6 Drone Surveying Applications Useful for Recovery Planning of Solar Power Plants

In solar power plants, various factors—typhoons, heavy rain, strong winds, sediment inflow, ground deformation, poor drainage, and overgrown weeds around equipment—can cause issues to power generation equipment and site grounds. When creating a restoration plan, it is important to quickly grasp where and what is happening, and to organize restoration priorities and the scope of work while avoiding hazardous areas. Drone surveying, which enables a broad aerial overview of the current condition of a solar power plant, is useful for this.

Table of Contents

• Why Drone Surveying Is Useful for Recovery Planning

• Use Case 1 Grasp the extent of damage spatially

• Use Case 2 Check for topographic changes and poor drainage

• Application 3 Organize abnormalities around panel rows and mounting frames

• Use Case 4 Determine whether access routes for deliveries and work flow paths can be restored

• Use Case 5: Consider recovery quantities and priorities

• Use case 6 Keep comparative records before and after recovery

• Precautions when using drone surveying in recovery planning

• Summary

Why Drone Surveying Is Useful in Recovery Planning

In a restoration plan for a solar power plant, it is first necessary to accurately grasp the on-site conditions. If you assess only part of the equipment, you risk overlooking the full extent of the damage. For example, what appears to be merely dirty panels may coincide with erosion of surrounding slopes or clogged drainage paths causing standing water. Simply walking the site and inspecting from the ground can make it difficult to understand how the entire site is interconnected.

Drone surveying is characterized by its ability to observe an entire power plant from above and organize the data as photographs, orthophotos, point clouds, and elevation information. This makes it easier to understand damaged areas as surfaces rather than as points. Especially at large power plants or those installed on sloped terrain, ground inspections can take time and may require approaching hazardous areas. By using drones, you can grasp the overall site as an initial check before entry, providing decision-making information that enhances the safety of restoration work.

In recovery planning, it is essential not only to repair the damaged areas but also to include a perspective for preventing recurrence. By checking whether water tends to collect in the same locations after heavy rainfall, whether there are routes prone to debris inflow, and how walkways and drainage facilities are functioning, it becomes easier to distinguish between emergency responses and permanent countermeasures. Data obtained from drone surveying is also useful as material for sharing the extent and positional relationships that are difficult to explain with on-site photos alone, and helps align understanding among property managers, contractors, maintenance personnel, and clients.

However, drone surveying is not a cure-all. Electrical faults in panels, anomalies in internal wiring, detailed damage to racking members, and the internal condition of foundations, among other issues, need to be assessed in combination with visual inspections and specialized testing. Positioning drone surveying in recovery planning as a tool to support understanding current conditions, defining the scope, comparative record-keeping, and sharing with stakeholders makes it more practical for use in the field.

Use Case 1 Understanding the Extent of Damage Spatially

The first step in a recovery plan is to ascertain how far the damage has spread. At a solar power plant, damage is not necessarily concentrated in a single location. After a typhoon, for example, debris on panel surfaces, fallen trees around fences, sediment on access paths, clogged drainage channels, slope failures, and exposed areas around cable racks can occur simultaneously in multiple places. Walking the site and checking sequentially from ground level makes it easy to find localized damage, but it takes time to organize the positional relationships across the entire site.

By using drone surveying, you can capture the entire power plant from a consistent altitude and confirm damaged areas across the site. Oblique photos can convey the overall situation, but when they are used for restoration planning it is important to record them in a format that makes spatial relationships as easy to organize as possible. Having planar data created by stitching aerial photos together, such as orthophotos, makes it easier to explain which panel rows are surrounded by debris, which access paths are unusable, and which slopes are showing signs of deformation.

When assessing the extent of damage, do not focus only on visible abnormalities; also check areas that could affect restoration work. For example, even if a row of panels is not directly damaged, muddy access paths in front of them can hinder material deliveries and workers’ movement. If part of a fence has fallen, you need to consider not only equipment damage but also third-party access and security management. Aerial data from drone surveys is well suited to confirming these surrounding conditions simultaneously.

Also, when sharing the extent of damage, it is important not just to line up photos but to organize them in a way that makes the locations clear. Standardizing the photo number, shooting position, the approximate range of the anomaly, and the inspection date makes it easier to move forward with discussions on the restoration plan. Linking this information to the names and identifiers commonly used on site—such as the plant’s block/section number, panel row numbers, walkway names, and fence positions—will help maintenance and construction personnel avoid confusion in the field.

Understanding the extent of damage directly informs decisions on emergency response. To distinguish locations that require immediate safety measures, those likely related to generation stoppage or output reduction, and those that can be addressed later, an overall picture is necessary. Area-based information obtained from drone surveying becomes the foundation of recovery plans and provides the basis for determining the order of on-site inspections and the allocation of work teams.

Use Case 2: Confirming Terrain Changes and Poor Drainage

One thing easily overlooked in restoration plans for solar power plants is changes in topography and poor drainage. Even if the power generation equipment itself shows no obvious damage, unevenness of the developed ground, scouring of slopes, blockage of drainage channels, and changes in watercourses can progress, creating a risk that damage will expand in the next heavy rainfall. In restoration plans, it is important not only to repair visibly broken parts but also to determine why the damage occurred and to confirm that it will not recur at the same location.

With drone surveying, aerial photographs make it easier to check the overall flow of water across a site and the condition of the ground surface. Places where water tends to remain after heavy rain, locations where sediment has accumulated, the direction in which vegetation has been flattened, and traces of flow along paths can all provide clues for estimating poor drainage and watercourses. Creating data that organizes elevation differences makes it easier to identify spots lower than the surroundings and areas where water is likely to collect.

Particularly at solar power plants on sloped terrain, attention is needed at the boundaries between the slope shoulder, slope toe, drainage channels, and maintenance access paths. If part of a slope face has been eroded away, repairing only that portion may still allow erosion to recur if the flow of water from above is not altered. Using drone surveys to confirm the continuity from upstream to downstream makes it easier to view the issue not as isolated damage but as a problem of the entire drainage route.

When checking for poor drainage, the timing of photography is also important. If you only shoot after a period of clear weather, puddles and wet spots can be difficult to detect. Conversely, immediately after rainfall, attention must be paid to on-site safety and flight conditions. In practice, after confirming conditions that allow safe flight, being able to compare the state immediately after the disaster with the state once it has dried somewhat makes it easier to grasp tendencies for sediment buildup and water accumulation.

When incorporating measures into a restoration plan, consider which tasks will be required, such as cleaning drainage channels, removing sediment, replenishing crushed stone, protecting slopes, installing temporary drainage, and leveling access paths. By using drone survey data to map the extent of drainage failures and the surrounding topography, the locations that need verification during field inspections become clear. This makes it less likely that restoration work will be merely a stopgap measure and makes it easier to develop a plan that includes measures to prevent recurrence.

Use Case 3: Organize anomalies around panel rows and mounting structures

In restoration planning for solar power plants, inspecting the condition of panel rows and the areas around the racking is also indispensable. After strong winds or sediment inflow, even if there is no major visible damage to the panel rows, the ground around the racking may have been scoured, sediment may have accumulated around the foundations, or driftwood and airborne debris may have entered beneath the panels. These abnormalities need to be confirmed by walking the site, but capturing overall changes with a drone beforehand makes it easier to narrow down the areas that require focused inspection.

When viewed from above, you can see the alignment of the panel rows, their relationship with access paths, the way shadows fall, and differences in the color of the surrounding ground surface. If panel rows are significantly disturbed or there are unnatural gaps in the middle of a row, it may indicate some impact around the mounting racks or foundations. However, you should avoid drawing definitive conclusions about structural safety from aerial photographs alone. Drone surveys are safest when used as material to locate areas that need inspection, to document them, and to share with stakeholders.

Dirt and deposits on panel surfaces are also included in restoration plans. Soil, fallen leaves, bird damage, and airborne debris remaining on panel surfaces can affect power output and maintenance work. Drone imaging makes it easier to determine whether the soiling is localized or spreading along particular wind directions or water flows. If the areas requiring cleaning can be identified in advance, it becomes easier to plan and arrange crews and materials.

Around the support structure, watch for signs of ground surface subsidence or scour. If soil is being washed away near the foundation, it may look minor at first glance, but if left unaddressed it can affect stability and maintenance. Using drone surveys to check the surrounding terrain and watercourses, and conducting detailed on-site inspections as needed, makes it easier to reduce oversights.

Also, in restoration plans, safety checks around electrical equipment and wiring are important. Even if anomalies are visible from the air, determining whether lines are energized or the insulation condition is sound requires expert inspection. Abnormalities identified by drone should be clearly recorded in terms of location and condition so electrical personnel and maintenance staff can verify them following safety procedures. Especially after a disaster, wet ground, fallen trees, damaged components, and exposed wiring may coincide, so the order of entry should be determined carefully.

Application 4: Determining Whether Delivery Routes and Work Flow Paths Can Be Restored

During restoration work, a major issue is not only the damaged area itself but also whether the access routes and work pathways to reach it are usable. Solar power plants are often located in mountainous areas, reclaimed land, or large unpaved sites, and after typhoons or heavy rain access roads can become muddy, drainage ditches can get clogged, and sediment can wash in from slopes. If restoration materials and work vehicles cannot access the site, it becomes difficult to carry out repairs even if a repair plan has been made.

By using drone surveying, you can check from above the condition of the routes from the power plant entrance to each equipment area. Because you can broadly grasp debris on the routes, such as fallen trees, puddles, shoulder collapses, and obstacles around fences, you can more easily determine which routes should be prioritized for restoration. In particular, even if you inspect only the area near the entrance from the ground and judge it passable, routes in deeper sections may be blocked. By checking the whole site from above, you can reduce rework after work begins.

When planning work routes and traffic flows, it is necessary to consider separately the movement of people, the movement of vehicles, temporary storage of materials, the entry of heavy machinery, and the removal of debris. A pathway that people can walk on is not necessarily safe for vehicles or heavy machinery. Check the road surface width, gradient, muddiness, corners, passing places, and drainage conditions, and organize the routes required for restoration work in stages. Using drone survey data as a background map makes it easier to overlay and evaluate the work area and routes.

Also, recovery plans may establish no-entry zones to ensure safety. Areas near slope failures, around energized equipment, locations with fallen trees, and spots with unstable footing need to be clearly delineated so workers do not enter them by mistake. If hazardous locations are organized or marked on aerial images taken by drone, they become easier to share during site morning briefings and pre-work meetings.

Confirmation of access routes affects the recovery schedule. If passageways must be restored first before equipment repairs can begin, the sequence of work changes significantly. Conversely, it may be decided to prioritize temporary measures within areas that can be inspected on foot and postpone tasks that require vehicle access to later stages. Drone surveying to map movement flows provides practical information for deciding where to start recovery given limited time and personnel.

Use Case 5: Consider recovery quantities and priorities

To make a recovery plan concrete, it is necessary not only to locate damaged areas but also to quantify how much work is required. Quantities such as the extent of soil removal, the length of pathway realignment, the approximate area of slope repairs, the rows of panels to be cleaned, the extent of fence repairs, and the sections of drainage ditches to be cleaned are essential for recovery work. Determining exact construction quantities may require on-site surveying and detailed investigations, but in the initial stages of a recovery plan, an approximate assessment using drone surveying is useful.

Using images and terrain data acquired by drones makes it easier to estimate the area and distances of affected zones. For example, being able to confirm the planar extent of areas where sediment has accumulated can help determine the personnel and equipment required for removal work. If the damaged sections of pathways are identified, it becomes easier to distinguish areas that can be dealt with by temporary repairs from those that require permanent restoration. Organizing cleaning and inspection tasks on a per-panel-row basis makes work instructions more specific.

When setting priorities, we comprehensively consider the impact on power generation, the impact on safety, the potential for damage to spread, the effect on work routes, and the need to explain decisions to stakeholders. For example, locations where slope scouring has progressed may not currently have a direct effect on power generation, but the damage could expand with the next rainfall. Blocked access roads become prerequisites for other restoration work and therefore have high priority. Dirt on panel surfaces may affect power output, but, separate from areas that require safety measures, the timing of that work can sometimes be adjusted.

Using drone survey data makes it easier to share these priorities with stakeholders. Rather than verbally saying "the back has collapsed," it is clearer to indicate the area on an aerial image and explain, "there is debris at the far end of the corridor on the right as seen from the entrance, and you cannot reach the section to be cleaned without passing through there." In recovery planning, it is important to prepare materials that stakeholders who are not familiar with the site can understand.

When estimating quantities, it is important not to claim excessive precision. The accuracy of drone surveys varies depending on flight conditions, imaging conditions, the placement of ground control points, analysis methods, and the state of vegetation and obstacles. Required procedures and accuracy control differ depending on whether the data will be used for preliminary planning, as the basis for construction quantities, or for as-built verification. In the early stages of a recovery plan, it is safer to clearly define the areas to be used for rough estimates and the areas that should be rechecked on site.

Use Case 6: Keep comparative records before and after recovery

In a recovery plan, recording the condition after recovery is as important as recording the condition before work. When responding to disasters or malfunctions, there are occasions when it is necessary to later explain what happened where and how it was restored. The parties who may require such explanations include management companies, clients, maintenance personnel, contractors, and those involved in insurance or administrative procedures. Drone surveying is an effective means of keeping comparative before-and-after records of recovery.

If drone data from before restoration is available, it becomes easier to objectively show the condition at the time the damage occurred. If the same area is photographed after restoration, you can compare whether sediment has been removed, access routes have been restored, drainage channels have become visible, and the extent of slope repairs can be confirmed. In particular, for restorations covering a wide area, aerial comparisons are useful because ground photographs alone make it difficult to convey overall progress.

When creating comparison records, it is important to keep imaging conditions as consistent as possible. If flight altitude, shooting direction, coverage area, time of capture, weather, or the way images are organized differ greatly, it becomes difficult to discern the differences before and after recovery. It may be hard to make the conditions exactly the same, but even photographing the same plot with a similar coverage will make the materials easier to use for comparison.

Records taken before and after restoration can also be used to assess measures to prevent recurrence. For example, if sediment accumulates again in the same spot after cleaning a drainage ditch, the issue may not be simply insufficient cleaning but a problem with upstream watercourses or slope protection. If a pathway becomes muddy again within a short period even after regrading, a review of drainage and the roadbed may be necessary. If you record the same location regularly, it becomes easier to track changes over time.

Recovery records are also useful for internal handovers. Solar power plants are facilities that are operated over the long term, and those responsible may change. If you have documents showing where damage occurred in the past and how it was restored, they can be applied to future inspections and maintenance planning. By organizing drone survey data together with the plant’s parcel information and inspection records, you can avoid treating recovery responses as one-off tasks and instead accumulate knowledge for operation and maintenance.

Considerations When Using Drone Surveying for Recovery Planning

When using drone surveying in recovery planning for solar power plants, you must not neglect safety management and operational rules. On sites after disasters or accidents, risks are higher than usual. The conditions to check before flight increase, including fallen trees, muddy ground, slopes at risk of collapse, damaged equipment, areas that may still be energized, and the effects of strong winds or rain. Before flying a drone, it is necessary to clarify whether entry to the site is permitted, the weather conditions suitable for flight, surrounding obstacles, contact with relevant parties, and emergency response procedures.

You must also check the laws and rules related to flight. Required procedures and restrictions may vary depending on the flight location, the method of flight, the condition of the aircraft, and the surrounding environment. Even within the premises of a power plant, you must consider airspace safety and the impact on third parties. In areas responding to disasters in particular, it is important not to interfere with manned aircraft involved in rescue and recovery. The more urgent the recovery, the greater the risk of flying without sufficient checks. It is important to establish internal operational standards in advance and to avoid making flight/no‑flight decisions dependent on individual judgment.

Pay attention to the accuracy management of survey data. In recovery plans, there are situations where a general overview is sufficient and situations where detailed surveying accuracy is required. For example, when sharing the extent of damage or examining work flows, aerial imagery alone can often be sufficiently useful. On the other hand, when performing earthwork volume calculations, confirming the formed geometry, or making judgments close to the as-built condition, more careful procedures such as installing ground control points, managing coordinates, and checking verification points are required. Using data without confirming the accuracy required for its intended use makes the basis for decisions ambiguous.

It is also important to distinguish between information that can be seen by drones and information that cannot. From the air, changes to the ground surface, sediment accumulation, the condition of access paths, the appearance of panel rows, and conditions around fences are easy to confirm, whereas internal equipment failures, electrical abnormalities, fine damage at racking joints, and the condition inside foundations cannot be determined. In recovery plans, it is necessary to combine on-the-ground inspections, electrical inspections, and structural checks based on anomalies found by drone surveys.

Data organization methods are also important in practical work. If items such as the capture date, flight coverage, the coordinate system used, imaging conditions, the reviewer, anomaly location numbers, and related ground photographs are not organized, they become difficult to use when reviewed later. In recovery operations, there are stages such as initial assessment, emergency response, detailed investigation, full restoration, and completion confirmation. If you avoid mixing the data obtained at each stage and manage it so that it is clear in chronological order, it becomes easier to explain to stakeholders and to use for the next inspection.

Finally, coordination among the personnel responsible for incorporating drone survey results into the recovery plan is indispensable. If only the surveyors view the data, its impact is limited unless it is reflected in construction methods and safety measures. It is important that maintenance personnel, electrical personnel, civil engineering personnel, and construction personnel look at the same materials to decide who will inspect which areas and in what order restoration will proceed. Drone surveys are most effective when used as a means to advance recovery plans based not solely on on-site judgment but on shared visual information.

Summary

In recovery planning for solar power plants, it is necessary not only to quickly locate damaged areas but also to comprehensively organize the overall site conditions, changes in drainage and topography, work flow paths, quantities required for restoration, priorities, and records before and after restoration. Drone surveying can be widely used—from initial assessments of the recovery plan to sharing with stakeholders—because it enables inspection of large plants from the air and an area-wide understanding of on-site conditions.

In particular, after typhoons or heavy rain, people tend to focus only on equipment damage visible from the ground. However, in reality, elements such as access paths, slopes, drainage channels, areas around mounting racks, fences, and material delivery routes are intricately related and affect restoration work. Using drone surveying makes it easier to organize these into a single planar dataset, making it easier to consider the order of restoration and the scope of work.

On the other hand, it is not appropriate to make all judgments based solely on drone surveying. Safety checks of electrical equipment, detailed inspections of structural members, and specialized assessments of foundations and ground should be combined with on-site confirmation or expert investigations as needed. The important thing is to use drone surveying as an entry point for recovery planning and to link any detected abnormalities to concrete inspection and repair plans.

Restoration efforts require both speed and accuracy. To assess the extent of damage, avoid hazardous areas, secure work routes, and proceed while aligning stakeholders’ understanding, clear situational data is indispensable. If you want to make a solar power plant recovery plan more practical, consider combining on-site inspections with drone surveys to enhance record-keeping and information sharing. Reliably documenting the conditions before and after recovery and applying that information to subsequent maintenance plans leads to power plant management that is more resilient to disasters and malfunctions.