No Special Equipment Required: LRTK Enables PVsyst-Compatible High-Precision Smartphone Surveying

In designing solar power plants, detailed on-site survey data is indispensable for accurately understanding sunlight conditions affected by site topography and surrounding obstructions. However, traditionally, high-precision surveying has required special surveying equipment and specialized expertise—such as total stations, RTK-GPS units, and drone surveys—and small-scale projects have sometimes omitted sufficient surveying for cost reasons. If high-precision surveying with a single smartphone were possible, it would become easy to obtain on-site data and reflect it in designs, leading to optimized layouts for solar PV systems and improved accuracy in power generation forecasts. This article explains how to acquire and utilize high-precision survey data compatible with simulations in PVsyst using the smartphone-mounted device “LRTK,” which leverages real-time kinematic positioning technology. From on-site constraints and the challenges of conventional methods to the principles and characteristics of LRTK technology, a concrete smartphone-based surveying workflow, applications of the resulting point cloud data for shadow analysis, and the impact on the design process, we detail the potential that end-to-end smartphone surveying can bring.

Challenges of Conventional Surveying Methods and On-Site Constraints

In the planning stage of a solar power plant, it is important to assess in advance the impact of the site’s terrain and surrounding buildings and trees. However, conventional surveying methods have the following challenges.

• Specialized equipment and personnel required: High-precision surveying required equipment such as total stations, high-performance GNSS receivers, and drones, and operating them demanded skilled survey technicians. On extensive sites, securing survey points often required multiple people, and preparation and setup were time-consuming.

• Cost and schedule burdens: Procuring surveying equipment or contracting external vendors incurs costs, and coordinating survey schedules is also necessary. In particular, for mountainous or remote sites, the cost of transporting equipment and deploying personnel is high, which has led small-scale projects to sometimes forgo adequate surveying.

• Variation in data accuracy: As a convenient alternative, relying on topographic maps, satellite imagery, or ordinary smartphone GPS can result in position and elevation errors on the order of meters. Consequently, there is a risk of reduced simulation accuracy due to mismatches between actual terrain and design, or underestimation of shading from overlooked obstacles.

• Site constraints and safety: On sloped terrain or in areas with dense tree cover, surveying with conventional equipment can be difficult. Limited space for setting up tripods, or the need to enter hazardous areas to secure lines of sight, are examples of site constraints that can affect surveying accuracy.

Due to these challenges, solar power projects often cannot obtain sufficient surveying data in the early stages and later find themselves forced to correct terrain slopes or revise power generation forecasts. A more convenient and flexible surveying method was needed.

Principles and Features of LRTK Technology

What is changing this situation is LRTK, a smartphone-compatible RTK positioning technology that has emerged in recent years. RTK (Real-Time Kinematic) is a method in satellite positioning that uses simultaneous observation data from a base station (reference station) and a rover in real time to correct positioning errors, enabling position determination with centimeter-level accuracy.

While typical smartphone GPS has errors of several meters, RTK can improve accuracy to a few centimeters.

LRTK（エルアールティーケー） is a solution composed of a dedicated GNSS receiver and a smartphone app that delivers RTK positioning in a palm-sized form. For example, the “LRTK Phone” is an ultra-compact RTK-GNSS module that can be attached to the back of a smartphone (iPhone/Android), and by simply launching the dedicated app it immediately performs high-precision satellite positioning. There is no need for the cumbersome antenna setup or external power supplies associated with traditional fixed GNSS equipment; just attach the battery- and antenna-integrated device to your smartphone and the smartphone itself transforms into a surveying instrument.

The main features of LRTK technology are as follows:

• Centimeter-level positioning accuracy: Using an RTK method that leverages the phase differences of satellite signals, horizontal positions can be determined within a few centimeters and heights with similar centimeter-level accuracy. By using the averaging function, stable positioning results on the order of millimeters can also be obtained.

• Real-time and instant sharing: Positioning results can be checked in real time on the smartphone, allowing on-site accuracy verification. Collected data can be uploaded to the cloud immediately and shared instantly with design staff in the office.

• Simple one-person surveying: With a compact device weighing only about 150 grams, one person can easily carry out surveys. Recording measurement points is completed with button operations on the smartphone screen only, eliminating the multi-person angle-measurement and note-taking tasks traditionally required.

• Low cost and high ease of adoption: It is dramatically less expensive than conventional equipment, and with just a smartphone, additional devices are minimized. The user-friendly design allows field staff without special training to operate it intuitively.

• Positioning in global coordinate systems: The LRTK app automatically converts obtained latitude, longitude, and altitude into map coordinate systems such as the Japanese Geodetic Datum (JGD2011) and the World Geodetic System (WGS84). Measurement points can be output in coordinate systems convenient for design, such as plane rectangular coordinates, making it easy to import survey data directly into CAD or simulation software.

• Out-of-coverage support via CLAS: When using LRTK within Japan, it supports the centimeter-level augmentation service (CLAS) provided by the Quasi-Zenith Satellite System Michibiki, maintaining high-precision positioning via augmentation signals from the satellite even in areas with unstable internet connectivity such as mountainous regions.

• Versatile applications (photos, AR, point cloud measurement): You can tag photos taken with the smartphone camera with high-precision coordinates and save them to the cloud, or use the obtained coordinates for on-site AR positioning (layout marking), making applications beyond surveying possible. It also features the ability to capture 3D point cloud data with high-precision coordinates by combining with the smartphone's LiDAR scanner.

In this way, LRTK enables RTK surveying—which traditionally required specialized equipment—to be carried out easily by anyone, making “one smartphone per person” surveying a reality.

High-Precision Surveying Workflow Using Smartphone + LRTK

Now, let’s look at the specific steps for surveying a solar power plant site by combining a smartphone with LRTK. Below is an example of a smartphone-only surveying workflow.

• Preparations and planning: Attach the LRTK device to the smartphone and launch the dedicated app. Set the positioning mode to RTK and confirm reception of correction information (reference-station data via the network or CLAS signals). Pre-plan the survey area and measurement items (e.g., elevation variations of the terrain, positions and heights of obstructions).

• Measuring reference points and boundaries: Upon arrival at the site, first position the site boundaries and any known reference points. Acquire the coordinates of the start point, then record survey points by pressing the button on the smartphone screen at important corner or vertex points along the property boundary. Each survey point automatically saves coordinates (latitude, longitude, elevation) and a timestamp, and notes can be added if needed.

• Collecting terrain data: Walk the site to collect point data to capture elevation differences. The LRTK app also has a continuous positioning mode, which can automatically record coordinates at fixed intervals along the walking route. This provides many point samples representing the surface undulations. In areas with steep slopes or large steps, collect dense points to gather material for detailed terrain models.

• Measuring positions and heights of obstructions: If there are nearby obstructions that could cast shadows on solar panels (for example, tall trees, utility poles, adjacent buildings), measure their positions and heights as well. For position, approach the base of the object and use GPS positioning; for height, use the smartphone’s LiDAR or AR functions to measure relative height. For example, use the phone’s AR surveying feature to measure a tree’s height, or obtain a tree point cloud with a LiDAR scan and calculate the height later. Because LRTK ties each datum to geographic coordinates, the accurate spatial relationships can be reproduced when inputting the data into PVsyst as described below.

• 3D scanning with smartphone LiDAR (if needed): In addition to point measurements for terrain capture, if a more detailed on-site 3D model is required, acquire point cloud data using the smartphone’s built-in LiDAR sensor or camera photogrammetry. With LRTK, the phone’s position is continuously corrected with high accuracy during scans, so the resulting point cloud is assigned global coordinates and there is no concern about distortion or scale errors even over wide scan areas. The resulting color point clouds or 3D models are useful later for checking in design software or taking required measurements.

• Saving and sharing data: Upload the recorded survey point data and point clouds to the cloud from the LRTK app while still on site. In the office, simply access the cloud via a web browser to immediately review the latest data collected in the field. For example, survey points can be plotted on a cloud map where each point’s coordinates and notes can be viewed. Survey data can also be downloaded in CSV format, allowing designers to import it into PVsyst or other software on their workstations and begin analysis.

As described above, by leveraging LRTK you can complete everything from on-site surveying to data organization almost entirely with just a smartphone. The resulting geotagged photos and point clouds are useful as materials for subsequent processes, and can streamline workflows such as topographic map creation and report preparation that previously required additional time.

Data Integration with PVsyst and Application to Shading Analysis

High-precision data obtained with a smartphone plus LRTK can be imported into the photovoltaic simulation software PVsyst, enabling more realistic energy yield predictions and layout evaluations. PVsyst has a mechanism to treat shadows from nearby obstructions (buildings, trees near the array, etc.) separately from the effects of obstructions on the distant horizon (such as mountain ranges). By utilizing the acquired data as described below, the accuracy of shading analysis can be improved.

• Reflecting terrain data: Using elevation data measured on the site with LRTK, reproduce the site’s terrain model in PVsyst. For example, you can create contours or meshes from measured points and import them into PVsyst’s terrain import function to reflect terrain elevation differences in the 3D scene. This allows the height and tilt of panel rows on sloping ground to be set according to the actual terrain, making irradiance and shading calculations more accurate.

• 3D modeling of nearby obstructions: Utilize coordinate information obtained from surveying to place nearby buildings and trees in PVsyst’s 3D shading scene. For example, if you know the base coordinates and heights of trees on the south side of the site, you can place objects of equivalent height (cylindrical or rectangular prism models, etc.) at the same positions in PVsyst to faithfully reproduce their positional relationship with the panel array. This enables simulation of the actual shadows cast on panels by season and time of day, and quantitative evaluation of generation losses due to shading.

• Setting distant horizon shading: At solar power plants, surrounding ridges or forests can block low-angle sunlight in the morning and evening. If you use LRTK to measure the horizon elevation for each distant azimuth on site (for example, by pointing a smartphone toward surrounding mountain ridgelines and recording the elevation angle), you can set that data as PVsyst’s horizon profile. In PVsyst, inputting the horizon elevation angle for each azimuth allows you to account for irradiance cut from distant shading in the calculations. If the high-precision coordinates obtained by smartphone allow you to determine the position and elevation of distant obstructions, it is also possible to virtually derive the horizon from the height difference relative to a horizontal reference.

• Detailed shadow analysis using point cloud data: Although colored point clouds and 3D models obtained with LRTK and smartphone LiDAR cannot be directly imported into PVsyst, they are highly useful sources of information for designers. Visualizing the point cloud reveals exactly how far tree branches and foliage extend and even fine terrain undulations. Based on this information, you can fine-tune obstruction models in PVsyst or make decisions about which trees may need pruning or removal. Additionally, the acquired point cloud itself can be used in external 3D software for irradiance simulation and comparison/validation against PVsyst results, enabling advanced analyses.

Thank you for your message. Reflecting smartphone survey data in PVsyst enables precise simulations that incorporate the effects of shading, as you noted. Because shading assessments that were previously based on approximations and empirical rules can now be performed using measured data, the reliability of power generation forecasts is significantly improved.

To assist you further, could you please provide the following details:

• The format and sampling interval of the smartphone survey data you intend to import into PVsyst.

• Whether the data includes time-stamped shading/occlusion measurements or only geometric profiles.

• Examples of the data files (if available) so we can confirm compatibility and suggest any necessary preprocessing steps.

Once we receive these details, we can advise on the best workflow to import the data into PVsyst and recommend validation steps to ensure forecast accuracy. If you prefer, we can also prepare a short checklist for data collection to maximize the usefulness of the measurements in PVsyst.

Best regards,

The Impact of High-Precision Survey Data on Solar PV Design

Incorporating high-precision survey data obtained with a smartphone and LRTK into the design brings various benefits to the solar power plant planning process.

• Improved accuracy of power generation forecasts: By faithfully modeling actual terrain undulations and shading elements, you can reduce the discrepancy between simulation-predicted generation and actual generation. In particular, correctly estimating irradiance losses in the morning and evening and during winter can reduce risks in project planning.

• Layout optimization and reduction of design revisions: Based on a detailed site model, you can optimize PV array placement, tilt angles, and row spacing. For example, you can arrange arrays to avoid locally shaded areas and, if necessary, make advance decisions about removing trees that would cast shadows. Also, using high-accuracy data at an early stage reduces rework from repeated design changes later.

• Incorporation into civil engineering and construction planning: High-precision terrain data is useful for earthworks planning as well. From the acquired point cloud you can calculate cut-and-fill volumes and develop optimal earthwork plans. Understanding the current terrain helps with racking designs suited to slopes and with drainage planning, improving the accuracy of civil engineering evaluations during the design stage.

• Faster decision-making and increased efficiency: Because the required surveying can be completed with a single smartphone, on-site surveys in the early stages of a project can be carried out quickly. This enables earlier decisions on land acquisition and layout selection. Where design work previously had to wait for survey results, being able to capture and analyze data immediately on site shortens the overall schedule and improves efficiency.

• Precise design possible even for small-scale projects: Lower surveying costs make it possible to design based on accurate site data even for small-scale solar projects and distributed installations. Detailed surveys, which were often omitted for cost-effectiveness reasons, can be carried out easily using LRTK, allowing pursuit of optimal designs regardless of project scale.

In this way, leveraging high-precision surveying data further enhances the accuracy and efficiency of solar power plant design, increasing the likelihood of project success.

Summary: The Potential of Fully Smartphone-Based Surveying and the Future Opened by LRTK

High-precision surveying that can be completed using only a smartphone—without relying on special equipment—is revolutionizing the design and development process of solar power plants. With flexible surveying that is less affected by site constraints and accurate data integration, designers can perform layout planning and power-generation simulations that more closely reflect real-world conditions. At the center of this is the LRTK technology introduced in this article. By using LRTK to turn a smartphone into a centimeter-accurate surveying instrument, anyone can obtain on-site data whenever needed, enabling nimble design unconstrained by conventional assumptions.

There's no longer any need to wait for specialized surveying teams or expensive equipment. With the realization of the end-to-end workflow—measuring, recording, and sharing with a single smartphone—solar power sites are undergoing a major transformation. Smartphone-only simplified surveying enabled by LRTK can be applied across a wide range, from small sites to large-scale developments, and its accuracy and convenience make it a trump card for on-site DX (digital transformation). To make the design of solar power plants even smarter and more reliable, why not consider this new surveying approach?

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