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Fox ESS PvCon Dir Fault

Updated June 2026 · Reviewed for technical accuracy · ~2 min read
⚠️ Do not touch the DC connectors while the panels are in sunlight. A live PV string holds hundreds of volts of DC, and pulling a connector under load can cause a sustained arc and serious injury. PvCon Dir Fault means a string is wired backwards. Correcting it is an installer job, not a reset.

PvCon Dir Fault (shown as Error 15 or 16 on some Fox ESS units) means a PV string has reversed polarity: the positive and negative leads, PV+ and PV-, are swapped at the inverter input. The inverter detects the wrong direction of voltage on that MPPT and stops to protect itself. This is an installation wiring error, and if it is left uncorrected it can cause irreversible damage to the MPPT circuit.

What usually causes it

  • PV+ and PV- swapped at the input. The two DC leads of a string were connected to the wrong terminals during installation or a recent service visit.
  • A mislabelled or re-terminated MC4 connector. A connector that was crimped or replaced with the polarity flipped.
  • A string extension wired the wrong way where a cable was added or joined and the colours did not match through.
  • Recent panel or rewiring work on the array that disturbed the original, correct connections.

How to handle it safely

  1. Do not try to swap the DC connectors yourself. The string is generating voltage in daylight, and unplugging a live connector is dangerous. This is the single most important step.
  2. Note which MPPT or string the inverter is flagging. The FoxCloud app or the inverter screen usually points to the affected input. This helps your installer find it fast.
  3. Leave the inverter as it is and call your installer. Treat PvCon Dir Fault as a stop-and-call fault. The longer a reversed string is left connected, the higher the risk to the MPPT.
  4. Let the qualified installer correct the polarity safely. They will work when the string voltage is low or zero, at dawn or dusk or with the panels covered, isolate the DC side, and re-terminate PV+ and PV- the right way round.
When to call a professional. Always, for this fault. Reversed PV polarity must be corrected by a qualified solar installer who can safely de-energise the string. Never open or swap live DC connectors, and do not keep restarting the inverter to clear the alarm, as that leaves the wiring fault in place and can damage the MPPT.

Related Fox ESS codes

PV Volt Fault ISO Fault Arc Fault

FAQ

Can I just unplug the string and swap the two connectors myself?

No. In daylight the string is live with high-voltage DC, and pulling a connector under load can draw a dangerous arc. Wait for your installer, who will de-energise the string at dawn or dusk, or by covering the panels, before touching anything.

Will PvCon Dir Fault clear if I restart the inverter?

It will not. The fault reflects a physical wiring error, so restarting only re-applies the reversed connection. Repeated restarts can stress the MPPT circuit. The alarm only clears once an installer corrects the polarity.

Helpful guides

Error codes explained How to safely restart your inverter What is an arc fault

Sources

  • Fox ESS inverter user manual and FoxCloud alarm list (PvCon Dir / Error 15 and 16 = PV string connected with reversed polarity, PV+ and PV- swapped).
  • Fox ESS installation guidance on PV string connection and DC polarity, including safe DC isolation before any connector work.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". PvCon Dir Fault involves live PV wiring and must be diagnosed and corrected by a licensed installer or electrician. Do not open, swap or test DC connectors yourself.