Smartphone × High-Precision GNSS Surveying Draws Attention at the Solar Power Expo: Achieving Time Savings and Labor Reduction

At the recent Solar Power Exhibition (PV EXPO), a new surveying solution that combines smartphones with high-precision GNSS attracted significant attention. The backdrop for this interest is the construction industry’s chronic labor shortage and the growing need to improve productivity, which has heightened expectations for technologies that reduce labor. This technology is expected to dramatically streamline surveying work at solar power plant construction sites, achieving both time savings and labor reduction. This article explains the background of the growing interest in smartphone × high-precision positioning technologies at the Solar Power Expo, the challenges of surveying, stake-driving, and layout design in solar power plant construction and their solutions. It also summarizes—from a field perspective—how much change a smartphone plus a high-precision GNSS receiver can bring, the differences and use-case comparisons with traditional surveying instruments such as total stations, and the benefits for design and construction companies. We touch on the trend of on-site DX including cloud integration and AR (augmented reality) technologies, and conclude by introducing a simple surveying solution using LRTK.

Growing Interest in Smartphone × High-Precision Positioning Technology at the Solar Power Expo

At the Solar Power Expo, an exhibition specializing in solar power generation, attention is focused not only on panels and storage batteries but also on digital technologies that lead to more efficient plant construction. Especially at this year’s expo, surveying technology that combines a smartphone and high-precision GNSS positioning drew many visitors’ eyes. For site surveys and stake-driving position setting of vast mega-solar (large-scale solar power plants), this “smartphone × high-precision GNSS surveying” can enable dramatic labor savings. If surveying work that used to require multiple people and several days can be completed quickly and with few people using just a single smartphone and a compact GNSS receiver, it is an innovation contractors and designers cannot ignore. Companies are accelerating initiatives with on-site DX in mind, and smartphone surveying is a representative example of this trend. In fact, demonstrations of real-time surveying using smartphones were held at booths at the Solar Power Expo and drew high attention as a technology that can contribute to labor reduction and shorter construction schedules.

Challenges in Surveying, Stake-Driving, and Layout Design for Solar Power Plant Construction

When constructing ground-mounted solar power plants (mega-solar), various surveying and design tasks are required from before construction begins. These include surveying the existing terrain during site selection, calculating earthwork volumes for development planning, staking out positions for piles according to the solar panel layout (requiring accurate placement of hundreds to thousands of piles), and post-construction as-built inspections. In these processes, the inefficiency of traditional, labor-intensive surveying has been a recurring issue. Specific challenges include the following:

• Wide sites require enormous time and personnel for surveying: For areas the size of a mega-solar site, conventional surveying using total stations or general GNSS equipment can take several days to several weeks to measure the entire site. Survey teams of two or more staff are tied up, and hilly terrain requires additional time for relocating equipment and ensuring line-of-sight.

• Tendency to rely on highly skilled specialists: Setting up and operating a total station and adjusting and converting surveying data into CAD drawings require experienced surveyors, forcing reliance on a limited number of senior staff within a company. With an advancing labor shortage, surveying work has become person-dependent, creating risk that progress halts when the responsible technician is absent. Outsourcing to surveying firms is costly, making frequent re-surveying difficult.

• Inefficient processing and sharing of survey data: Traditionally, field survey results were handwritten in field notebooks and later input and converted to drawings back at the office. Organizing large sets of survey point data manually is time-consuming and prone to recording or transcription errors. Moreover, survey data measured on-site could not be shared in real time with designers or other stakeholders, causing feedback delays from surveying to design and construction and contributing to schedule delays.

Thus, surveying for solar power plants has faced a double challenge of “surveying burden due to large site areas” and “inefficiencies of traditional methods.”

How the Field Changes with a Smartphone + High-Precision GNSS

A trump card to solve the above issues is one-person surveying using a smartphone combined with high-precision GNSS (RTK). By attaching a pocket-sized RTK-GNSS receiver to a smartphone, this “smartphone RTK” method enables centimeter-level positioning and is transforming surveying at solar power plant sites. The biggest change is that surveying work can shift from a multi-person assumption to being “completed by a single person.” Carry a smartphone with a receiver and walk to the point you want to measure, tap a button on the screen, and the high-precision coordinates of that point are instantly recorded. There’s no need to carry heavy tripods or prisms, and time-consuming equipment setup is eliminated. Because one person can measure point after point, work time is dramatically reduced, and overall construction schedules are accelerated. As long as the sky is open, positioning can be performed anywhere on large sites, and cases have been reported where surveying that used to take several days is completed in half a day to one day.

Smartphone surveying also excels in balancing measurement accuracy and usability. With RTK, the GPS error that used to be 5–10 m on smartphones is tightened to about ± several centimeters, making it sufficient for precise measurements such as panel placement. Vertical accuracy can be measured to approximately ±3 cm (±1.2 in), so accurate surveying including elevation is possible even on sites with large terrain undulations. At the same time, operation is intuitive: complicated calculations and instrument settings are automatically handled by the smartphone app. Coordinate system transformations and geoid height corrections (height adjustments) can be done with the press of a button, enabling accurate surveying even by non-experts. Digital support for aspects that used to rely on veteran intuition and experience allows younger staff to handle on-site surveying after only short training. In other words, introducing smartphones plus high-precision GNSS makes major efficiency improvements and labor reductions in surveying a practical reality.

Differences from Traditional Surveying Instruments (Total Stations, etc.)

Surveying with a smartphone + high-precision GNSS differs greatly in approach from the traditionally dominant total stations (TS) and large GNSS surveying instruments. The biggest differences are “survey mobility” and “required personnel.” Total stations measure targets optically and boast millimeter-level high precision, but once installed they can only measure within line-of-sight, requiring tripods to be moved and re-set to cover wide sites. Typically, TS work required a two-person team—one operating the TS and another holding a prism at distant points (robotic TS can be operated by one person, but are very expensive). In contrast, smartphone + GNSS receives signals from satellites, so as long as the sky is visible you can position anywhere and collect points continuously while moving across the site. The wider the survey area, the more advantage this mobility has over a stationary TS. Additionally, because it can be carried and operated by a single person, no team formation or personnel coordination is necessary.

In terms of measurement accuracy, the practical differences are minimal. While TS offers extremely high relative accuracy (angle and distance measurement precision), smartphone RTK achieves absolute accuracy of a few centimeters as noted above, sufficient for tasks like solar panel installation and pile positioning. Moreover, GNSS surveying acquires positions in a global coordinate system, making it easier to place survey results directly into maps and design coordinate systems (with TS, matching measured points to drawing coordinates requires ties to known points and coordinate transformations). As for use cases, total stations shine at detailed measurements of building foundations and structures, or in indoor and tunnel environments where satellites are not usable. On the other hand, for outdoor, wide-area measurements like those at solar power plants, the flexibility and ease of smartphone + GNSS often prevail. Although GNSS surveying can be difficult in forests or other areas where satellite signals are blocked, recent receivers support augmentation signals such as Japan’s Quasi-Zenith Satellite System Michibiki CLAS, enabling centimeter-level positioning even at mountain sites where mobile networks are unavailable.

Overall, the difference is between “smartphone GNSS for rapid wide-area surveying” and “TS for locally concentrated high precision,” and the former often fits solar power plant sites particularly well.

Benefits for Design and Construction Companies

Introducing smartphone × high-precision GNSS surveying brings various benefits not only to on-site efficiency but to the overall operations of construction and design companies. Summarized from a field perspective, the main advantages are:

• Improved work speed and cost reduction: Surveying days are drastically reduced, and the burden of personnel arrangement is lessened. This frees resources for other tasks and shortens overall construction schedules. For cases where surveying was outsourced, direct cost savings are realized. Quick, small-team surveying and earlier plant commissioning contribute to earlier revenue generation.

• Improved data management and sharing efficiency: Smartphone surveying allows acquired point data to be saved and shared to the cloud on site, preventing transcription errors from field notebooks and later data entry mistakes. Designers in the office can review data immediately after surveying and promptly revise layouts or move on to the next process, eliminating information transmission time losses. Centralized digital data management also facilitates progress visualization and report creation.

• Improved surveying accuracy and quality: Because the app automatically calculates and records data, the risk of human error is reduced. Stable quality can be achieved without relying on veteran intuition, preventing rework and construction misalignment due to incorrect positioning. Real-time verification of measurements on site allows immediate detection and correction of omissions or inconsistencies. As a result, the final accuracy and construction quality are improved.

• Contribution to personnel development and effective use of young staff: Simple operation enables non-veterans to handle the equipment after short training. This breaks the situation where only a few people could be entrusted with surveying, making it easier to make young employees and new hires effective. Reducing the burden of skills transfer helps maintain steady surveying operations amid generational change. Single-person workflows also have safety benefits: reducing manpower lowers accident risks in extreme heat or on steep slopes, and fits remote or contactless working styles increasingly in demand.

Accelerating On-Site DX with Cloud Integration and AR

Surveying using smartphones and high-precision GNSS is not simply about measuring point coordinates but connects to various functions that accelerate on-site digital transformation (DX). Representative examples are cloud integration and AR (augmented reality) utilization. As noted, survey data can be shared to the cloud immediately, enabling real-time information sharing between the site and the office and transforming construction management styles. For example, terrain data or pile coordinates measured on site can be shared with the design department via the cloud, and design adjustments can be made and fed back to the site as needed—enabling a seamless PDCA cycle. Compared with the era of paper drawings or carrying data on USB drives, this workflow is far faster and less error-prone.

Moreover, using AR to enhance on-site work is another important DX trend. By overlaying design drawings or 3D models on live camera images on the smartphone screen, the digital and the field are directly connected. For example, if you upload panel layout drawings or 3D models of support frames to the cloud in advance, simply pointing a smartphone at the ground can display virtual installation positions. This lets workers intuitively confirm stake-driving and equipment placement using AR navigation. On large development sites, arrows and markers on the screen guide users to stake positions without getting lost, dramatically reducing layout marking time. After construction, comparing the completed equipment placement with the plan via AR makes it immediately clear whether the installation matches the drawings. AR is effective for preventing rework and for quality inspection, and is useful as a tool to share the completed image on site and achieve stakeholder consensus.

Thus, smartphone × high-precision GNSS surveying, combined with cloud and AR technologies, becomes a core element of on-site DX. Japan’s Ministry of Land, Infrastructure, Transport and Tourism promotes “i-Construction,” encouraging the use of ICT construction and electronic delivery as part of leveraging high-precision GNSS and 3D data, and smartphone surveying is precisely a solution aligned with this trend. Such government-led digital technologies are likely to become standard practice on sites going forward.

Realizing Time Savings and Labor Reduction with Simple Surveying Using LRTK

As described above, surveying technology using smartphones and high-precision GNSS yields great effects at solar power generation sites. You may be wondering, “How exactly should we introduce it?” To close, we introduce our simple surveying solution, LRTK. LRTK is a surveying system comprising a compact RTK-GNSS receiver and a dedicated smartphone app, developed by Refixea Inc., a venture originating from Tokyo Institute of Technology. The LRTK smartphone app includes a variety of powerful features that support on-site DX: functions that automatically plot measured points on a cloud map for sharing, functions that import design data and provide navigation to pile locations, and functions that combine with a smartphone’s LiDAR sensor to capture detailed 3D point clouds. Used with an iPhone or iPad, the device instantly becomes a centimeter-precision surveying tool. Preparation is complete by simply attaching a device weighing just a few hundred grams to the smartphone, then following the app’s instructions and pressing the positioning button. It functions as an all-in-one surveying tool that enables a single person to perform on-site coordinate guidance for pile-driving positions, point-cloud scanning, and AR-based projection of design data.

LRTK is already being used on various civil engineering and construction sites, with feedback such as “surveying work took less than half the time it used to” and “even non-specialized young employees could handle it without issues.” Data is automatically linked to the cloud, making real-time sharing of survey results between the field and the office easy. You can immediately experience the time savings and labor reduction effects discussed in this article.

If you are interested in smartphone × high-precision GNSS surveying, please check the details of our simple surveying solution, LRTK. Product specifications and case studies are available on the [LRTK official site](https://www.lrtk.lefixea.com/lrtk-phone). For concrete use cases of one-person surveying, the [case study article](https://www.lrtk.lefixea.com/blog-js/2oneman-survey1) introducing on-site examples may also be helpful. With the simplicity of starting with just a smartphone and a small receiver and the intuitive operability that makes deployment easy, LRTK can be put into service as an immediate, practical tool. Reducing the burden of surveying work lets you allocate freed personnel and time to other important tasks, improving overall site productivity. Transform your surveying style with LRTK and spark a new efficiency revolution in your solar power plant projects. Now is the perfect time to step into surveying DX.