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Italian scientists have investigated the performance of drones and manned aircraft to carry out aerial inspections by infrared thermography at photovoltaic power plants. According to their conclusions, airplanes can be more profitable.
Researchers from the University of Genoa and the Italian aerial inspection company Wesii have compared aerial infrared (IR) thermographic results from photovoltaic plant inspections using classic thermal cameras mounted on unmanned aerial vehicles (UAVs) or high-speed thermal cameras. speed mounted on an airplane. Their research included an economic analysis of both remote sensing-based approaches to fault diagnosis and detection.
“The use of aerial drones speeds up the detection of failures in a large photovoltaic solar plant. However, if the infrared camera is not fast, the drones travel speed should be relatively low to avoid blurring effects,” the group explains. “A plane can cover a very large area in less time, resulting in more profitable flights. On the other hand, due to the speed of the carrier, the IR camera requires a high resolution and a higher number of frames acquired per second. These features are typically found in cooled thermal cameras, which are much more expensive than standard uncooled cameras.”
For their experiment, the researchers used the DJI Mavic 2 Enterprise Advanced UAV and a P2006T SMP human-crewed aircraft. Both have inspected two photovoltaic plants in northern Italy twice and at the same time. Installation 1 consists of 4,347 polycrystalline silicon photovoltaic modules, while installation 2 consists of 4,158 polycrystalline silicon photovoltaic modules. Both have an installed capacity of approximately 1 MW.
On all its flights, the UAV has used a DJI M2EA thermal camera with a 640 × 512 uncooled microbolometer detector, operating in the 8-14 µm wavelength range. The human-manned aircraft used on the first flight a FLIR A8580 with a 1280 × 1024 cooled sensor operating in the 7.5-12.5 µm wavelength range, while on the second flight, it used a FLIR X8581 InSb, 1280 × 1024 cooled sensor that operated in a different wavelength range of 3-5 µm.
“The reason for using a different thermal camera during the second inspection of the aircraft was to allow comparison between the thermal patterns obtained by two infrared cameras with different spectral responses, specifically the long infrared (LW) wavelength range for the drone. and the mid-infrared (MW) wavelength range for the aircraft,” the academics explain.
The visual and thermal images collected were processed on a computer, identifying and categorizing thermal anomalies in the photovoltaic plants.
“As for the most critical defects, such as defective subsequence, entire module, and a chain of modules, 99.6% of them were detected by both aerial platforms. Furthermore, 87.3% of modules with single or multiple hot spots, identified by UAV inspections, were also detected by aircraft inspections,” the researchers highlighted. “Overall, about 98% of thermal defects captured by drone inspections were confirmed by aircraft inspections, with only a 0.23K difference in temperature delta.”
The group concluded that the results show excellent agreement, which is encouraging for the use of an aircraft. With these results, the scientists began to do a comparative cost analysis.
"While UAV-based inspections, which are the market standard, entail daily equipment and labor costs that are not as high as those of the airplane, this last platform, however, allows a larger daily area to be covered," they noted. . “This implies that a threshold value, based on the size (and capacity) of the plants inspected, is likely to determine which technique is most economically viable.”
According to the Italian test case, the daily cost of a UAV is 800 euros ($876), including the operators expenses and the rental of the uncooled thermal camera. In addition, the cost of renting the aircraft, including the pilot, is 2,700 euros per day and 120 euros for the refrigerated chamber. However, it can be assumed that the UAV platform can inspect a maximum of about 20 MW in a single work day, while the aircraft can inspect 300 MW.
“The results show that inspections of any plant require more than two working days, and that the use of the plane is economically more convenient,” the academics said. “In addition, the threshold decreases (and the conditions for using the aircraft become more favorable) if the same amount of PV energy is distributed over a group of smaller plants in the same region.” |
