Yes, this is a serious and critical safety issue. Running 1247VDC through conductors rated for only 600V is a major code violation and creates a significant risk of: Insulation Breakdown

The voltage stress will likely degrade the conductor's insulation over time, and possibly rapidly, leading to eventual failure.

Arcing

If the insulation breaks down, high-voltage arcing can occur, which is incredibly dangerous. This can ignite surrounding materials and cause a fire.

Shock Hazard

Compromised insulation makes the entire system a shock hazard to anyone who comes into contact with it, even indirectly (e.g., touching the equipment enclosures).

Equipment Damage

The over-voltage could damage connected equipment (inverters, charge controllers, etc.) and the PV modules themselves.

Code Violation

This is a clear violation of electrical codes (like the NEC in the US), which mandates proper conductor insulation ratings for the voltages present in a system.

Fire

The conductor insulation can break down causing the conductor to heat up and start a fire.Here's a breakdown of why your assessment is correct and what needs to be done:1.

Over-Voltage Situation

You've correctly identified that the voltage rating of the conductors (600V) is significantly lower than the potential open-circuit voltage (Voc) of the PV array (1247V).2.

Worst-Case Scenario

Assuming the 1247VDC is the maximum Voc of all the arrays, this creates an extreme over-voltage situation. Even if it's the total array voltage (after being combined), it's still a problem if any individual conductor is exposed to that voltage.3.

PV Array Voc Considerations

The open-circuit voltage of a PV array is influenced by temperature. Voc increases as temperature decreases. The 1247 VDC you observed may be a value under cold conditions.4.

Immediate Action Required



Do Not Operate the System

The system must be shut down immediately and de-energized to prevent further damage or injury. Tag it out to prevent accidental re-energization.

Qualified Electrician/PV Installer

A qualified and licensed electrician with experience in PV systems must be called to inspect and rectify the problem. This is not a DIY repair.

Detailed Inspection

The electrician needs to determine the following:

Actual Voc of each array

Measure the open-circuit voltage of each array under the prevailing conditions (and consider the lowest expected operating temperature). Obtain the module specifications.

Wiring Configuration

Trace the entire wiring from the PV modules to the combiner box, inverter, and any other equipment. Identify all conductors and their voltage ratings. Determine what each conductor is connected to.

Combiner Box Contents

Access the combiner box to understand how the arrays are combined and what overcurrent protection devices (fuses/breakers) are installed. Check all wiring for proper size and connections.

Inverter Specifications

Check the inverter's maximum DC input voltage rating.5.

Possible Causes and Solutions



Incorrect Wiring

The most likely cause is that the wrong type of conductors were used in the wiring. Solution: Replace all incorrectly rated conductors with properly rated ones suitable for the maximum DC voltage of the PV array (accounting for temperature correction factors, per code). Use PV Wire, which is typically rated for higher voltages and is sunlight resistant.

Incorrect Inverter Selection

The inverter may have too low of a voltage rating for the PV array configuration. Solution: Replace the inverter with one that can handle the voltage (or reconfigure the PV array, but this is often less practical).

Series/Parallel Configuration Errors

The arrays may have been wired in series or parallel incorrectly, resulting in excessively high voltages. Solution: Correct the wiring to the appropriate configuration.*

Code Violations During Installation

The installation may not have followed proper code requirements for conductor sizing, voltage drop, overcurrent protection, and other factors. Solution: Correct all code violations to bring the system into compliance.6.

Documentation

Meticulously document all findings, measurements, and corrective actions taken. This will be essential for future maintenance and troubleshooting.

In summary: This is a very dangerous situation that needs immediate attention from a qualified professional. Do not attempt to fix this yourself unless you are a licensed and experienced PV electrician. Flag for review