The maintenance checklist most AMCs skip
Combiner box inspection, earthing continuity, and mounting-hardware torque checks rarely make the standard visit. Here's why they should.
5 min readWhat a typical AMC visit covers
Most operations and maintenance contracts are built around what's visible and quick: a visual inspection of panels, a check that inverters are online, maybe a cleaning pass if it's bundled in. That covers the faults that are easy to see and the ones that generate an obvious alarm. It misses almost everything that fails slowly.
Combiner box inspection
Combiner boxes sit exposed to heat cycling, moisture ingress, and rodent activity, and connection points inside them loosen over time even without any single dramatic failure. A loose or corroding termination adds resistance, which shows up as a small, gradual loss in string output that's easy to miss on a dashboard tracking whole-plant performance ratio. By the time it's obvious, there's often visible heat damage at the connector.
Earthing and lightning-protection continuity
Earthing continuity is a safety item first and a performance item second, but it's one of the easiest checks to skip because a failure doesn't show up in generation data at all until something else goes wrong. A degraded earth connection is invisible right up until a fault or a lightning strike, at which point it's the difference between a contained incident and a much larger one. It takes minutes to test and rarely gets scheduled.
Mounting-hardware torque checks
Rooftop mounting structures go through thermal expansion and contraction every single day, and fasteners back off gradually as a result. On plants with any vibration exposure, industrial rooftops near heavy machinery especially, this accelerates. A structure that was torqued correctly at commissioning can be measurably looser three years later, and it's not something a visual walk-through will catch without an actual torque check.
Why these get left out
None of these checks are hard. They get left out because they don't produce an alarm, they take slightly longer than a walk-through, and a contract priced on the minimum viable visit won't include them unless someone asks. Asking for them by name in the AMC scope, and asking to see the visit report that documents them, is usually enough to get them added.
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