Announcement

Collapse
No announcement yet.

Inverter cutouts - PG&E

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Inverter cutouts - PG&E

    I'm turning to this knowledgeable group with an issue I have: my rooftop PV system is stopping production on a semi-regular basis. To be more specific, it will start the day okay, then at some point around 11AM when the production is really ramping up, it will just stop cold and not produce any more for the day. The next day, it is like everything has been reset and things work fine. This often happens on perfectly clear days so it is not a matter of solar energy not reaching the panels. And it happens seemingly randomly; could happen once in one week, then not for 2 weeks, then happens twice in one week. One thing I have noticed, however, is that it tends to happen on (what would be) high production days - lots of sun. But it happens rarely enough that most high production days are fine.

    Today it happened again and I noticed that the inverter said "Reconnection fault grid". (I don't know if it says this every time it happens but it's a good guess.) The manual doesn't say much about this, only that the country setting, or some other parameter, could be set to a value not consistent with local requirements. Doesn't help me much. I'm not familiar with all the Sunny Boy settings, but if some setting were off, the inverter probably wouldn't be working most of the time just fine. When I look at the log book on the Sunny Portal app, for example for today, there was nothing.

    I have a Sunny Boy inverter and 9.6kW of LG panels on two different roof faces. There are some long wiring runs. POCO is PG&E (SF Bay Area). New 200amp elec panel. Solar PV system was installed July 2016.

    I called PG&E a few weeks ago about this. They said it wouldn't be anything on their end. I need to call my installer, but I thought I'd try here to get some input, as I'm not sure my installer will know what's going on.

    I've attached photos of the daily production for a few "error" days and one normal day, plus a photo of the Sunny Boy error screen from today (note that it was taken in the early evening when the sun was practically down).

    Thanks for any thoughts/advice.
    Attached Files

  • #2
    When your panels are producing power, any resistance in the feeder lines between the Inverter and the Pole Transformer, will cause voltage to rise, and that effect is what commonly trips inverters off-line in Mid day. You may need to call the Pwr Company and have them monitor your voltage for a couple sunny days, they may need to reset a tap on the pole transformer.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

    Comment


    • #3
      Much appreciated, Mike. This is the kind of issue that I don't know much about, but now I know what to ask PG&E.

      From an old post on this forum, I had an inkling that it could have to do with voltage issues. If that is indeed the case, could it also perform just fine on many (most, in fact) sunny days? And if an inverter does trip for this reason, is it normal for it to halt production for the whole rest of the day?

      Comment


      • #4
        There are 2 cures, (3)
        re-program the inverter trip points
        or
        Elect Co adjust the voltage
        or
        Increase the wire gauge to reduce the resistance and lower the voltage differential.

        The power company may install a power monitor for a couple days, to see what is happening, If there are several solar installs nearby, they all contribute to raising the Grid voltage to a Fault level.

        But the inverter should re-qualify the grid in 5 minutes, but if the voltage changes, it will not resume

        The easy way to test this, is to fire up some large 240VAC loads in your house for 10 minutes, and see if the inverter will restart.

        But an installer will never cut corners and use too small of wire, which can cause the same effect, but it's on you to fix, not the power co,
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment


        • #5
          The problem Mike described also happened to me. I see a 129V on your display, very high for a singe line to
          neutral. I would take a good AC meter and check line to line. It shouldn't exceed 240V when the inverter is
          shut down, which should operate OK. The voltage will rise when the inverter approaches peak power, check
          how much it increases. Too high will trip out the inverter; of course the PoCo will deny responsibility until the
          evidence is in their face. Inverters here monitor both line to line and line to neutral voltage, either could trip.
          However here, the Fronius will try to restart if the line isn't too high.

          Long DC runs from panels to your inverter don't affect this issue. Mine hit 400' each way with 1% loss.
          Bruce Roe

          Comment


          • #6
            My friend has a similar issue and initially the utility blamed the inverter. He did eventually get them to schedule a power quality meter installation. While waiting he talked to Fronius and they gave him a code to bump up the voltage range for the inerter which helped a lot but not 100%. Once the utility got their power quality results back they admitted that their were issues on their lines. It took them a few weeks and the problem went away in its entirety.

            I have three small grid tie systems that had to connected to a subpanel to get around some paper issues with bus bar rating on my main panel. I initially reused a wire that was in place to my outdoor production meter between the subpanel and the main panel. It had enough ampacity but was borderline on voltage drop. One of my inverters didn't like it and would trip out on occasion. I replaced the wiring with larger gauge and the issue went away.

            Comment


            • #7
              Does the SunnyBoy have a log in the inverter where you can see the "event number"? The SunnyBoy service manual list the causes for a lot of different codes.

              Comment


              • #8
                Update: I've been checking the line to neutral while the inverter is going, and it ranges from 126V to 130V. Seems high. Bruce, my Sunny Boy inverter does seem to measure the line to line voltage (it says L1L2). On one recent sunny day when the panels were putting out about 6300W the L1L2 number was 259V. (Full disclosure: I'm no electrician and I may not know what I'm talking about here.)

                I checked with my installer and he checked with SMA. Nothing seems to be wrong with the setup of the inverter, they definitely think it is the voltage.

                After my installer called, PG&E came out one day and took one measurement, in the early evening. They didn't leave a report or anything (as they are supposed to), but they guy told my father in law that he got a measurement of 125.7V, which is under the upper limit of normal of 126V. Sheesh. That was last week. I called PG&E again today and asked them to put a monitor; they didn't have an answer immediately but will get back to me.

                SMA did say that they could bump up the inverter operation range if absolutely needed. I'm sure it would help somewhat. What's the downside there - inverter life?

                Comment


                • #9
                  Originally posted by brainplanet View Post
                  Update: I've been checking the line to neutral while the inverter is going, and it ranges from 126V to 130V. Seems high. Bruce, my Sunny Boy inverter does seem to measure the line to line voltage (it says L1L2). On one recent sunny day when the panels were putting out about 6300W the L1L2 number was 259V. (Full disclosure: I'm no electrician and I may not know what I'm talking about here.)

                  I checked with my installer and he checked with SMA. Nothing seems to be wrong with the setup of the inverter, they definitely think it is the voltage.

                  After my installer called, PG&E came out one day and took one measurement, in the early evening. They didn't leave a report or anything (as they are supposed to), but they guy told my father in law that he got a measurement of 125.7V, which is under the upper limit of normal of 126V. Sheesh. That was last week. I called PG&E again today and asked them to put a monitor; they didn't have an answer immediately but will get back to me.

                  SMA did say that they could bump up the inverter operation range if absolutely needed. I'm sure it would help somewhat. What's the downside there - inverter life?
                  Typically things will trip out at 264/132VAC. Mine will reset in a few minutes, apparently yours doesn't. You are right
                  on the edge, some good sun and a line bump will knock you out. The inverter limit is probably a safety limit from the
                  factory, likely not its real limit. Since the PoCo controls the voltage, not you, one fix is program the inverter monitors
                  a little higher. Reduce your own line voltage rise, lean on the PoCo, or (heaven forbid) use an autotransformer to
                  knock 6V off what your inverter sees.

                  The PoCo is in no hurry to get you producing again, and I think they should not exceed 120V to neutral. Bruce Roe

                  Comment


                  • #10
                    Thanks, Bruce.

                    I may very well have to have my inverter set at a higher voltage limit, which is actually fine with me.

                    Like yours, my inverter is supposed to keep monitoring the voltage and switch back on when things are OK, but I'm not sure it's doing that. One day when it cut out and I happened to be home, I manually shut down the inverter, then re-started it. It powered up and worked fine for the last several hours of sunlight! That suggested to me that it wasn't coming back on when it was supposed to.

                    Comment


                    • #11
                      Originally posted by brainplanet View Post
                      Thanks, Bruce.

                      I may very well have to have my inverter set at a higher voltage limit, which is actually fine with me.

                      Like yours, my inverter is supposed to keep monitoring the voltage and switch back on when things are OK, but I'm not sure it's doing that. One day when it cut out and I happened to be home, I manually shut down the inverter, then re-started it. It powered up and worked fine for the last several hours of sunlight! That suggested to me that it wasn't coming back on when it was supposed to.
                      Most inverter software requires a 5 minute wait after shutting down before checking to see if the "grid" is OK to reconnect. After it passes that check it should automatically start working again.

                      Comment


                      • #12
                        Update in case anyone is interested: We made PG&E come out again and the guy measured the voltage at 260. He checked a capacitor bank nearby and found that one was "misfiring." He fixed that issue and the voltage dropped to 250, so ... hopefully that is the end of the story. So far so good.

                        Comment


                        • #13
                          Good work and glad they cooperated.

                          Comment


                          • #14
                            Inverter manufacturers work to the UL1741 listing which requires an inverter to drop out when the grid voltage / frequency is out of bounds. They can't just let you alter that parameter as it violates the UL listing. They are required to have you get permission from your utility before giving you the code allowing adjustment of these settings.
                            These problems are usually (as the OP found) due to regulation problems in the grid that the the utility is not accustomed to being called out on, and they really don't appreciate it when those pesky solar customers cause them even more grief by pointing out their problems. My advice is to avoid this situation by running long wire lengths between the inverter and the grid, and use oversize wire whenever possible.
                            BSEE, R11, NABCEP, Chevy BoltEV, >3000kW installed

                            Comment


                            • #15
                              Glad you didn't take their word about it the first time. They should have put a power quality meter on the line the first time around it and left it on line for a couple of days. Unfortunately they don't have a lot of these meters and its hassle as it requires two visits so they try to avoid it.

                              Comment

                              Working...
                              X