PV Panel Operation & Maintenance Guide

Most equipment requires regular maintenance to ensure long service life, and PV power plants are no exception—daily maintenance is essential to guarantee long-term stable operation.

This article explains how to maintain a PV power plant from 8 aspects, applicable to both distributed and utility-scale PV power plants.

1. Maintenance of PV Modules and Mounting Structures

(1) Keep the surface of PV modules clean. Use dry or damp soft clean cloths to wipe PV modules.

      Do not use corrosive solvents or hard objects to clean PV modules.

      Cleaning shall be performed when solar irradiance is below 200 W/㎡.

      Avoid using liquids with a large temperature difference from the modules.

(2) Inspect PV modules regularly. Replace or adjust modules immediately if any of the following issues occur:

      • Glass breakage, backsheet burning, or obvious discoloration;

      • Bubbles forming conductive paths between module edges or any circuit;

      • Deformed, twisted, cracked, or burnt junction boxes, and poor contact of terminals.

(3) Warning labels on PV modules must not be missing.

(4) For PV modules with metal frames, the frame and mounting structure must be well bonded,with contact resistance ≤ 4 Ω. The frame must be securely grounded.

(5) When operating without shadow shading, under solar irradiance above 500 W/㎡ and wind speed ≤ 2 m/s,the temperature difference on the outer surface (directly above cells) of the same PV module shall be less than 20 ℃.PV power plants with installed capacity above 50 kWp shall be equipped with an infrared thermal imager to detect surface temperature differences.

(6) Use a DC clamp meter to measure the input current of each PV string connected to the same DC combiner box under consistent irradiance.Current deviation shall not exceed 5%.

(7) All bolts, welds, and connections of the mounting structure shall be firm and reliable.Anti-corrosion coating shall not crack or peel; otherwise, re-coat promptly.

2. Maintenance of DC Combiner Boxes

(1) DC combiner boxes must be free of deformation, rust, water leakage, and dust accumulation.

      Safety warning labels on the box surface shall be intact. Waterproof locks shall operate smoothly.

(2) All terminals inside the combiner box shall be free of looseness and corrosion.

(3) The rating of high-voltage DC fuses inside the combiner box shall comply with design specifications.

(4) Insulation resistance of positive and negative DC output busbars to ground shall be greater than 2 MΩ.

(5) DC circuit breakers at the DC output shall operate flexibly and reliably.

(6) Surge protective devices (SPDs) inside the combiner box shall be effective.

3. Maintenance of DC Distribution Cabinets

(1) DC distribution cabinets shall be free of deformation, rust, water leakage, and dust.Warning labels shall be intact; waterproof locks shall operate smoothly.

(2) Internal terminals shall be tight and free of corrosion.

(3) Insulation resistance of positive and negative DC busbars to ground shall exceed 2 MΩ.

(4) Connections between DC input interfaces and combiner boxes shall be stable and reliable.

(5) Connections between DC output and grid-connected inverter DC input shall be secure.

(6) DC circuit breakers shall operate flexibly with stable performance.

(7) SPDs on the DC busbar output side shall be effective.

4. Maintenance of Inverters

(1) Inverter structure and electrical connections shall remain intact, free of rust and dust.Heat dissipation shall be sufficient. Inverters shall operate without excessive vibration or abnormal noise.

(2) Warning labels on inverters shall be complete and undamaged.

(3) Cooling fans of modules, reactors, and transformers shall start and stop automatically according to temperature.Fans shall run without abnormal vibration or noise. Disconnect power for inspection if abnormal.

(4) Periodically open the AC output (grid-side) circuit breaker; the inverter shall immediately stop feeding power to the grid.

(5) Replace DC bus capacitors in time if overheated or beyond service life.

5. Maintenance of AC Distribution Cabinets

(1) Metal frames and foundation steel shall be properly connected with galvanized bolts, with complete anti-loosening components.

(2) Labels indicating equipment number, name, or operation position shall be clear and neat.

(3) Busbar connections shall be tight, free of deformation, discharge traces, or insulation damage.Bolts shall be rust-free.

(4) Drawable cabinets shall move smoothly without jamming or collision.Moving and static contacts shall align properly and contact tightly.

(5) Switches and main contacts shall be free of melting; arc extinguishers shall be undamaged.Tighten terminals and clean dust regularly.

(6) Remove drawer-type cabinets, tighten terminals, check CTs, meters, and operating mechanisms.Clean internal dust.

(7) Heat dissipation of low-voltage devices shall be sufficient.Signal lamps, buttons, bells, and indicators shall operate correctly.

(8) Insulation resistance:

     • Feeder circuits > 0.5 MΩ

     • Secondary circuits > 1 MΩ

6. Maintenance of Transformers

(1) Thermometers shall function properly; oil temperature and level shall match ambient temperature.No oil leakage is allowed. Compare actual oil temperature with historical records.

(2) Bushing oil level shall be normal; no cracks, heavy dirt, or discharge traces.Oil shall be transparent and light yellow.

(3) Transformer noise shall be normal (uniform hum). Investigate and resolve abnormal noise immediately.

(4) Leads shall be free of broken strands; joints free of overheating.Silica gel in breather shall not be discolored more than 3/4.

(5) Tap changer position and power indication shall be normal.No gas inside gas relay. Grounding of tank and core shall be intact.

(6) Special inspections under severe weather:

     • Strong wind: check lead swing and foreign matters;

     • Heavy snow: check for rapid snow melting or discharge;

     • Heavy fog: check for spark discharge.

7. Maintenance of Cables

(1) Cables shall not operate under overload. Lead sheath shall not expand or crack.

(2) Cable entries and exits shall be properly sealed.Holes larger than 10 mm shall be sealed with fire-resistant putty.

(3) Cable supports shall be intact where pressure or tension is high.

(4) Cable conduits shall be free of holes, cracks, burrs, or heavy rust.

(5) Clean debris in outdoor cable wells; repair damaged cable sheaths.

(6) Protect indoor cables during inspection; ensure grounding and heat dissipation.

(7) Buried cable markers shall be intact.No heavy objects, construction materials, or corrosive substances along the cable route.

(8) Cable trench/well covers shall be intact; no water accumulation.Supports and armoring shall be free of heavy rust.

(9) For parallel cables, check current distribution and surface temperature to avoid overheating.

(10) Cable terminations shall be well grounded.Insulation sleeves shall be clean and free of discharge traces. Phase colors shall be clear.

8. Maintenance Under Extreme Weather

(1) If tripping occurs during rain, it may be caused by loose connections.Repair only after rain stops. Wrap terminals with insulating tape and observe.Report to maintenance or power supply station if tripping continues.

(2) During thunderstorms, turn off the air switch below the electricity meter to prevent equipment damage.Restore power after the storm passes.