Hardware Health Logs: Panels, Fans, and Capacitors

Monitor IV curves, fan motor hours, DC bus capacitor ESR, and per-optimizer statistics to catch hardware degradation before it becomes a failure.

Most hardware failures in a SUN2000 installation can be predicted months in advance. Three logs give you direct visibility into the physical health of the system’s most wear-prone components: the solar panels and strings, the cooling fans, and the DC bus electrolytic capacitors. A fourth log, available on installations with Huawei optimizers, lets you identify a single faulty panel among thousands without leaving the office.

sun_inpt_rec — Sun Input Record (IV Curves)

sun_inpt_rec stores the volt-ampere characteristic (IV curve) of each string, along with fan motor-hour counters. The inverter generates these curves by sweeping the string from near short-circuit current (Isc) to near open-circuit voltage (Voc), recording hundreds of current-voltage measurement pairs along the way.

Contents:

• Volt-ampere (IV) characteristic per string
• Fan motor-hour counters

O&M use cases:

• Detecting panel defects — a healthy IV curve has a flat current plateau transitioning smoothly to a steep voltage drop at Voc. A “broken” or stepped curve indicates micro-cracks in panel cells, severe soiling, or partial shading from a new obstruction. The shape of the anomaly points to its cause: steps indicate shading, a uniformly low plateau suggests soiling, and an irregular plateau with an elevated series resistance (Rs) points to micro-cracks.
• Planning fan replacement — the motor-hour counters in sun_inpt_rec tell you exactly how many hours each cooling fan has run.

Plan fan replacement at 30,000 hours of operation — do not wait for the fan to stop. A failed fan in summer will cause the IGBT power switches to overheat. Replacing burned IGBTs costs approximately 20 times more than replacing a fan on schedule.

capacitor_data — Capacitor Health

sun_inpt_rec tracks the strings and fans; capacitor_data monitors the DC bus electrolytic capacitors. These large capacitors smooth the DC voltage between the panel array and the inverter’s power stage. Over time, the electrolyte inside them dries out, reducing capacitance and increasing equivalent series resistance (ESR).

Contents:

• Internal capacitance test results for each DC bus electrolytic capacitor
• ESR (Equivalent Series Resistance) test results for each capacitor

O&M use cases:

• Proactive replacement — electrolytic capacitors typically degrade after 5–8 years of service. capacitor_data lets you track their condition continuously. A status change from Healthy to any other value is an early warning that the electrolyte is drying out. Acting on this signal lets you schedule a board replacement six months before the capacitor would have failed with smoke and a potential production outage.

Capacitor degradation accelerates significantly in hot climates. If your inverter operates in a high-temperature environment, review capacitor_data more frequently — annual checks are not sufficient for inverters beyond five years old in regions with sustained high ambient temperatures. Replacement is critical before the capacitor fails, as a catastrophic capacitor failure can damage surrounding power electronics.

opt_featdata — Optimizer Data

opt_featdata is available on installations where Huawei power optimizers are fitted to individual panels. Each optimizer reports its serial number and operating statistics back to the inverter.

Contents:

• Serial number of each connected optimizer
• Operating statistics per optimizer

O&M use cases:

• Pinpointing a single faulty panel — on a large site with hundreds or thousands of panels, finding one underperforming panel by visual inspection alone is impractical. opt_featdata lets you identify the specific optimizer (and therefore the specific panel) that is producing anomalous statistics. You can then dispatch a technician directly to that panel’s location rather than walking the entire array.