One Warm Cell, a Day of Travel, Six Weeks to the Next Visit

Correct answer: C) It can wait for the scheduled visit, provided today’s image is filed with its exact location, because one scan cannot say whether the anomaly is growing and the next one has to be compared against it

A thermal image is a photograph of one instant, and almost everything you want to know about a warm spot is about time. Is it new? Is it the same as last year? Is it getting worse, and how fast? A single frame cannot answer any of that, which means the most valuable thing this survey has produced is not a work order, it is the first entry in a series.

What is in front of you supports waiting. It is one cell rather than a module, so nothing is bypassed or disconnected. It is not at a junction box or a termination, which is where the genuinely urgent version of a hot spot lives. Production is normal. That combination describes something like a cracked cell or local soiling: a small production loss and a condition that changes over months rather than days.

So the decision is a real one and it goes against spending the money, which is worth saying plainly because it is not the reflex. A day of travel and a dedicated crew for a cell that is a few degrees warm is a poor use of a maintenance budget that has other calls on it, and it is the kind of spending that gets the budget cut for the things that do matter. The discipline is not in going, it is in recording precisely enough that the next survey is a comparison rather than a fresh discovery.

Precisely enough means location, image, date and conditions, filed where the next person will find it. A note saying "minor hot spot somewhere on the north block" is not a baseline; it is a rumour that will cost somebody an afternoon in six weeks.

The O&M point: drone surveys changed what is possible and not what is decidable. A site that used to be inspected in sections can now be imaged completely in an afternoon, which produces more anomalies than anyone can visit, and the constraint moves from finding things to deciding which ones are worth a truck. Every one of those decisions has to be defensible later, and the only thing that makes it defensible is the record you made when you decided.

Why the other options are wrong

A) Dispatch now — any thermal anomaly is a potential fire and cannot be left for six weeks

The instinct is sound and the rule is too blunt to survive contact with a 2 MW site. Treating every thermal anomaly as urgent means dispatching on findings that a complete survey will produce by the dozen, and a maintenance programme that cannot rank its findings will run out of money before it runs out of them. The urgent version of a hot spot exists, and it looks different from this one: it is at a connection rather than in a cell, and it is not a few degrees.

B) No action is needed: a few degrees on one cell is the normal variation you see between modules

Module-to-module variation is real and this is not it. Whole modules do run a little warmer or cooler than each other for reasons of airflow, position and tolerance, and that is the variation this answer is thinking of. A single cell standing out from its own neighbours, inside the same module and the same conditions, is a localised difference, and localised is what makes it a finding rather than scatter.

D) Wait for the scheduled visit and open a warranty claim now on the strength of the image

This acts on evidence that has not been gathered yet. One image showing a few degrees on one cell does not establish a defect, a cause, or that anything is outside what the module is warranted to do, and a claim opened on it will be rejected. Rejections are not free: they cost credibility with the manufacturer, and the claim you want taken seriously is the one you make after the second survey shows the spot has grown.

References

• NABCEP OMAT JTA v.2026.5 — Domain 4, Task 3.I: "Thermal camera", listed among the electrical test equipment and applications.
• No temperature difference thresholds or thermographic classification figures are quoted. Those come from standards the JTA does not name, and the answer here depends on what a single image can and cannot establish rather than on any number. The distinction between a warm cell and a warm termination is about where the heat is, not how much of it there is.