Arc Fault Troubleshooting Steps:

1. First Clear the alarm if there is one by following the instructions on the screen "Hold Esc button for 3 seconds". Then ensure your date and time are CORRECT , you can use this video to learn how to accomplish that: 

2. Next you need to check out the Alarm history log to see when your errors are occurring. This applies only IF the alarms are being cleared daily or often. When an inverter has an arc fault at the end of the day, the next morning the arc fault will create a new error message if it was not cleared the previous day. Which is why you will see an Arc fault for the previous day in the afternoon, and then again in the morning when the inverter turns on. You need to go back in the error log to find the first arc fault to determine when it happened. If you know it cleared and its still happening in the morning then your chances of it being an inverter issue are MUCH higher. If its occurring infrequently, or around noon when production is the highest, you need to inspect the system. To access the alarm messages, you need to into the "ADVANCED INFO" section of the menu. You will need to enter the password 0010, or DOWN DOWN UP DOWN. Then select "ALARM MESSAGES"

3. Isolating the fault to a single string or inverter is also another way to determine if the fault is in the array, or at the inverter. Disconnect all strings except one, and protect it from arcing to the inverter (wire nuts + tape). Then run the inverter with only one string, if an arc fault occurs, try running it with another string. Keep performing this with all the strings in the inverter. If ALL the strings cause an arc fault proceed  to the next step, if only one string, or no string causes an arc fault then proceed to step 4 

4. Inspecting the system components requires that you check EVERY DC connection between, including between modules. A component that is experiencing arc faults may be slowly degrading to the point of catastrophic failure. If a component is found that is failing, it needs to be replaced. Not just pushed back together.

5. If no failures are found then you need to do a due diligence check. Replace field made DC connectors, Remake any connections inside of junction boxes, and re-terminate the inverter DC connections. Inspect modules for any kind of damage or abnormal coloring. 

6. Replace the inverter as needed, if the fault occurs again with a new unit, you need to begin the troubleshooting procedure from the beginning.