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Troubleshooting low to zero output on older SunPower SPR-2000 / SPR-200 setup

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  • Troubleshooting low to zero output on older SunPower SPR-2000 / SPR-200 setup

    So I bought my house in 2014, which came with 10x SunPower SPR-200 solar panels (split in to two arrays) on the roof and a SPR-2000 2kW inverter (the sticker on the side lists "PV Powered" of Bend, OR as the OEM). The system was installed in 2005, which means the inverter is no longer under warranty, but the panels still are.

    It came to my attention the system was not producing any power, and while I'd like to get things up and running again, I'm planning a addition, which will mean new roof, which in turn will likely mean upgrading to a 6 or 7 kW system. However, if parts of the existing system are good, they could be moved to the detached garage. The original installer (Regrid) was acquired in 2008 and no longer has local presence. There are alternatives that will come out and take a look for $200-300, but my experiences with techs and contractors in this town has been so horrible that I try to do everything myself.

    When I give the system a full reboot, here's the sequence of events:
    1. Inverter shows green light, displays "fault code 0000 0000 0000". "PV input" displays between 140-200V DC
    2. After 5 minutes uptime, inverter makes a click sound and display says "SUNPOWER CORP". It also makes a humming sound
    3. "fault code" is replaced with an "AC power" display reading between -35W and 40W.
    4. After another 5 minutes of uptime, the there's a click, humming sound stops, and system goes back to "fault code 0000 0000 0000"
    5. If I open the panel and measure DC voltage, I get a near-zero value for positive and between -205 and -140 negative. Closed circuit volgage is 140 to 205 DC.
    Since the inverter itself consumes 30W during normal operations, the obvious conclusion here is there panels are kaput, damaged, or have a broken wire. But...here's where it gets weird.

    About every 5th reboot, the system runs for several hours, producing 100-400W AC output. "PV input" is still 140-205V DC, which matches the DC closed circuit reading. On open circuit, I'll see 18-20V positive and the same -205 to -140V negative. Sometimes, it will even run successfully overnight. Eventually though, it does click off and go back to "fault code 0000 0000 0000", which I've learned means it's not producing any power.

    Other things I've done:
    • Checked AC power coming & shutoff switch to the inverter and see no no issues. Line voltages is 117-119V, ground is good.
    • Replaced the 600V DC fuse (it was $6 on Amazon so why not).
    • Inspected wiring within AC and DC shutoff boxes. AC looks normal: black wired on terminals, white wire passes thru, ground wire attached to box. On the DC, positive wires goes straight thru the box, and negative is connected to the terminals. This seemed backwards, but I guess this wouldn't matter because the shutoff switch would still break the circuit
    • Inspected wiring within the inverter itself. Noticed red wire was connected to "DC out" negative and vice-versa. Obviously, this seems backwards, but it's been this way for 15 years so guess it's correct?
    Some pictures below, focusing on the DC wiring. The yellow & orange taping was done by the installer to mark the array pairs. I added red & black tape to mark pos/neg.

    IMG_1910.jpg


    IMG_1907.jpg


    IMG_1877.jpgIMG_1878.jpg


  • #2
    Also measured closed circuit with PV wires disconnected from inverter. Got 215V for "orange" pair, 200V for "yellow"

    Comment


    • #3
      From the looks of those inductors, my guess is the inverter technology is
      quite dated. Good time to up grade to something with most likely higher
      efficiency, and likely better output waveform. good luck, Bruce Roe

      Comment


      • #4
        Well, I agree that it's like time to move on from this inverter, even if it is functional.

        The larger question I'm trying to answer is what the status of panels is. I'm confuse what I should be seeing as closed circuit voltage. Is 200-215V normal? Or should I be seeing closer to 1000V (200V x 5 panels).

        Comment


        • #5
          Originally posted by johnnylingo View Post
          Well, I agree that it's like time to move on from this inverter, even if it is functional.

          The larger question I'm trying to answer is what the status of panels is. I'm confuse what I should be seeing as closed circuit voltage. Is 200-215V normal? Or should I be seeing closer to 1000V (200V x 5 panels).
          Well I guess the total voltage is dependent on the Vmp rating of those panels. Since it is old tech I am thinking the 200 value is the wattage and not the output voltage.

          Comment


          • #6
            Panel loaded and open circuit voltages should be on the label. In general
            each cell supplies power at 1/2 volt, so a 60 cell panel would have a loaded
            output voltage in the ballpark of 30 volts, open circuit voltage will be about
            25% more. I am quite sure your system was not operating near 1000V.

            In range voltages will allow you to put together a proper system, but only
            a test under a load and good sun will demonstrate how much current
            (and therefore power) can be delivered. Bruce Roe

            Comment


            • #7
              Originally posted by SunEagle View Post

              Since it is old tech I am thinking the 200 value is the wattage and not the output voltage.
              That is correct. The previous homeowner had kept the spec sheet for the SPR-200s and here's what it says:
              Rated Power 200 W
              Voltage at Rated Power 40 V
              Current at Rated Power 5.0 A
              Open Circuit Voltage 47.75 V
              Maximum System Voltage 600 V
              Makes sense: 10 panels @ 200W each = 2 kW.

              Here's pictures showing the 205V DC closed circuit for each pair:

              IMG_1914.jpgIMG_1912.jpg

              Comment


              • #8
                Couple more showing the 205V again, along with the sticker on the side of the inverter.

                IMG_1915.jpgIMG_1917.jpg

                Comment


                • #9
                  Originally posted by bcroe View Post
                  so a 60 cell panel would have a loaded
                  output voltage in the ballpark of 30 volts, open circuit voltage will be about
                  25% more.
                  If my counting is correct, these are 72 cell panels. They're arranged on the roof in groups of 4 and 6, but is it's 2 x 5 for the strings. Here's them during the cleaning process last summer:

                  IMG_0789.jpgIMG_0788.jpg

                  Attached Files

                  Comment


                  • #10
                    I have some of those, 36V per panel, or 180V loaded from a string of 5. Open
                    circuit (unloaded) voltage might be around 225V. However all the panels in a
                    string need to have the same orientation, can not see if that is true for you.
                    Bruce Roe

                    Comment


                    • #11
                      I found the manual on the Sunpower website in the support section. I'm not sure about posting web links, but it is the US Sunpower website and searched SPR-2000 for the inverter.

                      Download the manual and walk through the start up process and troubleshooting guide. There's information about timing, LED colors, etc. See if any of this matches what you are seeing.

                      1. If I open the panel and measure DC voltage, I get a near-zero value for positive and between -205 and -140 negative. Closed circuit volgage is 140 to 205 DC.
                      I think you measured 140VDC on string 1 and 205 VDC on string 2 when measuring between the + and - on each string.

                      But then you show a picture that shows both strings operating at 205 VDC on post 7. The string input operating limit of the inverter is 135 to 360 VDC. I'm not sure what would happen if one string is below 135VDC.
                      ​​

                      Comment


                      • #12
                        Originally posted by bcroe View Post
                        all the panels in a
                        string need to have the same orientation, can not see if that is true for you.
                        Bruce Roe
                        They all face due south.

                        Comment


                        • #13
                          Originally posted by oregon_phil View Post

                          I think you measured 140VDC on string 1 and 205 VDC on string 2 when measuring between the + and - on each string.

                          ​​
                          The closed circuit (measuring between + and - on each strand) varies from about 145 to 205V. Number is higher later in the day. Open circuit negative (measuring between - and ground) is a that same number but negative. The positive open circuit is typically close to zero, but around 20 the rare times the system is producing output.

                          Originally posted by oregon_phil View Post
                          I'm not sure what would happen if one string is below 135VDC.​​
                          In my measurements, both strands always show the same number within 1%. If both are below 135 the inverter would go to standby mode for sure.

                          Here we are 30 minutes til sundown and it's dipped below 190.



                          IMG_1923.jpgIMG_1924.jpgIMG_1925.jpg

                          Comment


                          • #14
                            What does the display say in the last picture? I can't read it. And you have a green LED.

                            Sunpower manual Start up procedure:

                            1. Turn the AC breaker ON.
                            2. Verify that a red LED light is illuminated.
                            3&4 doesn't apply to you
                            5. Turn the DC breaker ON (If installed)
                            6. doesn't apply to you
                            7. After 5 minutes, the SunPower Inverter will start to produce power into the AC grid if all necessary operating conditions are met. NOTE: During the initial 5 minutes prior to producing power, the inverter will display “0000 0000 0000”. This is a normal.

                            If the SunPower Inverter’s operating environment is safe to produce power into the AC grid, the “OK” (Green) LED is illuminated.

                            If at any moment the operating environment moves outside the safe operating limits, governed by UL 1741, IEEE 519, and NEC 690, the “STAND BY” (Red) LED indicator will be illuminated.

                            It looks like your inverter is working correctly at this moment in time.

                            Comment


                            • #15
                              Originally posted by oregon_phil View Post
                              What does the display say in the last picture? I can't read it. And you have a green LED.
                              189V, so same as the closed circuit measurements for each strand/array. It's now dropped to 60V as it's 8 PM and the sun has been down for 20 minutes. Inverter is in standby mode with a red LED light, as expected.


                              Originally posted by oregon_phil View Post
                              It looks like your inverter is working correctly at this moment in time.
                              I have to agree; the inverter shows no direct signs of problems, even though its warranty expired 5 years ago.

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