Complete with Just One Smartphone! A New Era of Mega-Solar Surveying Without Large Equipment

Mega-solar (large-scale solar power generation) projects require surveying vast sites. Traditionally, this has demanded extensive time and effort using manpower and large surveying instruments.

However, in recent years innovative surveying methods that can be completed with just a single smartphone have begun to emerge. This article reviews the traditional challenges and background of mega-solar surveying, explains the latest trends in smartphone surveying that promote workforce reduction and DX, and outlines the innovation of RTK (Real-Time Kinematic) technology. It also introduces the possibilities opened by smartphone-based point cloud scanning and AR (augmented reality) visualization, as well as efficiencies gained through cloud integration, and concludes with a proposal to introduce a smartphone surveying solution using LRTK. The new era of high-precision surveying completed with a smartphone is now imminent, and this wave is already reaching mega-solar sites.

Traditional Challenges and Background of Mega-Solar Surveying

Constructing a mega-solar facility requires vast land depending on generation capacity. Generally, installing a 1 MW (megawatt) system requires about 1–2 hectares (10,000–20,000 m²) of land. In other words, mega-solar plans at the scale of several MW can cover dozens of hectares, equivalent to multiple soccer fields. In addition, simulating shading caused by surrounding terrain and trees is important in mega-solar projects. To maximize generation efficiency, the impact of shade must be accurately estimated, and precise surveying data that captures elevation differences across the entire site and the locations of obstacles is indispensable.

For surveying such large sites, conventional practice involved teams of multiple people including surveyors using transits (tripod-mounted optical surveying instruments) and GNSS surveying equipment, measuring elevation and boundaries point by point. Covering large sites often required at least two people for a full day or more, and including preparation and packing up took an enormous amount of time and effort. In mountainous or uneven terrain, the physical burden on surveyors walking the site is substantial, and working among fallen trees or thick brush can be hazardous. Moreover, manual surveying carries constant risks of human error (misreading numbers, omissions in recording, etc.), and mistakes could lead to re-surveying or design rework.

Mega-solar sites are also often located in rural undeveloped areas or former woodland where transportation and communication infrastructure are limited, so repeatedly traveling to conduct surveys itself became a cost driver. Efficiently obtaining accurate surveying data has therefore been a major challenge for shortening project schedules and managing costs in mega-solar projects. In recent years, aerial surveying using drones has appeared and now allows wider areas to be measured in shorter timeframes. However, drone operation requires compliance with aviation regulations and specialized skills, and is affected by weather, so it cannot yet be considered an easily accessible option for everyone.

The Need for Workforce Reduction and DX in Surveying

Amid a severe shortage of workers and an aging workforce across the construction and civil engineering industries, surveying sites are no exception. Veteran surveyors are retiring en masse, making it increasingly difficult to continue work that relied on experience. At the same time, sites now demand more precise surveying data than ever before, so how to efficiently perform surveys with limited personnel has become a major issue.

Against this backdrop, digitizing and streamlining surveying to reduce manpower and boost productivity—surveying DX (digital transformation)—has become urgent. Japan’s Ministry of Land, Infrastructure, Transport and Tourism’s “i-Construction” initiative also promotes “efficient surveying with fewer people and in shorter time” and “improving on-site productivity,” accelerating surveying innovation using digital technologies. Particularly noteworthy is the new approach of leveraging satellite technologies such as RTK-GNSS (Real-Time Kinematic positioning) to enable surveys to be completed by a single person in extreme cases. Called one-person surveying, this method is expected to be a trump card that can simultaneously address labor shortages and improve surveying accuracy. With the latest GNSS technologies, even less experienced workers can survey wide areas in short timeframes, and the accuracy can equal or exceed conventional methods. What once seemed like a dream—one-person surveying—is finally becoming a reality on job sites.

The Innovation of RTK Surveying with Smartphones

RTK-based high-precision positioning has long been applied in surveying, but conventionally required expensive dedicated GNSS receivers and base station equipment. Full-scale RTK surveying, which sets an antenna on a tripod to establish a base station and operates in combination with a rover, often demanded investments of several million yen and specialized knowledge, limiting it to a small number of specialist surveying firms.

What has made RTK surveying easily accessible with just a smartphone is the recent emergence of ultra-compact RTK-GNSS devices compatible with phones. Using a receiver weighing only a few hundred grams that attaches to a smartphone or tablet turns a daily-use mobile device into a surveying instrument with centimeter-level accuracy. There’s no need to carry a tripod and heavy equipment—just take out your smartphone on site and start measuring immediately. Tasks that previously required multiple people can now be carried out quickly and accurately by a single person using smartphone surveying.

The innovation of smartphone RTK surveying lies in combining accuracy and ease of use. Errors of several meters are common with smartphone GPS, but by using RTK correction information, errors can be reduced to just a few centimeters. For example, correction data can be obtained via the internet from the network of permanent GNSS reference stations installed nationwide, or centimeter-class augmentation signals (CLAS) from the Quasi-Zenith Satellite System Michibiki can be received directly, enabling real-time high-precision positioning regardless of location. This allows smartphone-based surveying to meet the demands of high-precision tasks such as topographic surveys and boundary verification with positioning accuracy that belies the use of a smartphone.

Additionally, the simple configuration of a smartphone plus a small RTK device drastically reduces introduction costs. Compared to conventional high-precision surveying equipment, prices are far more affordable, making it realistic to equip multiple on-site staff with one device each. If such tools become widely available for anyone to use, it would be a direct innovation improving on-site surveying capabilities.

Expanding Possibilities with Point Cloud Scanning and AR on Smartphones

Surveying with smartphones goes beyond measuring point coordinates. By leveraging LiDAR scanners and high-performance cameras built into smartphones, it has become easy to acquire 3D point cloud data of sites. For example, a surveyor can simply walk around the site with a smartphone in hand to scan surrounding terrain and structures as dense point clouds. The acquired point cloud data can be tagged with accurate absolute coordinates (latitude, longitude, elevation) from RTK, allowing it to be used directly as an as-built model of the land. You can instantly calculate terrain contours or earthwork volumes, or import point clouds into CAD to create drawings. Also, using a smartphone camera that records capture location and orientation makes it possible to see at a glance on a map where and in which direction a photo was taken, aiding detailed recording and sharing of site conditions.

Even more groundbreaking is the AR (augmented reality) display capability on smartphones. By overlaying point cloud models obtained from surveys or the positional information from design drawings onto the camera view on a smartphone screen, virtual objects can be projected into real space. For example, visualizing the planned layout of solar panels or stake positions on the actual ground allows intuitive sharing of the finished image on site and enables accurate stakeout by a single person. Traditionally, placing stakes required cooperation between a surveyor and an assistant, but following AR guidance on a smartphone enables one person to set stakes without assistance, contributing to workforce reduction. With RTK’s high-precision position alignment, displayed AR objects align with real-world coordinates without positional drift. In this way, smartphone surveying offers unprecedented value by enabling on-site data to be used immediately in a visible form.

Completing Surveying, Recording, and Sharing with Smartphone and Cloud Integration

A major feature of smartphone surveying is the ability to instantly sync data collected on site to the cloud. Using a dedicated app, measured coordinates, photos, and note information are automatically uploaded to the cloud on the spot. Survey points and photos are plotted on cloud-based maps so colleagues in the office can check site conditions in real time from a web browser. Measurement results can be downloaded in prescribed formats such as CSV, PDF, or SIMA and used directly for CAD drawing creation or report preparation. Also, issuing a shareable link from the cloud system and sending it to stakeholders makes it easy to share the latest data with clients and partner companies.

Because site survey data is immediately digitized and shared, the time previously spent organizing and transmitting data after surveying can be drastically reduced. By measuring on site and uploading to the cloud, surveying, recording, and sharing are completed without the need to handwrite notes in a field book and bring them back, enabling seamless coordination between the field and the office. Management and clients can monitor progress and give instructions without visiting the site, which is another significant advantage. This truly enables real-time site visualization and strongly supports surveying DX.

On-Site Implementation Examples and Perceived Benefits

Sites that have actually adopted smartphone surveying report efficiency and labor-saving effects unlike anything before. At one mega-solar development site, a survey that traditionally required three people and two days was completed by one person with one smartphone in half a day, reducing outsourcing fees to surveying companies. At another site, being able to share high-precision point cloud data within the same day enabled design change decisions to be made the next day, directly shortening the construction schedule. Based on such examples, the main benefits of smartphone surveying are summarized below:

• Substantial time savings in surveying tasks – Surveying vast sites can be completed far more quickly than before. Tasks that once took several days have been completed within hours by leveraging smartphones and RTK technology. Shorter surveying times allow design and construction phases to start earlier, shortening overall project lead times.

• Reduced personnel burden and cost through workforce minimization – With the ability to survey with minimal personnel, on-site staffing plans become more flexible. Tasks that previously required two to three people can be completed by one, reducing labor costs and outsourcing fees to surveying firms. Even if experienced surveyors are scarce, staff familiar with smartphone operation can handle the work, easing personnel recruitment challenges.

• Improved safety and reduced physical burden – Lightweight smartphone equipment reduces the physical burden on surveyors in rough or steep terrain, enabling safer work. Hands-free surveying with a helmet-mounted smartphone frees both hands, and minimizing the number of people entering hazardous areas reduces the risk of secondary accidents.

• High-precision data and improved quality – RTK precision positioning and point cloud scanning technologies allow subtle terrain variations and obstacle locations to be captured more accurately and comprehensively than before. Reduced human error makes surveying mistakes less likely and helps suppress rework. High-density 3D data visualizes site details that 2D drawings can miss, improving the accuracy of design and construction planning.

• Faster data sharing and decision-making – Because measured data can be uploaded to the cloud on site and shared with stakeholders, information transfer between the site and the office is smooth. This enables same-day review of surveying results and consideration of design changes, accelerating on-site decision-making. Real-time awareness of site conditions supports efficient sequencing of construction with minimal rework.

• Ease of adoption and operation – Smartphone surveying uses familiar smartphones, making operation intuitive. It can be introduced on site without special qualifications or long-term training, lowering the barrier for the whole team to adopt the tool. This ease of use facilitates on-site penetration and broadens the scope of surveying data utilization.

Proposal for Introducing an LRTK Smartphone Surveying Solution

LRTK is a next-generation surveying solution that uses smartphones. Developed by a startup originating from Tokyo Institute of Technology, it is a smartphone-mounted high-precision GNSS receiver that achieves 1–2 cm positioning accuracy simply by attaching it to a phone. It is an all-in-one solution that covers the functions required for on-site surveying with a single smartphone: centimeter-accuracy RTK positioning, point cloud scanning using the smartphone’s LiDAR, AR display without positional drift, and cloud integration for data sharing. Tasks that previously required combining multiple devices and software can be carried out seamlessly on a single platform with LRTK.

Introducing LRTK to mega-solar surveying enables one person to efficiently complete everything from topographic surveys of vast sites to stakeout positions and as-built management. Moving away from traditional methods that relied on heavy machinery and veteran surveyors, smartphone surveying accessible to anyone can rapidly accelerate on-site DX. LRTK is already being used across diverse fields—construction and civil engineering, agriculture, disaster prevention, infrastructure management—and its effectiveness is being demonstrated. As the key to realizing a new era of surveying completed with a single smartphone, LRTK should become a strong partner for mega-solar operators. Advanced companies have already begun adopting smartphone surveying, leading to improvements in productivity and competitiveness. The use of such new technologies will become indispensable for future mega-solar projects. Why not take this opportunity to consider smartphone surveying and introduce the next-generation surveying style to your sites?