Tigo EI error 203 PV Isolation Low: what it means and what to do

Common causes

• An issue with the DC wiring or a solar panel creating a low resistance to ground.
• Moisture getting into panel connections, conduit, a junction box, the inverter, or the Tigo TS4 or TAP devices.
• Damaged grounding conductors, with chafing, cracks, blisters or exposed copper.
• Grounding connections that are not tightened to specification.

Safe steps to try

1. Keep clear of the system Tigo states that troubleshooting must only be performed by qualified personnel. Do not open the inverter, a disconnect, a junction box or any conduit, and do not touch the panels, racking or wiring.
2. Note when the error appears Check the Tigo EI app for when 203 was logged. Tigo notes that if it always happens in the morning but clears by the afternoon, moisture is probably the cause. That pattern is very useful to the technician.
3. Book a technician Tigo's procedure involves shutting the system down, checking grounding connections and wiring, looking for moisture, and testing the panels and wiring with a megohmmeter.

Frequently asked questions

I see a 203 warning that says PV1 or PV2 circuit short. Is that the same thing?

No. Tigo's code list uses 203 twice: as a warning, "PV1 or PV2 Circuit short", and as a system fault, "PV Isolation Low". Read the text next to the number and give your technician both.

Will a new inverter fix error 203?

Usually not. Tigo points out that inverters do not cause arc, ground or isolation resistance faults; they detect and report them. The fault is normally in the wiring or panels.

Other Tigo faults

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• Tigo CCA status light red or yellow: what it means and what to do