Perform String Polarity Test

The following procedure confirms all PV strings have been connected correctly, e.g. no positive and negative conductors are swapped.

Required Tools:
  • Standard DC voltage meter
  1. Safely shut the system down:
    1. Turn the Powerwall 3 switch OFF to shut the system down, then turn the integrated DC isolator OFF.
    2. Open the Powerwall 3 circuit breaker (turn OFF).
    3. Wait 30 seconds before proceeding with any work.
      Warning IconA warning icon, calling your attention to a possibly risky situation
      Warning
      Confirm Powerwall 3 is de-energized before proceeding. Confirm the breaker is open (OFF) and solar production is disabled in Tesla One.
  2. Set the voltage meter to DC test mode.
  3. Use a known source (e.g. proving unit) to confirm the meter is functioning correctly.
  4. Connect the voltage meter positive lead to the string's positive conductor.
  5. Connect the voltage meter negative lead to the string's negative conductor.
  6. Confirm the result is a positive number. If the number is negative, string polarity has been swapped.

In the following diagram, the top image displays a multimeter correctly connected to the positive and negative leads in the PV array, resulting in a positive voltage (though this is NOT the string voltage). The bottom image displays an array where the positive and negative PV leads are swapped, resulting in a negative voltage test result. Correct the meter probe polarity and test again.