Any ideas why I'm seeing big drops in production?

[Shygar]

I've contacted Tesla support many times and everytime they tell me everything is working normally. However, sometimes I get these big drops from my main solar array (I have two, one that is roughly 7.5 kW of energy with a Delta Soliva 6.6 Inverter / Trina panels from SolarCity installed in Sept 2017, and the other is a 4.8 kW Tesla Inverter / Forgot the panel brand, installed in April 2023). As far as I can tell from the data, the 4.8 seems to be generating just fine, but my 7.5 seems to be getting cut in half. Today I saw it happening and happened to be home, so I went out to the inverter and got this info from the Inverter, which doesn't look right to me. You can also see my 7.5 array in the pictures that none of them are shaded at the moment. Any suggestions? It looks like my PV2 voltage is very low and I am wondering what happened.

 

[arnolddeleon]

Instantaneous readings can be misleading. When the system is doing a Maximum Power Point Tracking (MPPT) sweep it can show really voltage/current because by definition it is trying to find where the maximum power point is. You should look at energy output for a longer period of time (say a few minutes) and also your daily output.

 

[power.saver]

Possibly a broken PV wire between the panels? Or open MC conector. Maybe a wire chewed by rodents? Do you have a rapid shutdown system on that group of panels?

 

[Shygar]

Instantaneous readings can be misleading. When the system is doing a Maximum Power Point Tracking (MPPT) sweep it can show really voltage/current because by definition it is trying to find where the maximum power point is. You should look at energy output for a longer period of time (say a few minutes) and also your daily output.

Ok good to know. My Tesla energy graph showed the drop all day after it started. Normally this is a pretty normal curve.

But over the last few months it periodically looks like this and sometimes comes back later in the day, but sometimes it's a full solid curve.

 

[Shygar]

Possibly a broken PV wire between the panels? Or open MC conector. Maybe a wire chewed by rodents? Do you have a rapid shutdown system on that group of panels?

I wondered about that but I'm not sure why it would come and go, unless it's sometimes touching, which would be bad. I guess I should get up there and see what I can see just to be sure.

 

[arnolddeleon]

Ok good to know. My Tesla energy graph showed the drop all day after it started. Normally this is a pretty normal curve.

But over the last few months it periodically looks like this and sometimes comes back later in the day, but sometimes it's a full solid curve.

That's a pretty telling graph. Since you have good history production data shows the problem I would just open a support ticket in the app and reference those days.

 

[Shygar]

That's a pretty telling graph. Since you have good history production data shows the problem I would just open a support ticket in the app and reference those days.

I'll try again but I've reported it to them multiple times and still they say everything is working properly.

 

[charlesj]

Is that drop about 11AM the same each time it happens but other days there is no drop, but production is up there about 7kW
Certainly drops sharply. Can this be shading? but that would not show such a drastic drop in a short time, I would not think.
I'd go with some connection issues that are intermittent, unless it is always at 11AM or so.
Is this drop supported by history or just very recent?

 

[JSNH1919]

Could be temperature related. A cold solder joint on a panel or loose wire.
I have 25 Trina 315 watt panels on my roof. I purchased all of them broken for $50 each 3 years ago. Each one had cold solder joints between the nickel strips from the cells to the blocking diodes in the connection block on the panels. Some panels had one one had 3. I dug all the potting out and pulled on the strips any loose just pulled right up. I soldered them and replaced the diodes. All are 100% good now.

 

[Shygar]

Is that drop about 11AM the same each time it happens but other days there is no drop, but production is up there about 7kW
Certainly drops sharply. Can this be shading? but that would not show such a drastic drop in a short time, I would not think.
I'd go with some connection issues that are intermittent, unless it is always at 11AM or so.
Is this drop supported by history or just very recent?

So the last 3 days it has happened between 11 and 11:20am, like one string is just dropped for some reason. I suppose it could be heat but it's currently 72 F, so not hot at all. I also wondered if it was shading but that's why I included pictures of the panels, I don't see any shading at this time of day, and I do get some in the afternoon but it doesn't cause this big of a drop.

One other thing to mention is this would happen off and on for various periods (not necessarily all day) since I had my 4.8 kW system installed April 2023. But recently it's been doing this thing right at 11am since I restarted my whole system. I was trying to diagnose an issue with my V1 backup gateway where my ethernet just died, and since the V1's don't have a reset button, the manual says to flip off all the breakers of the whole house for 1 minute, so that's what I did, then it started doing this thing that I reported here since then. I have a tier 2 ticket open with Tesla about the ethernet issue and I submitted the low solar production too but haven't heard anything yet (although I have reported that many times in the past and was always told it was normal, which didn't make sense to me).

 

[JSNH1919]

Could the inverter be dropping out due to either low ac voltage or out of frequency range? Check the ac voltage when it is normal and when it is acting up at the inverter and on the good operating inverter. Some inverters drop out at a set point. Some time it is set in the firmware but often it can be edited. The one dropping out might be set too sensitive.

 

[CrazyRabbit]

Could be temperature related. A cold solder joint on a panel or loose wire.
I have 25 Trina 315 watt panels on my roof. I purchased all of them broken for $50 each 3 years ago. Each one had cold solder joints between the nickel strips from the cells to the blocking diodes in the connection block on the panels. Some panels had one one had 3. I dug all the potting out and pulled on the strips any loose just pulled right up. I soldered them and replaced the diodes. All are 100% good now.

Probably the diodes shorted, causing the solder to melt while still on roof. Emi from lightning strike can cause that. I know!
Did you repot the diodes? I did!!!

 

[dtouma]

So the last 3 days it has happened between 11 and 11:20am, like one string is just dropped for some reason. I suppose it could be heat but it's currently 72 F, so not hot at all. I also wondered if it was shading but that's why I included pictures of the panels, I don't see any shading at this time of day, and I do get some in the afternoon but it doesn't cause this big of a drop.

One other thing to mention is this would happen off and on for various periods (not necessarily all day) since I had my 4.8 kW system installed April 2023. But recently it's been doing this thing right at 11am since I restarted my whole system. I was trying to diagnose an issue with my V1 backup gateway where my ethernet just died, and since the V1's don't have a reset button, the manual says to flip off all the breakers of the whole house for 1 minute, so that's what I did, then it started doing this thing that I reported here since then. I have a tier 2 ticket open with Tesla about the ethernet issue and I submitted the low solar production too but haven't heard anything yet (although I have reported that many times in the past and was always told it was normal, which didn't make sense to me).

I've been having the same exact problem! Around noon or 11:30 I lose one string and it's the same string every time. Some days it will stay active, most of the time it shuts down at noon. If I power off and back on the inverters the string comes back and stays active the rest of the day. I finally was able to convince Tesla tier 1 support this issue needs to be escalated to tier 2 since it is NOT normal. Once that happened tier 2 setup an onsite appointment to check the system in person. My guess is a bad MCI since I've had this problem before.

 

[charlesj]

So the last 3 days it has happened between 11 and 11:20am, like one string is just dropped for some reason. I suppose it could be heat but it's currently 72 F, so not hot at all. I also wondered if it was shading but that's why I included pictures of the panels, I don't see any shading at this time of day, and I do get some in the afternoon but it doesn't cause this big of a drop.

One other thing to mention is this would happen off and on for various periods (not necessarily all day) since I had my 4.8 kW system installed April 2023. But recently it's been doing this thing right at 11am since I restarted my whole system. I was trying to diagnose an issue with my V1 backup gateway where my ethernet just died, and since the V1's don't have a reset button, the manual says to flip off all the breakers of the whole house for 1 minute, so that's what I did, then it started doing this thing that I reported here since then. I have a tier 2 ticket open with Tesla about the ethernet issue and I submitted the low solar production too but haven't heard anything yet (although I have reported that many times in the past and was always told it was normal, which didn't make sense to me).

It is very strange it happens around 11 AM, not at 9 or 1PM or 2:30PM, all over the place.
There may have been another poster some time back with similar events at the same time when it happened. Forgot who or how it was fixed.
Bummer.

 

[dtouma]

It is very strange it happens around 11 AM, not at 9 or 1PM or 2:30PM, all over the place.
There may have been another poster some time back with similar events at the same time when it happened. Forgot who or how it was fixed.
Bummer.

Yea really weird and seems to be right around noon. Between 11:30 and 12:30 for me. Graph looks like this.

 

[charlesj]

Yea really weird and seems to be right around noon. Between 11:30 and 12:30 for me. Graph looks like this. View attachment 1056890

It is not natural, no ripple going down caused by small weather conditions as the rest of the edges show.
Tesla needs to see this especially it repeats like this. Mark the dates and tell them to check those dates out and if it doesn't happen in a day and graph is nice ask them why, you want an answer.

 

[Patrick66]

Do you have optimizers on that string? It looks like overheating electronics to me.

 

[JSNH1919]

Probably the diodes shorted, causing the solder to melt while still on roof. Emi from lightning strike can cause that. I know!
Did you repot the diodes? I did!!!

Yes I repotted the diodes. It was about a half hour of work for each panel. Diodes were just over $1 each and the potting compound was about $5 each. I went with the same type of professional potting compound we use at work. Stuff works great.

 

[BGbreeder]

Yes I repotted the diodes. It was about a half hour of work for each panel. Diodes were just over $1 each and the potting compound was about $5 each. I went with the same type of professional potting compound we use at work. Stuff works great.

What type/brand of potting compound did you use?

BG

 

[jjrandorin]

Yea really weird and seems to be right around noon. Between 11:30 and 12:30 for me. Graph looks like this. View attachment 1056890

When my graph looked like that, it ended up being a lost string of panels. The difference in mine is, it looked just like that, and production never returned to previous levels. I had noticed my production seemed low, and I went looking through the data on the tesla app for previous months, previous years etc.

After a bit of digging, I was able to find the date that my production dropped. It looked exactly like that graph, but as I mentioned it never returned back to previous levels.

Tesla came out and found a wire that was too taunt that had slightly pulled out of its connection, over time. The tech they sent out was a repair tech, and he repaired the connection. He then told me that they needed to retrofit some other connections on my roof, and he was gonna put in a ticket for that.

Since my production returned to normal after he fixed the wire, I just said "sure, no problem". Like 2 months later, I got a call from scheduling for the solar / PV install crew to come out. They showed up about 2 days from that call I received, and replaced some connection on every panel thats on my roof (I have 34 panels but they are like 250w or something).

Anyway, that definitely looks like a physical issue. Hope you get it resolved.