17kw solar production never topped 65kwh/day in August - normal? (Sunny SoCal)

[Nmtdriver]

It's been a couple months and it seems like my 17kw system should be making more. I modeled this out with pvwatts and it seems like I should still be making more than I am (been making in the 50's recently). Tesla hasn't been to helpful when I give them info from the modeling. They claimed to have done a remote diagnostic and said things are operating as they'd expect. I have 3 PWs that are almost never 100% charged, so I'm rarely ever capped (still pre-pto).

Notes:
MP1: 26 panels (400w each) = 10.4kwh @ 23 deg, 107 Azimuth
MP2: 16 panels (400w each) = 6.4kwh @ 23 deg, 287 Azimuth
When I model these out on PVwatts, I should still be making 70-80kwh/day in early October. I probably should have seen closer to 80-90/day in early august but only ever hit around 65 tops.

My friend helped me pull string data today. Looks like there are 5 strings which matches the plans. I'm assuming it's not string-inverter connections or inverter settings that are bad but probably an issue with some of the panels themselves or something aggregating the power from the panels within the strings. My brain is too smooth to figure out what to look for and call Tesla's attention to. Was hoping someone more familiar might have an idea. Would very much appreciate any help!

"Battery power level":"93%
Combined power metrics":{
"site":6,
"solar":7780,
"battery":7370,
"load":15151.25
}"Grid Power":"0.01kW
Solar Power":"7.78kW
Battery Power":"7.37kW
Home Power":"15.15kW

"String Data":{
"A":{
"Current":6.94,
"Voltage":165.70000000000002,
"Power":1136.0,
"State":"PV_Active",
"Connected":true
},
"B":{
"Current":0.0,
"Voltage":-1.1999999999999993,
"Power":0.0,
"State":"PV_Active",
"Connected":false
},
"C":{
"Current":3.62,
"Voltage":370.20000000000005,
"Power":1337.0,
"State":"PV_Active",
"Connected":true
},
"D":{
"Current":3.45,
"Voltage":370.8,
"Power":1286.0,
"State":"PV_Active_Parallel",
"Connected":true
},
"A1":{
"Current":0.0,
"Voltage":0.40000000000000036,
"Power":0.0,
"State":"PV_Active",
"Connected":false
},
"B1":{
"Current":0.0,
"Voltage":0.5,
"Power":0.0,
"State":"PV_Active",
"Connected":false
},
"C1":{
"Current":7.86,
"Voltage":266.2,
"Power":2080.0,
"State":"PV_Active",
"Connected":true
},
"D1":{
"Current":7.44,
"Voltage":266.2,
"Power":1974.0,
"State":"PV_Active_Parallel",
"Connected":true
}

 

[power.saver]

I have 3 PWs that are almost never 100% charged, so I'm rarely ever capped (still pre-pto).

Even though the PWs are not fully charged, you may still be limited in production by total current. If production exceeds the amount the PWs can charge at plus house load, then the solar will be curtailed because you are pre-PTO. This will reduce your overall production.

17kW solar is borderline for 3 PW as they typically are limited to 5kW charging each, or 15kW for you. If your house load is below 2kW this is what may be happening. You could try charging you EV during the peak of the day to increase house load and see if your production increases, or wait for PTO when you can operate you system without curtailment.

 

[taphil]

Looks like you have 5 strings, 2 of which are combined on the roof, so a total of 3 sets of wires come down to your inverter/PW+. The 400W panels peak at 37V and 10.7A.

Rough calculation:
"String 1" is a pair of strings with 11 panels each. At peak, it should generate 407V x 21.4A = 8.7kW
"String 2" is 5 panels in series. At peak, it should generate 185V x 10.7A = 2kW
"String 3" is a pair of strings with 8 panels each. At peak, it should generate 296V x 21.4A = 6.3kW
Total system is therefore about 17kW

According to your string data,
"string A" matches "string 2" above;
"string C/D" matches "string 1" above;
"string C1/D1" matches string "string 3" above.

"String 1" above isn't producing much current, 7A instead of 14A, (similar to string 3 producing 15A). My guess, based on the f*uck up with my system installation, is that one of the pair of strings is not connected on "string 1". In other words, you are missing 11 panels out of 43, so your production roughly is 25% lower than expected. This would align with your expectation of 66kwh per day rather than 50.

Anyway that's my guess.

 

[taphil]

For what it's worth, on my 8.16kW system in August, I averaged 44khw per day. With cooler temps and less daylight, yesterday I still produced 44kwh.

 

[taphil]

P.S. Tesla wouldn't look at my system to verify their f*uck up til after PTO.

 

[Nmtdriver]

Looks like you have 5 strings, 2 of which are combined on the roof, so a total of 3 sets of wires come down to your inverter/PW+. The 400W panels peak at 37V and 10.7A.

Rough calculation:
"String 1" is a pair of strings with 11 panels each. At peak, it should generate 407V x 21.4A = 8.7kW
"String 2" is 5 panels in series. At peak, it should generate 185V x 10.7A = 2kW
"String 3" is a pair of strings with 8 panels each. At peak, it should generate 296V x 21.4A = 6.3kW
Total system is therefore about 17kW

According to your string data,
"string A" matches "string 2" above;
"string C/D" matches "string 1" above;
"string C1/D1" matches string "string 3" above.

"String 1" above isn't producing much current, 7A instead of 14A, (similar to string 3 producing 15A). My guess, based on the f*uck up with my system installation, is that one of the pair of strings is not connected on "string 1". In other words, you are missing 11 panels out of 43, so your production roughly is 25% lower than expected. This would align with your expectation of 66kwh per day rather than 50.

Anyway that's my guess.

That’s good info! I will have to take that to Tesla when I get my PTO.

My experience mirrors yours - my advisor asked me to contact service and service said they wouldn’t do anything until after PTO so it looks like I’m stuck for a few months (or more lol). Oh well…haven’t been asked to fund my loan deposit yet and have been enjoying 2 months of almost no electric bill so I’ll chill until I’m making payments.

 

[jboy210]

Oh. No PTO. You might post you panel production graphs. I understand these days Tesla will automatically shut down production from the panels to limit you to filling your PWs + current consumption until you get PTO and could send the excess to the grid. A few years ago, when we got our system, we had to do this manually and ran around looking vehicles to charge with spare electrons. Also, we are well past the max delivery days near the summer solstice (June 21) and you have East and West Facing panels.

The bottom line is I think things will change for the better once you get PTO. But please post your production graphs and discuss any shading (chimneys, trees, etc.) so people can comment on what the system is doing.

 

[Nmtdriver]

I’ve never seen any clipping. The days have been hot and so we have been using more than we produce as we run the AC and charge the car a lot. Also have 3 powerwalls and am on self-powered mode so we haven’t had many days limited by full charge (though I have seen it and it does suck lol).

 

[jboy210]

I believe that Tesla can reduce production without clipping. It is as described in the warning on image you posted. Also, getting too hot can have an impact on production. My Delta inverters start self-limit at 115F. Fortunately, they are in shade most of the days and only reach that limit on 95+ days.

 

[buckets0fun]

It's the big box within your screenshots. all things working as designed. you're in 'self consumption' mode.

 

[Southpasfan]

You are fine. Its just eliminating any power back to the grid, which it would otherwise produce, and which it will produce after PTO.

Back in 2020, Tesla systems did not even have the official ability to operate pre-PTO! People who like to follow rules waited like months to turn on a perfectly good system. Then at some point they updated the software so you can use your system right away, but it limits itself.

So we were all running around turning the system on or off, one guy in Florida was disconnecting from the grid manually. It was a violation of the PTO application to run it at all. Ha!

For me, I realized that my utility didn't care, because pre-PTO the meter had no way to calculate energy sent back to the grid, and my electrician had confirmed that it was no problem, plus, the system would have automatically shut off in the case of an outage, so after awhile I just left it on.

Then when they were going to come out to swap out the meter and give me PTO, I turned it off for a day or so (so they would not see it had been on the whole time) and couldn't stand it.

 

[aimetti]

hey out of curiosity , how did you get the string data to work in pypowerwall. All my commands work fine aside from that , returns no data or blank.

 

[Nmtdriver]

hey out of curiosity , how did you get the string data to work in pypowerwall. All my commands work fine aside from that , returns no data or blank.

Dang - sorry for the late reply. My data analyst wife couldn't get it to work, so I bribed my software dev friend with some beers and food. He was having trouble too. I had no idea what was going on but it seemed like he was hung up on some commands as well. It seemed like we had to throw a hail mary and plug in our best guessed info into the part that prints the data and it worked. I think there was a part where we had to connect to the powerwall directly on wifi, extract the IP, switch back to our home network and plug in that IP data (or something like that). It's not the most elegant solution but it seems like it's doable with enough troubleshooting and attempts.

 

[aimetti]

No worries ! Thanks for replying. From what I found I did the same thing as you I believe , but the regular powerwalls cant get the data. Looks like only powerwall+ , which im assuming you have?

 

[sorka]

My 13 kw system was hitting 10 kw daily in early august on clear days in 100+ degree days.

 

[Nmtdriver]

No worries ! Thanks for replying. From what I found I did the same thing as you I believe , but the regular powerwalls cant get the data. Looks like only powerwall+ , which im assuming you have?

Ah I see - that could be it: System Design | Powerwall Support

That said, if you had tesla do your solar, you should be on powerwall+ because you'd be on tesla inverters if I'm not mistaken. I'm sure you're aware but just in case, these were the instructions to log into the gateway and find your system IP on your network: Connecting to Tesla Gateway | Tesla Support

 

[CrazyRabbit]

…
Then when they were going to come out to swap out the meter and give me PTO, I turned it off for a day or so (so they would not see it had been on the whole time) and couldn't stand it.

They can see it, but do they care? Mine asked me to turn off my system till I got PTO, I was operating on don’t export mode. Then URI hit and I turned it back on, they never said anything again.

 

[CrazyRabbit]

Can we ask Tesla to give us access to the standalone Tesla inverter data? It is uploading data to them.

 

[SilverSp33d3r]

Pre PTO my gateways were not combining production for my two powerwall + units. Once I received PTO they sent someone out to re-commission and it solved the problem.