5 methods to determine the mowing area of a solar power plant using drone surveying

In the operation and maintenance of solar power plants, determining how far to set the mowing boundary affects power generation, safety, and workload. Simply walking the site to make that judgment can lead to overlooking the overall density of vegetation across the site, potential shading around panels, and the condition of slopes and drainage. Drone surveying, which allows you to view the site from above and map out the areas that need attention, is useful for this. This article explains five methods for determining the mowing range at a solar power plant using drone surveying, aimed at field personnel.

Table of Contents

• Risks of deciding the mowing area by intuition

• Method 1 Subdivide the overgrown area from an overall bird's-eye view

• Method 2: Prioritize determining the panel's area of influence

• Method 3 Use management aisles and workflow paths as the basis

• Method 4: Focus on slopes and the areas around drainage facilities

• Method 5: Reassess the mowing area through regular comparisons

• Tips for making mowing plans easier to operate using drone surveying

• Summary

Risks of Setting the Mowing Area Based on Intuition

Grass cutting at solar power plants is not merely a cosmetic task. If weeds grow, they can cause shading of the panels, obstruct inspection walkways, reduce visibility around fences, impair drainage, and increase the risk of wildlife intrusion. Especially in summer and during periods of heavy rain, vegetation height can change rapidly, and areas that had no problems at the previous inspection may require a wider scope of work by the next inspection.

Conventional mowing plans often rely heavily on the on-site personnel’s experience and visual inspections. Of course, local experience is important. However, solar power plants cover large sites, and there are many areas to check, such as panel rows, pathways, slopes, fences, drainage ditches, retention ponds, and around electrical equipment. If assessments are made based only on what can be seen from the ground, rear sections, the backs of panel rows, lower parts of slopes, and areas around drainage routes can be overlooked.

Also, if the mowing area is set too wide, it creates more work than necessary. Conversely, if the area is set too narrow, there is a risk of leaving uncut spots that could affect power generation and maintenance inspections. Because mowing is performed regularly, a single misjudgment can lead to persistent cost increases and variability in management quality.

An effective solution is drone surveying, which inspects solar power plants from above and captures the site's conditions as a surface. By using drone surveying, it becomes easier to record the overall vegetation conditions across the site, the positional relationship with panel rows, the status of access paths, and the condition of slopes and drainage facilities. Based on the captured images and the generated planar information, you can delineate the areas requiring grass cutting on the drawings, making it easy to use for pre-work meetings and for giving instructions to subcontractors.

When determining the scope of mowing, it's not enough to simply look for areas with a lot of grass. You should distinguish between areas that could affect power generation, areas needed for inspection or emergency response, areas that should be prioritized for equipment maintenance, and areas related to rainwater or sediment flow. Drone surveying preserves those decision-making materials from the same perspective, making it easier to carry over management standards when personnel change.

Method 1: Segment Overgrown Areas Using an Overall View

The first method is to photograph the entire solar power plant from above and divide the weed growth conditions by area. When deciding the mowing areas, inspecting the site on foot inevitably draws your attention to the conditions immediately around you. However, grass growth is not uniform across the site. Depending on sunlight exposure, drainage, soil quality, slope, boundaries with neighboring land, and the site formation conditions at the time of construction, you can distinguish places that are prone to vigorous growth from those that are comparatively stable.

Drone surveying allows you to obtain aerial images of the entire site and roughly identify areas where vegetation appears dense, areas where grass height seems tall, areas close to bare ground, and areas where access paths are maintained. You should avoid definitively determining grass height from images alone, but they can be used to narrow down locations that should be prioritized for on-site inspection. This is especially useful at large power plants, where walking every section at the same density to check is burdensome, so using overhead images to make an initial assessment is effective.

When delineating overgrown areas, it is important not only to consider whether there is more or less grass, but also to overlay the positional relationships with equipment. For example, even if the grass appears to be growing to a similar extent, the mowing priority differs between locations near the front of panels and areas along the site perimeter where equipment impact is low. Also, areas around electrical equipment such as power conditioners and combiner boxes, access routes that may need to be approached during emergencies, and fence entrances may be higher management priorities even if the grass height is low.

By dividing the site into multiple management sections based on aerial images, it becomes easier to develop a mowing plan. For example, categorizing areas as the power generation area where rows of panels are densely packed, along the perimeter fence, main access routes, slopes, around drainage facilities, and unused spaces makes work instructions clearer. For on-site workers, it becomes easier to communicate specific directions—rather than the vague instruction to mow the entire site—such as focusing on mowing the southern access route of the power generation area and the lower part of the slope.

When using images obtained from drone surveys, attention must also be paid to the timing of the photography. Images taken immediately after grass cutting alone can make it difficult to identify locations that are prone to regrowth. Conversely, looking only at images showing the grass at full growth tends to lead to decisions to cut unnecessarily large areas. If possible, keeping images that allow comparison of conditions before cutting, after cutting, and after a certain period has passed will make it easier to identify areas that are likely to regrow.

The advantage of this method is that it allows the scope of management to be shared visually. Even managers, clients, or subcontractors who have not visited the site can more easily understand the situation if aerial images are available. In grass cutting at solar power plants, differences in understanding of the work scope can lead to missed areas or excessive work. By creating an overall bird's-eye view using drone surveying, it becomes easier to align understanding among stakeholders.

Method 2 Prioritize determining the panel's influence range

When determining the mowing area, particular priority should be given to the area that can affect the panels. In solar power plants, weeds that grow up to the front face or the lower edge of panels can cast shadows depending on the time of day and season. The impact of shading changes with the height of the vegetation, the panels' tilt angle, the rack height, the spacing between rows, and the sun's altitude, so simply planning to cut the area immediately around the panels may be insufficient.

Using drone surveying makes it easier to confirm the positional relationship between panel rows and weeds from above. In particular, checking how weeds grow in front of panel rows, between rows, and along the outer perimeter provides clues to areas prone to shading. Even when only some rows can be observed from the ground, aerial views allow multiple rows to be compared at once. It becomes easier to identify which rows are more prone to weed growth and the directions from which the infestation is advancing.

When setting the panel area of influence, it is important to consider not only directly beneath the panels but also a forward clearance area. Even if the grass is short now, you need to anticipate that it will grow over the coming weeks. If mowing frequency is limited, it is practical to set a management area with some margin rather than deciding the range based only on the current grass height, taking into account how much it may grow before the next work.

Also, the ends of panel rows are places that are easily overlooked. The centers of the rows are more likely to be in workers’ sight and are relatively easy to mow, whereas row ends, corners, rows near fences, and rows adjacent to slopes can be difficult to work on and tend to have grass remaining. By checking drone survey images, variations between rows become clear, allowing you to identify the end sections and corners that should be prioritized for mowing.

When checking the extent of panel impact, you should not only look for the presence of grass but also check how the panel surface appears. If parts of panels are hard to see in aerial images because of grass or shadows, a detailed on-site inspection is necessary. However, it is important not to determine the impact on power generation from images alone; make judgments in combination with on-site checks and trends in generation data. Drone surveys are practical when used as a means to increase the information available for decision-making and to narrow down the areas that need to be checked.

Clearly defining the panel impact area clarifies the priority of grass-cutting tasks. Even if it’s difficult to mow all areas at the same time, it becomes easier to plan a workflow where you address the areas most likely to affect power generation first, and then handle the perimeter and unused spaces. This prioritization is important when using drone surveys of solar power plants to inform grass-cutting plans.

Method 3: Base it on maintenance aisles and workflow paths

When considering the mowing area for a solar power plant, not only the areas around the panels but also the maintenance paths and work routes are important criteria. To carry out inspections, repairs, emergency responses, and the weeding work itself safely, it is necessary to keep clear routes for people and vehicles. If grass grows too tall, step hazards underfoot, drainage channels, cable protection areas, and surface irregularities become difficult to see, increasing the risk of trips and contact.

With drone surveying, you can get an overhead view to check areas where walkways are overgrown with grass, where vehicles have difficulty entering, and where the passage width between panel rows appears narrow. When walking on the ground, you may be able to check the path immediately in front of you, but it can be difficult to grasp whether circulation routes across the entire site are connected. Aerial images make it easier to confirm whether the routes from the entrance to major facilities, the perimeter inspection route, and the movement routes between panel rows are continuous.

When deciding mowing areas based on access paths, first identify the routes that must be kept clear. These include the route from the power plant entrance to electrical equipment, the routes into each block, the routes for inspecting the perimeter fence, and the routes workers would use to move during emergencies. By overlaying these routes on aerial images or site plans, it becomes clear which areas should be prioritized for mowing.

Particularly important are the access routes for mowing operations. If workers cannot move safely, it becomes difficult to bring equipment to the necessary locations. Rather than waiting until the grass has grown, securing the routes that will be used during work in advance increases the overall efficiency of mowing. By using drone surveying to check the condition of those routes beforehand, it becomes easier to plan which route to enter from and in what order to mow before work begins.

Also, the mowing area for access paths is not simply about securing width. If there are drainage channels, cables, foundations, or legs of mounting structures along the path, it is important to keep them visible. If grass hides the location of equipment, it can lead to missed checks during inspections or accidental contact during work. Even when aerial imagery cannot reveal all the details, you can identify areas where grass is dense and organize them as on-site verification points.

Defining mowing areas based on maintenance access paths and work routes is effective for stabilizing the quality of maintenance. Even in locations with little direct impact on power generation, if the routes required for inspections are not secured, problems may be discovered late as a result. In managing solar power plants, it is important to separate the area that protects power generation equipment from the area where people can move safely. Drone surveying is a means to visualize both.

Method 4: Prioritize slopes and the areas around drainage facilities

In solar power plants, mowing around slopes and drainage facilities is also important. It may seem lower priority compared with areas around the panels, but in fact these locations affect rainwater flow, sediment accumulation, erosion, and drainage problems, so they require many maintenance precautions. Even if overgrown grass appears to be a minor issue, it can hide clogged drains or changes in watercourses.

Using drone surveying, you can check from above variations in slope vegetation, occurrences of bare ground, channels where rainwater is likely to flow, and the growth of vegetation around drainage facilities. This is especially important for solar power plants installed on developed land, where it is essential to continuously monitor the condition of slopes and embankments. Upper parts of slopes and lower parts of embankments that are hard to see from the ground become easier to grasp as a whole with aerial images.

When mowing around slopes, cutting all the vegetation as short as possible is not always the best approach. In some places, the vegetation helps protect the soil surface. Cutting back more than necessary can make the topsoil more prone to being washed away by rain. Therefore, it is important to use drone surveys to inspect the entire slope and carefully determine the extent and degree of mowing, focusing on areas where it would interfere with equipment inspections or drainage checks, areas likely to become wooded, and areas that could affect fences or drainage routes.

Around drainage facilities, prioritize inspecting locations related to the flow of rainwater such as catch basins, side ditches, cross drains, and areas around detention ponds. When vegetation becomes overgrown, it becomes difficult to see the water flow and to assess the accumulation of sediment and fallen leaves. By confirming the positions of drainage routes with drone surveying and extracting the areas covered by vegetation, it becomes easier to plan the scope of cleaning and inspection to be carried out at the same time as mowing.

The area along the perimeter fence is also one that should be inspected together with the slopes and drainage facilities. When vegetation becomes dense beneath the fence, visibility of the boundary is reduced, making it easy to overlook signs of animal intrusion or damaged sections. It also becomes difficult to confirm vegetation encroaching from neighboring properties or spreading from the site onto adjacent land. By checking the entire perimeter with aerial images, you can identify where vegetation is thick and which corners are hard to see.

Focusing on slopes and areas around drainage facilities is an approach that treats mowing not merely as aesthetic upkeep but as part of civil-engineering maintenance. At solar power plants, maintaining not only the generation equipment but also the site’s stability and drainage functions is important for long-term operation. Using drone surveys to assess conditions from a wide perspective and restricting mowing to the necessary areas clarifies the purpose of the work.

Method 5 Reevaluate Mowing Areas Through Periodic Comparisons

The fifth method is not to treat drone surveying as a one-time task, but to carry it out regularly, compare the results, and review the mowing areas. Weed management at solar power plants varies with the seasons, weather, past mowing methods, and soil conditions. An area that had no problems one year may become heavily overgrown the next. Conversely, even if you mow the same area every time, in practice only part of it may need mowing.

By conducting drone surveys regularly and comparing them with past images, you can identify areas prone to regrowth, spots where mowing is often missed, and places where vegetation quickly returns after mowing. This information helps determine the mowing areas for future operations. A one-off on-site inspection only reveals the condition at that moment, but comparing images over time reveals management trends.

When making comparisons, it is preferable to capture images under as similar conditions as possible. If shooting altitude, coverage, timing, weather, or time of day differ greatly, the appearance of the images will change, making it difficult to judge increases or decreases in grass. It is not necessary to make the conditions exactly the same, but if you establish rules for shooting to make comparisons easier, it will be easier to use the images for ongoing management.

By performing periodic comparisons, mowing areas can be optimized step by step. In the first year, set a somewhat wider area on the safe side, then narrow down the locations that actually require management by comparing subsequent images. Conversely, if areas left uncut have affected power generation or inspections, add them as priority areas from the next cycle. In this way, by accumulating drone survey records, you can move toward a mowing plan that does not rely solely on the judgement of the person in charge.

Regular comparisons are also useful for managing subcontractors. If you keep before-and-after photos of mowing, it becomes easier to check whether the work area was as planned, whether any patches were missed, and whether priority areas were addressed. Areas that are hard to convey by verbal or written instructions alone can be clarified by showing them on images, reducing misunderstandings. Because they can also be used as post-work verification documents, there are benefits for both the client and the contractor.

Regular comparisons also lead to a review of the annual plan. If you can identify periods of rapid growth, periods when work tends to concentrate, and the areas that should be cleared before inspections, it becomes easier to adjust mowing schedules. In photovoltaic power plant management, responding proactively before grass grows — rather than rushing to deal with it after it has grown — leads to more stable operations. Drone surveying can be used as the record that supports those decisions.

Key points for making mowing plans easier to implement with drone surveying

When using drone surveying to determine the grass-cutting areas of a solar power plant, it is important not to stop at just shooting images. By converting the acquired images and survey data into instruction materials that can be used on site, practical effectiveness is more easily achieved. Aerial images can show the situation, but workers may not be able to act on them at the site without confusion. It is important to organize management zones, priority areas, and points of caution, and prepare them in a form that can be shared before work begins.

First, it is easier to manage mowing areas if you divide them into categories such as full treatment, focused treatment, and monitoring. Areas to be mowed comprehensively include the fronts of panels, main walkways, and areas around electrical equipment. Areas to be checked with priority include slopes, drainage facilities, perimeter fences, and sections where grass tends to grow tall. Monitoring areas are places that currently pose little problem but where you want to check growth at the next and subsequent visits. Dividing them in this way makes work priorities clear.

Next, it is indispensable to combine it with on-site inspections. Drone surveying excels at providing an overall view, but detailed assessments of grass height, ground conditions underfoot, contact with equipment, and blockages inside drainage ditches need to be verified on-site. Extracting areas of concern from aerial images and then focusing on those areas during on-site checks improves the efficiency of inspection work. The larger the power plant, the greater the benefit of narrowing down inspection points in advance.

Additionally, when determining the mowing area, safety considerations are also necessary. On slopes, in muddy ground, at level changes, in areas congested with equipment, and around electrical installations, you need to carefully reconsider the mowing methods themselves. Mapping the locations of hazardous spots with drone surveys can be used to provide warnings before work begins. This is especially effective at sites where subcontracted workers are entering for the first time, as sharing aerial images to highlight hazards and areas where entry requires caution is useful.

Keeping records after work is also important. Recording the condition before mowing, the work area, and the condition after work will be useful for planning next time. If records are kept each time, you can consider which locations repeatedly cause problems and which areas can have their work frequency reduced. Because maintenance and management of solar power plants spans the long term, an attitude of making improvements based on records rather than one-off decisions is required.

Incorporating drone surveying into grass-cutting plans makes it possible to review the entire power plant from the same perspective and makes it easier to explain the work areas. Having materials that can be shared among administrators, on-site personnel, and contractors reduces misunderstandings and clarifies the purpose of the grass cutting. Drone surveying of solar power plants is a tool that can be used not only during site development and inspections but also for routine maintenance.

Summary

To determine the mowing scope for a solar power plant, you need to do more than simply cut where the grass has grown; you must comprehensively consider the impact on power generation, inspection routes, safety, drainage function, and perimeter management. By using drone surveying, you can get an overhead view of the entire site, making it easier to identify dense vegetation areas, panel impact zones, maintenance and management paths, and slopes and areas around drainage facilities.

As five methods for determining mowing areas, you can: divide the areas of dense growth by taking an overall, bird’s-eye view; prioritize the zones affected by panels; use access paths and work-flow lines as criteria; focus on slopes and areas around drainage facilities; and review the area through periodic comparisons. By combining these approaches, you can reduce over- or under-coverage of work areas and make maintenance easier to match the condition of each site.

What is particularly important is making the results of drone surveys usable for on-site work. Rather than simply looking at aerial images and stopping there, organize management zones and priority areas, and accumulate them as before-and-after work records so they can inform future mowing plans. By incorporating decisions based on imagery and survey data in addition to the staff’s experience, it becomes easier to stabilize the management quality of solar power plants.

Because grass cutting is a recurring maintenance task, there is value in systematizing how its scope is determined. To efficiently inspect large sites and appropriately manage the areas that need attention, combining on-site checks with drone surveying is effective. If you want to make the mowing areas of a solar power plant easier to understand, explain, and manage on an ongoing basis, consider incorporating drone surveying into your maintenance operations.