Let smartphones handle pile-driving guidance! The new standard in solar installation that makes on-site work easier

Solar power plant construction sites require enormous amounts of work such as surveying and pile driving because thousands of solar panels must be 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 misaligned layout markings often led to construction defects and schedule delays.

In addition, working on slopes or muddy terrain was hazardous, and securing safety in such conditions demanded significant effort.

What is gaining attention is the new standard for 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—surveying, design, and pile-driving guidance—can now be carried out easily. In particular, attaching a high-precision RTK-GNSS receiver turns a smartphone into a centimeter-level surveying instrument, enabling a single worker to achieve accurate positioning. Furthermore, by utilizing AR (augmented reality) and 3D point cloud scanning capabilities, tasks such as overlaying design drawings and calculating earthwork volumes can be completed using only a smartphone. This article provides a detailed explanation of real-world examples and the benefits of solar construction using smartphones and the latest technologies.

Traditional challenges faced in solar installation

At mega-solar sites such as solar power plants, the traditional methods had the following issues.

• Manual, labor-intensive surveying and layout marking: Using total stations, tape measures, and spirit levels, multiple people conducted outdoor surveying and measurements. For each point they set up a tripod, aligned the instrument, took measurements, and marked the spot — a very time-consuming process that could require several trips just to install a single pile. Additionally, because the work had to be carried out while cross-checking the drawings, accurately determining positions was difficult without experienced staff, making the process a high hurdle for beginners.

• Working hours and labor shortages: Surveying and vast sites and marking them one by one requires a great deal of time and personnel. Moreover, as the shortage of skilled technicians worsens, a limited number of people must handle an enormous volume of work. Especially in rural and mountainous areas there are few experienced workers, so when only young or inexperienced staff are assigned, mistakes tend to occur.

• Safety concerns: When surveying crews carry out layout marking or guide pile driving around heavy machinery, there is a risk of slips 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, so safety concerns persist.

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

Realizing Construction DX by Leveraging Smartphones

In recent years, smartphones have been equipped with high-performance cameras, GPS, accelerometers and gyroscopes, LiDAR, and—when paired with dedicated apps—can make use of various positioning technologies. In particular, when combined with RTK (Real-Time Kinematic) technology, smartphone GPS errors can be corrected to enable high-precision positioning to within a few centimeters. By connecting a smartphone to a compact RTK-GNSS receiver, centimeter-accurate location information can be obtained without conventional surveying equipment, creating an environment where anyone on site can perform accurate surveying and position layout.

• Surveying and point-cloud scanning with a smartphone: Using dedicated devices or apps, you can perform 3D scans that leverage a smartphone camera or LiDAR sensor. For example, simply walking while holding your smartphone lets you acquire point-cloud data of the surrounding terrain and structures. Each point is assigned coordinates such as latitude, longitude, and elevation, so the survey results directly become an accurate 3D model. If you save this data to the cloud, you can view the site’s shape in real time from the office and streamline management of earthwork progress and soil volumes.

• Automated photo documentation: Photos taken with a smartphone automatically have the shooting location's coordinates and timestamp attached. This links photo records with location information, eliminating the need to keep paper notes. By photographing the construction status and sharing it to the cloud, responsible personnel and clients can check site progress at any time.

• Sharing work instructions and deliverables: By overlaying design drawings and point cloud data within a smartphone app, you can intuitively check the differences between the plans and current site conditions. Form creation for as-built management and similar tasks can also 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 smartphones and RTK

Particularly noteworthy is smartphone guidance for pile-driving positions. If you load the predesigned pile coordinate data from the construction drawings into a smartphone app, the app will display the direction and distance to the target point in real time on site. The steps to use it are simple. Once you use the smartphone to determine the position of a reference point installed on site, you can simply follow the on-screen directions to move and reach the exact pile location.

• Coordinate-based direction and distance navigation: On the screen, arrows and figures such as “0.5 m east, 1.2 m north to the target point” are displayed, showing the offset between the current location and the stake coordinates numerically. This eliminates the need to measure distances with a tape measure or to walk back and forth multiple times. Even beginners can place stakes in the correct position by following the app’s guidance.

• AR (Augmented Reality) guidance: When you approach the target point, a virtual pile marker is overlaid on the smartphone's camera feed. If you view the site through the screen, arrows and markers appear superimposed on the pile center positions where the piles should be installed, so you can immediately tell "this is the spot to drive the pile." By leveraging AR, even inexperienced workers can receive intuitive guidance and reduce positioning errors to virtually zero.

This greatly reduces the labor involved in layout marking and transit surveying, tasks that previously required multiple people. Because a single person can move around the site and work with a smartphone in hand, significant reductions in on-site work time and labor costs are possible.

3D Scanning and AR Streamline Large-Area Construction

The benefits of smartphone surveying go beyond pile-driving guidance. As mentioned above, using a smartphone's 3D scanning function allows you to convert large sites into digital point clouds in a short time. Progress management of earthworks is especially important for mega-solar projects, and by comparing initial terrain data with point cloud data captured during construction, the volumes of cut and fill can be calculated automatically. Whereas volume calculations were traditionally done by deriving cross-sections from elevation measurements at multiple points, now they can be completed instantly simply by computing the differences between point cloud datasets.

Additionally, you can display 3D models of design drawings—such as planned racking layout data—on a smartphone and overlay them onto the site view. High-precision positioning projects the virtual model without misalignment, allowing clients and supervisors to intuitively confirm the “finished image” on site. You can check on the spot whether the planned layout on the drawings matches 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

With smartphone-centered construction management, data sharing and information transmission are significantly improved. Survey data, point clouds, and photo 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 need to carry paper drawings or to recompile reports by hand.

Furthermore, the data recorded with the smartphone app can also be used to generate reports. For example, you can automatically create progress/quantity management tables from survey data or point clouds, or produce reports that plot photos onto drawings using the coordinate information embedded in the photos. This significantly shortens the time required to prepare daily and weekly reports, enabling a "DX" site that no longer relies on paper and Excel.

The New Standard for Smartphone Surveying: Simplified Surveying with LRTK

The solution drawing attention as the foundation for the various smartphone surveying techniques introduced so far is called LRTK. LRTK is an ultra-compact RTK‑GNSS receiver that attaches to a smartphone, integrating the antenna and battery into a single device. By mounting it on your phone and receiving correction data over a communication line, even a lightweight device weighing only about 150 g can achieve centimeter-level positioning.

Using LRTK makes on-site surveying remarkably simple. It displays stake coordinates from the construction drawings on your smartphone screen and provides real-time numeric guidance on deviations from your current position — “east by ◯m, north by △m.” When combined with the aforementioned AR function, arrows appear on the screen pointing to the locations to be installed, and as you approach, virtual stake markers are displayed. This enables even those with limited surveying experience to set out positions accurately without hesitation, greatly reducing the traditional workload.

LRTK also includes a smartphone app and cloud service, allowing captured point cloud data and photos to be stored and shared directly in the cloud. This enables pre-construction site measurements, pile-driving guidance, and as-built management to be coordinated from a single smartphone, allowing on-site DX to be completed using only a smartphone. By using 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 smartphone-centered solar installation methods have significantly improved on-site productivity and safety. With DX driven by ICT technologies, the era is approaching in which smartphones will become "installation assistants" at solar sites. Let’s quickly adopt this new standard on-site and improve installation efficiency.