Complete from Surveying to Design and Pile Driving with a Smartphone! Realizing DX for Mega-Solar Construction

Overview of Mega-Solar Construction and the Need for DX

On mega-solar (large-scale solar power) project sites, installing thousands of solar panels across vast areas requires enormous effort and time from surveying and design through to pile driving. Many installations occur on mountain slopes or undeveloped land, and precise surveying and accurate positioning on site are critical to a project’s success. However, conventional analog construction management requires manual measurement of a huge number of survey points and marking of pile positions over wide areas, leading to risks of rework due to staff shortages and human error, and extended construction schedules.

Moreover, as interest in renewable energy projects grows and mega-solar projects increase nationwide, sites in rural or mountainous areas face challenges such as a shortage of skilled personnel and harsh working conditions. In this context, leveraging digital technologies to reduce labor and effort while ensuring construction quality and safety is key to project success.

To address these challenges and balance quality, safety, and efficiency, promoting DX (digital transformation) in the construction industry has attracted attention. In particular, construction DX that leverages smartphones and advanced technologies is expected to digitally connect the entire process from surveying and design to pile driving, enabling consistent efficiency and improved accuracy. The Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative also supports this trend, accelerating the use of ICT and IoT technologies in surveying and construction. Even for renewable energy projects like mega-solar, DX is required to make work smarter and complete construction quickly and accurately with limited resources.

Problems with Traditional Methods and the Transformative Potential of Smartphones

Traditional construction sites required a lot of manpower and time for surveying and positioning. For example, surveying typically required a skilled surveyor to operate a total station, working in pairs with an assistant holding a target prism. Measuring many points across a large mega-solar site involves erecting and moving tripods, ensuring line of sight, and lengthy reading and recording at each point—sometimes taking an entire day. Marking pile positions (so-called layout marking) was also an analog process, using drawings, tape measures, and levels to find positions, then marking each pile center with wooden stakes or chalk. These methods heavily relied on field experience and intuition, and human error or measurement inaccuracies could lead to assembly failures or rework downstream.

However, recent advances in smartphones and digital technology have made on-site work innovation a realistic prospect. Smartphones now include high-performance GPS, sensors, and cameras, and when combined with external devices like RTK-GNSS receivers, centimeter-level positioning and 3D scanning—previously requiring specialized instruments—become possible. Using dedicated apps, one device can handle everything from surveying and displaying design data to navigating pile positions, linking field and office via data without relying on paper drawings or notes. In other words, smartphone-centered digital construction brings the potential to enable fast work with maintained accuracy even with fewer personnel.

Surveying: Accuracy and Efficiency of Solo Work through RTK–Smartphone Integration

For the high-precision surveying required on vast sites like mega-solar, the RTK (Real Time Kinematic) method is indispensable. RTK-GNSS can reduce typical GPS positioning errors of several meters down to within a few centimeters by applying correction information. This technology cancels errors by receiving satellite signals simultaneously at a base station and a rover (the surveyor’s receiver) and using their difference; in Japan, high precision is readily achievable using the electronic reference station network (GNSS reference station network) and the Quasi-Zenith Satellite System Michibiki’s augmentation signal (CLAS).

Attaching a compact GNSS receiver that supports RTK correction to a smartphone turns the smartphone into a precision surveying instrument. There is no need to carry heavy tripods or special instruments; a single worker walking the site with a smartphone can acquire the coordinates of required points one after another. For example, tapping a measure button in a surveying app instantly records latitude, longitude, and elevation and automatically converts and saves them in the project’s coordinate system, such as Japan’s plane rectangular coordinate system. Because control point surveying required for positioning can be completed by one person, work can start without spending days installing control points. Collected data can be uploaded to the cloud on the spot, eliminating the need to return to the office to transfer data to a PC. Smartphone RTK surveying dramatically improves the efficiency of terrain surveys and preliminary pile-position measurement across wide areas. If each field staff member carries a smartphone surveying device and conducts surveys in parallel, completing site investigations at many times the traditional speed is feasible. Moreover, the intuitive operation of smartphone apps makes them accessible to staff without specialized knowledge, helping to eliminate dependence on individual survey skills.

Design: Combining 3D Models and Point Clouds, Consistency Checks with AR

In the design phase based on field survey data, the benefits of smartphone-enabled DX are also evident. By using a smartphone or compatible device’s 3D scanning capabilities to capture point cloud data of the current terrain, you can create detailed digital terrain models. Three-dimensional surveys that once required drones or terrestrial laser scanners can now be more easily performed using a smartphone’s built-in LiDAR or camera plus RTK positioning. Point clouds obtained are georeferenced with global coordinates (latitude, longitude, and elevation), enabling use as an accurate as-built model when compared with design drawings. Sharing this point cloud in the cloud allows designers to study terrain in detail on office PCs while considering layout options. Optimizing racking placement considering slope and terrain constraints, or calculating the scale of earthworks required, becomes possible thanks to an accurate point cloud model.

Additionally, overlaying the planned 3D structural design data (BIM/CIM models, etc.) onto the current point cloud greatly simplifies consistency checks between design and site. For example, overlaying a LiDAR-scanned terrain point cloud with a 3D model of the solar panel racking lets you intuitively visualize the finished appearance if installed as designed. On a cloud platform, uploaded point clouds and design models are automatically aligned, so even slight discrepancies are noticeable. Functions that instantly calculate cut-and-fill volumes from elevation differences between the design model and the terrain are also available, aiding earthwork planning.

On site, supervisors can use a smartphone or tablet to view the design model in true scale via AR display, compositing it with the real background for verification. Because the smartphone’s position and orientation are determined with RTK-level accuracy, displaying a 3D model on site minimizes positional drift, and the virtual model can be fixed precisely where the design intends. This lets site managers and clients share the “post-construction appearance” on the spot and confirm whether the “plan on paper” fits site conditions. Intuitive consistency checks using AR are a powerful means to prevent rework caused by design errors or misunderstandings.

Pile Driving: Eliminating Offsets with Coordinate Guidance and AR Display

In pile driving—the foundation installation for solar panel racking—smartphone-enabled DX also proves highly effective. If the many pile position coordinates decided at the design stage (coordinate lists) are shared to smartphones via the cloud, workers can identify pile-driving points on site while navigating to those coordinates. Traditionally, survey teams marked each pile position, and construction teams relied on those marks to operate machines for pile driving. With digital coordinate guidance, the intermediate marking process can be greatly simplified. The smartphone screen shows the real-time direction and distance to the target pile coordinate, so the operator can move according to the instructions and reach the exact pile location. As the worker approaches the point, an AR virtual pile (AR marker) is superimposed on the camera view, making the pile center location instantly recognizable.

Combining coordinate guidance and AR display makes it possible to reduce pile-position offsets to nearly zero. On a mega-solar site with hundreds of piles, even small misalignments in each pile can affect the assembly accuracy of the entire racking system. However, with smartphone-based pile driving, piles are installed at the design coordinates, preventing issues such as misaligned bolt holes or undue stress at joints. If desired, measuring and recording the pile position again immediately after installation with the smartphone completes as-built verification on the spot. This digital pile-driving workflow enables novice operators to achieve high-quality installations without relying on veteran intuition, and electronic management of pile position data contributes to streamlined construction management.

Additionally, in steep slopes or soft ground where direct access for marking is difficult, AR can be used to virtually mark pile positions from a safe location and later incorporate those marks into machine operation plans.

Efficiency of Data Recording, Management, and Cloud Sharing

Smartphone-centered construction DX offers major advantages in centralized data management and real-time sharing. Survey results, design drawings, and construction records that were previously managed separately on paper field notebooks or spreadsheet files can be integrated digitally. For example, terrain data and pile coordinates obtained by surveying can be uploaded to the cloud immediately from the field, allowing designers and other stakeholders in the office to view the latest information right away. If a design change occurs, updating the cloud data automatically synchronizes new drawings and coordinate lists to field devices, eliminating the risk of construction based on outdated drawings or communication errors.

Progress information and as-built data during construction are also shared via the cloud. Recording the completed positions and inspection results for each pile on site lets supervisors monitor construction status remotely. It becomes possible to check in real time on a drawing which piles have been completed and whether elevations match the design, and to provide immediate feedback for corrections in the field if issues arise. Photos and notes are stored in a database with coordinates, so points noticed during construction (such as bedrock exposure or spring water locations) can be easily found on a map later. After completion, all of this data remains as a digital construction record ledger, serving as an asset for future inspections and maintenance.

Cloud integration enables site personnel, designers, and managers to share a common source of up-to-date information, eliminating wasted waiting time and information mismatches. As a result, overall project productivity and quality improve, and stakeholder communication becomes smoother. Removing the need to exchange data via paper or USB drives also reduces human error and enhances security. In this way, data recording and management DX goes beyond mere efficiency gains to become a critical element that transforms the construction process itself. Because the data is digitized from the outset, producing as-built drawings and construction reports becomes easier, and complying with electronic delivery requirements is smoother.

Case Study: Integrated Smartphone Surveying, Design, and Pile Driving Using LRTK

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

During the surveying phase, the site team performed a solo survey of the entire site using smartphones fitted with LRTK receivers. Even on large, undulating sites, LRTK RTK surveying allowed rapid acquisition of many survey points, reducing surveying time to less than half of what was required previously. Based on that data, designers quickly created panel layout plans and shared them via the LRTK cloud. The team also used LRTK app’s point cloud scanning function to 3D model key terrain and upload it to the cloud. Overlaying the design model with the existing point cloud on the cloud platform revealed that a minor height adjustment of the racking was needed on a certain slope, and making that design correction before construction avoided on-site rework.

In the pile-driving phase, the construction crew used LRTK-equipped smartphones on site and proceeded with pile driving by referencing pile coordinate positions retrieved from the cloud. The workflow involved guiding construction equipment to the designated positions with coordinate navigation on the smartphone screen and confirming the position with the AR-displayed virtual pile before driving. Approximately 500 piles were driven, and all pile centers were within the design tolerance (within a few centimeters), so no positional adjustment work occurred during subsequent racking assembly. After each pile was driven, its coordinates were automatically recorded in the cloud, allowing supervisors to verify the as-built condition in real time from the office.

By fully utilizing features such as smartphone-based RTK surveying, point cloud scanning, coordinate navigation, AR guidance, and cloud integration offered by LRTK, the mega-solar construction workflow was dramatically streamlined and enhanced. This approach addresses challenges like a shortage of skilled technicians and remote-site construction while maintaining quality and achieving shorter construction periods and cost reductions. This case is emblematic of the potential for DX in future construction sites. This smart construction technology is expected to have wide ripple effects not only in renewable energy but across civil engineering and construction industries as a whole. Field DX supported by digital technology will undoubtedly help shape the future of the construction industry. Indeed, a field revolution is underway.