5 Points to Leverage Drone Surveying in Weed Control Planning for Solar Power Plants

At solar power plants, the way weeds grow can affect power output, inspectability, safety, drainage, and relations with neighbors. In particular, at large sites or plants with many blind spots—on slopes, around retention ponds, along fences, and beneath mounting racks—it becomes difficult to uniformly assess vegetation conditions by visual inspection from the ground alone. An effective approach is to incorporate drone surveying and aerial photography records of the solar power plant into weed-control planning. By checking the site from above and organizing weed distribution, locations prone to shading, access routes for work vehicles, locations for collecting cut grass, and the areas to be inspected after work, it becomes easier to shift from ad hoc weed control to planned maintenance.

Table of Contents

• Why drone surveying is useful for weed control planning at solar power plants

• Point 1: Understand weed distribution from the air and set priorities

• Point 2: Prioritize management of locations that have a significant impact on panels

• Point 3: Organize workflow and hazardous areas in advance

• Point 4: Keep records before and after weeding to stabilize management quality

• Point 5: Anticipate seasonal changes and incorporate them into the next plan

• Precautions when using drone surveying for weed control planning

• Summary

Why Drone Surveys Are Useful for Weed Control Planning at Solar Power Plants

Vegetation control at a solar power plant is not simply the act of cutting grass short. It is maintenance carried out to improve visibility around power generation equipment, make inspections and patrols easier, reduce the impact of shadows on panel surfaces, and make it easier to detect abnormalities around drainage channels and fences. When grass height increases, the lower portions of panel rows and areas around the racking can be hidden more than they appear from ground level. In narrow walkways, it becomes harder for workers to walk, increasing the risk of missed inspections and trips or falls. Furthermore, when grass and cuttings accumulate around drainage channels and catch basins, water flow during rainfall can be impeded.

However, simply walking a large power plant site and inspecting it from the ground makes it difficult to grasp grass growth across the entire site according to the same standard. This is because judgments tend to vary depending on the inspector's walking route, the time of day when the inspection was carried out, the weather, and how the grass height appears. In particular, solar power plants have rows of panels arranged continuously, creating a repetitive landscape. From the ground, it can be difficult afterward to explain which row and which section the grass is growing in.

When you use drone surveying, aerial images and terrain data of the entire power plant make it easier to identify the areas that require weed control. If all locations can be photographed under conditions close to the same day, it becomes easier to compare spots with dense vegetation, areas that are difficult to work in, and locations that are more likely to be affected. Moreover, by comparing the previous imagery with the current imagery, you can also identify areas where weeds tend to grow and where maintenance tends to fall behind.

Drone surveying of solar power plants can be used not only for site development planning and creating as‑built/current-condition maps but also for developing operation and maintenance plans. The important thing is not to stop at leaving the images captured from above as mere "neat records." By using them to determine areas for vegetation control, consider the order of work, check hazardous spots before operations, confirm completion after work, and link them to the next management plan, the value of drone surveying is enhanced.

Point 1: Assess weed distribution from above and set priorities

One of the first things to clarify in a weed-management plan is where weeds are most abundant and which areas should be prioritized for work. At a solar power plant, grass does not necessarily grow uniformly across the entire site. Differences in sun exposure, drainage, soil type, the condition of topsoil after site development, seeds blown in by the wind, surrounding vegetation, and conditions along fences all cause variations in how grass grows. Even if the area near the entrance is well maintained, slopes farther in, beneath the mounting structures, and along drainage channels can have dense weed growth.

With only ground inspections, attention tends to be drawn to areas with tall grass, and the distribution of weeds that spread across surfaces can be overlooked. By contrast, when checked from above using drone surveying, it becomes easier to identify the areas across the entire power plant where grass appears dense, where walkways are becoming obstructed, and where differences in management are emerging between rows of panels. If you organize the condition of each section based on the captured images, it becomes easier to explain the prioritization of work.

For example, dividing a power plant into zones such as the entrance area, central area, rear area, slope sections, around drainage channels, and along fences makes it easier to create a weed control plan by zone rather than relying on a mere impression. If you can separate areas that require immediate work, areas to monitor until the next patrol, and areas where partial trimming will suffice, it becomes easier to estimate the workload. Even when outsourcing weed control, sharing images of the target areas can help reduce misunderstandings before work begins.

Also, when assessing grass distribution, it is important not to judge solely by whether there is more or less green. Areas where short grass spreads across the surface and areas where tall grass is blocking the front of panels or pathways have different weeding priorities. Because aerial images may not allow accurate determination of grass height, we combine them with on-the-ground inspections as needed. Drone surveys are a means to capture the overall picture, and on-site visual confirmation is also important for final decisions.

When deciding priorities, consider the combined effects on power generation, inspection work, safety, visibility from nearby properties and roads, and drainage. Even if it is difficult to mow an entire large area at once, clear priorities allow you to address the most important locations first within limited work time. Incorporating drone surveying of solar power plants into weed control plans makes it easier to make image-based decisions rather than relying solely on the experience of on-site personnel.

Point 2: Prioritize management of locations that have a significant impact on panels

When carrying out vegetation control at a solar power plant, particular attention should be paid to plants that could cast shadows on the panels. Even if grass grows, it does not necessarily cause a major impact immediately. However, vegetation in front of the panels, between rows, on south-facing slopes, growing up from beneath the racks, or tall plants along fences can cast shadows on the panel surfaces depending on the time of day and season. Because the effect of shading varies with system configuration and solar irradiation conditions, it should not be judged uniformly but assessed carefully according to on-site conditions.

Drone surveying allows you to get an overhead view of the positional relationship between panel rows and weeds. From the ground, your attention tends to be focused only on the grass height immediately in front of you, but from above it becomes easier to see which panel rows have concentrated grass in front of them and from which walkways or slopes vegetation is encroaching. In particular, because panel orientation and row spacing are fixed at solar power plants, it is easy to map on drawings or images the areas that are likely to be affected.

Areas that require focused management are not limited to locations near the power generation equipment. Vegetation growing on surrounding slopes and boundary areas can cast shadows depending on the time of day. Trees off-site or vegetation on adjacent properties may not be able to be removed without permission, so confirmation with managers and other stakeholders is necessary. However, if you record the current conditions using drone surveys, it becomes easier to use the records as explanatory material showing the extent of the impact. Rather than simply saying verbally that “vegetation is growing,” indicating the location on aerial images makes it easier to share the need for action.

When examining the impact on panels, pay attention to the time of day when you take photographs. The way shadows appear changes with the sun’s position. In the morning, around midday, and in the afternoon, the direction and length of shadows cast by the same vegetation differ. You don’t need to photograph every time of day each time, but if you want to confirm the effects of shadows, deciding the shooting time according to your purpose will make evaluation easier. It is important to distinguish whether the photographs are for a weeding plan or for checking shadow conditions.

Also, the impact of vegetation affects not only power generation but also the ability to carry out inspections. In areas where grass is tall, abnormalities in the racking, wiring, and around foundations become difficult to see. Traces of small-animal intrusion, scour, sediment inflow, poor drainage, and gaps under fences also become hard to confirm. If you identify areas of dense vegetation from aerial imagery, it becomes easier to decide where to focus ground inspections after weed removal.

In weed-control planning, it's more efficient to focus on areas that have a greater impact on panels than to manage the entire site at the same frequency. Using images obtained from drone surveys to identify rows where impacts are likely, slopes prone to rapid vegetation growth, and boundaries that are difficult to manage makes it easier to create management rules for each power plant.

Point 3: Organize workflow and hazardous areas in advance

Weed control requires not only the skill of cutting grass but also planning to move safely within the site, avoid damaging equipment, and carry out work efficiently. Solar power plants include panels, mounting structures, foundations, cables, junction boxes, power collection equipment, fences, drainage channels, slopes, and maintenance access paths. Because workers often need to approach equipment, choosing the wrong movement routes can lead to contact with equipment, trips and falls, slips on slopes, vehicles getting stuck in mud, or damage around cables.

When using drone surveying for weed control planning, you check not only the distribution of weeds but also the operational routes. Aerial images make it easier to identify the route from the entrance to the work site, passages that are easy for vehicles to enter, narrow sections, places that are hard to turn around in, and spots where materials or cut grass can be temporarily placed. When walking on the ground you can only see one passage at a time, but viewing from above allows you to consider the work sequence as an area.

For example, whether you work from the back of the power plant toward the front, proceed in order from the entrance side, tackle slopes first, or address the spaces between panel rows will affect the number of movements and the overlap of tasks. If you postpone areas with tall grass, workers will have to pass through them multiple times with poor visibility. Conversely, securing the main pathways and inspection routes first makes subsequent work and patrols easier. Using images obtained from drone surveys allows you to consider such work sequences in advance.

It also helps identify hazardous locations. At solar power plants, post-construction terrain can create slopes, steps, scouring/erosion, drainage ditches, mud, ruts, and areas of subsidence. When the grass grows, these hazards become hard to see from the ground. Drone images can hide details beneath the grass, but they make it easier to grasp changes in terrain, places where water tends to collect, breaks in access routes, and the relative positions of slopes. Sharing hazard locations before work makes on-site safety briefings more concrete.

When using weed-control machinery, you must also pay attention to distances from equipment and to flying debris. In areas close to panels and wiring, it may be necessary to change the type of machine or the working method. By using aerial images to separate areas that can be broadly mowed from areas that require manual work, it becomes easier to plan worker placement and time allocation. At sites where grass clippings need to be collected, collection points and removal routes can also be considered in advance.

Organizing work routes benefits not only workers but also power plant managers. If the work area, no-entry zones, caution points, and areas confirmed as completed can be shared on images, pre-work meetings become more concrete. Even workers entering the site for the first time can more easily grasp the overall picture. Drone surveying of solar power plants can be used not only to create drawings as survey deliverables but also as planning materials for safe, efficient, and low-waste weed-control operations.

Point 4: Keep records before and after weeding to stabilize management quality

Weeding work is often thought to be finished once the area looks tidy after completion. However, in power plant maintenance it is important to record when, where, and to what extent work was carried out. If the person in charge changes or when planning the next weeding operation, the same problems tend to recur in the same locations if past work records are not kept. Using drone surveys makes it easier to objectively preserve the before-and-after conditions of weeding.

In pre-weeding records, photograph the extent of overgrown weeds, the areas where pathways are obstructed, the areas where vegetation is encroaching near panels, and the conditions around slopes and drainage channels. In post-weeding records, verify the areas where work has been completed, the areas left untreated, and the areas requiring additional action. If before-and-after images can be taken at similar altitude, direction, and coverage, it will be easier to compare the changes.

When keeping records, it is useful to organize the shooting date, purpose of the photos, scope of coverage, weather, condition of the grass, work performed, and any observations made on site. Even if only images remain, people who view them later may not be able to understand the situation. This is especially true at solar power plants, where long runs of similar panel rows can make it unclear where an image was taken. Linking images to the on-site naming—such as plot name, panel row number, access-path name, or position from the entrance—makes it easier to verify things on subsequent visits.

Records after weed removal also help verify work quality. Even if it looks neatly cut from the ground, aerial views can reveal areas left uncut. Conversely, grass that appears to remain may have little impact on equipment and be within a range that can be addressed at the next visit. If managers and workers confirm using images, it becomes easier to reduce excessive criticism and misunderstandings.

Also, by accumulating records, trends for each power plant become apparent. You can determine whether grass grows in the same place at the same time every year, whether it tends to grow only along drainage channels during periods of heavy rain, or whether vegetation tends to become dense on certain slopes. This information helps in deciding the timing of the next weed control and the frequency of patrols.

Things that cannot be understood from a single inspection can be revealed by continuing to record using the same criteria, which leads to improved management.

To stabilize management quality, it is also important to standardize how records are taken. Deciding on the imaging coverage, guideline imaging altitude, imaging direction, storage location, file naming, reviewer, and criteria for determining task completion makes it easier to manage using the same workflow even if the person in charge changes. If you incorporate drone surveys of solar power plants into weed control plans, it is important to decide not only on the imaging itself but also on how to record and how to use those records.

Point 5: Anticipate seasonal changes and connect them to the next plan

Weed management is not something that can be completed with a single weeding. Some weeds grow rapidly from spring to summer, some gain vigor during the rainy season, some set seed in autumn, and some persist through winter; vegetation changes vary by season. At solar power plants, the layout of generation equipment and the terrain cause differences in growth even within the same site. When planning weed control, it is important to anticipate not only the current condition of the vegetation but also which locations are likely to become problematic at what times.

Keeping drone survey records in chronological order makes it easier to grasp seasonal changes. For example, you can confirm trends such as areas that were inconspicuous in early spring suddenly growing in summer; certain parts of slopes becoming overgrown every year; vegetation along drainage channels tending to grow after rain; and the influence of plants outside fences gradually increasing. These are things that are hard to notice from a single inspection, but by lining up aerial images side by side, they become easier to identify as management weaknesses.

To feed into the next plan, it is important not to stop at reviewing the weed-control results, but to determine the timing and scope of the next inspection. Areas where vegetation grows quickly may require bringing forward the timing of the next patrol. Conversely, areas where growth is slow and the impact on equipment is minimal may be deprioritized compared with other priority areas. These judgments can be made based on on-site experience alone, but having records from drone surveys makes it easier to explain them to stakeholders.

When considering seasonal changes, also look at the environment around the power plant. Adjacent forests, agricultural fields, vacant lots, roadsides, and areas near rivers or waterways can be affected by vegetation encroaching from outside the site. When vegetation near the site boundary grows, it can get tangled in fences, obstruct inspections, or create shadows. Managing off-site vegetation requires coordination with stakeholders, but images from drone surveys make it easier to explain the situation.

Also, in seasonal planning, not only the frequency of weeding but also the work methods should be reviewed. If addressed while the grass is short, it can be light work, but once the grass grows tall the workload increases. In rainy seasons the ground can become muddy, making it difficult for vehicles and workers to move. In hot periods the burden on workers also increases, so adjusting work hours and ensuring rest areas is important. If you understand the work area from aerial imagery, it becomes easier to estimate the on-site workload.

To improve weed-control plans on an annual basis, it is important to establish a workflow of imaging, assessment, operations, recording, and review. Drone surveying plays the role of visualizing site conditions within this workflow. Rather than re-evaluating the site from scratch each time, using the previous records as the baseline for the next plan makes it easier to improve the accuracy and efficiency of maintenance and management.

Precautions when using drone surveying for weed control planning

When using drone surveying for a weed-control plan at a solar power plant, it is important not to assume that everything can be determined just by taking images. Aerial images are excellent for grasping the overall picture, but grass height, small irregularities of the ground surface, the condition of wiring, blockages in drainage channels, and details beneath the mounting racks can be difficult to judge from images alone. It is realistic to combine ground inspections as needed and to verify on site the locations that look suspicious in the images.

Safety management for filming is also important. Solar power plants contain transmission equipment, electrical equipment, fences, surrounding roads, adjacent land, workers, vehicles, and other elements. Before flight, check the flight area, takeoff and landing locations, surrounding obstacles, power lines and elevation differences, third-party access, weather, wind, and communication status. Completing necessary procedures, contacting stakeholders, and confirming site rules are also indispensable. Because the required checks and procedures vary depending on the aircraft’s weight, flight location, flight method, flight altitude, and the condition of surrounding facilities, it is important to confirm the latest laws, whether permits or approvals are required, no-fly zones, and site management rules before conducting operations.

Also, when imaging for a weed control plan, image clarity is important. If you want to check the distribution of weeds but the shooting altitude is too high, the subject is backlit, or the shadows are too strong, it becomes difficult to assess. If the shooting conditions vary greatly each time, comparisons with previous images also become difficult. Clarify the purpose of the imaging, and by differentiating uses—such as for overall assessment, for inspecting priority areas, and for post-operation confirmation—you increase the value of the records.

Attention to data management is also necessary. Simply storing captured images and survey results will make them difficult to use later. It is important to organize them so it is clear which power plant, which section, and when the records are from, and to link them with work records and inspection records. When multiple personnel are involved, standardizing storage locations, naming conventions, and verification procedures reduces confusion during handovers.

When deciding on weed control operations, consideration for the environment is also necessary. Excessive disturbance of the ground surface can cause soil erosion and muddy conditions. On slopes and around drainage channels, completely removing vegetation is not always optimal. Taking into account impacts on power generation equipment, inspectability, safety, drainage, and the surrounding environment, it is important to determine a management level suited to the site. Positioning drone surveying as a means to increase the information available for such decisions makes it easier to use.

Furthermore, be mindful of the scope of image sharing. Images of a solar power plant may show equipment layout, maintenance access routes, the surrounding environment, and adjacent land. If you share them with parties outside the project team or store them externally, you need to check the applicable handling rules. While they contain information useful for operation and maintenance, they are also management information about the plant and must be handled appropriately.

Summary

By leveraging drone surveying in weed-control planning for solar power plants, it becomes easier to organize the site-wide distribution of weeds, locations where weeds have a major impact on panels, work routes, hazardous spots, changes before and after work, and seasonal trends. Weeding is not finished by cutting everything clean once; it is an ongoing management task that must be continually reviewed to keep the plant operating stably. Using aerial records makes it possible to identify areas that are easily missed during ground patrols and to align understanding among stakeholders.

What's important is not to treat drone surveying as mere photography. By using the captured images to decide which areas to prioritize, which locations to manage intensively, the order in which workers should operate, what to check after work, and when to review next, the effectiveness of the weed control plan improves. Especially at large solar power plants, management that combines images and records is easier to explain and to hand over than relying solely on experience and intuition.

Instead of relying solely on drone surveys, it is important to combine them with on-the-ground inspections and stakeholder confirmations as needed. Grass height, details around equipment, blockages in drainage channels, and the condition of slopes are things that can only be determined by checking them in person. By establishing a workflow that captures the overall situation from the air and then verifies priority locations on the ground, you can improve the accuracy of weed-control planning.

In the maintenance and management of solar power plants, not only power generation but also safety, ease of inspection, drainage, and consideration for the surrounding environment are indispensable. Incorporating drone surveying into weed-control planning provides an opportunity to comprehensively review these elements. If you want to keep a clear record of site conditions and establish a system that informs future decisions, consider an operational approach that combines drone imagery, survey results, ground verification, and work records tailored to the conditions of each plant.