6 Reasons to Use Drone Surveying for Operation and Maintenance of Solar Power Plants

Table of Contents

• Background: Why drone surveying is gaining attention in the operation and maintenance of solar power plants

• Reason 1: Can obtain an overview of large sites in a short time

• Reason 2: Easier to record changes in panels, racking, and graded surfaces

• Reason 3: Reduces the burden of inspecting areas that are difficult for people to access

• Reason 4: Helps investigate causes of decline in power generation

• Reason 5: Makes it easier to standardize operation and maintenance records

• Reason 6: Can preserve information to support repair planning and long-term management decisions

• Points to consider when using drone surveying for operation and maintenance

• Summary

Background: Why drone surveying is attracting attention in the operation and maintenance of solar power plants

In the operation and maintenance of solar power plants, it is important not only to inspect the generation equipment itself but also to continuously monitor the condition of the entire site. The items to check cover a wide range, including dirt or damage to panels, deformation around mounting structures, poor drainage, overgrowth of weeds, slope failures, and abnormalities around fences. Especially for ground-mounted solar power plants, equipment is spread across large sites, so even walking the site to check everything is a major effort.

In conventional maintenance, workers patrolled the site, took photographs, and recorded abnormal locations. While this method is still necessary, in large power plants the inspection coverage tends to be biased by the workers' patrol routes, and it is not easy to compare the same locations regularly. If the camera position or shooting direction changes each time, it becomes difficult to track changes in condition afterward.

One particularly practical method is drone surveying of solar power plants. By using drones, you can photograph the entire site from above and, as needed, organize the data into orthophotos, 3D models, terrain information, and other formats. Because it can be stored as georeferenced records rather than just simple aerial photos, it is well suited to operation and maintenance.

However, drone surveying for operation and maintenance of solar power plants does not completely replace on-site inspections. Detailed inspections of electrical equipment, checks of connection points, and tests related to insulation and power generation performance need to be carried out according to specialized procedures. At the same time, drone surveying is an effective supplementary tool for assessing the overall condition of the site, extracting abnormal areas, comparing with past data, and considering the scope of repairs.

In maintenance management, the important thing is not to rush to check after an anomaly occurs, but to detect signs of change early. By regularly incorporating drone surveys, it becomes easier to capture the condition of a site as an area and to identify changes that are difficult to notice with patrol inspections alone. To operate a power plant stably over the long term, it is important to combine visual inspections, electrical inspections, verification of generation data, and recording of current-condition data.

Reason 1: Quickly get an overview of a large site

The main reason for using drone surveying at solar power plants is that it enables an efficient aerial overview of large sites. With on-the-ground inspections, personnel tend to walk along aisles while checking rows of panels and the areas around the racking, so the inspection coverage often becomes linear. Site staff can understand in detail the areas they see, but it becomes difficult to grasp the entire site’s connectivity and the positional relationships of anomalies all at once.

Using drones, you can photograph the entire power plant from above and easily organize information such as panel layout, walkways, slopes, drainage paths, surrounding terrain, and fence locations into a single comprehensive dataset. This makes it easier to identify within the whole site which areas have overgrown weeds, which walkways are prone to water pooling, and which slopes show signs of collapse.

Solar power plants consist of repeated rows of similar panels, so ground patrols alone can lead to misidentification of locations. In particularly large plants, it can become difficult to determine later where a photo was taken, and sharing with repair personnel or managers often requires lengthy explanations. If aerial imagery from drone surveys is organized, it becomes easier to indicate anomalous locations on a map and reduce misalignment of understanding among stakeholders.

Also, photographing regularly under similar conditions makes it easier to compare changes across the entire power plant. By comparing previous images with the current ones, you can more easily identify the spread of weeds, areas of poor drainage, movement of sediment, and growth of surrounding trees. Because these remain as visual records rather than relying solely on people's memories or field notes, it becomes easier to make maintenance and management decisions consistent.

However, just because it’s quick to check doesn’t mean you can skip pre-flight preparations. You need to plan in advance the flight area, flight altitude, image overlap rate, takeoff and landing locations, obstacles, and checks of surrounding safety. At solar power plants, pay attention to panel surface reflections, overhead lines, trees, fences, slopes, and work vehicles. To leverage drone surveying for operation and maintenance, it’s important not to simply fly, but to be mindful of acquiring data that will be easy to compare later.

Being able to inspect a large site efficiently also helps speed up the initial response for maintenance and management. If areas of concern are identified from aerial images before on-site rounds, workers can check the highest-priority locations first. As a result, it becomes easier to allocate time for on-site work, and even with limited personnel the entire power plant can be managed more effectively.

Reason 2: Easy to record changes to panels, mounting frames, and ground surfaces

Continuous recording of changes in equipment and ground conditions is essential in the operation and maintenance of solar power plants. The condition of panel surfaces, the alignment of mounting structures, soil movement around foundations, settlement of developed ground, and deformation of slopes do not necessarily appear suddenly as major problems. Small changes can progress over time and eventually affect power generation efficiency and safety.

Using drone surveying makes it easier to preserve the overall condition of a power plant as images and three-dimensional data. With ground-level photographs, camera position and angle tend to vary each time, which can make comparison with past data difficult. If the data is captured from the air under consistent conditions, it becomes easier to compare the same area as a surface and to check for any changes.

For example, at solar power plants installed on developed (graded) land, the flow of rainwater may change after rainfall, and scouring may progress on parts of slopes. What appears from the ground as only small steps or channels can, when checked from above, affect a much wider area. If drone surveying can capture changes in topography and surface conditions, it can help in planning drainage measures and determining the scope of repairs.

Even around the mounting structures, ground settlement, tilting, or soil washout around foundations can occur, which may affect the panels' orientation and the alignment of rows. Although drone images alone cannot provide a detailed structural diagnosis, they can serve as a prompt to identify row irregularities or anomalies in the surrounding ground when viewed from above. If suspected abnormal locations can be narrowed down, on-site detailed inspections can be carried out more efficiently.

For panel surfaces, it becomes easier to identify dirt, fallen leaves, bird droppings, residual snow after snowfall, and the spread of shadows from surrounding trees. Using high-resolution visible images can provide clues to locations within the entire power plant where dirt or obstacles are concentrated. Furthermore, by combining them with inspection methods such as thermal imaging when necessary, they can serve as an entry point for investigating abnormalities that are difficult to detect by visual inspection alone.

The important thing is not to let the results of drone surveying end up as a single set of photos. Organizing the shooting date, flight conditions, survey area, weather, the reference points and check points used, and the data processing conditions will make it easier to compare results in future surveys. Especially when conducting checks close to topographic changes or as-built conditions, it is important to decide in advance the required positional accuracy, control points, verification points, and processing conditions.

Solar power plants are facilities designed for long-term operation. Even if the initial construction condition is sound, maintenance and management challenges change over time due to aging, weather conditions, and changes in the surrounding environment. Records from drone surveying are an effective means of objectively documenting such changes.

Reason 3: Can reduce the burden of checking locations that are difficult for people to enter

There are many areas in solar power plants that are difficult for people to access. Steep slopes, graded surfaces that easily become muddy, areas densely overgrown with weeds, around drainage channels, along fence perimeters, and locations tucked behind rows of panels not only take longer to inspect during on-site patrols but also pose risks of falls and accidental contact. Because maintenance requires inspections to be carried out safely, it is undesirable to rely solely on methods that force people to enter such areas to check.

By using drone surveying, you can check conditions from above before workers approach hazardous areas. For example, when slope failures or puddles are suspected after rain, first inspecting the whole site with a drone makes it easier to separate locations that require entry from those that do not. It is safer to understand the situation in advance and then proceed to detailed inspections than to go directly onto a slope on site.

Also, at solar power plants the spacing between panel rows can be limited, making it difficult to move while carrying equipment. Inspections under the mounting racks and between rows tend to force poor working postures, and in hot summer conditions the physical burden on workers increases. By expanding the area that can be inspected from above with drones, you can reduce ground movement while concentrating inspections on the locations that need attention.

When inspecting locations that are difficult for people to enter, preventing oversights is also a major challenge. On foot patrols, personnel can examine the areas around the routes they take in detail, but abnormalities a short distance away from those routes can be hard to notice. If drone surveying records the site as an area, locations outside the patrol routes can be checked afterward. Abnormalities that were not noticed on site can sometimes be discovered by reviewing the images in the office.

However, there are limits to the information that can be confirmed by drones. Looseness of bolts on the mounting structure, the condition of electrical connection points, minor component degradation, and insulation condition require direct on-the-ground confirmation or specialized measurements. Drone surveying is more practical as a means to find locations that require detailed inspection than as a substitute for detailed inspections. By gaining an overall view from above and then verifying suspicious areas on the ground, it becomes easier to balance safety and efficiency.

In maintenance operations, personnel and time are often limited. Rather than checking every location with the same density, it is important to focus on high-risk areas and places that are undergoing significant changes. If drone surveying can be used to prioritize the entire site, it becomes easier to plan work, and unnecessary travel and hazardous entries can be reduced.

Reason 4: Useful for investigating the causes of reduced power generation

When a solar power plant's generation is lower than expected, the cause is not necessarily a single one. Variations in solar irradiance, soiling of the panels, shading, equipment malfunctions, problems in the wiring system, overgrowth of weeds, snow accumulation or fallen leaves, changes in the surrounding environment, and other factors may be involved. To determine a drop in generation, it is necessary to check a combination of generation data, weather conditions, electrical inspection results, and on-site conditions.

Drone surveying is useful for understanding on-site conditions. When photographed from above, you can simultaneously check shadows falling across rows of panels, the growth of surrounding trees, the effects of weeds, uneven soiling on panel surfaces, and the condition of access paths and drainage. What may appear from the ground to be a problem limited to a few rows can, from above, be seen to be spreading along a particular direction or terrain condition.

When investigating declines in power generation, it is important to first identify sections or equipment systems showing anomalies in monitoring data and inspection records and then cross-check those locations with actual on-site conditions. If images and location data obtained from drone surveys are available, it becomes easier to determine which areas have concentrated soiling or shading. Even when on-site photos alone make it difficult to describe locations, indicating abnormal spots on aerial images makes it easier to share information among managers, inspection personnel, and repair contractors.

In particular, the impact of shading varies with the time of day and season. Surrounding trees, buildings, utility poles, slopes, fences, weeds, and the like can cast shadows on the panels at certain times of day. Using drone surveys to understand the overall layout of the plant and its surrounding environment makes it easier to identify locations where shading is likely to occur. If necessary, this can also lead to a decision to inspect the site at different times of day.

Also, dirt and deposits on panels can be a factor in reduced power output. If you can confirm the distribution of dirt from drone images, it becomes easier to determine whether a full cleaning is necessary or whether certain areas should be prioritized. Of course, you should avoid concluding the impact on power output based on images alone. It is important to make a decision by combining generation data, weather conditions, and inspection results.

Drones are also effective when combined with inspections that use thermal imaging. They can provide clues suggesting abnormalities in panels or strings, but the appearance can change depending on solar irradiance at the time of imaging, wind, temperature, the condition of the panel surface, the imaging angle, and so on. If a suspicious area is found, it is realistic to follow up with detailed on-site inspections and electrical checks.

When investigating the causes of reduced power output, narrowing down potential causes in advance is more efficient than beginning the search after arriving on site. By using drone surveying to capture on-site conditions across a wide area, you can more easily determine the inspection order and shorten the time required to pinpoint the cause.

Reason 5: Easier to standardize maintenance records

In the operation and maintenance of solar power plants, how inspection results are recorded is extremely important. Even if an anomaly is discovered on site, vague records make it difficult to verify the situation later. Problems such as not knowing where a photo was taken, failing to convey the extent of the anomalous area, different recording methods used by different staff, and being unable to compare with past inspection results can all cause a decline in the quality of operation and maintenance.

When drone surveying is introduced, it becomes easier to record the entire power plant in a consistent format. If aerial images are organized together with positional information, inspection photos can be managed on a map. By indicating abnormal locations on the images and attaching comments or management numbers where necessary, stakeholders can make decisions while viewing the same information.

The key to standardization is to acquire data under as similar conditions as possible each time. Deciding in advance on the flight area, flight altitude, flight route, imaging direction, how to handle reference points, and the data processing methods will reduce variability between inspections. This makes comparison with previous inspections easier and increases the value of the records for maintenance management.

Photos from on-site patrols are also necessary, but photos alone can make it difficult to understand positional relationships within the entire power plant. By using an overall image obtained from drone surveying as a reference and linking ground photos and inspection notes to it, explaining abnormal areas becomes smoother. For example, it becomes easier to share where along a panel row dirt is located, over which area of a slope a collapse has occurred, or which part of a drainage channel is clogged.

Maintenance records are used not only internally but also shared with the power plant owner, management company, construction contractor, repair personnel, and stakeholders involved in insurance and warranties. If the format of the records is standardized, it reduces the effort required to prepare explanatory materials. Conversely, if records vary by responsible person, it may require revisits for confirmation or lead to misunderstandings about the extent of anomalies.

Drone survey data are also effective as supplementary material for periodic inspection reports. By organizing overview images of the entire power plant, enlarged images of abnormal areas, and comparison images with past conditions, you can visually present situations that are hard to convey with text alone. In particular, vegetation overgrowth, sediment inflow, poor drainage, and slope deformations are easier to communicate when shown with images.

However, standardizing records also requires rules for data storage. It is important to organize items such as capture date, power plant name, section name, inspection type, person in charge, and data processing conditions, and save them in a form that is easy to search later. If surrounding roads, adjoining land, residences, etc. are captured, data management and privacy should be considered—for example, by avoiding sharing more than necessary. Drone surveying is effective when operational design includes not only image capture but also record management.

Reason 6: Can provide information to support decisions on repair plans and long-term management

A solar power plant is not finished once installed; it requires ongoing management to continue generating power over the long term. The longer it operates, the more issues accumulate: equipment deterioration, changes in ground conditions, drainage system failures, the growth of weeds and trees, and changes in the surrounding environment. If these are handled on an ad hoc basis, it becomes difficult to determine repair priorities, and necessary measures may be postponed.

Keeping regular records from drone surveys provides material for making decisions when planning repairs. For example, if you capture images at the same time each year, you can identify areas where weeds tend to grow, locations where drainage problems recur, and slopes where soil erosion is progressing. Even when a single inspection makes it difficult to determine whether a condition is a one-off or a persistent problem, multiple records allow you to confirm trends.

In a repair plan, it is important to decide which locations to address first. When it is difficult to fix everything at once, priorities should be set based on impacts on power generation, impacts on safety, impacts on the surrounding environment, and the likelihood of recurrence. If drone survey imagery and terrain data are available, it becomes easier to understand the extent of the problems and their spatial relationships, and to facilitate consultations with stakeholders.

Another advantage is that you can keep records of the before-and-after repairs. When you carry out maintenance such as cleaning drainage channels, repairing slopes, weed control, pathway maintenance, or fence repairs, recording the conditions with a drone before and after the work allows you to objectively demonstrate the measures taken. If the same location experiences problems again later, it also becomes easier to check the history of past responses.

In long-term management, you may also check whether the drawings made during the power plant’s design and construction match the current condition. Over the years, the way access routes are used, drainage flows, surrounding vegetation, and conditions near site boundaries can change. If you update current condition data with drone surveys, you can confirm the actual on-site conditions that cannot be understood from old records alone.

Furthermore, it is useful for post-disaster inspections. After heavy rain, strong winds, snowfall, or earthquakes, it is necessary to quickly ascertain the overall condition of the power plant. Even when ground patrols alone would take time to confirm, using drones to inspect the entire site from above can narrow down areas suspected of damage. Because it can also be used to document the damage, it facilitates developing recovery plans and reporting to stakeholders.

However, immediately after a disaster, there may be cases involving the designation of emergency operational airspace or requests to refrain from flying. It is important to confirm whether flying is permitted before conducting operations so as not to interfere with manned aircraft operations or compromise the safety of the surrounding area. Maintenance of solar power plants requires attention to both daily inspections and long‑term asset management. Drone surveying is a means not only to detect current anomalies but also to create records that can be used for future repair decisions.

Precautions When Using Drone Surveying for Operation and Maintenance

When incorporating drone surveying into the operation and maintenance of solar power plants, you need to understand not only the convenience but also the operational precautions. First, it is important to clarify what you want to check with drone surveys. The required shooting conditions and data processing methods vary depending on the purpose—whether a bird's-eye view of the entire site, the condition of weeds, poor drainage, slope deformation, soiling on panel surfaces, or comparisons before and after repairs.

If you capture images without a clear purpose, you may obtain aerial photos that look good but result in data that is difficult to use for maintenance and management. For example, if you want to compare with past data, you need to match the flight altitude and the coverage area. If you want to observe terrain changes, you must consider positional accuracy and how reference points are handled. If you want to check the condition of panel surfaces, you also need to pay attention to the shooting angle, the position of the sun, and the effects of reflections.

Safety management is also essential. At solar power plants, there are items to watch for during flight, such as mounting racks, panels, electrical equipment, fences, overhead lines, trees, and work vehicles. It is important to secure takeoff and landing sites, check flight routes in advance, and understand the presence or access status of workers and third parties. On days with strong winds or poor visibility, it may be necessary to decide not to fly.

Checking laws and rules is also important. For drone flights, depending on the flight location, the aircraft, and the flight method, registration, permission, approval, notification, or the consent of the facility manager may be required. Even within a power plant's premises, you need to check surrounding airspace, densely populated areas, areas near airports, airspace reserved for emergency operations, municipal rules, and any agreements with landowners or facility managers. If flights are conducted continuously as part of maintenance operations, it is advisable to put internal operating rules and safety procedures in place.

You should avoid excessive expectations about data accuracy. Drone surveying is effective for understanding conditions over wide areas, but it cannot automatically detect every anomaly. Deterioration of small components and electrical faults need to be combined with ground inspections and specialized measurements. The results obtained from drones are best used as material for determining priorities for on-site verification in practical work.

Data processing quality also affects the results of maintenance. If processing conditions such as image stitching, orthorectification, 3D reconstruction, and positional alignment are unstable, comparisons with past data can produce errors. When using this for routine inspections, it is important to keep the processing methods as consistent as possible each time and to establish verification points as needed.

When using drones internally, training for personnel is also necessary. They need to understand not only how to pilot the drone, but what to look for during maintenance, how to record it, and which anomalies should lead to ground verification. If the staff responsible for imaging, inspection personnel, and managers can handle data according to the same standards, it becomes easier to enhance the effectiveness of drone surveying.

Finally, the value of drone surveying increases with continued use. Rather than conducting a single survey and stopping, it is important to integrate it into regular inspections, post-disaster assessments, and records before and after repairs, and to accumulate it as management data for the power plant. By establishing operating rules and conducting surveys at a frequency suited to their purpose, you can improve the accuracy and efficiency of maintenance and management.

Summary

The reasons for using drone surveying in the operation and maintenance of solar power plants are that it enables efficient understanding of large sites, makes it easy to record changes in equipment and ground conditions, reduces the burden of inspecting areas that are difficult for people to access, helps investigate causes of power generation decline, makes it easier to standardize maintenance records, and preserves data for repair planning and long-term management decisions.

In power plant management, walking inspections on site will continue to be important. However, foot patrols alone may not fully capture the condition of a large site or changes over time. Combining drone surveying provides records with an aerial perspective and positional information, leading to more efficient inspections and improved information sharing.

On the other hand, drone surveying is not a panacea. Detailed inspections of electrical equipment and close-up checks of components must be carried out according to specialized procedures. If drones are positioned as tools for grasping the overall situation, identifying anomalous areas, comparing with past data, and supporting repair-planning, they become easier to incorporate into maintenance operations.

To ensure stable, long-term operation of a solar power plant, it is important not to treat inspection results as one-off events but to retain them as data that can be used for future decision-making. By combining power generation, inspection records, on-site photos, and drone survey data, you can not only detect anomalies early but also prioritize repairs and explain them to stakeholders.

If you are going to incorporate drone surveying into the operation and maintenance of a solar power plant, it is best to start by clarifying the objectives and standardizing the shooting conditions, recording methods, and comparison criteria. As a means to complement on-site patrol inspections and continuously visualize the entire power plant, drone surveying is an effective option for operations personnel.