Leave pile-driving guidance to your smartphone! The new standard in solar installation that makes on-site work easier

Construction sites for solar power plants require enormous amounts of work such as surveying and pile driving because thousands of solar panels are installed across vast areas. Traditionally, specialists used total stations and tape measures to survey and manually lay out pile positions based on drawings. This method required a large workforce and a lot of time, and surveying mistakes or shifts in layout markings could lead to construction defects and schedule delays. In addition, working on slopes and muddy terrain was hazardous and demanded significant effort to ensure safety.

What is attracting attention is a new norm in construction that leverages ICT (information and communication technology) and smartphones. By bringing just one highly portable smartphone to the site, tasks that previously required dedicated equipment—such as surveying, design, and pile-driving guidance—can now be carried out easily. In particular, when equipped with a high-precision RTK-GNSS receiver, a smartphone can quickly turn into a centimeter-level surveying instrument (cm-level accuracy, half-inch accuracy), allowing a single worker to achieve precise positioning. Furthermore, by utilizing AR (augmented reality) and 3D point-cloud scanning functions, tasks like overlaying design drawings and calculating earthwork volumes can be completed using only a smartphone. This article explains in detail real-world examples and benefits of solar construction using smartphones and the latest technologies.

Conventional Challenges Faced in Solar Installation

At mega-solar sites, such as solar power plants, there were the following challenges with conventional methods.

• Manual, labor-intensive surveying and layout: Using total stations, tape measures, and levels, several people conducted surveying and measurements outdoors. At each point they set up a tripod, align the equipment, take measurements, and mark the spot—the measuring and marking work was very time-consuming and sometimes required multiple round trips before installing a single stake. Furthermore, because the work had to be done while cross-checking the drawings, accurate positioning was difficult unless carried out by experienced personnel, making the process a high hurdle for beginners.

• Working hours and labor shortages: Surveying and marking each part of a vast site requires a great deal of time and personnel. Moreover, as the shortage of skilled technicians becomes more severe, the limited staff must handle an enormous workload. There was also the problem that, especially in rural and mountainous areas where experienced workers are few, mistakes became more likely when only young or inexperienced personnel were assigned.

• Safety concerns: When survey teams perform layout marking and stake-driving guidance around heavy equipment, there is a risk of slips, trips, and falls. On slopes or muddy ground footing is poor, and work can be delayed by changes in temperature and weather. With conventional methods it is difficult to avoid entering hazardous areas, and safety concerns have persisted.

To address these challenges, a construction method using smartphones and ICT was newly introduced. In the following sections, we will examine specific examples and their effects.

Achieving construction DX through smartphone use

Modern smartphones are equipped with high-performance cameras, GPS, accelerometer and gyroscope sensors, LiDAR, and can utilize various positioning technologies through integration with dedicated apps. In particular, combining RTK (Real-Time Kinematic) technology can correct smartphone GPS errors and enable high-precision positioning to within several centimeters (cm level accuracy, half-inch accuracy). By connecting a smartphone to a compact RTK-GNSS receiver, centimeter-level position information can be obtained even without conventional surveying instruments, creating an environment where anyone on site can perform accurate surveying and stakeout.

• Surveying and point-cloud scanning with a smartphone: By using dedicated devices or apps, 3D scanning that leverages a smartphone camera or LiDAR sensor becomes possible. For example, simply walking while holding your smartphone can capture point cloud data of the surrounding terrain and structures. Because each point is assigned coordinates such as latitude, longitude, and elevation, the surveying results directly become an accurate 3D model. If this data is stored in the cloud, you can view the on-site shape in real time from the office, streamlining site development progress and earth volume management.

• Photo record automation: Photos taken with a smartphone are automatically tagged with the shooting location coordinates and date and time. This links the photo records with location information, eliminating the need to keep paper notes. If you photograph construction progress and share it in the cloud, responsible staff and clients can check the site's progress at any time.

• Work instructions and sharing of deliverables: By overlaying drawings and point cloud data within a smartphone app, you can intuitively check the differences between the plans and the actual conditions. In addition, the creation of forms for as-built management and similar tasks can be automated, and daily logs and reports can be semi-automatically generated from photos and survey results. This significantly reduces administrative work and enables all stakeholders to quickly share the latest data.

Streamline pile-driving guidance with smartphone × RTK

Particularly noteworthy is smartphone guidance for pile-driving positions. If you load into a smartphone app the pile-driving coordinate data predesigned on the construction drawings, the app will display the direction and distance to the target point in real time at the site. The procedure is simple. If you use the smartphone to determine the position of a reference point installed at the site, you then only need to follow the directions displayed on the smartphone screen to arrive at the precise pile location.

• Coordinate-based direction and distance navigation: On the screen, for example, arrows and numbers such as "to the target point: East 0.5 m (1.6 ft), North 1.2 m (3.9 ft)" are displayed, showing the numerical offset between your current position and the stake coordinates. This eliminates the need to measure distances with a tape measure or to walk back and forth repeatedly. Even beginners can place stakes accurately by following the app's guidance.

• AR (Augmented Reality) guidance: There is also a feature that overlays virtual stake markers on the smartphone camera image as you approach the target location. By viewing the site through the screen, arrows and markers are superimposed on the stake center positions where the stakes should be installed, so it is immediately clear, "this is the point to drive the stake." By using AR, even inexperienced workers can be guided intuitively, reducing positioning errors to almost zero.

This greatly streamlines marking-out work and transit-based surveying that previously required multiple people. Because a single person can go around the site and work with a smartphone in hand, it enables substantial reductions in on-site work time and labor costs.

Streamlining Wide-Area Construction with 3D Scanning and AR

The benefits of smartphone surveying are not limited to guiding stake placement. As mentioned above, using a smartphone's 3D scanning function, a large site can be converted into a digital point cloud in a short time. In particular, for mega-solar projects, managing earthworks progress is important, and by comparing the initial terrain data with the in-progress point cloud data, the amounts of cut and fill can be calculated automatically. Work that traditionally calculated earthwork volumes by deriving cross-sections from elevations at multiple points can now be completed instantly simply by computing the differences between point cloud datasets.

You can also display 3D models of design drawings—such as planned mounting-frame layout data—on a smartphone and overlay them onto the actual site view. Because high-precision positioning prevents the virtual model from shifting when projected, clients and supervisors can intuitively confirm the “completed image” on site. This lets them check on the spot whether the plans on the drawings match the actual conditions, preventing installation errors before they occur. Even on steep slopes or in areas with poor visibility, stakes and lines can be displayed in AR for positioning, contributing to improved safety.

Maximizing Data Sharing and Work Efficiency

In smartphone-centric construction management, data sharing and information transmission are greatly improved. Survey data, point cloud data, and photographic data collected on site can be uploaded directly to the cloud and shared in real time with office PCs and other workers’ devices. This eliminates the information gap between the field and the office, enabling immediate decisions based on the latest drawings and data. There is no longer any need to carry paper drawings or spend time rewriting reports by hand.

Furthermore, data recorded with the smartphone app can also be used for report generation. For example, you can automatically generate progress management tables from survey data and point clouds, or create reports that plot photos on drawings using coordinate information attached to the photos. This significantly reduces the time required to create daily and weekly reports, enabling a "DX site" that does not rely on paper and Excel.

The New Standard for Smartphone Surveying: Simplified Surveying with LRTK

One solution that has attracted attention as supporting the various smartphone surveying technologies introduced so far is called LRTK. LRTK is an ultra-compact RTK-GNSS receiver that is attached to and used with a smartphone, integrating the antenna and battery into a single device. If attached to a smartphone and receiving correction information over a communications link, even a lightweight device of only about 150 g can achieve centimeter-level positioning.

Using LRTK makes on-site surveying astonishingly simple. It displays the stake coordinates on the construction drawings on the smartphone screen and, in real time, tells you the deviation from your current location numerically as "east by ◯ m (◯ ft), north by △ m (△ ft)". If combined with the aforementioned AR function, an arrow pointing to the point where the stake should be placed appears on the screen, and as you approach, a virtual stake marker is displayed. This allows even those with little surveying experience to set out positions accurately without hesitation, greatly reducing the traditional effort.

In addition, LRTK includes a smartphone app and a cloud service, allowing acquired point cloud data and photos to be stored and shared on the cloud as-is. This enables pre-construction site measurements, pile driving, and as-built management to be coordinated with a single smartphone, allowing on-site DX to be completed with just a smartphone. By utilizing LRTK not only for pile-driving guidance but also as a simple surveying tool, construction accuracy and work efficiency will be further improved.

As described above, new methods for solar installation centered on smartphones are greatly improving on-site productivity and safety. Through digital transformation (DX) enabled by ICT technologies, the era is coming in which smartphones will become "construction assistants" at solar sites. Let’s quickly bring this new common sense into the field and increase construction efficiency.