O&M Site Visit Checklist for SUN2000 Inverters

A step-by-step O&M site visit checklist for Huawei SUN2000 inverters covering log export, insulation checks, IV curves, and hardware health review.

A planned site visit every 6 to 12 months is the foundation of effective O&M for Huawei SUN2000 installations. Each visit should follow a consistent sequence: export the log data first, then perform physical checks, so that the log evidence and the on-site observations cover the same period and can be correlated during analysis. The steps below reflect the order recommended for maximum diagnostic value.

Do not wait for a fault alarm before reviewing log data. Proactive log analysis — particularly his_inv_rd for string voltage trends and capacitor_data for hardware health — routinely surfaces issues months before they produce a visible fault. Early detection avoids emergency callouts and prevents secondary damage to other components.

1. Export the full log package

   Open FusionSolar and use the Export Log function to download the complete log package from the inverter. This includes his_inv_rd, alarmg_history, sun_inpt_rec, capacitor_data, usrmg_usrlog_2, and the other log groups described in the log encyclopedia. Export before performing any other checks so that the log snapshot is not influenced by actions taken during the visit.

2. Check insulation resistance (Rin) in his_inv_rd

   Open his_inv_rd and review the Rin (Insulation Resistance) column. Rin measures the resistance between the PV string conductors and protective earth. A value below 100 kΩ indicates damaged cable insulation — this may be a cable pinched under a mounting rail, rodent damage to conduit, or water ingress into a junction box. Do not resume normal operation until the fault is located and repaired. Rin below 100 kΩ corresponds to error code 2062 (or code 313 on older 8–42 KTL series models).

3. Take IV curves for all strings

   Use FusionSolar (locally via the inverter’s Wi-Fi access point, or remotely via the cloud) to run an IV Curve Scan on every string. Review each curve for steps (indicating shading from a chimney, tree, or neighboring panel), a uniformly low but flat curve (indicating soiling), or an irregular plateau (indicating poor contacts or micro-cracks). For interpretation guidance, refer to the efficiency analysis page.

4. Review the event log for recurring errors

   Open alarmg_history and filter for “Grid Overvoltage” and “String Reverse” events. A handful of isolated Grid Overvoltage events is normal on many distribution networks; dozens or hundreds of events in a month indicates a structural grid problem that warrants a formal complaint to the grid operator with the log as evidence. String Reverse errors (code 2001) indicate that a string’s polarity was connected incorrectly and must be corrected immediately to prevent damage.

5. Check fan and capacitor health

   Open sun_inpt_rec and read the motor-hour counter for each cooling fan. Record the value and compare it against previous readings to track the rate of accumulation. Plan a replacement before the counter reaches 30,000 hours. Then open capacitor_data and confirm that all capacitor banks show a status of Healthy. Any other status requires follow-up — see the preventive maintenance guide for fan replacement thresholds and capacitor degradation timelines.