Symptoms

On the landing page, solar production is lower than expected. On the Powerwall 3 Device page, the correct number of strings is displayed (the connected strings appear as green), but the solar production value for one or more strings is lower than expected.

Steps to Troubleshoot

1. Once the system is started, wait up to 30 minutes for Powerwall 3 to start production. It may take time for production to start, particularly if it is a cloudy day; this is likely the issue if voltage is as expected (per the planset) but amperage is low.
2. If the voltage displayed in Tesla One is lower than expected:
   1. See Determine True String VOC for instructions to conduct an open air voltage test to see string VOC.
      Note

      Alternatively, select Stop System then Start System, then navigate to the Powerwall 3 device page. It is possible to see VOC during the PV Isolation Self-Test.

      

      It is important to note that this method will not identify instances of reversed string polarity (see Confirm String Continuity for more details. The open air voltage test DOES identify reversed string polarity.
   2. Confirm each string displays the expected voltage (VOC) as displayed on the planset.

      

      Note

      If strings do NOT display the expected voltage, review the VOC of all strings before proceeding. Consider the following scenario:

      • String A has an expected voltage of 350 VDC but displays a VOC of 410 VDC
      • String B has an expected voltage of 410 VDC but displays a VOC of 350 VDC

      In this scenario String A was mislabeled as String B and vice versa, and there is not production issue.
      Note

      If a planset with expected VOCs is not available, each string's expected VOC can be calculated by multiplying the panel VOC (found on the panel datasheet) by the number of modules in the string. For instance, a string of 5 modules that have a module VOC of 45.27 would have an expected string VOC of 226.35 V
3. If the VOC is significantly lower than the expected VOC on the planset, confirm the system stringing is correct according to the planset:
   1. Confirm all panels in the string are connected. Missing panels would result in a lower VOC than expected.
   2. Confirm all modules have been connected properly (positive to negative). Any module with reverse polarity (positive connected to positive and negative connected to negative) subtracts from the positive voltage of the string. For instance, if there are 5 modules connected with correct polarity, and 2 modules connected with reverse polarity, the string VOC will reflect only 3 modules.
   3. Confirm that any combined (paralleled) strings have been wired according to the planset, and that they have been combined correctly (both positives combined and both negatives combined, no positive combined with negative). Not paralleling strings as outlined will result in the system under-producing.
   4. Confirm that MPPT jumpers have been installed according to the planset.
      Note

      Jumpers are required when Imp > 13A. As displayed in the examples below, paralleled strings with a combined Imp < 13 A do not require an MPPT jumper.

      

      

   5. If all wiring has been performed correctly, look for evidence of damage that may be causing the string to under perform:
      • Inspect where the wires exit conduit, as nicked wires may occur here
      • Check for wires pinched by mounting hardware
4. If the VOC is correct (matches the expected VOC on the planset), confirm Powerwall 3 is not the issue by testing the string in another MPPT:
   1. Select Stop System on the landing page in Tesla One, then turn Powerwall 3 OFF.
      Warning

      Confirm Powerwall 3 is de-energized before disconnecting or connecting any PV strings.
   2. Disconnect a functional string (displays the correct voltage and amperage when the system is running) from its MPPT (consider this a functional MPPT).
   3. Disconnect the problematic string from its MPPT, then connect the problematic string to the functional MPPT.
   4. Turn the system back ON and Start System.
   5. If the problematic string now displays the correct voltage and amperage (while plugged in to the functional MPPT), contact Tesla Support for additional troubleshooting support.
      Note

      Turn Powerwall 3 OFF again and move the string back to its original (presumed faulty) MPPT to confirm that MPPT still does not function. If, upon moving back to the original MPPT, the string displays the correct voltage, the issue is resolved. No additional action is required.
5. If the string is still displaying low voltage while plugged in to the functional MPPT, the issue is not Powerwall 3. The system may have a faulty MCI; perform the troubleshooting steps in MCI Diode Test and Resistance Test (MCI Health Tests) to identify the faulty MCI(s).
6. If the amperage displayed in Tesla One is lower than expected and none of the previous troubleshooting steps have resolved the issue:
   1. Look for greater shade than anticipated (may be caused by snow or leaves). Heavy shade would result in a lower current than expected.
   2. Perform an irradiance test for each string on the roof:
      1. Place an irradiance meter on the roof, facing the same direction as the modules in the string.
      2. Calculate the expected amperage for the string by multiplying the irradiance value by the I_MP of the PV module, then dividing that value by 1000; for instance:
         • Irradiance reading = 363 W/m²
         • PV module I_MP = 9.12 A (found on module datasheet)
         • Expected amperage = (363 W/m² * 9.12) / 1000 = 3.31 A
      3. If the irradiance values are lower than 100 W/m², light levels are likely too low for accurate testing (meaning low amperage would be expected in the Tesla One interface).
      4. If the amperage displayed in Tesla One is significantly lower than the calculated expected amperage, measure each string's amperage individually. Confirm each string is producing an amperage value; if one is not, perform the troubleshooting steps in MCI Diode Test and Resistance Test (MCI Health Tests) to inspect the MCIs in that string.
      5. If a string is producing unexpectedly low amperage, inspect that string for wiring errors. For combined (paralleled) strings, confirm each individual string is producing amperage, and confirm they have been combined correctly and are connected properly.
7. If the issue persists, contact Tesla Support.