Solar Construction DX Frontline: Solving Labor Shortages with Smartphone RTK and AR

As the construction boom for solar power installations continues, labor shortages have become a major challenge on site. Solar construction sites, which install countless solar panels over vast areas of land, require a wide range of tasks including surveying, pile driving, and equipment installation checks. Traditionally, it was normal to deploy multiple personnel including experienced technicians, but recent shortages of young workers and aging of skilled technicians have made it difficult to maintain conventional methods. To complete projects with limited personnel, new approaches that dramatically boost productivity are indispensable.

One trump card attracting attention is the promotion of DX (digital transformation) on construction sites. In particular, “smartphone construction DX,” which combines smartphones with cutting-edge technologies, is enabling environments where precise work can be performed efficiently by a single person even on large-scale solar construction sites. This article explains the concrete effects and key points of innovations brought to the field by smartphone-based RTK surveying and AR technology. We introduce the frontline of solar construction DX that resolves labor shortages while achieving both improved construction accuracy and reduced work errors.

Labor shortages and challenges facing solar construction sites

Buoyed by the tailwind of renewable energy, solar power plant construction projects are increasing throughout Japan. Large-scale solar construction involves enormous workflows—surveying for installing thousands of panels, earthworks, pile driving, racking assembly, wiring work, and more. Many sites are also located in rural or mountainous areas, making the shortage of skilled workers and the burden of working in harsh environments a serious issue. Measuring numerous survey points and accurately laying out positions across expansive sites would normally require many people, but when staffing is hard to secure, the burden on each worker increases, raising the risk of schedule delays and quality degradation.

Analog-centered construction management methods have also exacerbated the labor shortage problem. For example, surveying traditionally used specialized equipment such as total stations, requiring teams of a surveyor and assistants to measure the site over several days. Marking pile-driving positions often relied on manual work guided by paper plans and tape measures, driving wooden stakes one by one based on experience and intuition. These methods are prone to human error, causing measurement mistakes and marking offsets that lead to assembly defects or rework in later stages. There is a limit to managing large areas with few personnel, and a fundamental reexamination of conventional methods is required.

DX paves the way to labor savings

A promising solution to these challenges is the construction industry's DX (digital transformation). DX is not merely digitizing tasks but an effort to transform business processes themselves through the use of data and IT technologies. On solar construction sites, DX promotion is accelerating moves to achieve both labor and effort reduction and advanced work accuracy.

As exemplified by the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative, the government is promoting the introduction of ICT technologies to construction sites, and practices such as 3D surveying, remote supervision, and real-time information sharing are spreading. Solar power plant construction sites are no exception, and there is a need to move away from manpower-heavy approaches and ensure efficiency and quality through digital tool-driven visualization and automation. DX not only compensates for labor shortages but also contributes to improved site safety and workstyle reform, so its importance will only grow.

Smartphone RTK surveying: high-precision layout by a single person

One concrete DX solution is smartphone RTK surveying. RTK (Real Time Kinematic) is a technology that dramatically improves positioning accuracy by correcting satellite positioning errors such as GPS in real time. Normally, a smartphone’s GPS can have errors of several meters (several ft), but using RTK can reduce that to within a few centimeters (within a few in). Recently, compact RTK-GNSS receivers that can connect to smartphones have appeared, and this combination turns a handheld smartphone into a high-precision surveying instrument.

Traditionally, surveying required carrying heavy tripods and expensive equipment and working in pairs—a surveyor and an assistant—over multiple days. With smartphone RTK surveying, a single worker can walk the site and collect point coordinates one after another. By tapping a button on a surveying app, the latitude, longitude, and elevation of a specified point can be recorded instantly, and the data are automatically saved to the cloud. There is no need to take handwritten notes in a field book or manually enter data back in the office. Because the entire process from measuring reference points to confirming coordinates of each pile position can be completed by one person, tasks that used to take several days for establishing reference points can be dramatically shortened. Even on large sites, if field staff each carry one smartphone surveying device per person, parallel work can finish topographic surveys and pre-piling position checks at several times the traditional speed.

Smartphone app interfaces are intuitive and easy to understand, making them accessible even to young staff with limited specialized knowledge. Compared to learning to operate complex surveying instruments, the lower barrier of intuitive smartphone operation helps raise on-site capability. Digital records also dissolve the personalization of surveying skills (reliance on specific veterans), enabling the whole team to share data and ensure quality. Smartphone RTK, which allows one person to perform accurate and efficient surveying, is a powerful ally for sites struggling with labor shortages.

Improved construction accuracy and error reduction with AR technology

Another revolutionary tool in on-site DX is AR (augmented reality) technology. AR, which overlays design data onto the real-world view via a smartphone or tablet camera, has great power in construction accuracy control. For example, projecting a panel layout or racking installation positions onto the site with AR makes virtual panel rows and pile positions visible on bare ground. When AR is combined with high-precision positioning, the overlay does not drift even after walking several meters (several ft), allowing the design and the actual site positional relationship to be checked in perfect alignment at all times.

This real-time verification can help prevent construction errors. At the foundation stage, simply holding up a smartphone to display virtual piles on the ground enables immediate checking of whether the actually driven piles match the design. Tasks that used to require tape measures and levels for manual checking can be intuitively recognized on screen with AR, reducing human error. Moreover, when clients or designers inspect a site, overlaying a 3D model of the completed facility on the smartphone screen helps everyone share the finished-image easily. This prevents recognition mistakes due to spatial perception mismatches and smooths consensus building.

AR also strongly supports single-person layout tasks. Using the navigation function on a smartphone, workers are guided to the direction and distance of coordinates specified in the design drawings. As the worker approaches the target point, a virtual marker indicating “place the pile here” appears on the camera view. Simply following this guidance allows one person to install piles at accurate positions even on expansive sites. Since accuracy can be maintained without intermediate marking steps, AR contributes significantly to labor savings and zero-error construction.

Progress management and quality assurance using point cloud data

Combining smartphones, RTK, and AR has made it easier to utilize point cloud data (3D scan data) on site. Point cloud data are collections of countless points acquired by LiDAR (light-based ranging) or photogrammetry that express the site’s terrain and structures in three dimensions in detail. Traditionally, 3D as-built surveying required special methods such as laser scanners or drone aerial photography, but recent smartphones include LiDAR sensors, and combined with RTK-based position correction, anyone can easily 3D-scan a site. By walking the site with a smartphone in hand, ground undulations and the volume of earthworks can be recorded accurately with coordinates.

High-accuracy point cloud data are powerful for construction progress management and quality checks. For example, if you scan and save the original ground before earthworks, you can later compare periodic scans to quantify where and how much soil was added or removed. Previously, surveyors measured heights at points and calculated volumes to manage earthworks, but with point cloud differencing, quantities are obtained in an instant. Overlaying the design terrain data (design model) with actual as-built point clouds makes any excesses or shortages in embankment/cutting and deviations in finished shapes immediately visible. Detecting discrepancies early helps prevent rework.

Point clouds are also effective for surveying entire expansive solar plant sites. Subtle terrain changes that are hard to spot by eye can be compared in detail with 3D data. Progress that once required walking every corner of the site can be visualized digitally with point clouds, making it easy to find delays or problem areas. This data-driven quality control enables small teams to comprehensively check large sites and ensure quality.

Direct connection between site and office through cloud sharing

A strength of smartphone DX is that all collected data can be immediately shared via the cloud. Previously, photos and survey data taken on site required returning to the office to transfer via USB or email or to reorganize into paper documents, which was time-consuming. With DX tools, information captured on a smartphone is uploaded directly to the cloud and can be viewed in real time from remote locations.

For example, photos taken with a smartphone app are automatically tagged with date, time, and coordinates, making it easy to organize “when and where a photo was taken.” There is no need to create folders and paste photos by drawing, and required information can be found immediately. Daily or weekly reports can also be auto-generated from data collected on site. Report forms are completed by fitting survey results and inspection records into cloud templates, greatly reducing the workload on personnel.

Centralized cloud management of data also strengthens team collaboration. Point cloud models and photos uploaded from the field can be immediately checked by office engineers or clients, and feedback can be sent—enabling smooth remote support. With always up-to-date information shared, mistakes like using outdated drawings are avoided. Furthermore, because construction history data are stored in the cloud after completion, records can be referenced immediately during inspections or maintenance, so the benefits of DX extend across the facility’s lifecycle.

Intuitive smartphone operation is friendly to both young workers and the field

A key to embedding DX tools on site is intuitive operability and ease of use. Smartphone-centered solutions have the advantage of running on devices that workers are already familiar with, making them readily accepted by craftsmen on site. Young staff, as well as veteran workers less accustomed to smartphones, can start using tools without resistance thanks to intuitive UIs and easy-to-understand operation flows. Compared with complex specialized equipment, DX tools that can be handled with a “smartphone feel” lower training costs while raising everyone’s baseline skills.

The psychological effects that smartphone DX brings to the site should not be overlooked. Utilizing cutting-edge technology makes on-site work smarter, and combined with reduced physical labor load and improved safety, it leads to improved workplace environments. Simplifying the formerly cumbersome surveying and recording tasks enables site supervisors and construction managers to focus on higher value-added work, and presenting modern technology as “cool” on-site can appeal to younger generations, helping recruitment. If a culture of data utilization takes root among site staff through DX, organizations can maintain high-quality construction without relying solely on individual craftsmen’s skills.

Effects and outlook of solar construction DX

Smartphone RTK and AR-enabled solar construction DX delivers substantial effects directly linked to solving labor shortages. As more tasks can be handled by one person, projects can proceed with limited personnel. As a result, it contributes to shorter schedules and cost reductions, providing business advantages. Also, through improved construction accuracy and reduced work errors, workmanship quality stabilizes and rework or complaints are prevented. Since solar power plants consist of many panels and equipment that operate for long periods as infrastructure, initial construction quality affects long-term power generation efficiency and maintenance costs. High-precision construction achieved through DX is therefore important from a long-term quality assurance perspective.

In the future, further on-site DX evolution is expected through integration not only with smartphones but also with AR glasses and autonomous construction machinery. However, the foundation is first to diffuse tools that “anyone can use with a smartphone” on site. The DX know-how cultivated at the frontline of solar construction is likely to spread to other civil engineering and building sites. Efforts in solar construction DX that respond to the structural problem of labor shortages with digital technologies serve as an example that can open up the future of Japan’s entire construction industry.

Realizing smartphone DX solutions with LRTK

A solution that strongly supports such smartphone-driven on-site DX is LRTK. LRTK (pronounced “el-are-tee-kay”) is a smartphone-based site DX platform that combines high-precision GNSS devices, a dedicated app, and cloud services to provide all-in-one functionality needed for construction management. Specifically, a single smartphone can realize the following functions.

• Centimeter-level positioning and 3D scanning: By using a small RTK-GNSS receiver attached to the smartphone, one can always know their position with an accuracy of a few centimeters (a few in). Combined with the smartphone’s built-in LiDAR, absolute-coordinate point cloud data can be obtained with a single tap. Topographic surveys of vast sites and measurements of embankment volumes can be performed on the spot.

• Design verification and navigation with AR: Design drawings and 3D models can be displayed as AR on the smartphone screen and overlaid onto the real scenery for verification. Because LRTK’s high-precision positioning prevents overlay drift, tasks such as inspecting structures by superimposing virtual models during construction or guiding pile-driving points with AR markers can be carried out by one person.

• Automatic organization of photos and records: Photos taken with the LRTK app are automatically tagged with positional coordinates and timestamps, and are linked on the cloud to maps and point cloud data for chronological management. You can also compare previously taken photos at the same location with AR, which is useful for monitoring progress and preparing reports.

• Cloud sharing and team collaboration: All data acquired with LRTK are instantly synchronized to the cloud and can be viewed and measured from an office PC via a browser. Point clouds and photos taken on site can be immediately checked by remote engineers, who can provide advice—enabling real-time collaboration.

By introducing LRTK, the processes of “measuring, verifying, recording, and sharing” required at solar construction sites can be almost entirely completed with a smartphone. Because LRTK implements the DX functions described in this article as a single integrated tool, on-site introduction is simple. Even in large-scale solar farm construction, LRTK can be a reliable partner for efficiency and quality improvement. Construction managers struggling with labor shortages should consider utilizing such smartphone-centric DX tools. LRTK helps update sites with cutting-edge technology so that, even with a small team, safe, reliable, and high-quality solar power plants can be built.