Find the panels that stopped pulling their weight
A thermal and visual drone flight over a solar array shows hot cells, dead strings, cracked glass and dirty rows in one pass. Your installer or O&M team gets a map of what to fix, not a guess.
Production drops quietly
A solar array rarely fails all at once. A cell cracks, a bypass diode fails, a connector overheats, a string trips, a row gets dirty or shaded by a growing tree. The monitoring shows output a little below expectation, and nobody knows which of hundreds or thousands of modules is responsible. Walking the array with a handheld camera is slow, and on a rooftop it means working at height next to live DC circuits.
A drone carrying a radiometric thermal camera and a visual camera flies the whole array in a grid while it is producing power. Faulty modules and cells run hotter than their neighbours, and the patterns tell a technician a lot: a single hot cell, a hot third of a module where a bypass diode has taken over a substring, a whole module or string at a different temperature, a hot junction box or connector. The visual images show cracked glass, soiling, bird droppings, debris, vegetation and shading.
Everything is tied to a map, so each anomaly has a row and module location. For larger sites we build a thermal and visual orthomosaic (see orthomosaics and photogrammetry) so the O&M crew can go straight to the right place. The thermal principles are the same as for buildings, covered on our thermal imaging page.
Safety is part of the reason to fly. A PV array produces DC voltage whenever light falls on it, and it cannot simply be switched off at the panel. Keeping people off the array until the images say where to go reduces time spent on a roof or among live equipment. On a house, the same flight also covers the roof around the mounts and penetrations; see roof inspection.
Common findings and what they usually mean
| Pattern | Likely cause | Who follows up |
|---|---|---|
| Single hot cell or small spot | Cracked cell, local defect or persistent shading and soiling | O&M technician checks, cleans or documents for warranty |
| One third of a module warmer | Bypass diode active on a substring, often from cell damage or diode fault | Technician tests module and diode |
| Whole module warmer than neighbours | Module disconnected or not contributing | Electrical check of connectors and module |
| Whole string at a different temperature | String offline: tripped fuse, inverter issue or wiring fault | Electrical contractor |
| Hot junction box or connector | High-resistance connection, a potential safety issue | Qualified electrician, promptly |
| Patterned warming in several modules along a string | Possible degradation such as potential-induced degradation | Asset owner's engineer and module maker |
| Visible dirt, droppings, pollen, debris | Soiling reducing output | Cleaning crew (see roofs and solar panels cleaning, coming) |
Flown to the way the industry measures it
Outdoor thermography of PV modules and plants is covered by IEC TS 62446-3, part of the IEC 62446 family that deals with testing, documentation and maintenance of PV systems. In general terms it asks for strong, stable sunlight on the modules (commonly cited as at least about 600 W/m² in the plane of the array), clear or lightly hazy sky, low wind, enough thermal pixels per cell to resolve faults, and viewing angles that avoid reflections. It also sets out how to classify anomalies by temperature difference and safety relevance.
In practice that means flying around the middle of a clear day, logging irradiance during the flight, and rescheduling when cloud keeps passing over. Our pilots capture to the spec your O&M provider or asset owner asks for, and the classification and recommendations come from a qualified thermographer or solar technician.
Who needs what from whom
Asset owner or building owner
- They need from you
- To know why production is down and what it will take to fix.
- You need from them
- Site access, the array layout and monitoring data for the period in question.
- On the DroneLink record
- The findings and every flight live in one DroneLink project record, shared by link with whoever does the work.
Installer or O&M provider
- They need from you
- Exact module locations, the pattern type and the conditions at the time of capture.
- You need from them
- Their layout drawing and naming convention, so our map uses the same row and module IDs.
- On the DroneLink record
- They pin comments on individual modules in the review tool and mark items fixed.
Module manufacturer or warranty provider
- They need from you
- Dated, radiometric evidence captured under suitable conditions.
- You need from them
- Their evidence requirements before the flight.
- On the DroneLink record
- Radiometric files and flight conditions are kept with the images, not lost in an email thread.
Building manager or strata
- They need from you
- Rooftop safety and no disruption to residents.
- You need from them
- Roof access rules and a site contact.
- On the DroneLink record
- No one walks the array during the survey. See for property managers and strata.
Solar surveys that miss
Flying under patchy cloud
Irradiance swings make modules look faulty one minute and fine the next.
A pretty map nobody can navigate
Anomalies marked on an image without row and module IDs.
Cleaning before a warranty survey
Soiling evidence disappears and the root cause is harder to prove.
Questions
Can a drone find faulty solar panels?
Yes. A radiometric thermal flight under strong sunlight shows modules, cells, strings and connectors running hotter or cooler than expected. A technician then confirms the cause on the ground.
What is the best time to do a thermal solar inspection?
Around the middle of a clear day with strong, stable sunlight and low wind. IEC thermography guidance calls for a minimum irradiance in the plane of the array, commonly cited as about 600 W/m².
How often should solar panels be inspected by drone?
Many owners fly after commissioning to set a baseline, then on a regular schedule and whenever monitoring shows unexplained losses or after hail and storms. Your O&M contract or warranty may set its own interval.
Can a drone inspect rooftop solar on a house?
Yes, and it avoids anyone walking on the panels or roof. The same flight can check the roof around the array.
Does a drone solar inspection show dirty panels?
The visual camera shows soiling, droppings and debris, and thermal can show the effect of heavy soiling on cells.
What standards apply to drone thermal inspection of PV?
IEC TS 62446-3 covers outdoor infrared thermography of PV modules and plants. Other parts of IEC 62446 cover system testing and documentation. Your asset owner may add their own spec.
What drives the cost of a solar drone inspection?
Array size and layout, rooftop versus ground mount, reporting level, weather waiting time and travel.
Keep reading
Tell us about your Vancouver site.
An address and what you need is enough to start. We reply with the price, who will fly it and when.