof on your engineering plans in the to right corner seems to be inconsistent with what the notes on the bottom indicate in terms of the voltages and currents expected on each wire. It's hard to tell what's supposed to be going on.

Did you always only have 3 strings hooked to the inverter? Do you have any shading on your roof when you took the screenshot of your inverter output? You said midday - is that before or after solar noon?
 
So it looks like you have 5 total strings: a 40 tile and a 39 tile strings on your SE roof, a 27 tile string on your SW roof, and two 27 tile strings on your NE roof.

The wiring between the inverter and roof on your engineering plans in the to right corner seems to be inconsistent with what the notes on the bottom indicate in terms of the voltages and currents expected on each wire. It's hard to tell what's supposed to be going on.

Did you always only have 3 strings hooked to the inverter? Do you have any shading on your roof when you took the screenshot of your inverter output? You said midday - is that before or after solar noon?
The midday inverter shot was right around 12:15, when the generation has been peaking lately.

I admit that I dont know what the inverter output was at this time last year when the system seemed to be working as advertised. Based on what you were saying, I'm now questioning if Strong 4 , which says "Not connected" should also be connected?

This is what the wiring in the inverter looks like
IMG_3027.jpg
 
The midday inverter shot was right around 12:15, when the generation has been peaking lately.

I admit that I dont know what the inverter output was at this time last year when the system seemed to be working as advertised. Based on what you were saying, I'm now questioning if Strong 4 , which says "Not connected" should also be connected?

This is what the wiring in the inverter looks like View attachment 814435
Well it looks like you have wires connected to all four inputs. The plans unfortunately show one of the connections goes to nothing but if you look at the notes 14 & 15 it implies going to the 40 tile string (given the voltage and current specified in the note) but given the inconsistencies in the design drawing I'm hesitant to believe anything on it.
 
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Does your Tesla Solar Roof contract include any language to the effect there is a monitoring or production guarantee?

For example, here's my contract with Sunrun. I have no guarantee for any lost production. In the event that Sunrun just shrugs and says "screw it" without providing service, it'd be in my best interest to get things fixed through another means. Luckily I've never had to do this.
1654748542792.png


If I were you, I'd look into getting someone out to my house who can diagnose the issue (even if it's on my own dime). Assuming Tesla has stopped being helpful, you should prioritize getting thigs diagnosed / fixed ASAP.

I could file and likely succeed with a small claim to get a few hours of electrician time re-paid due to a CA Licensed installer's failure to execute their warranty per their agreement.

I could file and likely fail with a small claim to get a few months of lost solar production back.

If you're near East Bay Northern California I can put you in touch with someone that knows solar and is a licensed electrician.
 
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From Inverter photo,
String 1, 348V 5.3A --> this is 40 tile, single string
String 2, 335V 5.3A --> this is 39 tile, single string
String 3, 245V 4.7A --> this is 27 tile, single string
String 4, Not connect, should be 27 tiles x 2 (parallel string)

If String 4 works properly, it should be like that,
String 4, 245V 9.4A (4.7A x 2)

Total production is, 348 x 5.3 + 335 x 5.3 + 245 x 4.7 + 245 x 4.7 x 2 = 7100W
 
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Thank you everyone for the continued help and insight. Perhaps SMao is right with String 4 being out.

I just got a note to schedule an appointment for Tesla indicating a need to evaluate and fix something (no details of course), but the first date that I'm available is next month. Since I'm generating some output, I'll wait until then to see if they fix it, and share this info with them.

Otherwise, holeydonut, I'll ping you for a consulting electrician (I'm in the Peninsula)