5 Steps to Organize Cable Routing at a Solar Power Plant Using Drone Surveying

In solar power plants, many cables that connect panels, junction boxes, collection equipment, power receiving and transforming equipment, and monitoring equipment are laid out on the site. Even if they are organized on drawings when newly installed, after the start of operation, repairs, expansions, disaster response, mowing, fence repairs, changes to site grading and other factors can create discrepancies between on-site conditions and the documentation. Especially in outdoor solar power plants, cable racks, buried conduits, exposed wiring, routes under mounting structures, and sections crossing slopes or drainage channels tend to become complex, and it can take time to grasp the overall picture by on-site inspection alone.

Aerial records from drone surveying are useful for that. Drone surveying is characterized by how it makes it easy to overview and organize the relationships of the site-wide layout, topography, pathways, equipment locations, drainage routes, fences, slopes, and cable routes. However, simply photographing with a drone does not automatically complete cable management. If you do not decide in advance how much to record, what to confirm on site, how to reconcile with drawings and registers, and at what level of granularity to retain updates, the results can become difficult to use later.

This article explains, for practitioners searching for information on "solar power plant drone surveying", how to organize cable routes by dividing the process into five steps. To make it useful for maintenance inspections, pre-renovation surveys, post-disaster checks, post-construction document organization, and preparing explanatory materials for clients, it summarizes the key on-site verification points.

Table of Contents

• Define the scope and purpose of the cable routes to be organized

• Confirm existing documentation and on-site conditions before drone surveying.

• Visualize the cable route using aerial photographs and on-site inspections

• Organize routes in conjunction with equipment locations and hazard points

• Manage cable routes as easily updatable documentation.

• Summary

Determine the scope and purpose of the cable routes to be organized

When organizing cable routes at a solar power plant using drone surveying, the first thing to decide is the scope— which cables you will organize and for what purpose. A solar power plant contains not only cables for collecting the generated power but also wiring with different purposes such as monitoring, communications, control systems, grounding-related work, and auxiliary inter-equipment wiring. If you try to organize everything with the same level of accuracy and the same level of detail, the burden of on-site surveys increases and, at the same time, information that is frequently used in practice can become buried.

For example, if you are organizing information for maintenance inspections, it is important that inspectors can verify things on site without getting lost. In that case, materials that show the positional relationships with junction boxes, power collection equipment, panels, rows of mounting frames, access routes, and fence entrances/exits are useful. If you are considering renovation work, you need to grasp the relationships between the locations of existing cables, crossing points, areas where underground burial is expected, and locations where heavy machinery or work vehicles may pass. For post-disaster checks, it is important to overlay the cable routes with evidence of inundation, sediment inflow, slope failures, clogged drainage channels, and scouring around mounting frames.

Thus, even when organizing the same cable routes, the areas you need to focus on change depending on the purpose. Before a drone survey, it is important to clarify who will use the deliverables. Whether they will be used by on-site personnel, a maintenance company, for explaining to the client, or for discussions with the contractor determines the required forms of presentation. For materials used on-site, clarity of positional relationships is more important than detailed technical terminology. For discussion materials, comparisons before and after changes and the rationale for risk locations are necessary. For record materials, you should clearly state the date of capture, the scope of verification, unverified portions, and what can and cannot be determined.

Also, even when we talk about cable routes, there are things that can be seen directly from above and things that cannot. Cable racks, protective conduits exposed on the ground, some routes under mounting racks, and protective members crossing walkways can often be located from photos if shooting conditions are good. On the other hand, buried conduits, parts hidden by grass, and areas obscured by the shadows of racks or panels cannot be determined from drone images alone. Therefore, if you consider drone surveying both as a means to record what is visible and as a way to create reference maps to supplement unseen parts through on-site inspection and existing documentation, you are less likely to misuse it.

When setting the scope, there are two approaches: organizing the entire site at once, or organizing it incrementally starting with the highest-priority areas. In large power plants, attempting to document every cable route in detail in a single survey can consume a lot of time for photographing, verification, drafting, and review. Prioritizing areas such as around substation and transformer equipment, zones where junction boxes are concentrated, areas near drainage channels and slopes, areas with vehicle traffic, and areas that have experienced past faults will make the results more practical for operational use. It is crucial not to leave areas outside the survey scope ambiguous. By dividing and recording "confirmed areas," "estimated areas," and "unconfirmed areas" in the documentation, you can help prevent misunderstandings later.

Verify existing documentation and site conditions before a drone survey

When organizing cable routes, preparation before flying a drone can affect the quality of the results. If you have existing as-built drawings, site plans, single-line diagrams, wiring diagrams, equipment registers, inspection records, past repair histories, or records of accidents and malfunctions, it is important to check them in advance. In particular, confirming whether the cable routes on the drawings match the actual equipment layout on site, whether any equipment has been added later, whether any wiring that appears to be temporary remains, and whether equipment names and numbers correspond to on-site labeling will reduce oversights during on-site verification.

In solar power plants, even if the as-built drawings remain, some wiring may have been changed after operations began. For example, additions of monitoring equipment, changes to communication routes, replacement of switchboards, addition of cable protection materials, and temporary measures taken during disaster recovery. If these changes are not reflected on the drawings, differences will appear between the current conditions obtained by drone surveys and the existing documentation. Rather than treating these differences as mere discrepancies, it is important to treat them as key verification points for understanding the latest on-site conditions.

In the preparation phase, consider at what height, over what area, and at what time of day to capture images with the drone. If you want to see cable routes, simply capturing the entire site may not be sufficient. Shadows from panels, mounting racks, dense vegetation, slope shading, or equipment box shadows can make the ground surface and protective conduits hard to see. During times when shadows are long, identifying cable racks and conduits can be difficult. Conversely, under certain sunlight conditions, surface irregularities may become easier to discern. If the objective is to understand cable routes, plan the shoot with conditions that make the ground surface and the areas around equipment easy to see.

The condition of the grass is also important. At solar power plants, when grass grows under the mounting racks or along the walkways, cable protection conduits and above-ground exposed sections become difficult to see. If images are taken before mowing, you can understand the broad terrain and equipment layout, but they can be difficult to use for checking the detailed cable routes. Conversely, immediately after mowing the ground surface is easier to see, but if cut grass is temporarily piled up, other oversights may occur. By recording the on-site conditions at the time of shooting, people who review the images later can more easily determine the reason something is not visible.

Safety checks are also indispensable. Solar power plants contain elements related to flight and access such as electrical equipment, overhead lines, fences, monitoring equipment, workers, vehicles, and boundaries with adjacent properties. While drone surveying can efficiently record from above, pre-flight safety checks, notifying stakeholders, managing flight areas, and consideration for third parties and equipment are necessary. In particular, near substations and transformer equipment or other high-voltage installations, it is important to decide not to perform close-proximity filming. Even when conducting surveys to organize cable routes, the premise is that the safe operation of equipment must not be impeded.

When reviewing existing materials, it is useful to establish reference markers for on-site matching. For example, organize in advance junction box numbers, power conditioner sections, racking rows, aisle names, fence entrances, drainage channels, access roads, etc., and make them identifiable on drone imagery. This clarifies which area is being referred to during post-flight image organization. Because cable routes are long and continuous, prepare to clearly record not only the start and end points but also intermediate bends, crossings, branches, convergences, and protection points.

Visualize cable routes with aerial photographs and on-site verification

A major advantage of drone surveying is that it allows you to view an entire solar power plant from above and easily organize the positional relationships between pieces of equipment into a single current-condition document. When visualizing cable routes, it is practical to first create an aerial photograph that serves as a baseline for the entire site and then overlay equipment locations and route information on top of it. This makes it easier to identify long routes and relationships that span multiple pieces of equipment, which can be difficult to grasp by walking the site on foot alone.

However, you should avoid determining cable routes based only on aerial photographs. Linear features shown in photos are not necessarily cables or protective conduits. Traces of drainage, mowing marks, ruts from pathways, shadows, temporarily stored materials, or differences in surface color can appear to be cable routes. Conversely, important cables may actually be present but not visible in photos due to being buried underground, under racks, or obscured by grass or shadows. Therefore, information visible in drone imagery should be treated as a starting point and substantiated through on-site inspections and existing documentation.

In the first stage of visualization, we make sure to secure equipment that can be identified on site. We verify connection boxes, collection equipment, power receiving and transformer (substation) equipment, monitoring panels, communication equipment, main racking rows, access roads, drainage channels, fence entrances and exits, etc., on aerial photographs and match them to their names and numbers. Once equipment locations are organized, it becomes easier to trace the start and end points of cable routes. In particular, routes from multiple connection boxes to the collection equipment and the plant’s trunk routes can be difficult to understand unless viewed together with the equipment locations.

Next, extract from the photographs the cable racks, protective conduits, above-ground exposed sections, pathway crossings, and equipment entry points that can be identified. At this stage, rather than simply drawing lines, organizing the basis for each confirmation separately will make the information easier to use later. If parts that are clearly visible in the photos, parts confirmed by on-site visual inspection, parts estimated from existing drawings, and parts that could not be confirmed due to vegetation or structures are mixed together using the same wording, readers of the documents may misunderstand the actual level of certainty. By recording confirmed areas and estimated areas separately, you can avoid overconfidence when planning renovation work or excavation.

During on-site checks, it is effective to walk the site carrying aerial photographs. At the site, confirm the direction of wiring and protective conduits visible from the ground and cross-reference them with positions on the photograph. In areas where you can go under the racking, check which direction the cables are being routed, whether there are any abnormalities in the condition of protective materials, whether any fastenings have come loose, whether cables are in contact with the ground, and whether they are covered by grass or soil and debris. Even if you are not conducting a full detailed inspection, recording items of concern during the route-organization stage will make it easier to connect to subsequent inspection planning.

Crossing points where pathways intersect should be organized especially clearly. In areas where vehicles or workers pass, protective conduits and cable protection materials can be easily damaged. Overlaying aerial photographs with the pathways and cable routes makes it easier to identify where they cross. On site, check the protection status of the crossing sections, level differences, subsidence, ruts, accumulation of soil and debris, and the occurrence of puddles. At solar power plants, daily inspection and mowing routes may overlap with cable routes, so organizing these as locations that require attention during work will be useful in practice.

Visualized documents can become harder to read if they are drawn with too much detail. Cable routes at solar power plants may include multiple routes running in the same direction. If you cram everything onto a single diagram, equipment names, route lines, points of caution, and on-site photo numbers can overlap, making it difficult for field personnel to use. Therefore, in the overall diagram indicate the relationships between main routes and zones, and supplement areas that need detail with enlarged zone maps or organized photos. The important thing is that someone who looks at the documents can find the same location on site.

Organize routes together with equipment locations and risk locations

Cable routes become more valuable when organized together with equipment locations and risk points than when organized on their own. At solar power plants, cables are closely related to site terrain, drainage, access paths, slopes, racking layout, fences, and equipment foundations. If cable routes are recorded only as lines, it can be difficult to understand why a location is a point of concern. Because drone surveying can simultaneously record these surrounding conditions, the data can more easily be developed into documentation useful for maintenance and retrofits.

First, check the relationship with drainage paths. In a solar power plant, rainwater on the site flows into access paths, slope faces, side ditches, catch basins, and drainage channels. Where cables and protective conduits cross water flows, run near drainage channels, or are located in low positions, attention is needed for sediment accumulation, scour, flooding, and the flotation or exposure of protective materials. Using aerial photographs and topographic information makes it easier to understand the relationship between areas where water tends to collect and cable routes. If inspection records after past heavy rains are available, overlaying and organizing that information makes it easier to prioritize areas that require attention.

Next, the relationship with slopes and development boundaries. Solar power plants are sometimes installed on sloped or developed land, and if cable routes run near slopes they can be affected by sediment inflow or changes to the ground surface. If drone surveys record the position of slopes, drainage flow, spots suspected of deformation, vegetation changes, and ground surface steps, it becomes easier to explain how close the cable route is. However, it is important not to determine safety solely from changes visible in photos; where necessary, follow up with ground inspections and professional investigations.

Don’t overlook the relationship with vehicle traffic lines. When maintenance vehicles, mowing machines, material delivery vehicles, or inspectors’ walking routes are close to cable routes, the risk of damage during routine operations can increase. In particular, at pathway crossings, temporary access roads, work areas in front of equipment, and near fence entrances and exits, it is necessary to check the condition of cable protection. Overlaying vehicle traffic lines on an overall map from drone surveying makes it easier to raise awareness before work and to explain the situation to subcontractors. It can also be used as a document to share “where it is okay to pass” and “where extra caution is needed” during on-site work.

When considering equipment upgrades or additions, it is important to check for interference between existing cable routes and the new work areas. Confirm that locations where new equipment foundations will be installed, temporary staging areas, planned excavation zones, the swing radius of heavy machinery, and locations for laying temporary cables are not in close proximity to existing cables. If you have an as‑is map created from drone surveying, site personnel can review the same drawings together, making it easier to reduce misunderstandings. Aerial photos also make it easier to explain site constraints that are difficult to convey with drawings alone, such as narrow spaces, bends in access routes, the distance to supports, and the positional relationship with drainage channels.

When organizing risk locations, instead of simply writing "danger," record specifically what could become a problem. For example, trampling or potential vehicle contact when crossing a passage, burial by accumulated sediment, flooding due to poor drainage, exposure caused by slope deformation, contact during mowing operations, interference from excavation during equipment renewal, and so on. Writing causes and conditions concretely makes it easier to link to consideration of countermeasures. Even if you cannot decide on countermeasures immediately, leaving them in management records as locations that need confirmation will make them less likely to be overlooked during the next inspection or pre-construction check.

Also, when organizing cable routes, it is important to link photo numbers and confirmation dates. If drone images, ground photos, notes, and the revision history of drawings are scattered, the basis for decisions will become unclear when reviewed later. By correlating positions on aerial photos with the shooting locations of ground photos and recording which locations were checked from which angles, explanations among stakeholders become smoother. Especially when reporting to clients or managers, materials that show the scope of verification and the evidence supporting it are more convincing than simply writing "site checked."

Manage cable routes as easily updatable documentation

The purpose of organizing cable routes with drone surveying is not just to create a neat set of documents once. Solar power plants have long operating periods, during which inspections, repairs, upgrades, disaster response, equipment additions, mowing, and site surface repairs occur. Each time, the on-site conditions may change little by little. Therefore, cable route documentation should not be a one-time deliverable but should be managed in a way that makes updates easy.

To make documentation easier to update, you should first separate the information into hierarchical layers. In the overall diagram, organize the equipment layout for the entire site, major cable routes, primary walkways, entrances and exits, drainage channels, and so on. In area-specific diagrams, organize the details you want to verify on site, such as around junction boxes, around collection equipment, sections where walkways cross, and areas adjacent to slopes. In the photo ledger, record ground conditions that are difficult to see in drone images and close-up views of points of concern. By dividing information in this way, you can avoid redoing everything when updating and make it easier to revise only the necessary parts.

It is advisable to clearly state the creation date, photo date, verifier, scope of verification, existing materials used, and unverified areas in the documentation. In particular, cable routes may include estimates. If you estimate the routes of underground installations or areas that were obscured by vegetation based on existing drawings or the relative positions of equipment, you must record that fact. Treating estimated information as if it were confirmed information can lead to incorrect decisions during future excavations or renovations. To improve the reliability of the documentation, it is important not to force conclusions about parts that are unknown.

Managing update histories is also important. For example, when a cable protection conduit was repaired in a certain area, protective material was added at a corridor crossing, a route was changed due to equipment upgrades, or part was partially restored after a disaster, it is necessary to record when, where, and what changed. If drone surveys are conducted regularly, comparing past images with new ones makes it easier to grasp changes in the ground surface and the conditions around equipment. Creating a mechanism to reflect changes in documentation makes it easier to maintain the latest on-site conditions.

When considering on-site use, clarity in documentation is essential. Overusing technical symbols and fine lines makes documents difficult for inspectors and contractors to use in the field. In particular, at solar power plants, documents are often viewed outdoors, whether printed on paper or checked on mobile devices. Clarifying the relationships between the overall plan, area maps, and photo log, and aligning equipment names and numbers with on-site labels, makes the documents practical for field work. If the names on on-site signs or equipment labels differ from those on the drawings, it is also necessary to decide which to use as the reference.

Consider how to share information with stakeholders as well. If the power plant operator, maintenance company, construction company, project owner, and designers are each looking at different documents, their understanding of cable routes can diverge. Using current site maps created by drone surveys as a common reference makes it easier to align the starting point for discussions. However, the materials to be shared may include information about electrical equipment and other critical facility-management information. It is desirable to decide in advance the scope of sharing, editing permissions, storage methods, and the scope of information for external submission.

Linking inspection results and defect records to the cable route increases the value of management documents. For example, if you associate the cable route diagram with areas that previously experienced communication failures, areas where leakage investigations were conducted, locations where protective conduits were repaired, and spots that require caution during mowing, it will make clear which places should be checked at the next inspection. Operated not as a mere drawing but as a record that accumulates field history, it will aid long-term maintenance management.

Finally, when creating materials that are easy to update, it’s important not to aim for a perfect single sheet. It can be difficult to fully grasp the cable routes of a large solar power plant at once. For the first version, organizing the main routes and points of concern and adding details during subsequent inspections or construction can be sufficiently effective in practice. What matters is keeping track of which information has been verified, which has not, and what should be checked next. Drone surveying can be used as the foundation for that ongoing updating.

Summary

For organizing cable routes at solar power plants, drone surveying is a useful method for capturing the overall picture and clearly recording relationships with equipment and terrain. Simply checking on foot from the ground can make it difficult to understand long routes or relationships that span multiple facilities. When used as a reference, aerial photos of current conditions make it easier to organize positional relationships with junction boxes, collection equipment, power receiving and substation equipment, access paths, drainage channels, slopes, fences, and so on.

However, it is not possible to determine the entire cable route using only drone images. Buried underground sections, parts hidden by grass or shadows, areas difficult to see under mounting racks, and locations where the drawings differ from the site must be supplemented with existing records and on-site verification. In practice, it is important to manage separately the visible parts, the parts confirmed on site, the parts inferred from existing records, and the unconfirmed parts. Clarifying this classification reduces misunderstandings during renovation works, inspection planning, post-disaster checks, and explanations to the client.

When organizing cable routes, first define the objectives and scope, review existing documents and site conditions, and visualize the situation by combining drone surveys with on-site inspections. Then, by overlaying drainage, slopes, vehicle movement routes, equipment replacement areas, past failure locations, and so on, you can create not just simple route maps but current-condition documents usable for maintenance management. Additionally, if you record the photo date, inspection scope, update history, photo numbers, and unconfirmed areas, it will be easier to update the documentation over long-term operations.

Cables at solar power plants are usually inconspicuous, but they are an important element that supports the stable operation of power generation equipment. If their routes remain unclear, the burden of verification increases for every inspection, repair, grass cutting, disaster response, and renovation work, and misunderstandings among stakeholders are more likely to occur. By using drone surveying to organize an overall view of the site and supplementing it with on-the-ground checks where necessary, it becomes easier to create management documents that are tailored to the field.

When organizing cable routes, it's more important to gradually accumulate information that can be used on-site than to try to get everything perfect at once. Start by identifying the main equipment and primary routes, clarifying locations that need attention, and establishing a process to update information during future inspections or renovations to increase the practicality of the documentation. When using drone surveys at a solar power plant, separate areas that are visible from those that are not, and manage existing records, aerial photos, ground checks, and revision histories together.