When you engage a solar panel inspector for a commercial rooftop array or a solar farm, the practical method is an aerial pass with a thermal camera and a high-resolution visual camera, flown over the whole array while it is generating. The thermal data shows which modules run hotter than their neighbours — and hot is the signature of almost every electrical fault a photovoltaic array develops.
We capture and deliver that data with every flagged module located on a map. A licensed electrician or accredited solar technician does the diagnosis and the repair. Worth stating up front — that split is what makes the deliverable useful.
Why a thermal camera sees electrical faults at all
A photovoltaic cell converts light into electrical energy and exports it. When a cell, connection or module can’t export that energy — a cracked cell, a degraded solder joint, a failed diode, an interrupted string — the energy still arrives from the sun. It has to go somewhere. It dissipates as heat.
So a healthy module sits at roughly the same temperature as its neighbours, and a faulty one runs hot. A degraded connection is a resistance, and current through a resistance produces heat. A shaded or soiled cell being back-driven by the healthy cells in series with it becomes a load rather than a source, and heats up.
The camera isn’t detecting “a fault” directly. It detects where energy is being wasted, and wasted energy in an array is nearly always a fault. That is why thermal is the standard first-pass tool at any scale: it turns an invisible electrical problem into a visible pattern, and the pattern indicates what kind of problem it is.
The fault types that show up thermally
Hot spots. A single cell, or part of one, running much hotter than the rest of the module — cell damage, a manufacturing defect, or persistent localised shading or soiling. They are self-accelerating: a hot cell degrades further, gets hotter, and can damage the module.
Bypass diode failures. A module is divided into substrings, each protected by a bypass diode. When a diode fails or activates, roughly a third or half of the module runs uniformly warm. That block pattern is easy to read off a thermal image.
String outages. A whole run of modules sitting uniformly different in temperature from the array around it. That points upstream — an isolator, a fuse, a combiner box, an inverter input, a broken connection. A dead string can sit unnoticed for months.
Module-level outages. A single module warm across its whole surface with normal neighbours — an internal failure or a connection at that module.
Cell cracking. Microcracks from handling, transport, hail or foot traffic often don’t show visually, but they interrupt current paths within the cell, giving a patchy, irregular warm area.
Soiling and shading losses. Bird droppings, lichen, dust along the lower edge of modules, a vent’s shadow, vegetation at a fence line. These show thermally because the affected cells are back-driven, and in the visual imagery too — which is why we fly both sensors.
Junction box faults. Heat at the junction box on the rear of the module, seen from above as a warm band at the module edge — usually a connection or diode issue inside it.
Connection issues. Degraded solder joints, corroded connectors, loose terminations. Where resistance has increased, heat follows: small, sharply defined hot points.
Why aerial beats walking the array with a handheld camera
A handheld thermal camera works fine on a small array. It stops scaling almost immediately.
Speed. A drone covers a large commercial roof or a solar farm in a fraction of the time it takes to walk it, capturing the array in one consistent session rather than across days of changing conditions.
Consistent standoff and angle. Thermal measurement is sensitive to viewing distance and angle, and glass is reflective in the infrared — an oblique handheld shot picks up reflected sky temperature that has nothing to do with the module. A planned grid at fixed altitude, looking straight down, gives every module the same geometry, so comparisons across the array hold.
No foot traffic on modules. Walking on panels causes microcracking, and microcracking is one of the faults you were inspecting for. An inspection method that creates the defect it looks for is a poor trade.
A complete georeferenced record. Every image carries position data, so flagged modules are placed precisely on an array map — row, table, string, module position. The repair crew is sent to a location, not handed a photo and asked to find it. On a site with tens of thousands of modules, that is the difference between a usable report and a useless one.
Conditions matter: when a thermal inspection is valid
Be sceptical of anyone who will fly a thermal solar panel inspection whenever it suits the schedule. Conditions materially affect whether the data means anything.
Irradiance. The array needs enough sunlight for faults to generate a detectable temperature difference. In low light, faulty and healthy modules sit at similar temperatures and the fault doesn’t appear. Industry guidance calls for a minimum irradiance level, measured on site, before capture.
Time of day. Around the middle of the day, sun high, gives strong even irradiance and less shadowing from structures. Early morning and late afternoon bring long shadows and low sun angles that weaken the signal.
Clear, stable conditions. Cloud shadow moving across an array mid-flight changes the thermal picture between one image and the next, so comparisons stop being valid. Wind cools modules convectively and reduces temperature differentials.
Array operating under load. The array must be generating and connected. An isolated or curtailed array isn’t dissipating energy in the way that reveals faults. If the inverters are off, the inspection is meaningless.
We check these before flying and record them in the delivery — conditions are part of the evidence. If the day isn’t suitable, rescheduling beats a dataset nobody can rely on.
Rooftop arrays, solar farms and large residential
Commercial rooftop arrays are the most common case — warehouses, factories, schools, cold stores. The roof is hazardous to access, the array is large, and generation has quietly slipped.
Solar farm inspection is where aerial capture isn’t merely convenient but the only sensible approach: walking a utility-scale site with a handheld camera isn’t realistic, and per-string monitoring narrows a fault to a string, not a module.
Large residential arrays are worth flying when a fault is hard to isolate or the roof is steep, high or fragile; for a small domestic system a technician with a handheld camera is usually proportionate.
What an aerial solar panel inspector delivers, and where the work stops
You get a radiometric thermal dataset, matching high-resolution visual imagery, an orthomosaic of the site, and flagged anomalies located on an array map with the thermal and visual image for each. Delivery is metadata-intact with a manifest and a methodology statement noting date, time, conditions and capture parameters, so the record holds up at a warranty claim or with an insurer.
What we don’t do: electrical testing, IV curve tracing, insulation resistance testing, isolation, rectification or certification. We are not electricians. A licensed electrician or accredited solar technician takes our data, confirms the fault at the module and carries out the repair — which is why several of them engage us for the capture.
CASA-compliant operation
We operate under CASA rules with a licensed remote pilot. That matters more than usual for solar work: solar farms sit in regional locations near aerodromes, airstrips or low-level flight paths, and airspace approvals can be the long pole in scheduling. We check airspace before quoting and arrange authorisations in advance.
Frequently asked questions
What does a solar panel inspector actually check?
An aerial solar panel inspector captures thermal and visual imagery of every module while the array generates, then flags modules with abnormal temperature patterns. Those patterns indicate hot spots, bypass diode failures, string or module outages, cell cracking, soiling, shading and connection faults. A licensed electrician confirms and rectifies each one.
Why does a thermal camera detect solar panel faults?
A working cell exports the sun’s energy as electricity. When a cell, connection or module can’t export it — cracking, a failed diode, a broken string, a degraded joint — that energy dissipates as heat instead. The faulty component runs hotter than its neighbours, and the thermal camera sees that difference.
What affects solar panel inspection cost?
Cost is driven by array size and module count, site access, travel and remoteness, any airspace approvals required, whether both thermal and visual capture are needed, and the depth of reporting. We price per site after a short conversation rather than quote a figure that won’t hold.
What conditions are needed for a valid thermal inspection?
The array must be connected and operating under load, irradiance high enough for faults to produce a detectable temperature difference, skies clear rather than broken cloud, and wind light. Middle-of-the-day flights with a high sun angle are most reliable. Poor conditions produce data nobody should rely on.
Do you repair the faults you find?
No. We capture and deliver the thermal and visual data with fault locations mapped. We do not carry out electrical testing, rectification or certification. A licensed electrician or accredited solar technician diagnoses the faults and does the work. The array stays running during capture — faults only show while it is generating.