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Adding new solar panel to existing array - all are SunPower but new is higher voltage

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  • Adding new solar panel to existing array - all are SunPower but new is higher voltage

    I was given a new solar panel by a friend and I’m thinking of adding it to my existing grid-tied array.
    New panel: SPR-X22-360-COM (59.1V and 6.09A)
    Existing panels: SPR-E230-WHT-U (41V and 5.61A)
    Inverter: SPR-4000m (grid-tied, string inverter)
    Existing configuration: two strings of 8 panels in series connected to the inverter (no charge controller or battery in this system)
    Proposing to add the new panel onto one of the two existing strings. Making 9 panels on one of the strings and 8 on the other.

    Can anyone identify an issue with me doing this?
    I know the new panel will be reduced to ~330 watts because the current will be limited to 5.61A instead of the 6.0A the new panel is optimized for).
    The inverter is appropriately sized for this addition so that shouldn’t be a problem.
    The inverter has a max voyage of 600V but because the existing system has two strings of panels the voltage of each string is below 400V so that may not be an issue.
    Will my system get fried if I plug in this panel to the existing array?
    Last edited by personalhygiene; 08-15-2021, 03:18 PM.

  • #2
    These are the calculations I've done. Adding the new panel will increase the operating voltage of the 8 panel string from 328V to 387.1V (with the 9th panel added). This is well within the optimal peak-power voltage range of 250 - 480 for this inverter. The open-circuit voltage of the string will go from 389.6V to 459.1V. This is well under the 600V maximum.

    My inverter is 10 years old. I also have a 2nd inverter (identical to the first one) that is in storage and will be installed when the first inverter fails.
    Last edited by personalhygiene; 08-15-2021, 03:21 PM.

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    • #3
      Originally posted by personalhygiene View Post
      New panel: SPR-X22-360-COM (59.1V and 6.09A)
      Existing panels: SPR-E230-WHT-U (41V and 5.61A)
      Inverter: SPR-4000m (grid-tied, string inverter)
      Old panels and old inverter are configured for positive grounding. New panel has no grounding restrictions. (see attachment)

      Others can comment on this configuration as I do not have experience with positive grounded configurations.

      Others on the forum have had issues finding inverter replacements for positive grounded solar panels. Search "Sun Power positive ground panels with dead inverter"

      This would be a larger issue for me than adding one more panel as the inverter supply for positive grounded solar panels are decreasing as the industry has moved on.



      Attached Files

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      • #4
        Thank you oregon_phil! I have an identical inverter in storage awaiting the failure of my first inverter (bought it from a distributor a few years after my system was installed).
        I think my SPR-230E panels (their family name is E18 series) are not the older positive ground panels. The E series was the first one after the SunPower positive ground panels were ended. Have you seen that the E-series panels are positive grounded?
        Last edited by personalhygiene; 08-15-2021, 03:49 PM.

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        • #5
          Check out this snip from the document that I attached in my last post. I am SPR-ZZZE-WHT-D where ZZZ is panel wattage are positive ground.

          The manual for SPR-4000M has positive ground installation methods. I'm pretty sure your panels are positive ground.

          I couldn't find any power curves for the SPR-X22-360-COM.

          Attached Files

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          • #6
            You are right, Phil! I'll look into another type of application for this solo new panel.

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