5 Drone Surveying Tips to Help with Preparing Reports for Solar Power Plants

In inspections, repairs, and maintenance of solar power plants, how the observations confirmed on site are incorporated into reports is crucial. By utilizing drone surveying and aerial photography, it becomes easier to organize information useful for aerial photographs, orthophotos, three-dimensional data, understanding terrain undulations, identifying drainage paths, and verifying equipment layout. However, the results obtained vary depending on shooting conditions, analysis methods, the handling of ground control points, on-site visibility, and vegetation conditions. The more data acquired, the harder the report becomes to read if organization methods remain ambiguous, and the more likely discrepancies in understanding will arise among the management company, power plant operator, construction contractor, and maintenance personnel.

Drone surveying of solar power plants is not simply the act of photographing the site. It is an essential part of operational work to organize information into a form usable in reports and to convert it into materials that make decision‑making easier. In this article, we explain, from five perspectives for practitioners, how to organize drone survey data to assist in preparing reports for solar power plants.

Table of Contents

• Clarify the purpose of the report and its audience.

• Organize the shooting conditions and on-site situation

• Organize survey results and position information

• Organize the abnormal locations and verification results

• Organize the rules for updating and sharing reports

Clarify the purpose of the report and its audience

When compiling a report of drone surveys for a solar power plant, it is important to clarify the report's purpose at the outset. Whether the report is intended to broadly document site conditions, to confirm the current state prior to refurbishment, or to check specific issues such as poor drainage or slope deformation will determine the photos, drawings, explanatory text, and points to emphasize. If a report is prepared while the purpose is unclear, it tends to become merely a collection of captured images, making it difficult for readers to know what they should judge.

In a solar power plant, the items to inspect cover a wide area, including power generation equipment, mounting racks, prepared surfaces, access roads, drainage facilities, fences, slopes, and surrounding trees. Because drone surveys make it easy to view these from above, there is a tendency to want to include a lot of information in the report, but if everything is given equal weight the important points will be buried. First, organize what the report’s readers want to know and clarify whether the document will be used for overall plant management decisions, for planning before on-site work, or for sharing among stakeholders.

Who will read the report also matters. When the readers are power producers or asset managers, the structure should make clear overall site trends, impacts on maintenance planning, locations requiring additional verification, and the areas that should be prioritized. When the readers are contractors or surveyors, specific, actionable information for on-site use is important, such as positions, extents, elevation differences, work routes, interference with existing equipment, and locations that require re-surveying. Anticipating the report’s audience makes it easier to decide, even with the same drone survey outputs, whether to present primarily photographs or drawings, and whether to provide detailed comments.

When organizing report objectives, it is effective to list in advance the items you want to verify before the on-site survey. For example, decide beforehand whether you want to confirm the layout of the panel rows, check for clogged drainage paths or potential water pooling, understand trends in settlement or scouring of the graded surface, or assess the condition of access roads and material delivery routes. This links the photography plan with the report structure, making it easier to avoid rework such as not having photos from the necessary angles or being unable to identify the locations you want to explain.

In reports for solar power plants, not only specialized surveying results but also explanations that are understandable to people unfamiliar with the site are required. Even when the results come from drone surveys, if spatial relationships and the basis for judgments are not organized within the report, the document becomes difficult to use in practice. Therefore, at the beginning of the report it is appropriate to concisely organize the survey objectives, scope, date of implementation, items checked, and types of deliverables, and in the main text to present the necessary information in sequence according to the objectives.

Also, clarifying the purpose of the report is important to avoid making unnecessary definitive statements. While many insights can be gained from images and terrain data obtained by drone surveys, some matters cannot be determined from aerial observation alone, such as internal equipment faults, electrical abnormalities, and the condition of underground structures. In the report, it is important to distinguish between facts confirmed by the drone survey and inferred items that require additional on-site verification. This helps prevent readers from being unduly misled and makes it easier to proceed to subsequent inspections or repair decisions.

Organize Shooting Conditions and On-site Conditions

In drone surveying, which is useful for preparing reports, it is essential to organize not only the image capture results but also the shooting conditions and on-site conditions. Solar power plants cover large sites, and their appearance can vary greatly depending on terrain and equipment layout. Even when photographing the same location, the way photos look and how easy they are to interpret change depending on the weather, time of day, sun angle, wind, the wetness or dryness of the ground surface, and the state of grass growth. When using the results in a report, keeping a record of the shooting conditions allows you to share the assumptions needed to interpret the images.

Especially at solar power plants, reflections on panel surfaces and the way shadows fall affect the clarity of reports. Depending on the sun’s angle, rows of panels, the area under mounting racks, drainage channels, and slope irregularities can become difficult to see. Also, low-angle light in the morning and evening casts longer shadows, which can make it easier to grasp terrain undulations, but can also hide parts of equipment in shadow and make details hard to confirm. When including photographs in reports, you should organize them not just by whether they look good, but by whether the items being inspected are discernible in the image.

Shooting altitude and direction are also important. Photos showing the overall layout should be organized so that the relationship between the site boundary, panel rows, access roads, drainage facilities, and the surrounding environment is clear. On the other hand, photos that show anomalies or items to be checked should ensure the subject is not too small within the frame, and are easier to understand when used together with location maps or enlarged views. In reports, separating images that provide an overall view from images that explain individual locations by role makes it easier for readers to understand where they are looking within the entire power plant.

When documenting on-site conditions, record information that affects the interpretation of survey results, such as differences before and after mowing, standing water after rainfall, ruts on maintenance roads, surface condition of slopes, sediment accumulation around drainage channels, and vegetation along fences. For example, if the purpose is to check for poor drainage, photographs taken after a prolonged dry spell and those taken after rainfall have different implications. If only dry conditions during sunny weather were observed, it is safer not to state in the report that there is no standing water, but to say that standing water was not prominent at the time the photos were taken.

In drone surveying, organizing the flight path and the photographed area also affects report quality. Clarifying whether the target area was completely photographed, whether the power plant’s perimeter and the edges of equipment were checked, and whether any locations could not be photographed due to access restrictions or obstacles makes it easier to enhance the report’s credibility. If there are areas that could not be photographed, record the reasons and how they will be checked in the future rather than leaving them vague, so readers can more easily understand the limitations of the findings.

You should also document on-site safety conditions. At solar power plants, flight plans need to be made with attention to transmission equipment, overhead lines, adjacent roads, nearby residences, workers, maintenance vehicles, and the like. You do not need to include every detail of the flight plan in the report itself, but organizing records that safety checks were conducted before shooting and that work was carried out with consideration for the scope of the area photographed and access conditions will make it easier to respond to explanations later.

Recording photographic conditions is also useful for re-inspections and comparisons over time. In the operation and maintenance of solar power plants, the same locations are periodically checked to track changes. If shooting altitude, angle, time of year, grass condition, or weather differ significantly between the previous and current inspections, it becomes difficult to determine whether observed changes are due to actual site changes or differences in photographic conditions. Organizing and recording the photographic conditions in the report provides a reference for the next inspection and makes it easier to improve the accuracy of ongoing management.

Organize Survey Results and Location Information

In reports for solar power plants, it is important to organize the results obtained from drone surveys by linking them to location information. Aerial photographs alone can make it difficult to tell which location is being shown. The larger the plant area, the more similar rows of panels and access roads continue, making it harder to identify locations from photographs alone. Therefore, it is necessary to combine orthoimages, plan views, simple location maps, plot numbers, equipment numbers, and management area names so that locations can be tracked within the report.

When organizing survey deliverables, first clarify the types of outputs. Bird’s-eye photographs for overall understanding, ortho images for position verification, terrain data for grasping topography and elevation differences, planimetric information for drafting, and enlarged photographs for checking specific locations each serve different roles. In reports, it is important not to mix these together but to arrange them according to their purpose. Start by showing the overall view, then describe the key areas to be checked, and add enlarged views or annotations as needed—this sequence makes it easier for the reader to follow.

When organizing positional information, attention must also be paid to the relationship with the reference coordinates and drawings. At solar power plants, multiple drawings may be used, such as design drawings, construction drawings, as‑built drawings, management drawings, and maintenance partition maps. If the references differ among these drawings, discrepancies can occur when overlaying drone survey results with existing drawings. In reports, it is important to clarify the reference used, the drawings compared, and the approach to alignment, and to indicate whether it is for rough verification or for detailed positional confirmation as necessary.

In drawings and images included in the report, organize them so that orientation, sense of scale, and the coverage are clear. Images without a known orientation make it difficult for readers unfamiliar with the site to judge. Also, if you include only close-up photos, it is unclear where they are located within the power plant as a whole. Indicating the position on an overall map and guiding readers to detailed photos using the same numbers or symbols improves the readability of the report. However, when using location numbers in the main text, always verify that they match the numbers on the drawings.

When including survey results in a report, care must be taken in how accuracy is described. Drone surveys are effective for obtaining a broad understanding of site conditions, but the accuracy of the results is affected by flight conditions, imaging methods, the placement of aerial targets, the handling of ground control points, processing/analysis parameters, and the visibility of the ground surface. In reports, avoid phrasing that implies results are more precise than warranted or that everything can be determined, and proceed on the assumption that accuracy verification appropriate to the intended use is required. Because the accuracy required differs depending on whether the material is used for management decisions or for checking construction dimensions, explanations tailored to the intended use are indispensable.

At solar power plants, the ground surface can be obscured by panels, racking, vegetation, and the like. When using drone surveying to understand terrain, extra caution is needed when judging elevation differences and drainage directions in areas where the ground surface is not sufficiently visible. In reports, it is practical to separate what was inferred from the visible areas from the areas that require additional verification. In particular, locations such as under the racking, between rows of panels, places with dense vegetation, inside drainage channels, and spots shaded by slopes may not be fully assessable from photographs alone.

Naming and storage rules for data and deliverables must not be overlooked when preparing reports. Organizing files using names that identify the capture date, target area, type of deliverable, update number, and so on makes it easier to find materials later. If the link between images published in the report and the original data becomes unclear, significant effort will be required for corrections or rechecks. Managing and distinguishing not only the compressed images used in the report but also the original images, analysis results, drawing files, and annotated documents makes it easier to respond to inquiries from stakeholders.

Organize abnormal locations and inspection results

What becomes particularly important in drone survey reports is the organization of abnormal and noteworthy locations. At solar power plants there are many items to check for maintenance management, such as poor drainage, sediment runoff, slope erosion, damage to maintenance roads, abnormalities around fences, vegetation overgrowth, causes of shading around panels, and sediment or debris accumulation around equipment. When compiling these into a report, it is important not to arrange photos in the order they were found but to organize them so that position, content, extent of impact, urgency, and whether additional inspection is required are all apparent.

When organizing abnormal locations, first separate the facts that can be confirmed from the potential impacts. For example, if sediment accumulation is observed around a drainage channel, the fact visible in the photograph is that sediment has accumulated. On the other hand, reduced drainage capacity or the risk of standing water during rainfall should be judged in combination with on-site inspection and past conditions. In reports, clarifying what can be confirmed from images and, where necessary, organizing recommendations for additional investigation or on-site inspection helps avoid making overly definitive conclusions.

When indicating the location of anomalies, it is effective to align the overall site map with detailed photographs. Because solar power plants often have repetitive scenery, it can be difficult to determine the exact on-site location from photos alone. In reports, showing the inspection points on the overall map, describing the condition of those points in the body text, and—when necessary—providing enlarged photos to show details makes it easier for readers to visualize the site. When on-site response is required, this approach also makes it easier for the person in charge to identify the location, helping to prevent missed checks and communication errors.

When reporting inspection findings, organizing priorities is also important. If all areas of concern are treated the same, it becomes difficult to understand the order in which they should be addressed. The report should make clear whether an item requires immediate action, can be checked at the next scheduled patrol, can be managed by observation over time, or needs confirmation by another specialist. However, when assigning priorities, it is important not to make definitive judgments when the supporting evidence is unclear. Make the basis for decisions explicit by organizing which areas were visible from drone surveys, which were verified by on-site inspections, and which were cross-checked against historical records.

In the maintenance of solar power plants, it is also important to track changes in abnormal areas. Being able to confirm, compared with the previous report, whether the extent of soil runoff has expanded, vegetation growth has progressed, watercourses have changed, or ruts on access roads have deepened makes it easier to reflect those changes in maintenance plans. Results from drone surveys can be used as one method to continuously record the same area. In reports, organizing information so that comparisons with past data are possible, rather than only presenting the current situation, is useful for long-term management.

When describing anomaly locations, attention is also needed to how photographs are presented. Wide-angle photos make it easier to grasp the overall situation, but they can make details difficult to see. Conversely, close-up photos make details easier to see but can make the positional relationship with the surroundings hard to understand. Therefore, in reports it is effective to organize information in the order of overall, surrounding, and detailed. When adding annotations to photos, too many arrows or boxes make them hard to read, so display only the key points to check. It is important to structure the presentation so the reader can tell at a glance what to look at.

Also, when reporting abnormal areas, it is important to avoid describing countermeasures in excessive detail. In drone survey reports, the primary roles are often to capture the current conditions and provide materials for decision-making, and decisions on design changes or repair methods may need to be considered separately. For example, even if deformation of a slope is observed, it is risky to decide on the cause or countermeasures based on photographs alone. In the report, organize the deformations that were confirmed, the anticipated impacts, and the need for additional checks, and by clarifying the scope that requires expert judgment, the report will provide safer content.

Organize the rules for updating and sharing reports

A report on a solar power plant produced using drone surveying is not a one-time deliverable. In plant operation and maintenance, inspections, repairs, mowing, drainage maintenance, renovation work, and post-disaster checks cause conditions to change over time. Therefore, it is important to establish rules for updating and sharing the report. If multiple documents exist with unclear revision histories, it becomes impossible to determine which is the latest, and there is a risk that stakeholders will proceed based on outdated information.

When updating a report, clearly indicate the creation date, survey date, scope, and the updates made. At a solar power plant, conditions can differ by area even within the same site, so it is clearer to state separately whether the entire report was updated or only specific areas. For example, adding only a drainage check after rainfall is very different in meaning from re-surveying the entire plant. By specifying the update scope, readers are less likely to misunderstand the effective scope of the document.

Under shared rules, it is important to separate the handling of the report itself from that of the raw data. The report is a document organized to be easy for stakeholders to read, but original images, survey results, and drawing data may be needed for re-checking or additional analysis. If only the report is shared and the storage location of the raw data becomes unknown, responding when detailed verification is required later will be delayed. Conversely, if only a large volume of unorganized raw data is shared, readers will not be able to find the information they need. Separating the roles of reports, drawings, images, and analysis data and standardizing their storage locations and management methods is effective in practice.

It is also necessary to adjust the level of detail in the report according to its recipients. For managers, organize the overall site trends, response priorities, and items requiring future verification in an easy-to-understand manner. For on-site personnel, indicate the location, scope, photos, and work-related precautions concretely. The tone and the content of annotations may differ between internal sharing and submission to the client. In any case, separating facts from assumptions and refraining from asserting unverified information is important to maintain the credibility of the report.

To stabilize the quality of reports, it is effective to determine a basic structure before creating them. For example, organizing the content in the same order each time—survey overview, scope, imaging conditions, deliverables used, overall condition, locations checked, analysis, additional items to verify, and attachments—makes it easier for readers to compare. If the report structure varies greatly depending on the person in charge, comparing with past materials and handing things over becomes difficult. To use drone survey results for ongoing management, standardizing the report format is essential.

In the final check, verify that the photos match the text, the locations on the drawings, the dates, the scope, the orientations, the notes, the file names, and the revision numbers. In particular, at solar power plants where many similar images exist, there is a risk of mistakenly publishing photos from different locations. Images used in reports need to be checked against the original data and reviewed to ensure there are no contradictions with the descriptions. Also, when reusing past reports, be careful that old dates or previous comments have not been left in. Even small clerical errors can affect on-site decisions, so pre-publication checks should be carried out carefully.

Drone survey reports serve not only as materials to convey on-site conditions to stakeholders but also as foundational documents for subsequent inspections and refurbishment plans. By organizing not just collected information but also the purpose, conditions, location, anomalous areas, and update rules, the reports become practical documents for field work. Photovoltaic power plants are facilities affected by the outdoor environment, so it is important to continuously monitor changes in topography, drainage, vegetation, and the surrounding environment. By utilizing drone surveys in report preparation, you can gain an overview of wide-area conditions and make it easier for stakeholders to make decisions based on the same information.

In managing solar power plants, the readability and reusability of reports affect the speed of on-site response and the accuracy of inspections. It is important not to leave captured images and survey results as one-off materials, but to preserve them in a form that can be used for subsequent inspections, maintenance planning, retrofit evaluations, and stakeholder briefings. By clarifying reporting objectives, recording imaging conditions, linking location information with inspection findings, and organizing update histories, it becomes easier to enhance the value of drone surveying.