Guide · July 2026
Your monitoring system says generation is down. It does not say which of the four thousand panels to walk to. Aerial thermal survey answers that in a single flight, without switching anything off.
A solar installation is judged by one number: how much it generates. But that number is an average across thousands of individual panels, and a shortfall never announces which panel is responsible.
An array can lose a meaningful share of its output to faults entirely invisible from the ground — a handful of failed cells here, a bypass diode gone there, a string that dropped offline weeks ago. The monitoring system reports lower generation. It does not report which panels to walk to.
The conventional alternative is a technician walking the array with a handheld meter, panel by panel. On a large installation that takes days, and it therefore happens rarely.
A drone thermal survey covers the entire array in a single flight and produces a map showing exactly which panels are running hot and where they are.
Speed matters, but consistency matters more. Every panel is assessed under the same irradiance and ambient conditions within a short window, which makes comparison across the array valid. A survey spread over two days does not have that property.
Nobody goes onto the roof or between live strings. Nothing is switched off, because inspection is passive and non-contact — the array keeps generating throughout. And every anomaly is located to a panel and delivered with coordinates.
Faults produce heat, because a cell or connection not converting light into electricity is converting it into warmth instead. That makes thermal the natural diagnostic tool for photovoltaics.
Hot cells and hotspots — a single cell running significantly hotter than its neighbours, commonly from cell damage, microcracking, shading or soiling. Left alone these degrade further and can damage the module.
Bypass diode failure, which shows as a distinct pattern, typically one third of a module running warm, because a failed diode takes a whole substring out of service.
String and connector faults, where an entire string reads uniformly warm or cool relative to its neighbours. Module-level failure, where a whole panel is out of service. And microcracking from hail, transport or installation stress, which appears as characteristic thermal patterns before output loss becomes obvious in monitoring data.
Because the survey pairs thermal with high-resolution visual imagery, physical damage — cracked glass, delamination, corrosion, mounting problems, bird fouling and new shading from growing vegetation — is captured in the same pass.
A thermal solar survey is only valid under the right conditions, and it is worth understanding why.
The array must be generating strongly for faults to produce detectable heat differences, so surveys are flown under high irradiance — broadly, clear-sky conditions around the middle of the day. Under weak sun a faulty panel and a healthy one look much the same.
Clear sky matters because passing cloud changes irradiance between one part of the survey and another, undermining comparison across the array. Low wind matters because wind cools module surfaces and suppresses the very differences being looked for. And heavy uniform soiling masks thermal signatures, so a survey after cleaning gives a truer picture of underlying faults.
A survey planned around these produces a definitive result, which is why timing is agreed in advance rather than left to the day.
Years of load shedding drove substantial commercial, industrial, agricultural and residential solar installation. A great deal of that capacity is now several years old — old enough for early-life failures, hail damage and connector degradation to be present.
Very little of it is being inspected. Most owners rely on inverter-level monitoring, which reports that output is down but not why or where. The gap between "generation is eight per cent below expectation" and "these fourteen panels in row twelve" is exactly what an aerial thermal survey closes.
Highveld hail is a real factor, causing microcracking that may not show in output data immediately but degrades performance over time. Post-event inspection provides both a maintenance picture and documentation for a claim.
And agricultural installations are often remote and unattended — borehole pumping, packhouse and irrigation solar frequently sits far from anyone who would notice a problem.
Module warranties typically depend on demonstrating faults rather than asserting them. Radiometric thermal imagery, with measured temperatures and panel-level location, is the kind of evidence a warranty claim or insurance submission needs — and it is considerably harder to argue with than a description.
A thermal orthomosaic of the array — a single heat map of the whole installation. A fault register giving every anomaly with panel location, GPS coordinates, measured temperature, temperature differential and fault classification. A panel-level annotated map, keyed to row and string where layout is available. Paired visual imagery for every anomaly. Severity prioritisation, so the maintenance schedule is ordered by impact. And summary statistics — how many modules affected, what percentage of the array, and the breakdown by fault type.
Thermal identifies which panels are affected and how severely. Confirming the precise underlying cause happens on site — with your maintenance team knowing exactly where to go and what they are looking for.
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