Under performance

[GuyHall]

Waiting for PTO, but very concerned about the low level of generation. Tesla told us the we should expect daily averages of between 11kwh and 22kwh for November and December. Our average for those months was under 4kwh.

Tesla won't tune the system until pto, would we see that big of a difference? Concerned that they may have not properly accounted for shade, roof pitch, etc.

Any insights?

I'm hopeful but pessimistic.

 

[sorka]

Confused. If it's not turned on, then how do you know?
What's your system size? I'm making 38kWh a day when there are no clouds on an 8.16kw system in Merced CA.

 

[Ampster]

Any insights?

Need more data before I would have any insight.
Sytem size, azimuth, tilt, latitude?

 

[sorka]

Why I ordered 22+ kw solar glass roof for $134k

21KW system in your location should be pulling in about 97kwh a day with all panels facing south at an angle of 25 degrees and no shading at this time of year. So even if things were not optimal I don't see how you could be making only 4kwh a day.

 

[getakey]

To the OP, I'm nearby in EDH
I have a 11.8 kW system For 1/19 thru 1/21, it produced 25kWh each day

 

[wjgjr]

Why I ordered 22+ kw solar glass roof for $134k

21KW system in your location should be pulling in about 97kwh a day with all panels facing south at an angle of 25 degrees and no shading at this time of year. So even if things were not optimal I don't see how you could be making only 4kwh a day.

I would agree that number seems a lot more reasonable for the ideal situation. And, even assuming a non-optimal arrangement, it should still be half or so of that number. So, it will be interesting where that 4 kWh/day number comes from.

As a point of reference, I am on the opposite coast, but only about 0.2 degrees north of you in latitude. With a mostly-sunny (but not quite full sun) day, our system produced 18.8 kWh today on an ~8.2 kW solar roof, with only half pointed south (187 degrees) and half north, and a 34 degree pitch. I suspect with full sun, it should have been almost exactly 20 kWh. That lines up pretty well with what @sorka suggested and what I would generally expect to see. Other than some cloud edge effects, our maximum instantaneous generation was around 3.1 kW.

It sounds like one or more strings and/or inverters are either not on, mis-configured, or are working but not properly reporting on the app. You might be able to tell be looking at data on the inverters themselves.

 

[h2ofun]

Why I ordered 22+ kw solar glass roof for $134k

21KW system in your location should be pulling in about 97kwh a day with all panels facing south at an angle of 25 degrees and no shading at this time of year. So even if things were not optimal I don't see how you could be making only 4kwh a day.

To the OP, I'm nearby in EDH
I have a 11.8 kW system For 1/19 thru 1/21, it produced 25kWh each day

Not today and for looks like a week

 

[jboy210]

Waiting for PTO, but very concerned about the low level of generation. Tesla told us the we should expect daily averages of between 11kwh and 22kwh for November and December. Our average for those months was under 4kwh.

Tesla won't tune the system until pto, would we see that big of a difference? Concerned that they may have not properly accounted for shade, roof pitch, etc.

Any insights?

I'm hopeful but pessimistic.

Do you have shading?

My 12.75 kW roof generates 6-8 kWh/day because of shading this time of year. There is a big drop from 11:30 AM to 2:30 PM because of a tree on the Energy Use graph.

In the solar summer (months around June 21) the roof can generate 80+ kWh/day because the sun is high enough that the tree casts minimal shading on the roof.

 

[MXLRplus]

97 kWh a day in Jan out of an advertised 22kW array?
Wow, that's very, very good.
Granted, my 22kW array (advertised) is optimized for the summer, but I average about 60 kWh for Januarys over the last 4 years. July on the other hand is about 140 kWh a day average.

 

[sorka]

97 kWh a day in Jan out of an advertised 22kW array?
Wow, that's very, very good.
Granted, my 22kW array (advertised) is optimized for the summer, but I average about 60 kWh for Januarys over the last 4 years. July on the other hand is about 140 kWh a day average.

I DID say on a sunny clear day. I'm making 38 a day off an 8KW system and I'm even further north:

That's also with 20 minutes of down team at the peak of day because I was installing a power monitor and needed power to flow from the grid towards the house instead of away from it.

 

[SVDNN]

Waiting for PTO, but very concerned about the low level of generation. Tesla told us the we should expect daily averages of between 11kwh and 22kwh for November and December. Our average for those months was under 4kwh.

Tesla won't tune the system until pto, would we see that big of a difference? Concerned that they may have not properly accounted for shade, roof pitch, etc.

Any insights?

I'm hopeful but pessimistic.

Have a similar size solar roof as you and certainly would imagine all of your tiles are not perfectly aligned to the south to give the estimates listed above. But unless you have some really serious shade issues over most of your house (I actually have significant shading due to many large trees around property at this time of year), I would say you are certainly under performing.

My system was setup with some issues that I knew was off for performance when they were testing system at final completion during mid day with full sun (getting only 1-2 Kw peak at that time). I insisted on getting Tech support to come out (prior to PTO) and they figured out some issues with direction of PV current going to grid unaccounted, download new firmware for inverters and maybe gateway, as well as problems with one of my Delta M8 inverters (which is still unresolved, and still waiting for tech coming back out to readdress). Despite this, currently making around 18-22KwH per day as of mid Jan.

RECS: Just persist, wait for PTO if needed (cannot imagine that is really necessary for them to test and troubleshoot system), but keep on reaching out to them about poor performance....particularly since they gave you those estimates.

 

[getakey]

I did not see the link to the 21 kW roof. That is way under performing. That said, system installed in Sept and still waiting for PTO?

 

[GuyHall]

I did not see the link to the 21 kW roof. That is way under performing. That said, system installed in Sept and still waiting for PTO?

The contract says the following:
Site & Design Assumptions for your Purchase Solar Roof system size: 21.98472 kW DC Estimated gross annual electricity production in kilowatt-hours (kWh) from your Solar Roof in Year 1: 25,259 kWh

Tesla said their models showed a daily average of 11kwh to 22 kwh for November and December. From the Tesla app we see an average for those two months as just under 4kwh.

Major problem with shade from trees we don't own and I fear the pitch of the roof. The north side of the roof probably doesn't get any sun in December.

Actually the system was installed in mid aug. The followed up on our concerns and tore off all the panels (defective) and replaced them. We didn't see much change. Permit sign off failed because they didn't install gutter guards (as required in our region. ) Tesla finding a sub was a week, and the 3 more weeks for Tesla to sign the work order. Finally they applied for pto on 12/4. When in called PG&E on ~1/5, PG&E said they rejected it on 12/17 - inconsistent part numbers. Asked PG&E again today and they said still no word from Tesla.

I'm really freaking out that this will not be anywhere near the production they claim. problem with shade from trees we don't own and the pitch of the roof. Should I still be hopeful or do I have to start taking other steps?

 

[h2ofun]

The contract says the following:
Site & Design Assumptions for your Purchase Solar Roof system size: 21.98472 kW DC Estimated gross annual electricity production in kilowatt-hours (kWh) from your Solar Roof in Year 1: 25,259 kWh

Tesla said their models showed a daily average of 11kwh to 22 kwh for November and December. From the Tesla app we see an average for those two months as just under 4kwh.

Major problem with shade from trees we don't own and I fear the pitch of the roof. The north side of the roof probably doesn't get any sun in December.

Actually the system was installed in mid aug. The followed up on our concerns and tore off all the panels (defective) and replaced them. We didn't see much change. Permit sign off failed because they didn't install gutter guards (as required in our region. ) Tesla finding a sub was a week, and the 3 more weeks for Tesla to sign the work order. Finally they applied for pto on 12/4. When in called PG&E on ~1/5, PG&E said they rejected it on 12/17 - inconsistent part numbers. Asked PG&E again today and they said still no word from Tesla.

I'm really freaking out that this will not be anywhere near the production they claim. problem with shade from trees we don't own and the pitch of the roof. Should I still be hopeful or do I have to start taking other steps?

I have seen many installations with panels on north, and lots of trees with shade. I just shake my head and wonder what the solar sales person told them.

 

[wjgjr]

Just looked at the layout you posted in the layout thread, and I see that over half (11.7 kW) of your array is pointing nearly north, with only 8.2 kW south, and 2.0 kW west. With those numbers, I can certainly see why in the winter numbers would be very low, but 4 kWh is still way too low. How many inverters do you have, and what does each inverter indicate for production, if you can get that data? If you have two inverters and one was assigned to your north-facing panels, 4 kWh is plausible (though still seemingly low, depending on roof pitch) for the daily output for those panels. What was your actual number for yesterday, assuming it was a sunny day? It would be interesting to know both the total for the day (in kWh) and the maximum production (in kW) you are seeing around noon.

 

[trautmane2]

How many inverters do you have, and what does each inverter indicate for production, if you can get that data?

In case it helps and assuming you have Delta inverters for the solar roof, you can use an app from Delta called Delta M Professional to see current and prior day data directly from your inverter(s). For my install, I have to be very close to (basically right in front of) the inverter to connect to it. The password to connect is the "Date Code" on the label.

 

[Redhill_qik]

@GuyHall You don't have PTO yet, so where are you getting the 4kWh number from? I'm thinking that you are briefly turning on the system and seeing 4kW in the Tesla all powerflow which is an instantaneous number versus leaving the system on for the whole day and getting a total amount of kWh that was generated by the system.

Getting a peak of 4kW for your sub-optimally located panels is probably in the ballpark, but that would be generating 11-22kWh over the day.

 

[SVDNN]

Based on other posts...I imagine what is being stated about output is correct. And sorry to hear you have had a disappointing experience so far.

Would agree w- trautmane2... start looking into output from you inverters if you can. Sometimes with Tesla, you just need to “help” them and you by taking some things into your own hands. Kind of why this forum is so popular in some ways. Unfortunately, this is the state of Tesla at this time ... big kudos for their innovation and design, less so for consistency, quality and customer service.

As an aside, I imagine the solar roof vs solar panel customer overall will have somewhat different priorities....which may vary w- regard to PV output for layout, aesthetics / curb appeal, home value and cost. Even though I could likely get a much better PV output with my system if I cut down several very large trees on my property, PV output and ROI for the system does not override the retained curb appeal that contributes to home value in the end. Everyone will have their own breakpoint in these priorities....

 

[jboy210]

Based on other posts...I imagine what is being stated about output is correct. And sorry to hear you have had a disappointing experience so far.

Would agree w- trautmane2... start looking into output from you inverters if you can. Sometimes with Tesla, you just need to “help” them and you by taking some things into your own hands. Kind of why this forum is so popular in some ways. Unfortunately, this is the state of Tesla at this time ... big kudos for their innovation and design, less so for consistency, quality and customer service.

As an aside, I imagine the solar roof vs solar panel customer overall will have somewhat different priorities....which may vary w- regard to PV output for layout, aesthetics / curb appeal, home value and cost. Even though I could likely get a much better PV output with my system if I cut down several very large trees on my property, PV output and ROI for the system does not override the retained curb appeal that contributes to home value in the end. Everyone will have their own breakpoint in these priorities....

Agree about the aesthetics. That was a major reason we went with the Solar Roof over conventional panels

 

[h2ofun]

Agree about the aesthetics. That was a major reason we went with the Solar Roof over conventional panels

I looked more at it from a maintenance angle. Will stick with my panels. Gives me so much more flexibility.