How to Use the Japanese Translation of PVSyst: Improve Design Efficiency with High-Precision Positioning Data

PVsyst is a world-standard software widely used for designing photovoltaic power systems and simulating energy production. By inputting meteorological data and panel layouts, it can calculate generation, losses, and performance ratio (PR) with high accuracy. It can also account for shading effects from surrounding buildings and trees, enabling simulations that faithfully reflect site conditions.

However, the English interface can be a barrier for Japanese users. No matter how good a simulation is, insufficient on-site input data prevents realizing true performance. This article explains in detail how to set up the Japanese-translated interface of PVsyst and how to use high-precision positioning data such as LRTK to streamline design work.

What PVsyst is

PVsyst is a solar PV simulation software developed in Switzerland. PV engineers worldwide use it to calculate annual energy yield, various losses, and performance ratio (PR) based on meteorological data and the configuration and layout of panels and inverters. It also offers flexibility to incorporate various meteorological datasets from around the world (domestically, datasets such as NEDO solar radiation data), allowing simulations under solar irradiation conditions appropriate for the design location. Because it can account for shading effects from surrounding terrain, structures, and trees, PVsyst enables highly accurate energy forecasts that faithfully reflect site conditions. Simulation results can be output as detailed reports that automatically summarize monthly and annual predicted generation, breakdowns of losses, and performance metrics (such as PR). These results can be used to support financial planning and optimization of equipment configuration for power plants. From large utility-scale plants to rooftop residential systems, PVsyst is an indispensable tool for predicting energy yield and optimizing layout during design.

How to use PVsyst in Japanese and tips

PVsyst allows changing the interface display language from English to other languages, including Japanese. Even users who are not comfortable with English will find menus and settings easier to understand when displayed in Japanese. The steps to switch to Japanese display and tips for using it are as follows:

• Change the language setting to Japanese: After launching PVsyst, select "Language (言語)" from the main menu and switch to "Japanese (日本語)". Depending on the version, it may automatically select Japanese on first launch by detecting your PC language settings.

• Toggle between Japanese and English display: Some translations can be too long and overflow the screen, or technical terms may remain hard to understand. In such cases, press the `F9` key on the keyboard to temporarily switch that screen to English for confirmation (press `F9` again to return to Japanese). This feature is useful because it allows you to compare the Japanese translation with the original English and understand the operation better.

• Understanding technical terms: PVsyst manuals and help are basically in English. If some technical item names remain unclear after switching to Japanese, it is useful to know the English terms. On the translated UI, use the `F9` key to confirm the English term, then search official documentation or case studies using that keyword to help solve problems.

Using the Japanese interface makes it easier for users who are not familiar with English to understand PVsyst settings and reports. Especially for first-time users, start with the Japanese display to grasp the overall picture, and as you become more familiar, refer to the English where necessary to use PVsyst efficiently.

The importance of on-site data that affects design accuracy

Although PVsyst enables detailed simulations, their accuracy heavily depends on the correctness of input data. In layout design and energy yield prediction for PV plants, the key is how faithfully you can model local terrain and surrounding obstructions. In PVsyst, in addition to meteorological conditions and panel layout, you can account for site altitude, terrain slope, and shading effects from nearby structures and trees. For example, if the site is surrounded by mountains or high ground, you can set the horizon profile as horizon elevation angles per azimuth, and nearby trees or utility poles can be placed as 3D objects under the "Near shading objects" section to include their shadow effects in calculations. The more precise the on-site data you input, the higher the reliability of the simulation results, leading to an optimal design without waste.

However, obtaining such detailed on-site data is not easy. Traditionally, field surveys and measurements took time and effort and required specialized skills. Typical methods used to obtain field shadows and terrain information include:

• Manual measurement of shadow angles: Using a compass (bearing) and an inclinometer to measure obstruction angles at main directions on the horizon to understand the angle of the surrounding horizon relative to the solar altitude.

• All-sky camera analysis: Using a fisheye-lens camera to capture 360° of the sky and deriving the shading range (shadow times) from image analysis of surrounding buildings and trees.

• Detailed topographic surveying: Surveyors perform leveling and GPS surveys on-site to obtain cross-sectional terrain profiles and contour data including elevation differences. Recently, drones are also used to capture aerial photos and create 3D terrain models (point clouds or DSM).

• Estimation from map data: Referring to existing geographic data such as topographic maps, aerial photos, and satellite images from the Geospatial Information Authority of Japan to estimate site elevation and surrounding environment.

Each of these methods has challenges. Manual measurements and all-sky cameras require relatively simple equipment but have limitations in accuracy and coverage when measured manually at multiple points. Professional topographic surveys and drone photogrammetry yield high-precision results but incur significant time and cost, and require expert knowledge and heavy equipment operation skills. Estimation from maps and satellite images avoids on-site visits but faces issues such as resolution limits and data age. For example, a few-years-old aerial photo may not show newly built structures, or tree growth may have changed shadow conditions.

As a result, no matter how precisely you calculate in PVsyst, if the input data diverges from actual site conditions, simulation results will differ from reality. Even a well-planned plant can risk not achieving expected generation due to unforeseen shading impacts.

Using high-precision positioning data in PVsyst

So how can high-precision on-site data be concretely used to improve design? Here we introduce points for importing data obtained by high-precision GPS positioning into PVsyst to enhance design accuracy.

• Accurate horizon profile settings: By using LRTK high-precision positioning to acquire terrain information around the site (heights of distant hills or buildings), you can accurately determine horizon elevation angles for each azimuth. Reflecting that data in PVsyst’s "Horizon definition" tool allows precise consideration of shading relative to sunrise/sunset times and solar altitude throughout the year. As a result, generation losses in early morning and late evening can be evaluated more realistically.

• Shading simulation of nearby objects: Measured position coordinates and height data of nearby trees, utility poles, and structures can be used with PVsyst’s 3D shading functions. By placing objects in the 3D scene at the same scale based on measured dimensions, you can precisely simulate shadows cast on panels by season and time of day. For example, by positioning multiple trees measured by GNSS, you can quantitatively assess how much shade each tree casts on panels over the year and, if necessary, adjust layout (avoid shade by optimizing placement or spacing).

• Introducing detailed terrain models: On large or undulating sites, the terrain itself affects energy yield. If you acquire high-precision positioning data at many points with LRTK, you can create a 3D terrain model of the site from the point cloud. Importing such terrain models into PVsyst (or adjusting array layouts on PVsyst to match terrain cross-sections) and setting panel tilt angles and heights to reflect field conditions allows reproduction of the effects of slopes on generation and shadowing from valleys and hills. In practice, advanced analysis is possible, such as arranging panels on a 3D model generated from precise LRTK point clouds and importing that directly into PVsyst to animate shadows on each panel. These analysis results are useful for detecting potential problem areas during design (for example, a particular row receiving long morning and evening shadows) and applying design corrections in advance.

By utilizing high-precision positioning data obtained with LRTK, the reproducibility of PVsyst simulations dramatically increases. Using models that correctly reflect site realities makes post-construction performance predictions more reliable, enhancing confidence in investment decisions. Also, when making fine adjustments during design (minor layout changes or equipment selection), basing decisions on measured data reduces unnecessary rework, resulting in overall design process efficiency improvements.

Simple surveying with LRTK and on-site deployment benefits

A recently notable method to obtain high-precision on-site data is the use of smartphones for simple surveying. (The i-Construction initiative promoted by the Ministry of Land, Infrastructure, Transport and Tourism also emphasizes ICT-based and labor-saving surveying.) A representative solution is called "LRTK," which makes centimeter-level surveying—previously only done by specialists—easily achievable.

What is LRTK? In short, it is an ultra-compact high-precision GPS receiver (RTK-GNSS device) that can be attached to a smartphone. Using RTK (Real-Time Kinematic) technology to correct positioning errors, it reduces typical GPS errors of several meters to an accuracy of a few centimeters. By connecting an LRTK device to a smartphone and launching a dedicated app, you simply press a button at the point you want to measure, and the latitude, longitude, and elevation of that point are recorded immediately with high precision. Because measurement results are automatically converted to Japan’s plane coordinate system and elevation data, the coordinates obtained on site can be easily used directly in design drawings and CAD coordinate systems.

The on-site benefits of surveying with LRTK are summarized as follows:

• Easy surveying by a single person: LRTK is designed for intuitive smartphone operation and can be used by non-specialist surveyors. The compact device weighs only a few hundred grams, with antenna and battery built-in, eliminating bulky tripods and long cables previously required. You can walk around the site holding the device in one hand and operate the smartphone with the other to record survey points continuously. Tasks that used to require two people can now be done by one person over large areas in a short time.

• Immediate sharing and use of acquired data: Measured position data can be uploaded to the cloud in real time or plotted on a map on the smartphone for verification. Multiple measured site coordinates can have distances and elevation differences calculated on the spot, eliminating the need to record notes by hand. Because data can be reflected in PVsyst design work immediately after acquisition, lead time from field survey to simulation is greatly shortened.

• Positioning possible even outside radio coverage: LRTK supports augmentation signals derived from Japan’s Quasi-Zenith Satellite System, allowing centimeter-level positioning to continue in mountain areas and remote islands where mobile phone signals do not reach. As many PV project candidate sites are in suburban or mountainous areas, the ability to survey without relying on communications infrastructure is a major advantage. No additional base stations or communication equipment are required, keeping the equipment configuration simple and reducing troubleshooting.

If multiple LRTK devices are available, several team members can measure simultaneously. You can divide and cover a large site in a short time, finishing surveying in one day in cases where it used to take several days. In addition, combining the LiDAR scanner on the latest iPhones with LRTK makes it possible to acquire 3D point cloud data of site terrain and structures in a short time. Since acquired point clouds already have high-precision position coordinates, they can be converted directly into 3D terrain models and used in detailed PVsyst simulations.

Introducing smart simple surveying with LRTK dramatically improves the efficiency of PV system design. Being able to quickly collect necessary on-site data yourselves allows planning from the initial design stage based on accurate information. Outsourcing surveys that were previously performed by specialized contractors can be brought in-house, yielding benefits in schedule coordination and cost. Actual projects have reported reductions in rework from design changes and improved accuracy in energy yield estimates when using data obtained by LRTK. For example, precisely measuring a ridge line with LRTK and revising the layout to account for a previously overlooked mountain shadow resulted in an improved annual generation forecast. In another case, recognizing a gentle slope on what was thought to be flat ground with centimeter accuracy and optimizing support frame heights prevented unexpected generation losses after construction.

If you want to improve PV plant design efficiency and on-site productivity, consider introducing LRTK-based simple surveying. Smart surveying using the latest technology enables reliable design with limited personnel and contributes to overall project optimization. Furthermore, as digitalization (DX) progresses from surveying to design, PV project execution will become increasingly efficient and reliable. For more information about LRTK, see [here](https://www.lrtk.lefixea.com).