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

At the recently held Solar Power Generation Expo (PV EXPO), a new surveying solution that combines smartphones with high-precision GNSS attracted significant attention. The backdrop to this interest is the construction industry's chronic labor shortage and growing demand for productivity improvements, which drive heightened expectations for labor-saving technologies. This technology is expected to dramatically streamline surveying operations at solar power plant construction sites, delivering time savings and labor reduction. In this article, we explain the background of growing interest in smartphone × high-precision positioning technology at the Solar Expo, the surveying, piling, and layout-design challenges in solar power plant construction and their solutions. We also summarize, from a field perspective, how much change a smartphone + high-precision GNSS receiver can bring to the site, the differences and comparative use cases versus conventional surveying instruments like 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 finally introduce a simple surveying solution using LRTK.

Growing attention to smartphone × high-precision positioning technology at the Solar Expo

At the Solar Expo, a specialized exhibition for solar power generation, attention is focused not only on panels and storage batteries but also on digital technologies that contribute to more efficient power-plant construction. Especially at this year's expo, surveying technology that combines smartphones and high-precision GNSS positioning drew many visitors' eyes. For surveying large mega-solar sites and marking piling positions, this "smartphone × high-precision GNSS surveying" can enable dramatic labor savings. If surveying work that used to take several people and many days can be completed in a short time and with few personnel using just a single smartphone and a compact GNSS receiver, it's a must-see innovation for contractors and designers. Companies are accelerating initiatives with on-site DX in mind, and smartphone surveying is a representative example of that trend. In fact, booths at the Solar Expo featured demonstrations of real-time surveying using smartphones, garnering strong attention as a technology that leads to reduced labor and shorter construction periods.

Surveying, piling, and layout-design challenges in solar power plant construction

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

• Vast sites require enormous time and personnel for surveying: For mega-solar scale areas, conventional surveying using total stations or typical GNSS equipment can take several days to several weeks to measure the entire site. Survey teams of two or more personnel may be tied up, and in uneven terrain additional time is needed for relocating equipment and ensuring line-of-sight.

• Heavy dependence on highly skilled specialists: Setting up and operating total stations and adjusting survey data and converting it into CAD drawings require experienced surveyors’ skills, forcing reliance on a limited number of senior staff within a company. With advancing labor shortages, surveying work has become person-dependent, creating the risk that projects stall when the responsible person is absent. Outsourcing to external surveying firms is also costly, making frequent re-surveying impractical.

• Inefficient processing and sharing of survey data: Traditionally, survey results obtained on-site were handwritten in field notebooks and later entered into a computer and converted into drawings back at the office. Manually organizing large sets of point data is laborious and prone to recording or transcription errors. Additionally, on-site measurement information could not be shared in real time with designers or other stakeholders, causing feedback delays from surveying to design and construction that contributed to schedule extensions.

Thus, solar power plant surveying has faced a dual challenge of the “surveying burden caused by large sites” and the “inefficiency of conventional methods.”

How smartphone + high-precision GNSS will change the field

A trump card to solve the above challenges is one-person surveying using a smartphone combined with high-precision GNSS (RTK method). By attaching a pocket-sized RTK-GNSS receiver to a smartphone, this "smartphone RTK" approach enables centimeter-level positioning and is rapidly transforming surveying at solar power plant sites. The biggest change is that surveying work can shift from requiring multiple people to being “completed by one person.” Holding a smartphone with a receiver, you can walk to the point you want to measure and tap a button on the screen to instantly record the high-precision coordinates of that point. There is no need to carry heavy tripods or prisms, nor to spend time on complex equipment setup. One person can measure point after point, so work time is dramatically reduced, speeding up the overall construction schedule. As long as the sky is visible, positioning is possible anywhere on vast sites, and cases have emerged where survey work that used to take days can be completed in half a day to one day.

Smartphone surveying also excels in balancing measurement accuracy and usability. With RTK, the typical smartphone GPS error of 5–10 m is reduced to around ± a few centimeters, making it suitable for precise measurements like panel installation locations. Vertical accuracy is also around ±3 cm, allowing accurate surveying that includes elevation even on highly undulating sites. At the same time, operation is intuitive: the smartphone app automatically handles complex calculations and specialist equipment settings. Coordinate system transformations and geoid height corrections can be completed with a single tap, so non-experts can perform accurate surveys. Digital support replaces parts that depended on veteran intuition and experience, allowing junior staff to be trained to handle on-site surveying in a short time. In other words, introducing smartphone + high-precision GNSS makes significant efficiency gains and labor savings in surveying a practical reality.

Differences from conventional surveying equipment (total stations, etc.)

Surveying with smartphone + high-precision GNSS takes a very different approach from conventional total stations (TS) and large GNSS survey instruments. The biggest differences are "survey mobility" and "required personnel." Total stations are optical instruments that measure targets with millimeter-level precision, but after being set up they can only measure within line-of-sight, requiring tripods to be moved and reset to cover large sites. Typically, one person operates the TS while another person holds a prism at a distant survey point—work done by a two-person team (robotic TS can be operated by one person but are very expensive). In contrast, smartphone + GNSS receives signals from satellites, so positioning is possible anywhere with a view of the sky, and points can be collected continuously while moving across the site. The larger the survey area, the more advantage smartphone GNSS has in mobility compared to stationary TS. In addition, because the equipment can be carried and operated by a single person, team organization and personnel adjustments are unnecessary.

In terms of survey accuracy, the practical difference is also minimal. While TS offers extremely high relative accuracy (angle and distance measurement precision), smartphone RTK— as noted earlier—achieves absolute accuracy at the centimeter level, which is sufficient for tasks such as solar panel installation and pile positioning. GNSS surveying also has the advantage of capturing positions in a global coordinate system, making it easier to place survey results directly into maps and design coordinates (with TS, aligning measured points with drawing coordinates requires matching known points and coordinate transformations). Regarding use-case differences, total stations excel at detailed measurements of building foundations and structural elements, and in indoor or tunnel environments where satellites are unavailable. Meanwhile, for wide-area outdoor measurements like solar power plants, the flexibility and ease of smartphone + GNSS prevail. Although GNSS surveying can be difficult in forests or other areas where satellite signals are blocked, recent receivers support supplemental signals (CLAS) provided by Japan’s Quasi-Zenith Satellite System "Michibiki," enabling centimeter-level positioning even at mountain sites without mobile network connectivity.

Overall, there is a distinction between "smartphone GNSS for rapid wide-area surveying" and "TS for localized high-precision work," and in many solar power plant scenarios the former is a highly suitable choice.

Benefits for design and construction companies

Introducing smartphone × high-precision GNSS surveying brings various benefits to contractors and design firms, beyond on-site work efficiency. Summarized from a field perspective, the main advantages are:

• Improved work speed and cost reduction: Surveying days are greatly reduced and the burden of personnel arrangements is eased. Resources can be reallocated to other tasks, shortening overall construction periods. For projects that previously outsourced surveying, direct cost savings can be realized. Completing surveys quickly with fewer people also contributes to earlier plant commissioning and revenue realization.

• Efficient data management and sharing: With smartphone surveying, acquired point data can be saved and shared to the cloud on the spot, preventing transcription errors from field notebooks or later data entry. Designers at the office can review data immediately after measurement and promptly revise layouts or proceed to the next step, eliminating time loss in information transmission. Centralized digital data management also smooths progress visualization and report preparation.

• Improved surveying accuracy and quality: Since the app automatically calculates and records data, human error risks are reduced. Stable quality surveying is possible without relying on veteran intuition, preventing rework and construction deviations due to positioning errors. Real-time verification of measurements on-site allows immediate detection and correction of omissions or inconsistencies, leading to overall improvements in as-built accuracy and construction quality.

• Support for training and utilization of younger staff: Simple operation means non-senior staff can become proficient quickly. This helps break dependence on a few people who could previously be entrusted with surveying, making it easier to turn young employees and newcomers into productive staff. The burden of skill transfer is reduced, enabling stable surveying operations even as generations change. Single-person operations also have safety benefits: reducing manpower lowers the risk of accidents on hot days or steep slopes and fits modern remote-work and contactless work styles.

Accelerating on-site DX through cloud integration and AR use

Surveying with smartphones and high-precision GNSS is not just about measuring point coordinates; it is linked with various functions that accelerate on-site digital transformation (DX). The leading examples are cloud integration and the use of AR (augmented reality). As mentioned, immediate cloud sharing of survey data enables real-time information exchange between the field and the office, transforming construction management practices. For example, terrain data or pile coordinates measured on-site can be shared with the design department via the cloud and, if needed, design corrections can be made on the spot and fed back to the field—enabling a seamless PDCA cycle. Compared to the era of paper drawings or carrying data on USB memory sticks, this creates a much faster and less error-prone workflow.

Moreover, AR-enhanced field work is an important DX trend. By overlaying design drawings or 3D models on live camera images on a smartphone screen, the digital and the field become directly connected. For instance, if a layout diagram or 3D model of the mounting structure is uploaded to the cloud in advance, merely pointing the smartphone on-site can display virtual installation positions on the ground. This enables operators to intuitively confirm piling and equipment placement using AR navigation. On large development sites, on-screen arrows and markers guide users to pile locations without confusion, dramatically reducing layout marking time. After construction, comparing the as-built layout to the plan on AR makes discrepancies immediately apparent, aiding rework prevention and quality inspection. AR is also useful for sharing the completed image with all stakeholders on-site to quickly build consensus.

In this way, smartphone × high-precision GNSS surveying becomes a core element of on-site DX when combined with cloud and AR technologies. The Ministry of Land, Infrastructure, Transport and Tourism’s "i-Construction" initiative promotes ICT construction and electronic delivery as part of its policies, encouraging the use of high-precision GNSS and 3D data, and smartphone surveying fits squarely within this trend. Such government-backed digital technologies are likely to become increasingly standard on worksites.

Realizing time savings and labor reduction with simple surveying using LRTK

As described above, surveying technology using smartphones and high-precision GNSS delivers great benefits on solar power sites. You may wonder, "How exactly should we introduce it?" To conclude, we introduce our LRTK as a simple surveying solution that makes smartphone surveying easy to implement. LRTK is a surveying system developed by Lefixea Inc., a venture from Tokyo Institute of Technology, consisting of a compact RTK-GNSS receiver and a dedicated smartphone app. The LRTK smartphone app includes features that automatically plot positioned points on a cloud map for sharing, import design drawings and navigate to piling points, and combine with the smartphone’s LiDAR sensor to capture detailed 3D point clouds—a variety of capabilities that strongly support on-site DX. Used with an iPhone or iPad, the device instantly converts the terminal into a centimeter-precision surveying instrument. Preparation is complete simply by attaching a device weighing only a few hundred grams to the smartphone, then following the app prompts and pressing the positioning button. It functions as an all-in-one surveying tool that allows a single person to perform coordinate guidance for piling positions, point-cloud scanning, and AR projection of design data while moving around the site.

LRTK is already being utilized on various civil engineering and construction sites, with feedback such as "surveying work now takes less than half the time it used to" and "non-specialist young employees could handle it without issue." Data is automatically linked to the cloud, making real-time sharing of survey results between the field and the office straightforward. 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 simple surveying with LRTK. Product specifications and case studies are available on the [LRTK official site](https://www.lrtk.lefixea.com/lrtk-phone). For specific one-person surveying use cases at work sites, see the [case study article introducing real-world examples](https://www.lrtk.lefixea.com/blog-js/2oneman-survey1). With just a smartphone and a small receiver, it’s easy to get started, and the intuitive operation makes deployment straightforward so that the system can be used as an immediate asset on site. Reducing the burden of surveying lets you reassign freed personnel and time to other important tasks, improving overall site productivity. Why not transform your surveying style with LRTK and spark a new efficiency revolution in your solar power plant projects? Now is the perfect opportunity to step into surveying DX.