Balancing PV strings

zoneblue
zoneblue Solar Expert Posts: 1,220 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
At some point i want to try to rearrange our panels into matched pairs. I have previously measured up to 13 percent variance in the strings current. (3 strings of 2)

Has anyone tried doing this? My plan is basically to remove the mc4s, and measure isc/voc of each panel, and group them into like pairs.

Given that the power tolerance is +/-3%, Is 13 percent variance even to be expected? Im guessing that the variance in the indiv panels will be accentuated depending on their exact combination. But to my mind it makes sense to allow the stronger panels to go unhindered by being paired with a weaker panel.

Lastly any tips on how to remove the mc4s without breaking something. I know there is a tool, but is there another way?
1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar


· Share on Twitter

Comments

  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #2
    Re: Balancing PV strings
    zoneblue wrote: »
    Lastly any tips on how to remove the mc4s without breaking something. I know there is a tool, but is there another way?

    I found it to be very easy to disconnect MC4s by holding the locks with small pliers.
    · Share on Twitter
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Balancing PV strings

    Current differences between paralleled strings is irrelevant.

    Current differences between panels within a string will only matter if the variance exceeds 5%.

    Even "identical" panels will have that amount of variation.

    Panel output does not remain the same day to day nor year to year.

    You're making unnecessary work for yourself.
    · Share on Twitter

Categories