Solar Panel Inspections by Drone

Certified Thermographers

At Thermal Imaging Ireland, quality is the cornerstone of our foundations, with all our Aerial Thermal Imaging Solar panel inspections being carried out to meet and exceed ISO: IEC TS 62446-3, unless otherwise requested by our clients.

All our eight certified Thermographers are experienced UAV/Drone pilots are trained & certified by the IAA, carrying all the necessary H&S qualifications. On the face of it one could be forgiven for thinking that it would be fairly straightforward at first glance, but it's really a lot more complex than it looks. The following outlines answers to some of the most frequently asked questions we get about solar panel inspections using Thermal Imaging.

Q1: Why use an Unmanned Aerial Vehicle? (UAV)

Why use a drone to carry out Thermal Imaging on Solar installations? Not to put too fine a point on it, the main reason is efficiency. With a Thermal Imaging camera on a drone, we can detect thermal anomalies in a large solar field/park in a fraction of the time it would take to do it with a team of technicians each with a Thermal Imaging Camera on the ground.

This is especially true if we're creating Thermal Imaging orthomosaics where we can pinpoint & identify possible faults, enabling us to show technicians the exact locations to remedy.

Q2: What is it that we are actually looking for?

At the most basic level, we're looking for differences in temperature, or delta t's, that can indicate a problem or anomaly that needs further investigation. These could be minimal cell level defects or larger problems like entire strings that are offline. String defects are of the most paramount importance to find. They can significantly degrade an installation's output efficiency and are often due to something relatively easy to fix, like connection or cable problems. While finding a single bad cell probably won't justify replacing an entire panel unless there's a related safety issue, knowledge is power and it's still important to note these faults so they can be tracked as a baseline over time.

What looks like a cell level defect could just be bird droppings or other organic soilings that will hopefully be washed away with the next good rain, or it could be an actual fault that can grow into a larger problem over time, depending on what's causing the problem. That old saying "a stitch in time saves nine" is especially applicable to Thermal Imaging and Solar panel installation inspections.

Something else worth bearing in mind is that UAV/drone Thermal Imaging Solar installation inspections aren't just for older solar installations.

In fact, believe it or not, the optimal time to start a Thermal Imaging aerial inspection program is right when the solar array is being commissioned and handed over from installation to operations. At this point we can ensure that the solar panels themselves are free from any manufacturing defects, that the installation was done correctly and that everything is operating as it should. It's also the best time to get baseline data against which the utility can compare later inspections. Insurance companies are increasingly specifying Thermal Imaging Solar Installation inspections annually. Thermal Imaging Ireland are currently involved in the inspection of the largest solar park in ireland to ISO:IEC TS 62446-3 standards.

Q3: We are often asked how do we fly our inspections?

There are multitudes of topics including but not limited to, irradiance, cloud cover, wind speed, precipitation angles and altitude. In today's discussion let us just deal with Angles and Altitude, the two A's. With angles there are no hard and fast rules. To capture optimum data, we need to find a delicate balance between the look-down or elevation angle of the camera, the angle of the panels, and the location of the sun. The goal is to minimize sun reflections or glare from the panels, which requires an element of experimentation in the field.

If we get a sun reflection in the image, we adjust the viewing angle of the Thermal Imaging Camera to reduce the impact of the reflection. If we're not quite sure if what we're seeing is a reflection or a fault, we look at that section of panels from a different angle. If the hotspot stays in one place, it's a legitimate Thermal anomaly. If it moves, it's a reflection. How high to fly is another finely tuned balancing act, but this time between our clients' Thermal Imaging requirements and the installation we're flying. If we're capturing images that will be stitched into an orthomosaic, we need to fly high enough to capture enough area in each image to be useful, but not so high that we can't detect cell level defects. Given that our Thermal Imaging Cameras give results the equivalent of having 327,680 thermometers in each image, we can confidently fly quite high.

Q4: Can we really diagnose problems with just the Thermal Images that we capture?

No, it is inherently difficult to make a definitive fault diagnosis based solely on your Aerial Thermal Images. They are absolutely invaluable in that they can lead ground-based technicians directly to a problem and drastically reduce inspection time; other troubleshooting will inevitably be required to determine the precise failure mechanism. Our main focus is to concentrate on getting the best Thermal Imagery possible, and work with our clients and the utility technicians to define the actual fault. There's an awful lot more to successful Thermal Imaging Inspections of solar panels from a drone.

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