Dramatic Efficiency Gains in Mega-Solar Surveying! Easy Single-Person Measurement with Smartphone RTK

Surveying the site is an indispensable step in the construction and operation of mega-solar (large-scale solar power plants). However, for mega-solar sites that span several hectares to tens of hectares, traditional methods have tended to require a great deal of time and manpower. There have been cases where multiple-person survey teams spend days using total stations or GNSS surveying equipment, creating significant burdens in terms of labor costs and scheduling. High-precision surveying often relies on the skill of experienced technicians, meaning surveying work can become personnel-dependent.

Amid this situation, a new surveying method that leverages smartphones and RTK (Real-Time Kinematic) positioning technology is attracting attention. By attaching a compact RTK-GNSS receiver to a smartphone to enable centimeter-level positioning—so-called "smartphone RTK"—mega-solar surveying can be dramatically streamlined, making precise measurements easy for a single person. Streamlining surveying processes also shortens construction schedules, which is important for securing revenue by bringing mega-solar projects online sooner. This article explains in detail the innovations smartphone RTK brings to mega-solar surveying from the perspectives of simplifying surveys, eliminating personnel dependence, reducing labor costs, and shortening project timelines.

Challenges of Conventional Methods in Mega-Solar Surveying

Mega-solar surveying serves various purposes. For example, topographic surveys for site selection and current-condition surveys for grading plans; stake layout for placing solar panels (staking may require accurately placing thousands of stakes depending on project scale); inspections of as-built results after construction and earthwork volume calculations. While there is a need to measure extensive areas accurately, conventional surveying methods have faced the following challenges:

• Large sites require significant time and manpower: For areas on the scale of mega-solar sites, the survey area is so vast that pole-and-staff surveys with a total station or conventional GNSS surveys across the entire area can take days to weeks. Surveys typically require teams of two or more people, and measurement efficiency drops further in mountainous terrain or other areas with poor lines of sight.

• Advanced specialized skills are required: Setting up a total station and adjusting/processing measurement data for drawing requires specialized knowledge, often relying on skilled surveyors. With a growing shortage of personnel, securing experienced staff is difficult, creating a risk that tasks become dependent on specific individuals. Outsourcing can be costly, making frequent survey updates difficult.

• Inefficient data processing and sharing: Traditionally, survey results are recorded in field notebooks and then entered into a PC and drawn up after returning to the office. Surveys of large sites generate large volumes of data, and manual organization takes time. Point data obtained on-site cannot be shared immediately with stakeholders, creating a time lag between surveying and feedback to design and construction, which can delay the overall project schedule.

As described above, mega-solar surveying faced a double challenge of "surveying burden due to large area" and "inefficiency of conventional methods."

The Era of Single-Person Surveying Opened by Smartphone RTK

A solution emerging to address these challenges is a surveying method that utilizes smartphone RTK. Smartphone RTK refers to a technology that attaches a pocket-sized high-precision GNSS receiver to a smartphone to enable real-time centimeter-level positioning. RTK positioning uses correction information delivered from known reference points such as electronic reference stations, and by combining signals from multiple satellites like GPS and QZSS (Michibiki), it reduces standalone positioning errors that were several meters down to a few centimeters. RTK surveying, which used to require fixed, expensive equipment, can now be achieved easily with a smartphone and a small receiver.

Introducing smartphone RTK into the field is expected to bring the following revolutionary changes to mega-solar surveying:

• Easy and fast surveying by a single person: With smartphone RTK, survey tasks that previously required two to three people can be completed by one person. Simply carry the smartphone with the receiver attached to the point you want to measure and tap a button on the screen to record high-precision coordinates. There is no need to carry heavy tripods or prisms, enabling many points to be measured in a short time. Compared with conventional methods, work time can be drastically reduced, directly speeding up the overall construction process. Since positioning is possible anywhere with a visible sky, even on very large solar power sites, the hassle of setting up equipment or moving between setups for surveying is greatly reduced.

• Intuitive operation that does not rely on specialist skills: Smartphone app-based surveying offers easy-to-understand interfaces, with the app handling specialized calculations and complex instrument operations. Processes such as conversion to the plane rectangular coordinate system and geoid corrections for elevation are automated, allowing accurate surveying even without experienced personnel. On-site staff, including younger workers, can master the tools with short training, reducing the burden of skills transfer and education. Eliminating expertise as a bottleneck ensures stable surveying quality even when personnel change, removing personnel dependence.

• Real-time cloud sharing and immediate utilization: Measurement points and observation data collected with smartphone RTK can be uploaded to the cloud and shared on the spot. Immediately after field surveying, office PCs can check the data and reflect it in design drawing revisions or construction plan adjustments, enabling process shortening. Because data are managed digitally in a centralized way, errors from handwriting in field notebooks or later transcription mistakes are prevented. Smoother information linkage between surveying and design/construction improves project-wide efficiency.

There are also cost benefits. Handheld GNSS receivers used with smartphone RTK are less expensive than traditional total stations or dedicated surveying GNSS units, and because existing smartphones can be used, initial investment is significantly reduced. There is no need to purchase multiple expensive devices, and operations such as equipping every field staff member with a smartphone RTK unit become realistic. This leads not only to labor cost reductions but also savings on equipment rentals and outsourcing. Costs previously incurred when commissioning external surveying companies may be eliminated, enabling quick recovery of the introduction cost and providing substantial management benefits.

Main Functions and Benefits Achievable with Smartphone RTK

A range of features once unthinkable can now be realized on a single smartphone thanks to smartphone RTK solutions. Below are the main functions and benefits particularly useful at mega-solar sites.

• Centimeter-level high-precision positioning: Using RTK corrections, GPS errors that were 5–10 m in standalone mode can be reduced to about ±1–2 cm. Stable accuracy can be achieved even in mountainous areas away from reference points, and vertical positioning is possible to around ±3 cm. Even on vast solar power sites, the exact positions of each panel can be measured and managed, contributing to improved construction accuracy.

• Guidance to stake coordinates (staking layout): If coordinate data from design drawings are imported into the smartphone, the app can navigate the user to the point and indicate where to place stakes. As you approach the target coordinates, the app provides audio cues and on-screen guidance, directing you to the exact point for staking. This enables quick and accurate stake layout across large grading areas, dramatically improving layout efficiency.

• 3D point cloud scanning and earthwork volume calculation: Modern smartphones include LiDAR scanners and high-performance cameras, and dedicated apps can capture surrounding structures and terrain as 3D point cloud data. When combined with smartphone RTK, each point in the model is assigned accurate coordinates, allowing generation of high-precision 3D models without distortion during scanning. For example, scanning terrain before and after grading enables automatic calculation of volumetric differences for fill and cut, aiding daily earthwork management. Obtained point clouds can be exported to CAD software or CIM systems, further promoting data linkage from surveying to design and construction.

• On-site display of design information with AR: AR (augmented reality) display functions that overlay design data on live camera imagery are gaining attention. Uploaded plans or 3D models can be projected onto the actual site view, allowing intuitive verification that construction matches the design. For instance, you can visually check through the smartphone whether mounting structures or panel layouts match the drawings, helping prevent rework and supporting quality control. Overlaying the completed image on-site also aids stakeholder explanations and consensus building.

• Geotagged photos with chronological management: Smartphone RTK automatically records high-precision coordinates and orientation with photos, which can be organized and viewed in the cloud. If photos taken from the same point are displayed chronologically, it becomes easy to review construction progress and equipment changes later. Photo management linked to survey data is powerful for report creation and stakeholder sharing, making on-site visualization and information sharing more efficient.

• Positioning even outside communication coverage: Many mega-solar sites are built in mountainous areas where cellular coverage may be absent. However, the latest smartphone RTK receivers support Japan’s QZSS (Michibiki) "CLAS" satellite augmentation signals, enabling centimeter-level positioning even where mobile networks are unavailable. This allows stable surveying operations without depending on communication infrastructure.

• Cloud sharing and web browsing: Surveying data, point clouds, and photos obtained on a smartphone are immediately saved to the cloud and can be viewed and shared via web browsers. Without dedicated software, office PCs can display site data in 3D or measure distances, areas, and volumes between points as long as an internet connection is available. This enables real-time sharing of the latest survey information with remote project stakeholders and speeds up decision-making.

As described above, smartphone RTK offers numerous functions that directly contribute to survey simplification (anyone can easily measure), elimination of personnel dependence (not relying on specific experts), labor cost reduction (efficient work with fewer people), and process shortening (fast data utilization). It balances the accuracy and speed required for mega-solar surveying and supports safe and reliable construction management as a powerful tool.

:contentReference[oaicite:0]{index=0}A scene showing the smartphone RTK app’s coordinate navigation function guiding a stake point. Following the on-screen guidance, even inexperienced workers can reach the target point without hesitation. Moreover, by combining broad-scale terrain models created from drone photogrammetry with detailed survey point data and point clouds acquired with smartphone RTK, it is possible to construct an integrated digital surveying workflow from the air to the ground. Connecting data from ground staking to as-built management is expected to further accelerate DX (digital transformation) on mega-solar sites. This also aligns with the Ministry of Land, Infrastructure, Transport and Tourism’s proposed i-Construction (improving construction productivity using ICT), making smartphone RTK a representative new technology of on-site DX.

Dramatic Efficiency Gains in Smartphone Surveying with LRTK

One concrete tool for implementing smartphone RTK is a solution called LRTK. :contentReference[oaicite:1]{index=1}A pocket-sized LRTK receiver attached to an iPhone. By attaching it with a dedicated case in one touch, the smartphone quickly becomes a high-precision surveying device. LRTK is a smartphone-mounted RTK positioning device developed by a startup spun out of Tokyo Institute of Technology; attaching it to an iPhone or iPad transforms the device into a high-precision surveying instrument. Although pocket-sized—weighing only about 125 g and about 1 cm thick—it includes an internal battery that allows approximately 6 hours of continuous measurement. It can be attached in one touch via a dedicated case, and with an optional monopod (pole) it is comfortable to measure elevations and perform staking work. Its pocketable convenience means it can be carried at all times and quickly used when needed, which is a significant advantage on-site. In addition, its multi-frequency, high-sensitivity antenna provides stable accuracy, and because it supports the aforementioned Michibiki CLAS, it can maintain precision even outside communication coverage. There have been reports confirming high accuracy in environments where GNSS reception is unstable, such as under forest canopy, demonstrating LRTK’s positioning performance and stability.

By utilizing LRTK, the features introduced in this article—centimeter-precision positioning, stake guidance, point cloud scanning, AR display, photo recording, cloud sharing—can be obtained in an all-in-one package. It has quietly become popular at civil engineering sites as a "one smartphone per person" surveying tool, and cases have been reported where on-site personnel performing their own surveys have dramatically improved productivity. For example, at sites where work had been halted waiting for surveys, after introducing LRTK on-site staff were able to perform the necessary surveys immediately, eliminating wait times and smoothing construction. In mega-solar surveying, introducing smartphone surveying with LRTK can realize easy surveying that anyone can use, leading to shorter schedules, cost reductions, and improved quality. In the near future, it may become commonplace to see workers surveying with a smartphone in hand at mega-solar sites. If you are struggling with surveying tasks, consider adopting these latest smartphone RTK solutions.