PVsyst Japanese Translation Q&A: Solving Common Questions from Renewable Energy Designers

In the design of photovoltaic power generation, PVsyst is the global standard simulation software. Although the interface and manuals of this overseas-made software are basically in English, many renewable energy designers in Japan also use it for generation forecasts and system design. However, because Japanese-language information is limited, users often get confused about how to use and configure it. In this article titled "PVsyst Japanese Translation Q&A," we address frequently asked questions about PVsyst and provide clear answers from a practical practitioner perspective. We cover a wide range of topics, from how to use PVsyst in Japanese, setting design parameters, thinking about influencing factors, handling solar radiation data, shading analysis using 3D scenes, interpreting output reports, installation methods, and error prevention.

Question 1: Can PVsyst be used in Japanese?

Answer: Yes, the PVsyst interface can be switched to Japanese. PVsyst’s base language is English, but it has been translated into multiple languages such as French and German, and Japanese is included among them. If you select Japanese under Preferences (設定) -> Language (言語) in the menu, the buttons and screen displays will become Japanese. However, the Japanese translation is not perfect, and you may find some unnatural expressions or text overflowing its frames. In such cases, you can press the F9 key to temporarily switch the display back to English and check the original text (press F9 again to return to the previous language). Note that the official PVsyst documentation is currently available only in English, but Japanese explanations like those on this blog can sufficiently cover practical usage.

Question 2: What can PVsyst do and what kinds of simulations are possible?

Answer: PVsyst can simulate the energy production and losses of photovoltaic systems in detail. Specifically, at the design stage you can consider the following items.

• System capacity and configuration design: You can select and combine panels (modules) and power conditioners (inverters), set quantities, string numbers, and wiring configurations. PVsyst supports grid-connected systems (on-site consumption or feed-in) as well as off-grid systems, and you can include batteries in the configuration if necessary.

• Layout and tilt/azimuth: Input the panel tilt angle and azimuth, and the layout (e.g., rooftop vs. ground, multiple rows), and evaluate differences in irradiance capture due to geometric placement and the effect of self-shading.

• Generation forecast using meteorological data: Based on local annual solar radiation and temperature data, you can calculate monthly and hourly generation. In addition to long-term meteorological-data-based annual energy balance forecasts, you can obtain seasonal variability and annual performance indicators (for example, annual generation and performance ratio (PR) values).

• Analysis of loss factors: By setting various loss factors such as degradation over time, temperature characteristics, wiring resistance losses, module mismatch losses, and soiling losses, you can compute their impacts on generation. In particular, you can quantify how much system efficiency is reduced by real environmental conditions such as shading and temperature.

• Shading analysis: Using the 3D scene feature, you can calculate the effects of nearby object shading (near shading). You can analyze the impact on generation from buildings, trees, and adjacent panel rows over time and evaluate annual generation losses due to shading.

As such, PVsyst is a powerful tool that comprehensively handles everything from system design to environmental impacts and output forecasting. At the practitioner level, it is widely used from initial feasibility studies (preliminary design) to detailed design stages.

Question 3: What are the main design parameters to set in PVsyst?

Answer: To perform high-accuracy simulations in PVsyst, several important parameters must be appropriately configured. The main design parameters include the following.

• Meteorological conditions: The basic meteorological data for the simulation such as solar radiation and temperature (details below). Use reliable data corresponding to the site’s latitude and longitude.

• Site and orientation: Specify the latitude, longitude, elevation of the installation site, and the panel tilt and azimuth angles. These are fundamental parameters that determine incident solar radiation.

• Module specifications: Select module characteristics from the database such as nominal power, conversion efficiency, temperature coefficient, and dimensions. PVsyst includes module data from major manufacturers and allows you to register new modules.

• Inverter (PCS) specifications: Choose or input inverter rated capacity, European efficiency, MPPT range, etc. The DC/AC ratio (inverter sizing relative to total module power) is also important; check that the sizing is neither too small nor too large.

• System configuration: Set system-wide configuration parameters such as the number of modules in series (string length), number of parallel strings, modules per string, and maximum input voltage limits. Proper configuration lets you verify whether the inverter input range and voltages are within specifications.

• Wiring and other losses: You can optionally set wiring resistance losses (calculated from cable length and cross-sectional area), transformer losses, soiling rates due to dust or snow, downtime, etc. Estimating these values to reflect the real environment improves the accuracy of simulation results.

By properly setting these parameters, you can obtain generation forecasts close to an actual system. When designing in Japan in particular, it is important to localize parameters according to regional meteorological conditions and installation environments.

Question 4: What are the main factors that affect PVsyst simulation results?

Answer: The generation and performance metrics obtained from simulations are influenced by various factors. The main factors include the following.

• Variability in solar radiation: Naturally, the more solar energy incident on the system, the more generation you get. If the annual solar radiation differs by 10%, generation will change by roughly the same proportion. Thus, the quality and reliability of the meteorological data used greatly affect the results.

• Tilt and azimuth angles: The amount of solar radiation received changes with panel tilt and orientation. Deviation from the optimal tilt reduces annual generation. In Japan, depending on latitude, south-facing panels with a tilt around 30 degrees often produce the most energy, but optimal values vary with installation conditions.

• Temperature: PV module output decreases as temperature rises. High summer temperatures increase output losses, so regions with lower average temperatures are advantageous for annual energy yield. PVsyst calculates temperature-related losses from module temperature coefficients and ambient temperature.

• Near shading and horizon obstruction: Shadows from surrounding buildings, trees, or other panel rows reduce irradiation, especially during morning/evening times and in winter. The greater the proportion of shading, the larger the generation loss. PVsyst can analyze near shading in detail using a 3D scene, and annual shading losses are included in reports.

• Equipment configuration and losses: Factors such as incorrect inverter sizing (over/under sizing), poor string layout causing generation losses, wiring resistance, soiling accumulation, and degradation all affect total generation. It is important to optimally select and configure equipment and minimize loss factors.

Considering these factors comprehensively in simulations enables reasonably accurate predictions of actual generation. For large-scale mega-solar projects, a 1% difference can significantly affect the financial outcome, so properly estimating each factor is essential.

Question 5: How do you obtain the meteorological data such as solar radiation used in PVsyst?

Answer: Long-term meteorological data (especially solar radiation) for the site are essential for PVsyst simulations. PVsyst can connect with several meteorological databases and import external data. Common ways to obtain data are as follows.

• Data bundled with PVsyst: The installation includes representative site data for many locations worldwide and a function to estimate data from Meteonorm by specifying coordinates. Meteonorm, by METEOTEST in Switzerland, generates annual meteorological data for arbitrary locations using station and satellite data worldwide.

• Import data obtained externally: You can obtain satellite-derived solar radiation data from sources such as SolarGIS, NASA, or JAXA, or for Japan, NEDO solar radiation databases (MONSOLA-11 or the latest MONSOLA-20), and import them into PVsyst in CSV or TMY format. Because measurement periods and resolutions differ among data sources, you must choose data with appropriate accuracy and period from the available options.

• On-site measured data: If you have on-site pyranometer or weather sensor measurements at the candidate site, you can convert them to PVsyst format and use them. On-site measurements reflect site conditions most accurately, but without at least one year of observation they are hard to use for long-term forecasts.

When multiple data sources are available, annual solar radiation values may differ. For example, Meteonorm and NEDO data may show different annual totals. Therefore, depending on the project’s importance, it is advisable to compare multiple sources and adopt the most reasonable value. We also introduce characteristics of each meteorological database on our site’s meteorological database explanation page: https://www.lefixea.com/japan/wetherdatebase

Question 6: Can PVsyst simulate shading using 3D scenes?

Answer: Yes, PVsyst can perform detailed simulations of near shading using the 3D scene feature. In project detailed design mode, open the [Near Shadings] settings screen to access the 3D scene editor. On this editor you can configure and operate features such as the following.

• Terrain settings: For uneven or gently sloping sites, you can reflect terrain elevation differences. You can import elevation data to reproduce undulation or set a horizon profile to consider far-field terrain obstructions.

• Object placement: Place objects that may cast shadows on panels—such as buildings, trees, and transmission towers—in 3D space. By setting sizes (height and width) and positions to match the site layout, you can simulate shading at different times of day. Shadow lengths and positions relative to the sun’s movement are calculated automatically to derive annual shading impacts.

• PV plant layout: To evaluate self-shading, place the PV array itself within the 3D scene. For example, for multiple-row racking, set inter-row spacing and row heights to calculate when and how long the front rows shade the rear rows.

• Quantitative shading evaluation: The 3D simulation outputs hourly generation losses as a “shading factor.” PVsyst uses this to report monthly and annual shading loss quantities. If shading is significant, this helps inform design changes such as layout adjustments or tree removal.

By leveraging the 3D scene feature, you can model site shading conditions in considerable detail. However, the more accurate the input data (object dimensions and positions), the more reliable the results. Recently, workflows using drone surveys, LiDAR scanning, or simple 3D surveying with smartphones to obtain point cloud data and construct PVsyst scenes from that data have become more common.

Question 7: What is included in PVsyst output reports and how should they be interpreted?

Answer: When you run a simulation in PVsyst, a detailed output report is generated. This report contains a wide range of information from project overview to system specifications and simulation results. The main items are as follows.

• Project overview: Summarizes the simulation assumptions such as the site location (latitude, longitude, time zone), the meteorological data used, and whether horizon data were included.

• System specification summary: Lists the designed system configuration. For example, module and inverter model numbers and quantities, number of strings, total DC and AC capacities, DC/AC ratio, wiring loss settings, etc.

• Simulation parameters: A list of detailed parameters you set. For example, tilt and azimuth, albedo (ground reflectance), and various loss factors (e.g., soiling loss X%, downtime Y hours) can be reviewed here.

• Simulation result summary: Summarizes aggregate results such as annual generation, performance ratio (PR), energy per rated power (kWh/kW), and financial-related figures (self-consumption rate and grid feed-in, where applicable). The PR value indicates the ratio of actual generation to theoretical maximum generation; a higher PR means a more efficient system.

• Monthly generation and performance: Monthly generation, PR values, and average efficiencies are shown in tables and graphs. Seasonal variation in generation and efficiency differences between summer and winter are easily seen.

• Loss breakdown: One of the most important sections, this shows the breakdown of energy losses from incident horizontal irradiance to the final energy delivered to the grid. For example, the flow “horizontal irradiance -> tilted plane irradiance -> module incident irradiance -> DC generation -> inverter input -> AC output -> grid supply” is illustrated and losses such as reflection, temperature, wiring, conversion, and shading are shown as percentages. Reviewing this helps you identify dominant loss factors and provides hints for design improvements.

If it’s your first time viewing a PVsyst report, the volume of information may be overwhelming, but focusing on the points above makes it easier to grasp the overall picture. For a more detailed explanation, see our PVsyst Japanese guide page where each part of the simulation report is explained: https://www.lefixea.com/japan/pvsyst-jp

Question 8: How do you obtain and install PVsyst?

Answer: PVsyst can be installed by downloading the installer from the official website. It is Windows-compatible software; PVsyst 7 and later run on Windows 10/11. Installation is the same as for typical software: run the downloaded setup file and follow the on-screen instructions. On first launch you can select a language; if you choose Japanese, the menu display will be in Japanese (you can change this later).

After installation you can try the software in an evaluation mode (trial), but continued use requires a purchased license. If you intend to use it in operations, obtain a license contract from the official site as needed.

PVsyst is relatively lightweight, but PC performance affects large-scale simulations and 3D rendering. At minimum, 8GB or more of memory is recommended, and a multi-core CPU improves comfort. While a dedicated GPU is not mandatory for 3D scenes, better graphics performance makes operations smoother.

Question 9: Is PVsyst free to use? What is the licensing structure?

Answer: PVsyst is commercial software and is generally paid. However, a free evaluation mode (trial) that allows full-feature testing for a limited period is provided. Specifically, the first launch activates a 30-day evaluation mode during which nearly all functions can be used without restriction (the report will display an “Evaluation copy” watermark, but simulations are not limited). After the evaluation period expires, the software moves to a demo mode with some functional restrictions.

To continue using full functionality, purchase a license from the official site and register the software with the issued activation key. The current licensing model is subscription-based (time-limited license), and during the subscription period you can use all features including updates. When the subscription expires, functionality reverts to the restricted mode, but renewing the subscription restores full use.

Educational or classroom licenses for students may also be available for learning purposes. Check the official licensing information for details. In any case, it’s recommended to try the evaluation version first to confirm the feel and functions, and then contract a license if needed.

Question 10: Does PVsyst support battery storage and off-grid system simulations?

Answer: Yes, PVsyst supports simulations for systems that include batteries and for off-grid systems. Specifically, PVsyst includes a Standalone mode for off-grid systems, allowing calculation of the energy balance for an entire power system consisting of PV panels + battery +, if needed, a generator. In off-grid mode you can examine battery capacity from seasonal generation and consumption relationships and evaluate power shortfall times (loss of supply) due to insufficient supply. For grid-connected systems, PVsyst can also simulate cases combined with batteries. From PVsyst 7 onwards, functions were added to set battery charge/discharge strategies for grid-connected systems, allowing analyses that assume operation modes such as “self-consumption priority” or “peak shifting.” This enables rough estimates of effects such as reducing purchased electricity by storing daytime surplus for nighttime use or the duration of power provisioning as a backup during outages. However, battery control logic and degradation modeling are relatively simplified compared to specialized tools; PVsyst is primarily a PV-focused simulation tool but is sufficiently useful for evaluating basic battery integration effects.

Question 11: What are common mistakes and cautions when running PVsyst simulations?

Answer: Here are some common mistakes made by newcomers to PVsyst and practical points to watch.

• Incorrect location or time settings: Errors in site latitude/longitude or time zone can shift solar radiation and daylight hours, significantly affecting results. In Japan, select “GMT+9 (JST)” as the time zone in principle and input accurate latitude and longitude.

• Improper use of meteorological data: Reusing meteorological data from different regions or relying on data that only provides monthly values can reduce accuracy. Always use annual data near the design site and, if possible, cross-check multiple sources.

• Equipment selection mistakes: Module-inverter pairings can result in voltages or currents outside specifications. For example, Voc may rise too much in winter and exceed inverter input limits, or string count may be too small and fall below the minimum MPPT voltage. PVsyst flags such issues with warnings, but verify carefully at the design stage.

• Omission of shading: If shading is possible but not considered in the simulation, actual generation may be much lower than calculated. For sites with large trees or adjacent buildings, at minimum input the horizon or a simplified 3D scene to account for shading.

• Misreading results: Misinterpretations such as confusing annual total generation with first-year generation (after considering degradation) or misunderstanding what PR indicates can lead to incorrect evaluations. Understand the definitions of terms and what each metric is comparing.

• Forgetting to save data: Failing to save a project or export reports can make reproduction difficult. When iterating with parameter changes, save versions frequently. Also get into the habit of exporting final results to PDF for records.

By paying attention to these points, you can use PVsyst with greater confidence. Initially, the number of settings may feel overwhelming, but with experience you can run simulations smoothly and without errors.

Conclusion

This Q&A covered PVsyst’s Japanese support and key usage points. As a world-standard simulation tool, PVsyst can greatly improve the efficiency and accuracy of PV design work when used appropriately. However, improving simulation accuracy on the desk requires using input data that reflect actual site conditions. Recently, solutions such as LRTK make on-site surveying simpler and allow fast acquisition of accurate terrain and surrounding environment data. LRTK is a system that uses a compact high-precision GNSS device attached to a smartphone and features cm-class positioning (cm level accuracy (half-inch accuracy)) and 3D scanning that can be performed without specialist knowledge. For example, even on a large PV site, a single person can walk around to collect point cloud data of terrain undulation and the positions/heights of structures that could cast shadows. From the acquired data you can generate a local terrain model and obstacle models and import them into PVsyst’s 3D scene to achieve simulations that are more faithful to reality than before.

By incorporating these new technologies into the design process, you can expect improved planning accuracy and more efficient site surveys. For renewable energy designers, combining PVsyst simulations with rapid on-site information acquisition using LRTK offers major benefits in project reliability and efficiency. Please actively utilize the latest tools to help design better photovoltaic power generation systems.