Improving Solar Farm Inspections Using DJI’s M-300 RTK

Today's solar panels are built to last decades- however, longevity and production efficiency are not interlinked. Using three M-300 RTKs, each equipped with the Zenmuse H20T, the FEDS Team collected data at the rate of 2,200 panels per day. With the 55min flight time and improved accuracy thanks to RTK, we collected data of the entire solar farm in just five days.

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Solar power is one of the significant sources of renewable energy. There’s no denying the return on investment on solar energy is highly valuable both financially and environmentally. Today’s solar panels are built to last decades- however, longevity and production efficiency are not interlinked. Let’s find out how we can keep our solar power plants operating at maximum efficiency through regular inspections and the role drones play in making solar renewable energy competitive with fossil fuels. 

All solar panels degrade over time as an inevitable result of being exposed to the elements. Studies find that solar panels degrade at the rate of 0.5-3% per year, which worsens with intense heat and humidity. In addition to general degradation, you also have to worry about the strain of use causing degradation in the form of PID (Potential Induced Degradation) and LID (Light Induced Degradation). While LID is pretty manageable in that its effects stop in a few hours, PID is less understood and does not ever stop affecting solar panels. Currently, it is accepted that high humidity mixed with sodium buildup can cause electricity to arc and cause damage. 

Tests conducted by the German Fraunhofer Institute found that PID can cause solar panels to lose more than 30% of their production capacity. In adverse cases where PID isn’t identified and addressed, these panels can lose as much as 90% of their production. This loss of production is purely from PID; when you add the degradation from other sources like inadequate ventilation, intense heat, and more, you’re looking at a lot of energy loss. However, the silver lining is that if electricity isn’t being produced, then that energy escapes in the form of heat in most cases. This heat can be detected as hotspots using thermal sensors.

DJI M300 RTK
DJI M300 RTK Equipped with H20T

Inspecting Solar Panels

Given that solar panels degrade and lose production over time, the key to maximizing efficiency is through routine inspections followed by maintenance drives. But, when you’re looking at an industrial-sized solar plant, inspections become an enormous task.

The Traditional Method

Most solar panel defects are visible via thermal sensors. In order to collect this data, teams of inspectors or workers equipped with handheld thermal sensors walk through the plant and take readings. Unfortunately, the traditional solar inspection method is a slow and labor-intensive process. So- you can either increase your workforce to save time or use a smaller team which in turn increases turnaround time- regardless, you can’t consider either scenario a win.

Additionally, suppose your panels are on the roof this adds another layer of complexity and hazards. Another disadvantage of handhelds is the sun reflecting on the panel and improper data collection. A worker walking along the perimeter of rows does not have the luxury to capture data from different and more optimal angles, making avoiding reflections challenging.

Capturing data from suboptimal angles and interference of reflections may cause some faults or issues to go undetected. Slow, labor-intensive, and sometimes inaccurate solar farm inspections result in decreased energy production and increased inspection costs.

Drone Solar Farm Inspection

While the traditional solar inspection methods are slow, laborious, and sometimes dangerous- solar inspections using drones are fast, accurate, and safe. Drones equipped with thermal sensors can capture data from large farms quickly and efficiently. Perhaps the most significant benefit is the reduced manpower requirement. Previously, teams of inspectors would walk around the plant for weeks, but now drones make short work of data collection, turning days and weeks into hours.

Let’s talk numbers- let’s say the average number of solar panels a singular person can inspect by foot is 60 per day. The speed increases when you add more inspectors but at a cost. Using drones, we managed to inspect about 740 panels per drone. If you go the drone route, that’s around a 1,130% increase in inspection efficiency.

Aspects to Consider

When collecting thermal data, timing is always crucial. In some cases, it’s best to do it early on in the day so you can capture asset temperature before the ambient temperature increases. But in the case of solar panel inspections, inspecting when the sun is out, and shining is advisable. It helps ensure that the hotspots are indeed caused by faults which increases your inspection efficiency

Keeping that in mind, the position of the sun is equally important. Glare from the sun can cause whiteouts and render collected data to be ineffective. However, as sensors advance and improve, you can mitigate this- for example, when using DJI’s H20T, we found that the sun’s reflection did not skew our data.

Finally, we have accuracy and altitude. While higher altitudes allow you to cover more area in less time, it also yields less accurate data. So flying at a lower height can help you gather better data. This comes in especially handy when the delta T or mean temperature difference is considerably less. For example, to collect data from a solar farm in the desert, we flew at the height of 40 m (131 feet) to ensure data integrity.

DJI M300 RTK equipped with Zenmuse H20T

Using DJI M-300 RTK and Zenmuse H20T to Conduct Solar Farm Inspections

As we’ve already established, inspecting solar plants on foot is difficult; inspectors would walk between solar panels in the scorching heat, waving sensors over the panels to collect data. This is a laborious and time-consuming process, not to mention inefficient.

The Muhammed bin Rashid Al Maktoum Solar Park is a massive 300-megawatt farm that spans 3.4 square kilometers at the time of writing. Previously, inspecting this plant required scores of workers to be outfitted with handheld sensors to comb through the massive 11,000 solar panel farm. As a result, inspecting this entire solar farm the traditional way took them about two months to complete with a team of 4-5 inspectors. 

A time-sink this large on a process that is repeated yearly or even more frequently is simply not going to work. Slower turnaround times mean the solar power plant operates at a reduced production capacity for longer, bringing down the overall plant production efficiency. Additionally, beyond faults and issues causing a direct drop-in production, damaged panels can sometimes act as a load that holds in power instead of generating it. This further reduces the output of the farm. 

We would be flying in a dusty environment and intense heat, so we wanted our drone to be as robust and rugged as possible. To conduct this inspection, we selected the M-300 RTK paired with the H20T. DJI’s M300 is easily the most reliable outdoor inspection drone. 

Hot spots detected using thermal sensor

As for the payload, Zenmuse H20T is a clear winner. Its accurate thermal output paired with multiple sensors make it favorable for drone solar farm inspections. While the thermal sensor detects hotspots, the RBG visuals collected can help diagnose other issues and eliminate false hotspots.

The FEDS Team began by dividing the entire 11,000-panel large farm into segments and sub-segments. This helps us keep track of our progress and ensures safety on the field. Then, splitting up into three teams where each team flew their own drone, we captured data. Here the segmentation provides the additional benefit of ensuring that the drones have no overlay and don’t risk coming in contact with each other.

Using three M-300 RTKs, each equipped with the Zenmuse H20T, the FEDS Team collected data at the rate of 2,200 panels per day. With the 55min flight time and improved accuracy thanks to RTK, we collected data of the entire solar farm in just five days. The data was collected flying at an altitude of 40m from ground level. 

Flying through the day, one feature that helped improve our inspection efficiency was the hot-swappable battery which let us continue flying with minimal breaks. Given the region’s intense heat combined with the panels reflecting the sun’s rays back up at the drone, we received a heat warning as we neared the end of our day. But, even in the harsh heat and adverse weather conditions, the M-300 efficiently captured effective data.

The M-300 RTK and H20T helped transform solar farm inspections, which were slow and laborious, in a fast and efficient process. This results in issues and faults being diagnosed and addressed quicker and more effectively, which in turn ensures that the solar farm can perform at max capacity. Are you interested in making your solar farm more competitive? Get in touch with us.

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