enter image description here

I have a setup consisting of three solar panels connected in series, which supply power to a variable frequency drive (VFD) that runs a three-phase motor. I am planning to incorporate an MPPT (Maximum Power Point Tracking) charge controller into the system to charge my batteries.

electrical parameters of the components involved:

PV modules: Open Circuit Voltage (VOC): 50 volts Short Circuit Current (ISC): 10 amperes

VFD: Minimum Voltage (Vmin): 120 volts

MPPT Charge Controller: Maximum Voltage (Vmax): 60 volts

Considering these specifications, my question is: How will the circuit behave when I connect the MPPT charge controller to only one of the solar panels in the series connection?


1 Answer 1


It depends on the state of the battery.

But basically it'll limit the current available from the whole string (to the VFD) to whatever is left over after battery charging.

You'd probably be better either adding another panel for the battery, OR finding a charge controller that accepts the string voltage, whichever you can find most cheaply.

  • \$\begingroup\$ The PV cells are (more or less) constant current sources. Steeling current from one will decrease the current from the three cells. \$\endgroup\$
    – user338146
    Commented Jul 8, 2023 at 18:45
  • \$\begingroup\$ @ronsimpson exactly. \$\endgroup\$
    – user16324
    Commented Jul 8, 2023 at 21:15
  • \$\begingroup\$ Unless the VFD is designed specifically to be run via solar cells, I doubt if it will work as the VFD will most likely want a stable power source, which solar cells are not. \$\endgroup\$
    – Kartman
    Commented Jul 9, 2023 at 7:49
  • \$\begingroup\$ @Kartman Yes, that is another (and very real) problem. \$\endgroup\$
    – user16324
    Commented Jul 9, 2023 at 11:29
  • \$\begingroup\$ @Kartman where I am from, VFD is used to run submersible water pumps. Although not specifically designed for that purpose. Most famous model is CHF100 of INVT company. \$\endgroup\$
    – Bilal Khan
    Commented Jul 10, 2023 at 0:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.