How to set up preventive maintenance rounds for a solar plant

Plants differ a great deal. A rooftop array on a factory has short strings and one inverter room, while a ground-mounted plant has hundreds of strings, combiner boxes and a transformer yard.

List the assets first. Count the inverters, combiner boxes, string monitoring units, weather station, transformer and earthing pits, because the round sheet follows that asset list line by line.

Each task gets a frequency, a person and a reading to record. A task without a reading is just a walk. Decide who signs the sheet at the end of the round. Decide who reviews it within two days. Without a reviewer, abnormal readings pile up unread and the sheet becomes a ritual.

At each combiner box, record string current and open-circuit voltage for every string, noting irradiance from the pyranometer at the same time. Compare each reading with its neighbours rather than a fixed number. One string a third lower than the rest points to soiling, a loose MC4 connector or a failed bypass diode.

Download the inverter event log at every round. Look for repeated insulation faults, grid undervoltage trips and fan alarms, and note when the firmware was last updated. Check the grounding and surge protection status lights as well. A dead indicator on a surge protector is easy to miss and costly to ignore.

Keep units the same each time. A screenshot in place of a number makes trends impossible to read.

Cleaning frequency depends on dust, bird droppings and rainfall. Record the date, method and water used for each block, then compare generation before and after, so you learn which blocks need washing more often. Over a season this gives you a cleaning calendar based on evidence rather than habit, and a clean number to show the plant owner.

A thermal camera finds hotspots that string readings miss. Walk the plant on a clear day with good irradiance and record the module number, the temperature difference against neighbours and the photo reference.

Raise a ticket for each hotspot. Do not tuck it into a notes column.

A round sheet that only lists observations is a diary. Each abnormal reading should open a ticket carrying the plant, asset, finding, priority and assigned technician, so that nothing depends on a supervisor remembering. Short, plain titles help. A ticket named string 14 low current at combiner box 3 can be acted on at once by whoever picks it up.

When the technician closes the ticket, he records the parts used, such as a fuse, a connector or a surge protector. Stores then see consumption by plant. They reorder before the shelf is empty, not after the next outage.

This keeps the client report honest. The monthly summary lists rounds done, tickets raised, tickets closed and parts used. Clients read it in a minute.

Print the sheet and carry it on the next scheduled visit. Note which tasks took too long, which readings nobody could take and which assets were missing. A spare combiner box behind the inverter room is a common miss.

Fix the sheet that same evening. Then load it into a phone form so the next supervisor starts with the improved version. Share it with the client’s site contact too. They often spot an asset or a gate rule that your team has missed.