Drone solar panel inspection is becoming more and more feasible, and here’s why [case study]

PCL Construction is the largest construction company in Canada, and one of the largest in the United States. It’s drawn an impressive amount of business on the simple premise of building success for its clients. The company tackles projects ranging in size and scope, bringing to life the goals of their customers through an innovative approach. Drone data has been integral to all of this lately. So when solar construction projects started showing up on the radar, of course PCL was interested in them. But there was just one problem when it came to drone data capture.

“Once we started running regular flights, we quickly realized we weren’t going to make it with the quadcopters or the multirotors,” said Sean Maland, Surveyor and UAV Pilot at PCL.

Even with a larger, leading-brand multirotor, the PCL team saw that they wouldn’t be able to keep up. After all, solar field construction projects are not like standard building workflows. They’re repetitive and demand reliable data to conduct daily monitoring. 

PCL construction logo
Application
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Challenge
Demanding construction pace requiring repeatable daily drone data capture over large areas at a consistent high quality enabling consistent processing and analysis

We had the understanding of drone operations, but we didn’t have the right drone. That’s when WingtraOne came in. We started to look at your website, and we saw what you can achieve with coverage, and we were like ‘okay this is what we need.’

Alex Ramirez
Senior Manager, Business Technology at PCL 

Solar panel inspection using drones

PCL takes on solar projects that range in size, from small to massive. Once construction gets flowing on the larger fields, it happens in “waves,” with production teams driving more than a thousand piles a day, and module crews placing five times as many solar panels in that same time, Maland said. It’s exacting, breakneck-speed construction that offers a limited view from the ground, making drone data all the more valuable.

“In a large building or civil project, production tracking is important but it’s not as repetitive,” Ramirez said. “You can react in a week and maintain your schedule. With solar projects, if you are talking about how many thousand units are going up on a daily basis, and you let a few days slip, you may be in big trouble for the end of the job.”

For this reason, PCL needs reliable data capture every day, and they need a dependable workflow plus a processing engine that delivers orthomosaics to the superintendent every night.

“The superintendent starts his day at 5 am, opens his ortho and just starts navigating—zooming in and zooming out,” Ramirez said. “He’s checking where things are and whether what was planned for yesterday is done. He’s basically doing what other superintendents would do by walking, but he’s doing it on a big screen navigating the orthomosaic.”

So we fly as frequently as we can with the Wingtras, and then that data is pushed to our processing partner so that they can provide us with an update on the dashboard. I’ve flown WingtraOne about 8000 minutes (133 hours) so far.

Sean Maland
Surveyor and UAV Pilot at PCL 

Wingtra's RX1R II and a6100 payloads

Upgrading from QX1 to RX1R II

The PCL team flies two GEN I WingtraOne drones. They started out with the 20 MP Sony QX1 payload (which has now been replaced by the 24 MP a6100 as the entry-level RGB option on the GEN II). After a successful start, they upgraded to the RX1R II. While both payloads deliver excellent and reliable results, Maland explains how those megapixels offer a new pair of glasses to view the world under study:

“At first when I saw the [RXIR II] orthos come back, I said ‘well I don’t know if it’s too much of a difference.’ But then we started flying all the time, and I was looking at those images. And then we flew the QX1 a bit again, and I could really see the difference.”

For more information and a comparison of outputs from Wingtra’s entry-level and advanced RGB options, visit this blog.

The importance of a “snapshot in time”

When it comes to drone inspection of solar panels, being fast for the sake of being efficient is not the only consideration. Surveys need to capture a moment in time, rather than a puzzle of moments under varying lighting and weather conditions.

“What I see with the team flying the WingtraOne is that it provides that snapshot in time,” Maland said. “‘This is what happened on this day, at this time.’ We can actually see how things are progressing with a historical series of images, and it helps us get through the project more efficiently.

“You can walk around the panels, but you could be walking for days, and they all look the same. But when you look from the air, you can see areas we have left behind for whatever reason and where our production is.” 

The team uses the data for different solar project inspection objectives—from volume calculations, to progress tracking, to surface comparisons. To do this most efficiently, it partnered with AI Clearing, a technology company that rapidly incorporates design and drone data into project insights through visually rich dashboards.

“We mainly use orthos, and AI Clearing takes them and uses computer vision to accurately determine production and gives us our counts,” Maland said. “We also use a lot of the data with our survey equipment. You can turn the point cloud into a surface and load it into survey equipment to check where things are and if they match their designed location.” 

Solar field project
Solar panel drone inspection demands frequent data capture and a reliable system to deliver accurate and clear results so that the project stays on track.

PCL also uses the WingtraOne solar panel drone inspection data for surface comparisons, whereby they turn the point cloud into a 3D surface and compare volumes. All of this information needs to be accurate and time stamped in a way that serves the project.

Finding the best drone for solar inspection

Planning the mapping of large solar fields involves gauging the capacity of the drone and where data capture is needed over time. For the 3300 acre (1335 ha) project PCL took on, the project was so massive that they just focused on the areas where work was happening—i.e., the leading edge of the wave. Still, this area was too big for their previous solution.

“With the quadcopter, we started to get overwhelmed with how much we were going to have to fly … it would be nonstop,” Ramirez said. “WingtraOne turned that planning around, and Sean could strategically see what areas he was going to fly on which days and in what order. It was no longer feeling like we were never going to finish.”

Even if they did get the data every day with the multirotor, and process it every night, they’d lose that snapshot in time. Maland said it would involve stitching multiple flights together for the same result as one WingtraOne flight, because “what you could fly with the WingtraOne in one hour may take you an entire day with a large multirotor.”

Since they are an important part of their production tracking and site management workflow, PCL has flown their WingtraOnes a lot in many kinds of conditions and plenty of wind in open solar fields. In fact, as a team, they’ve logged nearly 200 hours of flight time with them so far. 

We’ve flown in some wild weather, and it’s been a really reliable drone. It has always come back, and we don’t have to re-fly to get our data.

Sean Maland
Surveyor and UAV pilot at PCL 

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