Digitizing Mega-Solar Site Management – Point Clouds and AR Completed on a Smartphone

Current state and challenges of mega-solar site management

As attention to renewable energy grows across Japan, the construction of large-scale solar power plants, so-called “mega-solar” facilities, is increasing. On these mega-solar sites, large earthworks and installation works are carried out to install tens of thousands of solar panels over vast areas of land. Site management requires a wide range of tasks, including topographic surveying, verification of earthwork progress, checking the layout of panels and racks, and recording construction status.

However, many analog methods remain in use for managing mega-solar sites. For example, surveying typically requires specialized surveying instruments and personnel, survey results are often handwritten onto paper drawings, and work instructions are commonly communicated orally or via phone and email. On vast sites, simply grasping progress requires staff to walk every corner of the site, which is a heavy burden.

On large sites, insufficient information sharing across processes tends to cause mistakes and rework. For instance, confirming whether the land has been leveled to the planned elevation in earthworks can take time, and if discrepancies are discovered later, additional man-hours are required to correct them in subsequent processes. Management of site photos and report creation is also often done manually, placing a large burden on staff. With labor shortages and a lack of skilled technicians becoming serious, it is necessary to rethink the traditional, person-dependent, and inefficient site management methods.

Background necessitating DX

One key solution drawing attention to address these site management challenges is DX (digital transformation) in construction sites. DX refers to fundamentally transforming business processes using digital technologies to improve efficiency and sophistication. There are several factors behind the need for DX in mega-solar construction sites.

First is labor shortages and the aging of skilled workers. Managing vast sites requires many personnel, but the construction industry as a whole is short of young talent and experienced workers are aging. To operate complex sites with limited staff, improving individual productivity is essential, and advancing labor-saving and automation through DX is an urgent task.

Second is growing pressure to shorten construction periods and reduce costs. With increasing demand for renewable energy, early operation of mega-solar facilities is required, making efficient execution of construction work important for business. Using digital technologies to shorten surveying and inspection times and to share data instantly is expected to reduce wasted waiting time and rework.

Third is a nationwide and industry-wide push for DX. Initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction policy recommend the use of ICT and 3D data in civil engineering and construction. Mega-solar sites are no exception, and the adoption of the latest technologies for visualization and remote supervision is expected to improve safety and quality.

From these backgrounds, what is needed is not merely replacing traditional methods with digital ones but transforming site management itself through DX.

Surveying, recording, and management completed with a single smartphone

So, what kind of tools are effective for DX? One answer is “site management completed with a single smartphone.” Recent smartphones have become highly capable, and some models now include high-precision GPS units for positioning and 3D scanners (LiDAR). By leveraging these, tasks that previously required dedicated surveying instruments and computers can increasingly be completed with a single smartphone in the palm of the hand.

For example, by attaching a dedicated RTK-GNSS receiver to a smartphone, the smartphone can quickly become a centimeter-level surveying instrument (half-inch accuracy). Traditionally, a surveying technician capable of operating a total station or large GPS surveying equipment was required, but with a smartphone app the user can record position coordinates simply by pressing a button, allowing site staff themselves to immediately survey needed points. The acquired latitude, longitude, and elevation data are automatically saved, eliminating handwritten notes.

Also, utilizing a smartphone’s camera and sensors greatly streamlines site condition recording. When you photograph an area of concern, the photo is automatically tagged with the shooting location coordinates and timestamp. There is no need to scribble notes on paper drawings while taking photos; everything is recorded digitally. The recorded data can be uploaded to the cloud on the spot, reducing the work of reassembling reports after returning to the office.

By centering operations on a single smartphone, an environment is being established where surveying, recording, and information sharing can all be completed on site. Because operations are performed on familiar smartphones, they are easy for site workers to adopt, and using them as a one-device-per-person digital field tool enables unprecedented mobility and efficiency.

Progress verification and volume management using point cloud data

In mega-solar construction, large-scale shaping of terrain and large embankment and cut-and-fill operations are performed, so accurately understanding the site’s shape and managing progress and earth volumes is critically important. This is where the power of 3D point cloud data comes into play. Point cloud data are three-dimensional survey data that record the surroundings as an enormous collection of points (a point cloud).

Traditionally, such 3D surveying used specialized methods like laser scanners or photogrammetry from drone surveys. However, in recent years some smartphones have begun to include LiDAR (light detection and ranging) sensors, and by combining these with high-precision positioning, anyone can now easily perform 3D scans of the site. Simply walking around the site with a smartphone allows you to capture point cloud data of terrain and structures; furthermore, each point is assigned global coordinates (latitude, longitude, and elevation), so scan results can be recorded with accurate positional information.

Using this 3D point cloud data dramatically improves efficiency for progress verification and earth volume management. For example, scanning the terrain before earthworks begins and saving that data, then comparing it with subsequent periodic scans, makes it possible to quantify how much material has been cut or filled. Tasks that previously required surveyors to measure heights at multiple points and compute volumes from cross-sections can now be done by subtracting point clouds to automatically calculate volume differences, saving significant time. Overlaying scanned as-built data with planned design terrain data also makes discrepancies (excess or shortage of earth or shape deviations) immediately apparent.

Point clouds are also powerful for progress verification. Subtle terrain changes or progress that are hard to see can be compared in detail with 3D data. This allows early detection of areas that are behind schedule or have finishing issues so that countermeasures can be taken. On vast sites like mega-solar facilities, it was difficult to uniformly grasp the entire site, but by using point cloud scans the whole site can literally be visualized in digital points.

Real-time reconciliation of design and site with AR

AR (augmented reality) technology is another promising solution for mega-solar site management. With AR, you can overlay design data onto real site views through a smartphone or tablet screen. In other words, you can reconcile planned designs on drawings with actual on-site conditions in real time.

Specifically, you can display the mega-solar layout plans or earthwork 3D models as AR and composite them into the on-site view. Looking through the smartphone camera, rows of solar panels not yet installed or equipment locations appear as if they exist there. When combined with high-precision positioning, AR will not shift after walking a few meters (a few ft); the display remains precisely aligned with the design and actual positions.

This AR reconciliation can help prevent construction mistakes and improve quality. For example, during foundation work you can project the rack installation positions with AR and confirm that the marking positions are correct. Tasks that used to require a tape measure or transit for layout can be intuitively confirmed with AR, reducing human error. In addition, when clients or designers visit the site, AR allows them to share the completed image. Showing “this is how the panels will be arranged” as a 3D overlay on the actual scene makes it easier for all stakeholders to share a spatial image.

AR is also useful for layout in difficult-to-access locations. Even on steep slopes or areas that are hard to enter, AR can virtually display markers (stakes or lines) so position confirmation can be done safely. By utilizing AR in this way, the gap between design and construction site can be closed in real time, supporting smooth construction with no rework.

Automation of photos, records, and forms and cloud sharing

The benefits of site DX extend beyond surveying and design reconciliation. DX also brings major effects to the efficiency and automation of daily photo records and reporting tasks. During mega-solar construction, many recording tasks occur, such as photographing progress, recording various inspections, and creating daily work reports. DX can automate as many of these tasks as possible and build a system for sharing them on the cloud.

For example, when you take a photo with a smartphone app, metadata such as date/time, location information, and the person in charge are automatically attached to the photo file. You can separate albums by work area or simply enter descriptions according to templates to keep standardized records. Since captured data is uploaded to the cloud in real time, there is no need to copy photos via USB or send them by email after returning to the office.

Form generation can also be simplified by DX. Daily and weekly reports, as-built control documents, and other records that onsite supervisors previously created in spreadsheets or on paper can be automatically generated from digital data collected on site. For example, simply fitting surveying data and photos into a prescribed cloud format can almost complete a quantity/progress report. Of course, cloud-based management allows everyone to access the latest information, preventing mistakes like referring to outdated drawings or data.

Cloud sharing is also effective as a bridge between the site and remote locations. Managers or clients at distant offices can view site progress data and photos at any time via the Internet. This eliminates the need to print and carry large amounts of paper for reporting meetings, speeding up decision-making. With centralized data management, construction records can be easily referenced during maintenance and inspection after handover, allowing DX benefits to be realized across the entire lifecycle of a mega-solar facility.

Case studies and implementation effects

In practice, when a certain mega-solar construction site introduced a smartphone-complete DX tool, on-site management changed dramatically. As-built surveys that had previously been outsourced to an external surveying company about once a week could be carried out daily in a short time by site staff themselves, enabling construction management based on always up-to-date terrain data. AR design reconciliation greatly reduced construction mistakes and prevented additional works. Photos and records shared in the cloud were available in real time to headquarters and partner companies, significantly improving communication among stakeholders. Reported results of such on-site DX introduction include the following outcomes:

• Shortened surveying and inspection times: Work time was reduced to a fraction of the previous time, leading to labor cost reductions and shortened schedules.

• Improved construction quality: Checks using AR and point clouds reduced rework and cut losses caused by mistakes.

• Faster information sharing: Immediate cloud synchronization of data shortened waiting times for instructions and reports.

• Easier skills transfer: Smartphone-centered tools are intuitive for both veterans and younger workers, making it easier even for those not good with ICT to become proficient.

• Safety and environmental benefits: Survey tasks in dangerous locations were reduced, and paperless operations by reducing paper materials contributed to environmental benefits.

Thus, DX-driven innovation in site management improves not only productivity and quality but also work style and safety. The effects are particularly pronounced on extensive sites such as mega-solar installations.

Promoting site DX with LRTK and suggestions for its utilization

One solution attracting attention as a strong support for such site DX is LRTK. LRTK is a smartphone-based site DX platform that delivers all-in-one functionality required for site management through a dedicated compact GNSS receiver, an app, and cloud services. Specifically, LRTK enables the following advanced functions with just a smartphone:

• High-precision positioning and point cloud scanning: By attaching an RTK-GNSS receiver to the smartphone, the user’s position on site is always known with centimeter-level accuracy (half-inch accuracy). Combining this with the smartphone’s LiDAR allows one-touch acquisition of 3D point cloud data with absolute coordinates. Fill volume measurement and progress visualization can be performed instantly on site.

• AR reconciliation of site and design: Design drawings and 3D models can be displayed as AR on the smartphone screen and overlaid onto the real scenery for confirmation. LRTK’s high-precision positioning keeps AR displays accurately aligned with the site without shifting. Uses include overlaying virtual models onto structures under construction and marking stake positions with AR.

• Automatic organization of photos and records: Photos taken with the LRTK app are automatically tagged with coordinates and timestamps and managed on the cloud alongside maps and point cloud data in chronological order. It is also possible to AR-display past photos taken at the same location for comparison, aiding observation of changes over time and report preparation.

• Coordinate navigation: The app can navigate you to any point on the design drawings. This enables a single person to reliably perform tasks such as “install a stake at the specified coordinate” or “place equipment X meters from here.”

• Cloud sharing and team collaboration: All data captured with LRTK is automatically synced to the cloud and can be viewed and measured immediately from a PC via a browser. Office-based technicians can instantly review point clouds and photos taken on site and provide advice, enabling smooth real-time collaboration.

By utilizing LRTK, the surveying, inspection, verification, recording, and sharing processes needed for mega-solar site management can be completed with just a smartphone. Because the DX functions described so far are realized in one integrated tool, implementation on sites is simple. For construction sites of large-scale solar power plants, LRTK can be a powerful partner for efficiency and quality improvement. When considering DX for site management, consider adopting such smartphone-complete cutting-edge technologies.