5 Advantages of Using Drone Surveys to Inspect Hard-to-Reach Areas of Solar Power Plants

At solar power plants, there are often locations that are difficult for people to approach, such as slopes on reclaimed land, areas around drainage channels, along fences, the far side of racking, plots where weeds have overgrown, and muddy or easily collapsing slopes. These hard-to-access spots tend to be deprioritized during routine patrols, yet they are also places where changes such as rainwater flow, soil movement, weed growth, alterations around racking, and abnormalities in peripheral equipment are likely to appear. One useful method is drone surveying, which allows the current situation to be checked from above. By grasping the overall picture before entering the site, you can concentrate inspections on necessary areas while reducing dangerous approaches, helping to improve the accuracy of operation and maintenance and renovation planning for solar power plants.

Table of Contents

• The significance of inspecting hard-to-reach areas with drone surveying

• Advantage 1 Reduce dangerous close approaches by on-site workers

• Benefit 2 Allows an overview of peripheral areas and slopes that are easily overlooked

• Advantage 3: Easier to understand changes in rainwater pathways and sediment movement.

• Advantage 4: Easier to save patrol records with images and location information

• Advantage 5 Easier to determine priorities for repairs and weeding

• Precautions when using drone surveying in hard-to-access areas

• Summary

The Significance of Inspecting Inaccessible Areas with Drone Surveying

In the maintenance and management of solar power plants, on-site patrols in which personnel walk the site to visually inspect it are fundamental. Damage to equipment, overgrowth of vegetation, warped fences, clogged drainage channels, and changes to the ground are difficult to assess without actually seeing the site. However, walking every area of a plant at the same inspection density each time is not easy. In particular, plants installed in mountainous or sloping terrain often include locations with poor footing, spots that become slippery after rain, and areas where the ground surface is hard to see because of grass cover.

Difficult-to-access areas are not simply places where people cannot enter. They also include locations that can be entered but carry high risks such as tripping, slipping, stepping through unstable surfaces, contact with pests or animals, or difficulty moving due to mud. In practice, locations that are hard to approach even when there is something to inspect—such as behind support frames, deep between rows of panels, around drainage facilities, or on steep slopes along the perimeter fence—are also treated as difficult-to-access areas.

If you force personnel to walk through such areas to inspect them, not only does the inspection itself become dangerous, but the time required also increases. Moreover, when the inspection coverage varies depending on the field staff’s experience and physical strength, the quality of the records tends to be unstable. Using drone surveying makes it easier to survey the entire power plant from above and to capture the condition of hard-to-access areas as images and terrain data. You can identify hazardous spots before anyone enters and narrow down the locations that require on-site checks, making it easier to improve both safety and efficiency.

Drone surveying at solar power plants is not just for capturing attractive aerial images. It can be used to inform site management decisions such as revising inspection routes, planning vegetation control, verifying drainage, assessing sediment runoff, checking for abnormalities around racking, and prioritizing repair plans. Especially in areas that are difficult to access, where what can be seen from the ground is limited, the perspective from above is particularly valuable.

On the other hand, there are limits to the information visible from drones. Small sinkholes hidden beneath grass, loose bolts, and fine damage to cables may not be fully discernible from images alone. Therefore, it is important to consider drone surveying not as a complete replacement for on-site inspections but as a means of narrowing down the locations that need to be checked while reducing risk. In managing hard-to-access areas, combining the broad aerial perspective with detailed ground-level checks allows you to create an inspection regime that is more practical for field operations.

Benefit 1: Can reduce dangerous proximity of on-site workers

A major advantage of using drone surveying to inspect hard-to-access areas of solar power plants is that it reduces the number of times field workers have to approach hazardous locations. Within the plant site there are many places that require caution when walking: steep slopes, ground eroded by rainwater, muddy areas, places where weeds obscure the ground beneath your feet, and steps or ledges along the perimeter fence. Especially after rain or typhoons, or in sections that have not been patrolled for a long time, you cannot assume you can walk them the same way as before.

In conventional patrols, an inspector first had to approach the area to confirm whether any abnormalities were present. However, if the route to the inspection target itself is hazardous, the initial on-site check carries risks. By using drone surveying, the situation can be assessed from above before workers enter. Because you can see in advance slope failures, scour around drainage channels, intrusion of fallen trees and branches, inflow of soil from outside fences, and the state of vegetation growth, there is less need to suddenly step into dangerous areas.

This has significant implications for patrol safety management. For example, if part of the perimeter is at risk of a landslide, you can assess the extent with drone imagery before approaching from the ground, rather than only noticing it when you get close. If necessary, you can revise the number of personnel, equipment, access routes, and the order of inspections. If you judge the danger to be high, it also becomes easier to decide not to force a patrol and to switch to arranging inspection or repairs by a specialist contractor.

In power plant maintenance, balancing inspection frequency and safety is a challenge. The more hazardous a location is, the more you want to check it, but sending people in every time is a heavy burden. By conducting regular drone surveys, changes in hazardous areas can be monitored remotely, making it easier to pinpoint when on-site verification is actually needed. This makes it easier to reduce unnecessary approaches while maintaining the quality of inspections.

Furthermore, hard-to-reach areas are difficult to assess even for experienced personnel. Those most familiar with the site may be more likely to walk through assuming conditions are as they were before. However, the ground and drainage environment at solar power plants can change due to heavy rainfall and long-term erosion. By first checking the latest conditions with drone surveying, you can avoid relying too heavily on past memories and make decisions based on current risks.

Improving safety not only protects workers but also contributes to the overall stability of power plant management. If accidents or injuries occur during patrols, inspection work may be halted and additional responses may be required. By reducing approaches to hazardous areas and organizing the inspection scope in advance, on-site response planning can be improved. Drone surveying is an effective means of shifting the premise from forcibly walking into hard-to-reach areas to check them to first assessing them from the air.

Benefit 2: Provides a bird's-eye view of peripheral areas and slopes that are easily overlooked

In solar power plants, the central parts of panel rows and areas along aisles are relatively easy to inspect, whereas peripheral areas, slopes, and the far sides of drainage channels tend to be overlooked. The larger the plant, the more difficult it becomes to uniformly inspect the entire site within the limited patrol time. In particular, along the perimeter fence vegetation tends to grow easily and, being close to adjacent properties, visual inspections take more time.

Using drone surveying, you can get an aerial overview of areas that are easily overlooked. Even locations that are obscured from ground-level view by grass or mounting racks become easier to understand in terms of layout and extent from above. You can confirm information that is difficult to grasp through ground patrols alone, such as trees overhanging from outside the fence, weeds growing behind rows of panels, surface changes on slopes, and sediment accumulation around drainage channels.

The advantage of a bird's-eye view is not simply that it shows a wider area. It also makes it possible to compare where signs of abnormalities are concentrated across the entire power plant. For example, if vegetation in only one section is growing faster, there may be differences in sunlight exposure, drainage, or ground conditions. If only part of a slope shows a change in color or shape, surface runoff or water concentration may be occurring. If only a portion of the perimeter fence appears distorted, it can prompt checks for earth pressure, fallen trees, or animal intrusion.

On-ground patrols tend to bias information toward the areas visible from the route the inspector walks. Locations away from the path, the back side of panel rows, and subtle changes at the toe and shoulder of slopes are difficult to confirm unless you get close. With drone surveying, by predefining the flight area and acquiring images with a certain amount of overlap, you can verify the entire power plant area in a planar manner. This enables records that are not overly dependent on the patrol personnel's walking routes.

Aerial overview images also have the advantage of being easy for multiple people to review. When only the person who went to the site knows the situation, it takes time to align understanding with managers, construction personnel, and repair personnel. With images captured by drone surveying, everyone can look at the same screen and discuss where the problems are and which areas should be prioritized for inspection. When explaining areas that are difficult to access, using aerial overview images makes it easier to reduce misunderstandings than conveying the location by words alone.

Perimeter areas and slopes are locations that are critical to the stable operation of a solar power plant. Abnormalities in the perimeter fence can affect security and safety management, and abnormalities in slopes or drainage can lead to soil erosion or changes in ground conditions around the racking. Using drone surveys to get an overhead view of these areas and detect changes at an early stage helps prevent equipment troubles. Making hard-to-see locations visible provides great value for areas that are difficult to access.

Benefit 3 Easier to understand changes in rainwater pathways and sediment movement

What deserves particular attention in areas of a solar power plant that are difficult to access is the flow of rainwater and the movement of soil and sediment. Solar power plants often cover large areas, and on developed or sloped sites rainfall can concentrate in specific locations. If drainage channels become clogged, parts of a slope are eroded away, or sediment flows into access routes, it can not only hinder inspections and maintenance but also potentially affect the stability around racks and foundations.

Rainwater flow paths can be difficult to grasp by simply walking the site and checking from the ground. Because water flows from higher to lower locations, the overall slope of the plant, the placement of drainage facilities, surface irregularities, and the density of vegetation are all relevant. Even if you find a puddle at a particular spot, it is hard to determine whether its cause is poor drainage upstream, local ground subsidence, or blockage by plants or sediment without looking at the surrounding area as a whole.

Using drone surveying makes it possible to inspect a wide area from above, making it easier to determine which directions rainwater is likely to flow and where sediment has accumulated. Capturing images after rain can sometimes reveal the distribution of puddles and wet ground. Even when imaging during dry periods, you can often infer trends in rainwater pathways from traces of sediment flow, changes in vegetation, and color differences around drainage channels. This information provides clues to narrow down problem areas before on-site inspection.

Even for checking soil and sediment movement, drone surveying is effective. Small slope failures, sediment accumulation in drainage channels, inflow beneath mounting frames, and scour of access roads may appear as localized anomalies when viewed from the ground. However, from above it becomes easier to identify which slope the sediment is coming from, which drainage routes it is following, and which areas are being affected. Because causes can be separated from the extent of the impact, it also becomes easier to organize repair priorities.

Furthermore, by regularly photographing the same location, you can compare changes. By comparing the previous images with the current ones, it becomes easier to notice places where sediment has increased, where vegetation has begun to cover drainage channels, or where the paths of rainwater have changed. In areas that are difficult to access, precisely because you cannot walk and inspect every time in detail, it is important to keep chronological records. If you accumulate drone survey images and terrain data, it becomes easier to determine whether an abnormality is temporary or is continuously progressing.

However, the appearance of rainwater and sediment varies depending on the time of imaging. Immediately after rainfall it is easier to confirm water flow, but flight conditions and safety management require careful attention. During dry periods, puddles may not be visible, yet traces of sediment or disturbed vegetation can sometimes indicate their presence. The important thing is not to draw conclusions based solely on drone survey results, but to assess them together with the site’s topography, past inspection records, rainfall conditions, and the layout of drainage facilities.

Rainwater routes and sediment movement are deeply involved in the long-term maintenance of solar power plants. If small changes are left unaddressed, their effects can spread during the next heavy rainfall. By checking hard-to-reach areas with drone surveys, you can assess conditions before attempting to enter dangerous slopes or muddy spots and consider necessary countermeasures sooner.

Advantage 4: Easier to keep patrol records with images and location information

In managing solar power plants, it is important not only to detect anomalies but also to record when, where, and in what condition they occurred. Especially in hard-to-access locations, even if on-site personnel describe the situation verbally, it can be difficult to convey it accurately to managers or repair personnel. If the location identification is vague, later reconfirmations or work instructions can take more time.

Using drone surveying makes it easier to link inspection records with images and location information. Aerial images capture the overall layout of the power plant, rows of panels, walkways, perimeter fences, drainage channels, slopes, and so on, making it easier to grasp the positional relationships of anomalies. Even when ground photos alone make it difficult to understand the surrounding context, aerial images make it easier to explain which section and which direction an anomaly is located.

The quality of inspection records tends to vary depending on the person in charge. With text-only records, the same "sediment accumulation" may not convey the amount, extent, or urgency to the reader. Even when photos are attached, if their shooting direction and distance are unknown, it can be time-consuming to pinpoint the location within the power plant. By using drone survey images, you can view abnormal areas from above and, when necessary, combine them with ground photos and notes, thereby improving the resolution of the records.

Image records also help align understanding among stakeholders. A solar power plant involves multiple parties, such as power producers, operations and maintenance personnel, construction contractors, vegetation-control staff, and repair personnel. When sharing problems in hard-to-access areas, if only the person who visited the site knows the situation, decision-making tends to rely on individual judgment. By keeping images and location information, stakeholders who have not been to the site can check the situation and have concrete discussions about the scope of work and priorities.

Drone surveying is also useful for time-series management. If you photograph the same location under similar conditions, you can compare past and present conditions. Vegetation growth, sediment accumulation, clogged drainage channels, and slope changes can be difficult to judge from a single inspection. However, when multiple records are lined up, it becomes easier to see whether an abnormality is progressing or a temporary change. This time-series comparison is particularly important in areas that are difficult to access.

Furthermore, if inspection records are organized, they can also be used to verify conditions after repairs. For example, by comparing images taken before and after the removal of sediment from drainage channels, it becomes easier to demonstrate the results of the work. The condition after weed removal, the condition after slope repairs, and the state of restoration around fences can also be recorded with aerial images and retained as part of the management history.

However, to make use of records, rules for storing captured data are also important. If you do not organize the shooting date, target area, flight purpose, detected anomalies, response status, and so on, it will take time to find the images you need later. The positional information and image accuracy recorded by the drone vary depending on the aircraft, positioning method, shooting conditions, and processing method, so it is also important to decide how to verify them according to the required management accuracy. To continuously manage areas that are difficult to access, a perspective that turns observed information into usable records is indispensable.

Benefit 5: Easier to prioritize repairs and weeding

In areas of a solar power plant that are difficult to access, even if problems are found, it is not always possible to address all of them immediately. Tasks to be addressed include weeding, cleaning drainage channels, removing sediment, repairing slopes, fixing fences, and maintaining access paths, among others. To manage efficiently with limited personnel and time, it is necessary to decide where to start.

Drone surveying helps with this prioritization. By observing the entire power plant from above, it becomes easier to grasp the extent of anomalous areas, their relationship to surrounding equipment, the ease of access for work vehicles, and the impact on other sections. For example, even when weeds are similarly overgrown, the priority for response differs depending on whether they are casting shadows on panels, blocking drainage channels, or spreading beyond fences to the outside. If the extent can be confirmed with images, it becomes easier to concretize the work plan.

Overview information is important even when making repair decisions. If part of a slope has collapsed, the response will differ depending on whether the collapse is a small, localized incident or shows signs of spreading to the surrounding area. If sediment has accumulated in a drainage channel, it is necessary to determine whether simply cleaning that spot is sufficient or whether measures are needed to stop sediment outflow from upstream. By confirming the surrounding conditions with drone surveying, it becomes easier to consider not only the visible anomaly but also its causes and the extent of its impact.

It can also be used for weed-control planning. At solar power plants, vegetation growth varies by section. In areas with high moisture, different sunlight conditions, where seeds easily enter from the perimeter, or places that are hard to see from maintenance paths, the progression of overgrowth differs. By using drone survey images, you can compare vegetation conditions across the entire plant and more easily determine which areas should be prioritized for weeding. When grass grows in locations that are difficult to access, anomalies on the ground surface and the condition of drainage channels become harder to see, so timely decisions are important.

It also helps with pre-work planning. When carrying out repairs or weeding in hard-to-access areas, you need to consider where to enter, where to place materials, and in what order to perform the tasks. If you check current conditions with drone surveys, you can reduce the time spent hesitating after arriving on site. You can also plan routes to avoid dangerous slopes or muddy spots, and share the work area in advance.

Furthermore, clarifying priorities makes it easier to explain them to stakeholders. In power plant management, there are situations where items are separated into those that require immediate attention, those to be monitored until the next inspection, and those to be repaired on a planned basis. With drone survey imagery, you can visually explain why a particular location is being prioritized. This is also effective for work requests, internal approvals, and adjustments to maintenance schedules.

In managing hard-to-reach areas, merely finding problems is not sufficient. Deciding the order in which to address identified problems, how extensively to respond, and when to recheck them makes inspection results useful in actual operations. Drone surveying is an easy-to-use method as a basic resource for determining priorities for repairs and vegetation control because it allows judgments to be made by comparing wide areas.

Precautions When Using Drone Surveying in Areas Difficult to Access

Drone surveying offers many advantages for inspecting hard-to-reach areas of solar power plants, but if used improperly it may not yield sufficient results. The first and most important step is to decide in advance what you are flying to observe. Whether you are confirming the safety of inaccessible areas, checking drainage conditions, determining the extent of vegetation control, or comparing before-and-after repairs will affect the area to be photographed, the flight altitude, and the level of image detail required.

If you take photos without a clear purpose, the images may remain but become difficult to use for practical decision-making. For example, a wide overhead image is sufficient if you only need to check the overall condition of a power plant, but if you want to check clogging or sediment buildup in a drainage channel, you need a resolution that sufficiently shows the area of interest. When tracking changes to a slope, it is also necessary to take steps to keep the shooting position and timing as consistent as possible so comparisons with previous images are easier.

Next, it is important to separate the information that can be confirmed by drone from the information that should be checked on site. Aerial images make it easy to grasp extent and spatial relationships, but they can make it difficult to judge details such as the strength of components, looseness of members, the condition of cables, or steps hidden under vegetation. If a potential anomaly is found in the images, it is safer to conduct a ground inspection as necessary to verify the actual condition. Drone surveying should be used not just to replace on-site inspections, but to make them safer and more efficient.

Attention must also be paid to flight conditions. At solar power plants, it is necessary to consider panel surface reflections, the effects of wind, distances to mounting racks and electrical equipment, surrounding trees and terrain. Especially in mountainous areas and on slopes, even if the wind feels light at ground level, wind conditions aloft can change. Before flight, it is important to check the weather, wind, visibility, surrounding environment, and takeoff and landing sites, and determine whether conditions are safe for flight.

Operations that take into account the plant’s equipment and surrounding environment are also indispensable. Avoid getting too close to panels, mounting racks, and electrical equipment, and if workers are present, be sure to share the intended flight area with them. When checking the perimeter, you must also pay attention to adjacent properties, roads, and places where third parties may be present. Drone surveying is a convenient method, but it presupposes on-site safety management and consideration for the surroundings. As necessary, it is also important to confirm in advance the laws related to flight, the facility manager’s rules, and safety procedures appropriate to the surrounding environment.

In terms of data management, how you organize the images you capture is important. Recording the shooting date, target section, purpose of inspection, any anomalies, and the status of responses will make the images easier to use when reviewed later. Simply saving images can result in losing track of why they were taken over time. Because areas that are difficult to access require ongoing management, it is important to organize images so they can be compared with past images.

Finally, it is necessary to consider how to incorporate the results of drone surveying into on-site operations. It is not enough to simply capture images; only when the results are reflected in revisions to patrol routes, work instructions, repair plans, weed control plans, and items to check at the next inspection will they be effective. Especially in areas that are difficult to access, it is important to use the information obtained from the images to determine which locations require personnel entry, which can be left for monitoring, and which should be addressed promptly.

Summary

Areas of a solar power plant that are difficult to access are easy to overlook in management, yet they are important locations for the plant’s safety and long-term operation. Slopes, drainage channels, perimeter fences, behind mounting racks, sections overgrown with vegetation, muddy or easily collapsing ground, and the like can be difficult to inspect by ground patrols alone. If people force themselves to approach, the risk of trips and slips increases, and the inspection itself can become dangerous.

By using drone surveying, you can get an aerial overview of an entire power plant while reducing workers’ dangerous proximity. It reduces oversights of the perimeter and slopes, allows you to understand changes in stormwater paths and sediment movement, and enables you to keep inspection records that combine images and location information. Furthermore, it serves as material to help prioritize repairs and weed control. Rather than simply avoiding hard-to-access areas, a major advantage is being able to check conditions from above and focus responses on the locations that need them.

On the other hand, drone surveying is not a cure-all. Rather than determining detailed abnormalities from images alone, it is important to make judgments by combining on-site verification and past records. By clarifying the purpose of imaging, checking flight conditions, organizing the acquired data, and reflecting it in patrol and repair operations, only then can it lead to improved management quality.

In the maintenance and management of solar power plants, it is important to shift from inspections that force entry into dangerous areas to inspections conducted from the air that verify conditions and inform decisions. If you want to safely and efficiently understand hard-to-access locations, consider using drone surveying tailored to the plant’s scale, terrain, management objectives, and required accuracy.