Solar Roof

12.8 kWh Tesla Solar Glass roof only outputs MAX PEEK now is 5.0 kWh

Starting a new thread now that Tesla has been on site a few times . They did find a few ground faults which were more than likely the cause of the dropout on the 2 Inverters when it hit 7-8 kWh. The NEW problem now is that that my MAX is 5.0 kWh. Tesla is activity investigating. The 3 PowerWalls only charge to to around 10% daily. Tesla support did say they believe it's only producing about 40% of what they would expect. So at least they've admitted there is an issue. (Inverters are M4 & M8 with firmware 3.03)

Comments

  • Sort of having the same issue here. It's been lees than a week so far.

    Initially the system would not charge the powerwall, after calling they saw the solar supply was reading negative causing some faults. The CT is likely installed in reverse, they were able to invert it in software. Prior to the swap I was seeing up to 8.2kW (w/o the powerwall charging) . Now I get a max of 5kW, especially when the powerwall is charging (which is all the time).
  • I took Thermal Image shots via Drone and showed them either missing tiles or non working tiles (can't see how to post picts here) . Tesla was pretty thankful for the shots and will be out here again next week to check MCIs, Tiles, and strings.
  • Instantaneous *power* production is in Watts (W), or Kilowatts (kW). That's usually indicated as a theoretical maximum rating, usually not achievable anywhere but in a lab, so don't expect the nameplate rating anywhere but in ideal conditions.

    The *energy* produced is power over time, and is in Watt-hours (Wh), or Kilowatt-hours (kWh).

    Under ideal conditions, a 300W panel can produce 300Wh in an hour. A 10kW array can commonly produce 50kWh in a day, depending on many variables, such as weather, siting, etc.

    I'm not trying to minimize your concerns about your system under-performing. It clearly has issues. I'm just trying to bring some clarity to proper unit usage.
  • I feel your pain. I have a 10.4 kW system that peaked once around 7.1 kW and never above 5.1 kW since. Production has been hovering around 28-30 kWh per day (the best I saw on the truly perfect day with the 7.1 kW peak was 43 kWh).
  • Fortunately, your contract with Tesla has a 24 month production guarantee. Be sure to continue to download all of your data, if filing a claim is appropriate.
  • > @dhelmly said:
    > I took Thermal Image shots via Drone and showed them either missing tiles or non working tiles (can't see how to post picts here) . Tesla was pretty thankful for the shots and will be out here again next week to check MCIs, Tiles, and strings.
    >

    Personal drone or did you hire someone to get the shots? I'll get up there with my thermal camera and have a look, my DJI drones are currently useless due to updated airport restrictions.
  • Wow! You can't even use them below 400'?
  • thermal drone shots were taken via DJI Inspire with an optional thermal camera. Tesla emailed me today and will be out here next week.
  • We are suffering a similar issue. 12.75kW system. Going to month view we generated 1,100 kWh in June, 1,120 in July, 980 in August, 600 so far in September. We wonder if it has something to do with all the ash & dust on the panels. Hosing them off seems does not seem to make them look any cleaner.
  • jerry, What you're "suffering" from appears to be celestial mechanics. The angle of the Sun, relative to your roof pitch, changes from month to month, as does the temperature of your panels. PV likes temperatures in the low 70s, and loses efficiency as temperature rises. These are two reasons why Tesla's performance guarantee is over a running 24 month period. It smooths out inconsistencies of weather, season and a host of other variables.
  • https://www.youtube.com/watch?v=YQM2SeUHQXo
  • solarroof_98682105, are you in Vancouver, WA? Asking as I am in Seattle and we should have similar angles to the sun... Would love to learn more details on your roof size & angle, installed system size, direction, production amount... THX!
  • So many variables, but everyone's systems described sounds about right. Winter has a lot less solar production than the summer. I'd also be less focused on the peak power during the day and the total power for the day. Other variables include how warm it is outside (not a big factor), location of cells relative to the sun (a big factor), your latitude, cell orientation (NWSE), and how much water and dirt is on the roof. On the latter, some of us with a lot of ash went to almost zero output until we cleaned off the roof or got some real rain. I also find at this time of the year it takes a few hours for the morning dew to dry off, which also impeeds some solar generation.

    My 10.8 kW solar roof peaks at about 45 kWh/day in the summer. Yesterday, which was sunny, I got 16 kWh for the day. My roof is now fairly clean, but I bet I could get 10% more if I really cleaned it off well. Waiting for the rains to do the next round of cleaning. I'm in the bay area, California. Those north to me is likely to have even less production this time of the year.
  • > @AM001 said:
    > solarroof_98682105, are you in Vancouver, WA? Asking as I am in Seattle and we should have similar angles to the sun... Would love to learn more details on your roof size & angle, installed system size, direction, production amount... THX!

    Apologies for the delay in replying.

    Re: Solar Roof:
    Location: Alameda, CA.

    We settled on a 9.1kW Solar Glass system, and two 14kWh Powerwalls.

    The majority of the solar glass is on the south and west facing sides of the roof, with about 1.2kW on the north side. The roof is a basic rectangle, with the longest side aligned to the south. It has a fairly steep roof pitch. (8/12)

    The system went online in early May, 2020.

    The early days in May-September were the 'salad days.' We were 100% self-powered, the Powerwalls were charged by 2PM, and any excess was sold to the local utility for pennies on the dollar. (We got the pennies. :)

    The roof produced a peak of 0.7MWh in June - almost double our power consumption for the month.

    As winter fell, it turned out that a huge tree (https://goo.gl/maps/kLBcHDqkqRSaVcs19) on the other side of the block casts a giant shadow across the entire roof, and blocks solar generation after 1-2PM.

    Mid-October was the last week we were 100% self powered. (Not counting those few weeks in September that the SF Bay Area was living in an apocalyptic hellscape. https://www.youtube.com/watch?v=dSreOPz0Zcs )

    The roof produced 241kWh in November, 2020. Averaging about 58% self-powered.

    I set up a webcam and made a time lapse of an average winter day:
    "Owner of a Solar Roof" - Winter of my discontent.
    https://www.youtube.com/watch?v=YQM2SeUHQXo

    I'll do another one on 12/21, the winter solstice.

    Things can only get better from there, eh? :)
  • The time-lapse is clever! How did you make the video graph overlay?
  • Things probably won't start to get better until after December 21st...the Winter Solstice.

    Having solar sure puts one more in tune with celestial mechanics. I now have more appreciation for the Pagans.
  • > @"TeslaTap.com" said:
    > The time-lapse is clever! How did you make the video graph overlay?

    Thanks!

    The Powerwall data is recorded using Home Assistant on a Raspberry Pi. (The Powerwall integration saves 9 data points, every half minute. I've accumulated about 6-7 months of data.)

    The image data is recorded using the motionEye add-on on the same platform. (The MPEG stream is passed through to a local NAS for long term storage.)

    One day of data was extracted into a CSV file, using "DB Browser."

    The graph was made in LibreOffice, using the Scatter plot option.

    Final composite was in After Effects 5.5.
  • Just an update from my original post. Production is up quite a bit from where it was. Tesla did fix string issues and also moved several tiles to a different roof location and also added a few more tiles to help with production. I also had a few tall trees removed (in the backyard) as we are planning to replant different trees this spring. As most have said here, winter months are hard to gauge with no previous data. I have seen my system now hit 6.7 kWh peak in December which is a great first step.

    Tesla did a full report for the local solar team lead . Here's the email:
    --------------------------------
    [TESLA SOLAR] It seems that the performance of the system has considerably been increase since 10/26/2020 (since the trees are removed – as noted below).

    This system is estimated (modeled) to perform 10.5 kWh (as_built), in the month of November, which is affected by the weather fluctuations seen on site.

    The average November daily actual production is 16.82 kWh (Max production – 28.6 kWh and Min production 0.15 kWh).

    The monthly schedule modeled is as follows:
    Month
    monthly estimated (kWh/month) as_built (kWh/day)
    January
    242.3438 7.817541935
    February
    479.8998 17.13927857
    March
    920.3578 29.68896129
    April
    1259.1625 41.97208333
    May
    1503.3317 48.49457097
    June
    1544.7357 51.49119
    July
    1556.0786 50.19608387
    August
    1325.1372 42.74636129
    September
    1025.037 34.1679
    October
    636.8058 20.54212258
    November
    317.2414 10.57471333
    December
    192.8355. 6.2205
    Total
    11002.9668

    The total estimated annual production is 11,002.966 kWh.

    Estimated gross annual electricity production in kilowatt-hours (kWh) from your Solar Roof in year 1: 11,003 Source: Solar Purchase Disclosure

    The monthly actual energy produced until now looks like this:
    July 2020 83.448 - system showed faults (ground issue)
    Aug 2020 630.304- system showed faults (ground issue)
    Sept 2020 551.539 - some tiles relocated and string issues
    Oct 2020 308.347- string issues (trees also removed)
    Nov 2020 478.273
    Dec 2020. 15.810

    In first 4 months, it was seen that there were some on-going stringing issues, which led to under-performance PLUS the tree was hampering the performance quite a bit too. So the system has under produced. Overall high weather fluctuation, seasonality, shade, electrical issues has contributed to under-performance until October end.

    As noted below, the trees have been removed and the stringing issue is taken care of, we can see the spike in the actual production numbers in the month of November.

    The estimated total production in the month of November is 317.24 kWh and the system actually produced 478.27 kWh, which is considerably higher à which in turn proves that the system has over-performed in the month of November.

    When the irradiance data is taken into consideration, the system performance comes out to be approx. 134%, which is indicative of over-performance in the month of November.

    As noted above, the customer can compare the monthly actual production in kWh (even daily kWh) with the estimated production in the ‘kWh’ and not ‘kW’, this way we will be able to explain the customer, the working of the system and at what percentage the system is performing.

    -------------------------

    The MOST important thing to keep the dialog open with Tesla Solar roof team. They are not very fast at responding but they DO respond ,both locally and the 800#. Build a relationship with your local team if you can. They are the key.. For now, I'm basically restating my expectations starting from November 2020 into 2021 and recap my findings this summer as I compare .

    Dave
  • @solarroof_98682105 - Thanks for the details. I sort of figured it was complex to do! It really came out nice. You might try and do one around 21-Dec and another on 21-Jun to show sort of the min/max.
  • > @"TeslaTap.com" said:
    > @solarroof_98682105 - Thanks for the details. I sort of figured it was complex to do! It really came out nice. You might try and do one around 21-Dec and another on 21-Jun to show sort of the min/max.

    Thanks. It wasn't that complex, once I had all the pieces in place. (When it comes to parsing the Linux priesthood, the Home Assistant team takes the cake. :)

    I plan on doing a time lapse for the entire solar year, but haven't figured out how to slice the data yet.
  • The entire year would be really slick! I hope it comes together.
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