Complete surveying, design, and pile driving with a smartphone! Achieving DX for mega-solar construction

Overview of mega-solar construction and the need for DX

On mega-solar (large-scale solar power) construction sites, installing thousands of solar panels across vast land areas requires enormous effort and time from surveying and design through to pile driving. Many installations are on mountain slopes or undeveloped land, so precise surveying and accurate stake-out in the field determine project success. However, conventional analog construction management requires manual measurement of a huge number of control points and manual marking of pile locations across wide areas, creating risks of rework due to labor shortages and human errors and leading to prolonged schedules.

As interest in renewable energy grows and mega-solar projects increase nationwide, sites in rural and mountainous areas face shortages of skilled personnel and harsh working conditions. Under these circumstances, leveraging digital technologies to reduce labor and effort while ensuring construction quality and safety is key to project success.

Promoting DX (digital transformation) in the construction industry is attracting attention as a way to resolve these issues while balancing quality, safety, and efficiency. In particular, construction DX that leverages smartphones and advanced technologies is expected to digitally connect the entire process from surveying through design to pile driving, achieving consistent efficiency and accuracy gains. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative also supports this trend, accelerating the use of ICT and IoT in surveying and construction. For renewable energy projects like mega-solar, DX-driven smart workflows are required to complete construction quickly and accurately with limited resources.

Problems with traditional methods and the transformative potential of smartphones

Traditional construction sites required large amounts of manpower and time for surveying and stake-out. For example, surveying with a total station needed a skilled surveyor and typically a two-person team with an assistant holding a target prism. Measuring numerous points across a wide mega-solar site required repeatedly setting up and moving tripods, ensuring line-of-sight, and reading and recording each point, sometimes taking an entire day. Marking pile-driving positions (so-called stake-out) was also analog: determining positions with tape measures and spirit levels while referring to drawings, and marking each pile center with a wooden peg or chalk. These methods relied heavily on field experience and intuition, so human mistakes or measurement errors could cause assembly defects or rework in later stages.

Recently, advances in smartphones and digital technologies have made field-work innovation realistic. Smartphones now include high-performance GPS, sensors, and cameras, and when combined with external devices such as RTK-GNSS receivers, centimeter-level positioning (half-inch accuracy) and 3D scanning that previously required specialized equipment are now possible. With dedicated apps, one device can connect surveying, display of design data, and navigation to pile coordinates, linking field and office via data without relying on paper drawings or notes. In other words, smartphone-centered digital construction creates the potential to proceed quickly while maintaining accuracy even with a small crew.

Surveying: accuracy and efficiency of solo work through RTK-smartphone integration

For high-precision surveying required at large sites like mega-solar farms, the RTK (Real Time Kinematic) method is indispensable. Using RTK-GNSS, applying correction information can reduce GPS positioning errors that are typically several meters (several ft) down to within a few centimeters (within a few inches). This technology cancels errors by having a reference station and a rover (the surveyor’s receiver) simultaneously receive satellite signals and compute differences; in Japan, high-precision performance can be readily achieved by using electronic reference point networks (GNSS reference station networks) and the Quasi-Zenith Satellite System “Michibiki” augmentation signals (CLAS).

If you attach a compact GNSS receiver that supports RTK corrections to a smartphone, the smartphone itself transforms into a precise surveying instrument. There is no need to carry heavy tripods or special instruments; a single worker can walk the site with a smartphone and rapidly acquire coordinates for required points. For example, tapping a survey button in a surveying app records latitude, longitude, and elevation instantly and automatically converts and saves them into the project’s coordinate system such as the plane rectangular coordinate system. Because baseline surveys needed for stake-out can be completed by one person, work can begin without spending days installing reference points. Data can be uploaded to the cloud on the spot, eliminating the need to return to the office to import data into a PC. Smartphone RTK surveying dramatically improves efficiency for wide-area topographic surveys and pre-measurement of pile positions. If each field staff member carries a smartphone-based surveying device and works in parallel, it is feasible to complete site surveys at several times the speed of conventional methods. Furthermore, the intuitive operation of smartphone apps makes them easy for non-specialist staff to use, helping to eliminate dependence on individual surveying skills.

Design: combining 3D models and point clouds, consistency checks with AR

DX benefits using smartphones are also evident in the design phase based on field survey data. By using a smartphone or compatible device’s 3D scanning functions to capture point cloud data of existing site topography, you can digitally create detailed terrain models. Three-dimensional surveying that previously required drones or terrestrial laser scanners can now be performed easily using smartphone-built LiDAR or camera-based scanning combined with RTK positioning. The acquired point clouds include global coordinates (latitude, longitude, and elevation), so they can be used as accurate as-built models when compared with design drawings. Sharing this point cloud data on the cloud enables designers in the office to thoroughly understand the terrain and evaluate layouts. Designers can optimize racking layouts considering slopes and terrain constraints or calculate the scale of earthwork (land leveling) needed, tasks made possible by accurate point cloud models.

Moreover, overlaying and visualizing 3D design data (BIM/CIM models, etc.) with the existing point cloud makes it dramatically easier to verify consistency between design and site. For example, overlaying a LiDAR-scanned terrain point cloud with a 3D model of the solar racking allows intuitive understanding of the expected completion appearance if installed as designed. On cloud platforms, uploaded point clouds and design models are automatically aligned, so even slight discrepancies are not overlooked. There are functions to instantly compute volumes for cut-and-fill based on elevation differences between the design model and terrain, which support earthwork planning.

In the field, designers and stakeholders can view the design model at full scale through AR on a smartphone or tablet screen, composited with the real background for on-site verification. Because the smartphone’s position and orientation are obtained with high precision via RTK, 3D models displayed in the field are less prone to positional drift and remain fixed exactly where designed. This enables supervisors and clients to share the “post-completion appearance” on site and verify together whether the plan on paper fits the actual conditions. Intuitive AR-based consistency checks are a powerful means to prevent rework due to design errors or misunderstandings.

Pile driving: eliminating offsets with coordinate guidance and AR display

Smartphone-enabled DX also proves powerful for pile-driving—the foundation work for solar racking. If numerous pile coordinates determined during design are shared to smartphones via the cloud, field crews can identify pile-driving points by navigating to those coordinates. Traditionally, survey teams marked each pile location, and construction crews used those marks to guide equipment; with digital coordinate guidance, the intermediate stake-out step can be greatly simplified. The smartphone screen displays the direction and distance to the target pile coordinate in real time, and workers can reach the exact pile location simply by following the instructions. As the worker approaches the point, a virtual pile (AR marker) is overlaid on the camera view, making the pile center immediately recognizable.

Combining coordinate guidance and AR display allows pile-position deviations to be reduced to nearly zero. On mega-solar sites with hundreds of piles, small offsets in each pile can affect the overall racking assembly accuracy. Smartphone-based pile driving enables driving each pile to the design coordinates, preventing later issues such as misaligned bolt holes or undue forces on connections. If desired, the pile position can be re-measured and recorded with the smartphone immediately after driving, enabling instant verification of the as-built condition. Such digital pile driving allows novice operators to achieve high-quality construction without relying on veteran intuition, and electronically managing pile coordinate data contributes to labor savings in construction management.

Using AR also permits virtual marking of pile locations from safe areas for steep slopes or weak ground where direct access is usually difficult, allowing these marks to be reflected later in equipment-based construction planning.

Efficiency of data recording, management, and cloud sharing

In smartphone-centered construction DX, unified data management and real-time sharing are major strengths. Survey results, design drawings, and construction records that were previously managed separately on paper field books or spreadsheet files can be integrated digitally. For example, terrain data and pile coordinates obtained by surveying are uploaded to the cloud from the field and immediately accessible to designers and other stakeholders in the office. When design changes occur, updating cloud data syncs new drawings and coordinate lists to field devices, eliminating the risk of construction based on outdated drawings or miscommunication.

Progress information and as-built data during construction are also shared via the cloud. If each completed pile position and inspection result are recorded on site, managers can monitor construction status from the office. It becomes possible to check in real time on drawings which piles are completed and whether elevations match design, and to provide immediate feedback to the field for corrective action if problems arise. Photos and notes are stored with coordinates in a database, so site observations (such as exposed bedrock or springs) can be easily located on a map later. After completion, all this data remains as a digital construction record ledger and becomes an asset for future inspection and maintenance.

Cloud connectivity ensures that field, design, and management personnel share a common, up-to-date information set, eliminating idle time and communication discrepancies. As a result, overall project productivity and quality improve and stakeholder communication becomes smoother. Eliminating data handover via paper or USB memory reduces human error and enhances security. Thus, DX in data recording and management is not merely an efficiency measure but a transformative element of the construction process. Because the data are digital from the start, preparing as-built drawings and construction reports becomes easier and electronic delivery is smoothly supported.

Case study of integrated smartphone surveying, design, and pile driving using LRTK

As an example of implementing a smartphone-centric construction DX tool, we present a mega-solar construction case that utilized an LRTK smartphone-compatible positioning system provided by our company across the entire workflow from initial ground surveying to pile driving.

During surveying, site staff used an LRTK receiver attached to a smartphone to perform one-person surveys of the entire site. Even on large and undulating land, LRTK RTK surveying enabled rapid acquisition of many survey points, reducing surveying time to less than half compared with conventional methods. Designers used that data to quickly create panel layout plans and shared them on the LRTK cloud. Staff also used the LRTK app’s point-cloud scanning function to 3D-model key terrain features and uploaded them to the cloud. Overlaying the design model with the existing point cloud on the cloud platform revealed that a racking height adjustment was needed on a particular slope, allowing the design to be revised before construction and avoiding on-site rework.

In the pile-driving phase, the construction crew used LRTK-equipped smartphones on site and proceeded with pile driving based on pile coordinate lists retrieved from the cloud. The workflow guided equipment to the designated positions via the smartphone navigation and confirmed virtual piles displayed in AR before driving. Approximately 500 piles were driven, and every pile center fell within the design tolerance (within a few centimeters (within a few inches)), so no adjustments were required during subsequent racking assembly. Each pile’s completed coordinate was automatically recorded to the cloud upon completion, enabling supervisors to verify as-built status in real time from the office.

By fully utilizing functions such as smartphone-based RTK surveying, point-cloud scanning, coordinate navigation, AR guidance, and cloud connectivity offered by LRTK, the mega-solar construction workflow was dramatically streamlined and upgraded. This approach addresses issues such as shortages of skilled technicians and remote-site construction, achieving schedule shortening and cost reduction while maintaining quality. This case exemplifies the potential of DX in future construction sites. This smart construction technology, which changes conventional on-site practices, is expected to have a broad ripple effect across civil engineering and construction beyond renewable energy. With digital technologies as an ally, on-site DX will open up the future of the construction industry. A true on-site revolution is underway.