How to Use Drone Surveying Before and After Solar Power Plant Construction

In the planning and construction of solar power plants, it is important to continuously record site conditions—from understanding topography before site preparation, to monitoring progress during earthworks, to verifying as-built conditions after site formation, and through to post-completion maintenance. In particular, in forests, unused land, slopes, and large development sites, there are situations where it is difficult to grasp the whole picture quickly from ground-level inspections alone. One of the easy-to-use methods for this is drone surveying.

Drone surveying is a method that captures the entire site from the air and visualizes the current conditions in forms such as photographs, orthophotos, point clouds, and terrain models. At photovoltaic power plants, it is useful for checking items such as pre- and post-construction terrain differences, drainage plans, panel layouts, access and maintenance roads, slopes, detention basins, and fence locations. However, simply filming with a drone does not automatically achieve the accuracy required to use the data as survey deliverables. It is important to combine shooting conditions, control points, coordinate management, analysis procedures, and on-site verification according to the purpose.

Table of Contents

• Background on why drone surveying is necessary for solar power plants

• What can be checked by drone surveying before site preparation

• How to interpret terrain data for use in site-preparation planning

• Drone surveying for progress management during site preparation

• Key points to check during as-built verification after site preparation

• How to use it to inspect drainage, slopes, and maintenance roads

• How to integrate with panel layout and pile location planning

• Approach to combining field surveying and drone surveying

• Preliminary preparations to ensure stable accuracy

• Tips for using survey deliverables in construction management and coordination materials

• Common pitfalls to watch out for in drone surveying

• Summary

Background: Why Drone Surveying Is Necessary at Solar Power Plants

Unlike equipment installed on building roofs, solar power plants often place generation equipment across a wide expanse of land. Depending on the site, terrain conditions can vary greatly: land developed by clearing forest, land converted from agricultural use, idle sloped land, and sites of former facilities, among others. Even land that appears flat may actually include subtle changes in elevation, water flow, existing structures, weak ground, and remnants left after clearing, information that cannot be fully captured by planning drawings alone.

In construction of solar power plants, multiple trades are involved, such as site formation, drainage, racking, piles, panels, electrical equipment, access roads, and fencing. Small misalignments in one trade can lead to major rework in later processes. For example, if the finished surface elevation differs from what was assumed, it can increase the amount of racking adjustment required, cause insufficient drainage gradients, and affect the grades and drainage handling of access roads. If pile positions interfere with the terrain or drainage facilities, relocation or design verification may be necessary.

By using drone surveying, you can record the entire site from an overhead perspective, making it easier for stakeholders to share the same view of the current site conditions. Features that are difficult to convey with ground-level photos—such as the extent of earthworks, the locations of slopes, the status of tree clearing, changes in earth volumes, stormwater flow, and the condition of temporary roads—become easier to understand from the air. This is especially effective on large sites like solar power plants, where relying solely on on-foot inspections can easily lead to missed areas, so area-based records captured by drones are valuable.

On the other hand, drone surveying is not万能. In areas where the ground is covered by trees, where grass is densely grown, where strong shadows occur, on highly reflective water surfaces or panel surfaces, and on steeply undulating slopes, there are limits to the information that can be obtained. Also, when using the results as surveying deliverables, management of coordinates and elevations is important, not just the visual appearance of the photographs. Therefore, when using drone surveying at solar power plants, you need to clarify which decisions it will be used for before and after site development, and choose the accuracy and deliverable formats appropriate to that purpose.

What Can Be Confirmed by Drone Surveying Before Site Development

The first thing to confirm with pre-development drone surveying is the overall picture of the existing topography. By identifying the site's elevation differences, the orientation of ridges and valleys, connection points to existing roads, low-lying areas where water tends to collect, conditions near boundaries with neighboring properties, and the locations of existing waterways and drainage outlets, you can clarify the assumptions for the development plan. For solar power plants, not only energy output but also constructability and maintainability are important, so it is essential to accurately understand the land’s shape at an early stage.

Before site development, trees slated for clearing, bamboo groves, weeds, existing fill and cut scars, unnecessary structures, farm roads, drainage ditches, utility poles, existing fences, and the like may still remain. These features may not be fully apparent from design drawings or cadastral maps alone. Aerial photography with a drone makes it easier to assess the extent of removal required, access routes for heavy equipment, potential material storage locations, the layout of temporary roads, and separation distances from neighboring properties.

Pre-development records also serve as useful materials for explaining site conditions later. By recording what the terrain looked like before construction, where trees were located, and where existing watercourses were, those records become easier to use when identifying the causes of problems that arise after development and when consulting with stakeholders. Because the flow of rainwater and the movement of sediment are often influenced by the pre-development topography, it is important to preserve the pre-construction condition.

Drone surveying before site development is not sufficient if it only involves taking attractive aerial photos. For use in the design and construction of solar power plants, data that reveals topographic relief, images that allow verification of distances and areas, and data that enable height comparisons when necessary are required. Creating orthophotos makes the entire site easier to work with as a minimally distorted, top-down image. Generating point clouds and terrain models makes it easier to evaluate height distribution and earthwork volumes.

However, if the ground surface prior to site development is covered with trees or grass, the heights obtained by photogrammetry may represent the surfaces of tree canopies or vegetation rather than the ground itself. Using pre-clearing data as-is for earthwork volume calculations can lead to discrepancies from the actual ground elevation. Therefore, it is important to supplement with ground surveys or on-site inspections where necessary and to make clear what the drone survey data actually represents.

How to Interpret Topographic Data for Use in Site Development Planning

Topographic data obtained from drone surveys can be used to inform site development plans. For solar power plants, while you want to place generation equipment as efficiently as possible, excessive grading increases the amount of earthwork, slope work, drainage issues, and maintenance burden. Therefore, it is important to carefully read the existing terrain and strike a balance between panel placement and grading strategy.

First, what I want to confirm is the overall slope of the site. If the slope is gentle, it may be possible to accommodate it by adjusting the mounting rack height while keeping earthwork to a minimum. On the other hand, if there is a steep slope or valley terrain, planning for cut-and-fill, terracing, slope protection, and drainage facilities becomes important. Using terrain data from drone surveying allows you to spatially verify where elevation differences are concentrated and in which directions water is likely to flow.

Next, it is important to distinguish between surfaces that are easy to install panels on and those that are difficult to install panels on. At solar power plants, not only insolation conditions but also the ease of racking installation, the ease of pile driving, access paths for maintenance inspections, interference with drainage facilities, and impacts on neighboring properties must be considered. By using terrain data, you can check the slope and elevation differences of each candidate area, making it easier to determine locations where panels should not be forcefully packed and areas where space should be left for operational access.

In site development planning, forecasting earthwork volumes is also important. If the balance between cut and fill is poor, consideration of surplus-soil disposal or importing fill becomes necessary, which affects the schedule and construction plan. Recording pre-development topography with drone surveying and comparing it to the planned formation surfaces can help obtain rough estimates of earthwork volumes. However, when using this for volume calculations, it is necessary to define the reference surface, target extent, data density, removal of extraneous objects, effects of vegetation, and so on. Don’t over-rely on the numbers alone; it’s important to judge them together with on-site conditions.

Terrain data also pairs well with drainage planning. At solar power plants, it is necessary to check where surface water will flow after site development, whether water will concentrate on slopes, whether maintenance roads will become drainage channels, and whether water will flow onto neighboring land. If predevelopment valley topography or existing watercourses are overlooked, problems such as muddy areas, scouring, slope deformation, and deterioration of access paths are likely to occur after completion. Visualizing elevation differences with drone surveying is effective for detecting these risks early.

Drone surveying for progress management during site development

Drone surveying during site development helps to identify discrepancies between the plans and the actual site early. Because earthwork operations change the terrain daily, a single survey cannot capture the site's current condition. Especially at large-scale solar power plants, cut-and-fill operations, compaction, slope shaping, drainage works, access roads, retention ponds, and temporary yards may proceed concurrently. Periodic aerial documentation with drones makes it easier to maintain an overview of the entire construction process.

For use during site development, it is important to record continuously under as consistent conditions as possible. If flight altitude, capture area, capture direction, control points, or data processing conditions change significantly each time, it becomes difficult to compare differences with previous data. By photographing the same area from fixed points and ensuring that data from before, during, and at completion can be overlaid for review, it becomes easier to use the data for progress management and as-built verification.

In progress management, you can check whether the earthworks area is proceeding according to plan, whether there are any unexpected excavations or fills, whether temporary roads are in a safe, usable condition, and whether material storage yards are not obstructing construction. Work areas that are only partially visible from the ground become easier to distinguish between completed and uncompleted areas when viewed from the air. For progress reporting to stakeholders, using images or terrain data that show the entire site makes it easier to align understanding than explaining only with text.

Drone surveying during site preparation is also effective for preventing rework. For example, the earlier you find problems such as a drainage channel being too close to the planned panel installation area, the width or curvature of the maintenance road not fitting heavy machinery or service vehicles, the slope shoulder or toe deviating from the design limits, or large steps remaining on the planned surface for racking foundations, the easier they are to deal with. If discovered after completion, regrading or re-surveying may be required.

However, active construction sites have heavy machinery, workers, temporary structures, dust, strong winds, and other hazards, so safety management for flights and filming is indispensable. Drone surveying is convenient, but it should not be carried out if it would compromise construction safety. Work hours, flight zones, takeoff and landing locations, notification to stakeholders, and access control must be organized in advance and incorporated into the construction workflow without disrupting operations.

Key Points to Check During As-Built Verification After Site Development

In post-construction drone surveying, we verify how well the completed terrain conforms to the plan. At solar power plants, installation of mounting structures and piles often proceeds after site formation is finished, so checks at this stage have a major impact on the stability of subsequent work. We check formed surface elevations, slopes, level differences, drainage directions, slope geometry, and the alignment of maintenance roads, and look for any significant deviations from the construction drawings and planning conditions.

Particularly important is the ground condition of the area planned for panel installation. If large irregularities remain on the prepared surface, the burden of pile driving and racking adjustments increases. If low areas tend to collect water, it can cause muddy conditions during construction and affect maintenance after completion. Creating orthoimages and terrain models through drone surveying makes it easier to identify widespread unevenness and traces of standing water that are easy to miss by visual inspection alone.

Inspection of slopes cannot be overlooked. At solar power plants, slopes may form along the site perimeter or at the boundaries of terraced grading. Confirming the slope gradient, length, connections to drainage, signs of erosion, and any areas prone to collapse makes it easier to reduce later repair risks. Drone aerial photographs are useful for grasping the continuity of the entire slope and its relationship to drainage routes. However, cracks, seepage, or soft/weak conditions are difficult to judge from photographs alone, so on-site checks should be conducted as necessary.

When checking management roads and work paths, inspect the width, curvature, grade, drainage, turning space, and material delivery routes. Solar power plants continue to require inspections, mowing, replacement work, and emergency responses after completion. If management roads are difficult to use at the time of site formation, operational burdens will increase. Using drone surveying to confirm the overall road layout and to review the relationships with panel rows, electrical equipment, drainage facilities, and fences makes it easier to identify problems from a maintenance and management perspective.

Data collected after site preparation is also valuable as construction records. Keeping information that allows comparison between the pre- and post-preparation conditions makes it easier to explain which areas were worked on and how. If ground subsidence, poor drainage, slope deformations, or other abnormalities occur later, these records serve as documentation to verify the condition at completion. Because photovoltaic power plants are intended for long-term operation, keeping completion records also helps with future maintenance and management.

How to Use to Check Drainage, Slopes, and Maintenance Roads

One area where drone surveying is particularly useful at solar power plants is checking drainage and slopes. The plant site is extensive, and when it rains water collects from a large area. Inadequate drainage planning can lead to surface erosion, slope deformation, muddy access roads, pooling beneath panels, and runoff to neighboring properties. Drone surveying, which can verify terrain across the site before and after land development, is well suited to preventing these problems.

In drainage checks, you first look at where water flows from and to. Identify the natural gullies before site development, existing watercourses, low-lying areas, ponds, roadside ditches, and boundaries with neighboring properties, and verify that the flow of water has not changed excessively after development.

Even if the surface appears to have been flattened by development, slight differences in slope can cause water to concentrate. Using a terrain model or contour-like representations makes it easier to confirm slope directions that are hard to see from ground-level photos alone.

On slopes, the concentration of water and the condition of surface protection are important. When water accumulates at the top of a slope, erosion can begin from the shoulder. If water ponds at the toe of the slope, the ground can loosen and drainage facilities can be overloaded. Photographing slopes with a drone from an oblique angle makes it easier to identify unevenness and signs of deterioration that cannot be seen in vertical overhead photos alone. By photographing regularly and comparing the images, changes over time can also be more easily detected.

Access roads serve different roles during construction and after completion. During construction they are used as routes for heavy machinery and material transport, and after completion they become routes for maintenance inspections, mowing, and equipment replacement. Therefore, at the post-development stage it is important to check the road gradient, drainage, curves, sightlines, shoulders, and turnout spaces. Conducting drone surveys to understand the road’s overall positional relationships makes it easier to detect interference with panel rows, fences, and drainage facilities.

Drone photography after rain can also be useful. This is because puddles, muddy patches, runoff paths, and the direction of turbid water flow that are not visible in clear weather can become apparent. However, flights in rainy or high-wind conditions should be judged carefully from the perspectives of safety and aircraft protection. If conditions allow for filming, rather than pushing it immediately after the rain, recording the site at a time when safety can be ensured can provide material to identify weaknesses in drainage.

How to Coordinate Panel Layout with Pile Position Planning

At solar power plants, linking the results of drone surveys with panel layouts and pile location plans can improve the accuracy of pre-construction assessments. If you only look at panel layout drawings, you may overlook how they relate to site slopes, level changes, drainage facilities, and existing obstacles. Overlaying the layout plan onto the current-condition data produced by drone surveys makes it easier to compare the plan shown on drawings with the actual site conditions.

Pile location planning requires particular alignment with the terrain. In areas with steep slopes, adjustments to pile length and mounting-structure height may be necessary. In embankment areas or soft ground, verifying support conditions is important. Piles located near drainage channels or maintenance roads can affect working space during construction and maintenance after completion. Using terrain data from drone surveying makes it easier to assess in advance whether candidate pile locations are compatible with site conditions.

When laying out panels, the effects of shading must also be considered. If there are surrounding trees, slopes, utility poles, existing structures, or adjacent hills and buildings, shadows can occur depending on the time of day and season. While drone photography alone cannot fully determine annual shading, recording existing obstacles and surrounding topography makes it easier to identify locations that require shading analysis. Recording the surrounding conditions before site development also helps when considering tree removal or layout adjustments.

When considering the installation of mounting structures and panels, on-site workability is also important. The spacing of panel rows, maintenance aisles, material delivery routes, heavy equipment access areas, and worker movement paths may be feasible on drawings but can become difficult to use due to on-site slopes or level changes. Using orthophotos from drone surveys makes it easier for stakeholders to check the relationship between the existing terrain and the planned layout on the same screen. It can also help reduce misunderstandings during pre-construction meetings.

It is also effective to perform a final check before pile driving using drone survey data collected after site formation. If there is a discrepancy between the site formation plan and the actual formed surface, it can affect pile positions and mounting frame heights. If a problem is discovered after pile driving has begun, resurveying or changes to construction procedures often become necessary, so it is important to confirm consistency with the plan upon completion of site formation.

Approach to Combining Field Surveying and Drone Surveying

While drone surveying can efficiently capture large areas, it does not replace all types of surveying. In the construction of photovoltaic power plants, there are situations where on-site surveying is required to verify reference points, boundaries, critical structures, pile locations, and elevation control. Drone surveying and on-site surveying are most effective when their roles are divided and combined.

Drone surveying excels at capturing area-based information. It can broadly confirm the site’s overall existing conditions, the extent of earthworks, changes in earth volume, progress, slopes, drainage routes, access/maintenance roads, and surrounding conditions.

Ground surveying excels at highly accurate verification of specific points and at managing positions and elevations based on reference standards. Instrument points, control points, boundary markers, design stakes, and important elevation benchmarks need to be reliably verified on site.

In solar power plants, a practical approach is to use drones to get an overall view before site preparation and to supplement that with on-site surveys for critical locations. During site preparation, drones record progress and terrain changes, while heights and positions that are important for design are verified by on-site surveys. After site preparation, drones check the as-built surface, and benchmarks and coordinates required for pile driving and equipment installation are managed by on-site surveys. Clarifying roles in this way makes it easier to strike a balance between efficiency and accuracy.

Setting reference points is also important. To align drone survey results with drawings and design coordinates, it is necessary to establish reference points on site and properly manage their coordinates and elevations. If images are captured with ambiguous references, they may be easy to view but lack the accuracy required for construction management. Especially when comparing conditions before and after site development, it is important to ensure they can be handled in the same coordinate system and with the same vertical datum.

Also, the practice of verifying drone survey results on site is indispensable. Areas that appear anomalous in point clouds or images may actually be due to grass or shadows. Conversely, ground soft spots, springs, cracks, boulders, and mud that are hard to discern from images can be difficult to assess without being on site. Using drones to obtain a broad view and establishing a workflow to check any areas of concern on the ground makes it easier to reduce oversights.

Preparations to Stabilize Accuracy

To stabilize the accuracy of drone surveying, pre-flight preparation is important. Solar power plant sites are large and include slopes, trees, embankments, heavy equipment, and temporary structures, so flying on a whim can easily lead to missed coverage or poor data quality. If the results are to be used for construction management, you need to decide in advance the objectives, scope, required accuracy, deliverables, and imaging conditions.

First, clarify the purpose of the survey. Depending on whether it is to capture the current conditions before earthworks, to estimate earthwork volumes, to monitor progress during earthworks, to verify as-built conditions after earthworks, or to inspect drainage and slopes, the photographic coverage and required deliverables will differ. If photos are taken without a clear purpose, problems can occur later, such as lacking photos from necessary angles, insufficient control points, or slightly incomplete coverage of the area.

Next, determine the area to be photographed according to site conditions. In addition to the area within the site boundaries, including drainage outlets, access roads, adjacent elevation changes, surrounding trees, and construction vehicle routes as needed will be useful for later review. Because the relationship with areas outside the site is often important for solar power plants, it is advisable to confirm permissions and the scope of safety management with landowners, managers, and nearby stakeholders, and to record any necessary surrounding information.

Capture conditions take into account photo overlap, flight altitude, camera angle, weather, sunlight, wind, and ground surface conditions. In photogrammetry, insufficient overlap between images tends to make analysis unstable. Time periods with excessively strong shadows or conditions with a lot of overexposure can make it difficult to detect ground feature points. If grass has grown too tall it becomes hard to determine ground elevation, so it may be necessary to decide to photograph after mowing or after tree removal as needed.

Managing reference points and verification points is also important. For data used in construction, it is reassuring to use local reference points to align coordinates and elevations and to establish points where you can check for discrepancies in the results. Reference points should be easily visible from above, distributed evenly across the capture area, and placed where they are unlikely to be disturbed by site operations. On active construction sites, reference points can be lost to heavy machinery or earthworks, so you should also plan procedures for their protection and re-verification.

Furthermore, before flight it is necessary to check safety and legal matters. Confirm aircraft registration, flight location, flight altitude, flight method, flight plan, surrounding people, vehicles, heavy equipment, power lines, transmission towers, trees, strong winds, takeoff and landing sites, and emergency landing sites. At construction sites for solar power plants, because construction personnel may be working over a wide area, it is essential to share the planned flight schedule and manage access control. The latest rules and required procedures should be confirmed before flight using public information and guidance from relevant authorities.

Tips for Using Deliverable Data in Construction Management and Coordination Documents

Drone survey results provide information that is easy to use for construction management and consultation materials. However, simply producing the data does not ensure it will be used on site. It is important to organize the data with an awareness of who will use it, in what situations, and what decisions they will make. In photovoltaic power plants, multiple stakeholders are involved, including clients, designers, contractors, surveyors, electrical contractors, and maintenance managers. Survey results must be prepared in a form that is understandable to non-specialists.

Orthophotos are useful for providing an overall view. Because they can be treated as images of the site viewed from directly above, they make it easier to share the development area, progress, roads, drainage, slopes, and planned panel layout areas. Even when drawings alone do not convey a sense of the site, using orthophotos allows stakeholders to discuss while looking at the same location. When using them in meeting materials, clearly indicating the capture date, area covered, orientation, and key points to be checked will reduce misunderstandings.

Point clouds and terrain models are well suited to situations where heights and cross-sections need to be checked. They can be used for comparing conditions before and after development, verifying slope shapes, assessing the gradients of access roads, determining drainage directions, and estimating earthwork volumes. However, point clouds and terrain models can be difficult for those unfamiliar with them to interpret. For this reason, measures such as indicating the required cross-section locations, displaying elevation differences clearly, or highlighting and explaining only the critical areas are necessary.

When using it for construction management, it is important to organize the data by photography date. If you record at milestones in the process—before site formation, after clearing, after rough grading, after drainage work, after completion of site formation, before pile driving, during rack installation, and after completion—it becomes easier to track changes later. If photo and data file names, storage locations, coordinate systems, and processing conditions are inconsistent, they will be unusable when needed. You should organize them so that the site name, date, process, scope, and type of deliverable are clear.

When using these materials for discussions, it is important to avoid overly definitive wording. Drone survey results are a valuable resource for explaining site conditions, but errors can arise due to vegetation, shadows, imaging conditions, and the state of control points. Numerical values related to height and earthwork volumes, in particular, should be handled with the underlying assumptions clearly stated. For items that directly influence construction decisions, it is safer to retain a process for cross-checking with on-site surveys and design drawings and for re-verifying as necessary.

It is effective to carry data forward into maintenance management. Recording the as-built topography, drainage facilities, maintenance roads, slopes, fences, and equipment layout makes it easier to detect changes during inspections after operation. Because you can compare changes such as altered watercourses after heavy rain, erosion on slopes, deterioration of maintenance roads, or vegetation growth beginning to cause shading, this also helps with long-term power plant management.

Common Pitfalls to Watch Out for in Drone Surveying

One common cause of failure when using drone surveying at solar power plants is believing that simply capturing images will produce all the required deliverables. Drone surveying only becomes practically useful when the flight plan, control points, analysis, field verification, and organization of results are all in place. Even if the aerial photographs themselves are fine, the survey deliverables can suffer from insufficient coverage, insufficient accuracy, unclear reference points, or inappropriate timing.

The first point to note is the influence of trees and vegetation. In forested or grassy areas before land development, the surface shown in photographs may be vegetation rather than the ground. If elevation is assessed in that condition, it can appear higher than the actual ground surface. When using the data for earthwork volumes or development planning, supplementary surveys after clearing or ground-based surveying may be necessary. Using data without understanding the influence of vegetation can lead to errors in estimating earthwork quantities and slopes.

The second issue is the lack of reference points and verification points. If you are checking progress only with visual images, it may not become a major problem, but when overlaying design drawings or comparing heights before and after earthworks, managing reference and verification points is important. If there are few reference points, their placement is biased, they are hard to see from above, they moved during earthworks, or the coordinate and elevation records are ambiguous, the overall reliability of the deliverables decreases.

The third consideration is how to choose the timing of shooting. The information you obtain changes depending on whether you measure before site preparation, after tree clearing, during site preparation, or after completion. For example, shooting before tree clearing will show the current extent of trees, but makes it difficult to determine ground elevation. If you photograph for the first time only after site preparation, you cannot confirm the differences from before. If there is information you want to compare later, you need to record it in a planned manner starting before construction begins.

The fourth issue is that the intended use of the output data has not been decided. If photos are taken but no one reviews them, they cannot be overlaid with drawings, their storage location is unknown, and they cannot be compared with past data, they become difficult to utilize for site management. When introducing drone surveying, it is important to decide in advance what format the data will be organized in after capture, who will review it, and in which meetings or process decisions it will be used.

The fifth is insufficient consideration of legal requirements and safety management. Drone flights require checks according to conditions, such as aircraft registration, flight location, flight method, flight plan, safety confirmation, and notification to relevant parties. At development sites where heavy machinery and workers are operating, the flight itself can become a risk. Do not prioritize surveying efficiency alone; operations must be carried out only after confirming the flight plan, takeoff and landing locations, emergency response measures, and separation from the work area.

The sixth is overestimating the accuracy of drone surveys. In practical work on photovoltaic power plants, drones are effective for grasping large areas, but final stake positions, boundaries, critical elevations, and interfaces with structures should be determined in combination with on-site surveys and design verification. Drone surveys are a means to increase the information available for decision-making, not to replace on-site verification.

Summary

Using drone surveying before and after the site formation of a solar power plant makes it easy to clearly record the overall terrain and construction status of the site. Before site formation, you can identify elevation differences across the site, existing waterways, trees, obstacles, heavy equipment routes, and drainage destinations, and organize the assumptions for the plan. During site formation, you can continuously monitor progress and terrain changes, making it easier to detect deviations that could lead to rework at an early stage. After site formation, you can verify the formed surfaces, slopes, drainage, access roads, and pre-piling conditions, leaving records that can be used for subsequent work and maintenance.

Especially at solar power plants, which cover large sites, there are cases where it is difficult to grasp the overall picture from ground-level inspections alone. By utilizing orthophotos, point clouds, and terrain models from drone surveying, it becomes easier to share the current conditions among stakeholders, and these products become useful decision-making materials for design, construction, consultations, and maintenance management. Elements that are prone to cause problems after completion, such as drainage and slopes, can also be checked early by comparing conditions before and after land development.

On the other hand, drone surveying is not something that is completed simply by capturing images. It requires a shooting plan tailored to the purpose, installation of control points and check points, combination with on-site surveying, data organization, and safety management.

If there are impacts from trees and vegetation, insufficient control points, timing discrepancies in shooting, or inadequate management of deliverable data, it becomes difficult to leverage the collected data for construction decision-making. At solar power plant sites, it is practical to use drone surveying to obtain a broad overview and to supplement important positions and heights with on-site verification.

Keeping detailed records before and after site preparation not only streamlines construction but also facilitates maintenance and management after completion. If drainage checks after heavy rain, slope changes, deterioration of access roads, vegetation growth, and changes in the surrounding environment can be compared with past data, early response becomes easier. There is great value in systematically incorporating drone surveying from the site preparation stage to ensure the long-term, stable operation of solar power plants.

If you want to apply drone surveying consistently before and after the development of a solar power plant—for site condition assessment, progress management, as-built verification, and maintenance—it is important to organize in advance the surveying objectives, required accuracy, flight conditions, control point plan, and the method for managing deliverable data. Assuming site safety and legal compliance, combining drone surveying with ground surveying makes it easier to maintain usable records for the design, construction, and maintenance stages.