Solo Solar Site Survey: Easily Design PVsyst with iPhone × LRTK

Challenges in Solar Power Plant Site Survey

Accurate on-site survey data is indispensable for the development and design of solar power plants. In particular, power generation simulation software widely used in the industry—such as PVsyst—relies on inputs like terrain undulation and shadows from surrounding obstructions to greatly influence the accuracy of generation forecasts. However, traditionally, such field surveys required team-based work and presented several challenges.

First, typical surveying uses specialized equipment such as total stations or RTK-GNSS receivers, requiring multiple personnel to go to the site. One person sets up and operates the instrument while another holds a prism at a distant point, so the work has routinely demanded manpower and time. Drone-based surveying methods have also emerged, but they require expertise in piloting and data processing and are subject to weather conditions. As a result, it has been difficult to conduct detailed surveys in the early planning stages, and some developers have progressed with designs based only on topographic maps or satellite imagery. This can lead to discovering unexpected obstacles or elevation differences on site later, causing redesigns and errors in generation forecasts.

Furthermore, team surveys come with cost issues. Outsourcing to external surveying firms incurs fees that can be burdensome for small-scale projects. Scheduling is also necessary, and if it takes time to obtain data, design work stalls in the meantime. Even if you want to run precise simulations in PVsyst, results are unreliable when the underlying survey information is coarse. Thus, for many years the design field of solar power plants has faced the problem that it is not easy to perform high-accuracy on-site surveys.

A Revolutionary Solution: iPhone × LRTK

To address the challenges above, the combination of smartphones and high-precision GNSS has recently begun to emerge as a solution. A representative example is the solo site survey using iPhone × LRTK. This innovative approach enables surveying tasks traditionally done by a team to be completed by a single person by attaching a small RTK-GNSS receiver called “LRTK” to a high-performance iPhone.

The latest iPhones include a LiDAR scanner (an infrared-based distance sensor) that rapidly measures distances to surrounding objects and records them as point cloud data (a collection of many distance measurement points). While smartphone-only AR technology can scan spaces, ordinary GPS accuracy has errors on the order of meters, so the resulting point cloud is offset from real-world coordinates. That’s where LRTK comes in. LRTK is an ultra-compact RTK-GNSS module attachable to iPhones and iPads; by using correction information from network RTK or quasi-zenith satellite systems, it enables centimeter-level positioning even with a smartphone. This device, often called an LRTK Phone, is pocket-sized at about 125 g and only 1.3 cm thick, and can be attached to a smartphone with a one-touch dedicated case. The battery and antenna are integrated, making it easy to carry without worrying about external power or cables.

With the iPhone × LRTK combination, the following surveying workflow becomes possible on site. First, the surveyor attaches the LRTK device to the iPhone and launches a dedicated app. By walking around while looking at the phone screen, the terrain and structures ahead are recorded one after another as 3D point cloud data. For example, walking around a site with uneven ground will capture the site’s elevation differences and the shapes of surrounding trees and buildings as point clouds. Because the LRTK measures highly accurate latitude, longitude, and elevation in real time and ties them to LiDAR point clouds, the resulting data becomes a 3D model aligned to measured coordinates. In the past, aligning points between measurement locations and tying them to control points was troublesome, but this method yields point cloud data already consistent in an absolute coordinate system from the start.

Additionally, by combining the iPhone camera, it is possible to create point clouds or 3D models with color photo textures. The resulting digital twin of the site reproduces the location visually and intuitively. The LRTK system also allows immediate cloud sharing of acquired data, making it easy to inspect the site point cloud model from the office. In short, you can create a detailed digital 3D map of the site with just a smartphone using iPhone × LRTK. This enables solar project designers to quickly obtain the necessary survey information themselves and reflect it in the design on the spot, allowing agile responses.

Main Effects and Benefits of Introducing Solo Surveying

Introducing the innovative solo surveying enabled by iPhone × LRTK brings various benefits to the solar power plant development process. Here we summarize the main effects from the perspectives of operational efficiency and design accuracy.

• Dramatic improvement in work efficiency: Surveys that previously took several people half a day to several days can now be completed quickly by one person. There is no need to transport and set up heavy equipment, and surveying can start whenever you decide, eliminating waiting time for scheduling. This allows detailed site data to be obtained even in the early project planning stages, significantly shortening the cycle from design initiation to revision. Labor cost reductions and savings from outsourcing are also notable.

• Improved reliability through high-precision positioning: RTK-GNSS corrections provided by LRTK ensure centimeter-level positioning accuracy in the acquired data. Because survey outputs are obtained directly in map coordinate systems (such as plane rectangular coordinates), cumbersome tasks like converting data to match control points later are unnecessary. Important boundaries and reference heights are captured accurately, reducing discrepancies between design drawings and the site and enabling designers and constructors to proceed with confidence.

• Acquisition of detailed point cloud data: Point cloud surveying provides rich information, from subtle ground surface undulations to the height and position of individual trees. Unlike traditional surveys that record only limited points, this approach digitally captures the site comprehensively. For example, on sloped terrain, the full distribution of gradients can be analyzed later, and on-site and off-site obstructions are fully visualized in the model. This prevents issues such as “a depression we missed” or “neighboring trees are taller than expected,” enabling well-informed decisions from the initial layout stage.

• Seamless integration with PVsyst design: Accurate 3D data obtained from solo surveying directly benefits PVsyst simulation work. For instance, generating a digital terrain model from point clouds allows layout design in PVsyst that accounts for undulation. Also, importing surrounding trees and buildings as proximity shadow objects into PVsyst enables shadow analysis based on actual conditions. These capabilities dramatically improve the accuracy of PVsyst generation forecasts, strengthening the credibility of project financial estimates and equipment specifications.

• Improved shadow analysis accuracy: Shadow impact assessment is critically important for solar power. From point clouds acquired by solo surveying, you can precisely determine the horizon and obstruction elevation angles around the site. Analyzing the annual motion of shadows using this data allows accurate prediction of which panels will be shaded and when on representative days such as the equinoxes and solstices. As a result, layouts can be optimized to avoid shaded areas, and preemptive measures such as tree removal or negotiations on height restrictions can be considered in advance—enabling designs that incorporate thorough shadow mitigation. Using on-site survey data makes possible detailed shadow simulations that cannot be achieved by desk-based estimates.

• Immediate reflection in design data: Digitized survey results are easy to incorporate directly into design documents and various data sets. For example, creating contour lines from the acquired point cloud produces a detailed topographic map that serves as the basis for layout decisions. Overlaying panel layout proposals on the survey data allows quick checks for conflicts with current conditions. LRTK also enables sharing coordinate data via the cloud, so designers can receive data at their desks on the same day the survey is conducted and load it into CAD software or GIS to proceed with design tasks. This greatly reduces information transfer loss between the site and the design office, enabling swift decision-making and design changes.

Use Case: From Solo Survey to Design Implementation with iPhone × LRTK

Let’s look at a case where an engineer conducted a solo site survey using an iPhone and LRTK and applied the data to design. For example, consider a medium-scale (several MW) solar power plant planned on hilly terrain. In this project, the lead engineer visited the site alone in the early development stage, attached the LRTK to an iPhone, and carried out the survey.

First, the engineer walked along the site boundary while scanning point clouds on the smartphone. In just a matter of tens of minutes, point cloud data capturing the entire site’s terrain undulation and the height information of surrounding forest was acquired. At the same time, notable features (such as the location of a large rock on site or major trees) were recorded with precise coordinates using a point positioning function. The acquired data was uploaded to the cloud immediately, allowing the office design team to review the 3D model almost in real time.

Next, a 3D terrain model of the current condition was built from the point cloud data, and planned layout proposals were overlaid for review. In PVsyst simulation, surrounding woodland extracted from the point cloud was imported as shadow objects, and seasonal impacts on generation were analyzed in detail. As a result, it was found that the forest on the southeast side would cast shadows on some panel rows on winter solstice mornings. However, having this information in advance allowed the design team to perform layout optimization to avoid shadow impacts. Specifically, the panel rows predicted to be shaded were shifted by several meters to positions less affected by shading. The data also provided supporting material for discussions with stakeholders regarding potential tree removal when necessary.

Furthermore, the high-precision data contributed to civil engineering design. Using accurate elevation data derived from point clouds to estimate cut-and-fill volumes for earthworks revealed areas where the initial estimates could be reduced, enabling revisions to the construction plan and cost savings. This entire process, which in the past would have required waiting for reports from a surveying team and repeatedly going back and forth between site and drawings, proceeded extremely quickly and accurately thanks to the immediate usability of solo survey data. The engineer was able to work with the sense of “bringing the site back for design,” and stakeholder explanations and consensus-building were facilitated by sharing the 3D model. This case is a good example of the practical value that solo site surveys using iPhone × LRTK can bring to the solar power business.

Future Outlook: The Future Opened by Smartphone-Only Surveying

The solo surveying method that combines smartphones and high-precision GNSS has the potential to become a standard not only in the solar industry but across construction and civil engineering. In particular, smartphone-only surveying solutions like iPhone × LRTK—being compact, lightweight, and easy for anyone to use—are likely to spread as a “one-person, one-device” tool on sites. Lower introduction costs compared to conventional surveying equipment will also drive adoption, making the technology accessible to small projects and companies and expanding the reach of site digital transformation.

Tasks that used to be left to specialized surveyors will increasingly be performed routinely by site managers and design engineers themselves, accelerating digital transformation of operations.

What is expected next is stronger integration between such field survey data and various design software. Point cloud data can already be imported into CAD and simulation software, but in the future the integration will likely become more seamless. For example, it may become possible to export terrain and obstruction object data for PVsyst with a single button from the surveying app. Also, by leveraging precise position information from surveys, AR (augmented reality) applications that project designed layouts onto the site for verification will advance. LRTK already achieves high-precision AR display that prevents virtual objects from drifting even after extensive walking, and using this for panel layout verification would make it easier to share the completed-image among stakeholders before construction.

Further accuracy improvements are also anticipated. With enhancements in smartphone sensor performance and expansions in satellite positioning services (such as broader augmentation signals from regional quasi-zenith satellite systems), an era in which centimeter-level accuracy is easily attainable is approaching. This will enable stable positioning and surveying even in mountainous areas or out-of-coverage locations, smoothing the process of site suitability surveys for solar power.

Finally, the LRTK that emerged from this wave of technological innovation is truly a key solution for smartphone-only simplified surveying. By simply attaching it to an iPhone, LRTK enables both high-precision positioning and point cloud scanning, making “solo solar site surveying” a reality. Seamlessly connecting on-site surveys with PVsyst simulations from investigation to design and construction will enhance the efficiency and reliability of the entire process. Stakeholders in solar power plant development are encouraged to consider adopting this smartphone surveying technology. With the spread of innovative tools like LRTK, the deployment sites for clean energy are expected to evolve to become faster and smarter.