PVSyst: Summary of Solar Design Know-How and Points to Note Learned from Japanese Translations

Introduction: Why Solar Design Is in the Spotlight Now

In recent years, driven by efforts to achieve carbon neutrality by 2050 and the need to improve energy self-sufficiency, the shift to renewable energy has accelerated, and especially the design of solar power systems has attracted attention. New projects are increasing domestically and internationally, from utility-scale solar to residential installations, and design choices at the planning stage have a major impact on generation efficiency and investment returns. Whereas parts of the process used to rely on experience or simple calculations, precise energy yield simulations and the use of digital tools are now indispensable. With projects growing in scale, financial institutions and developers require highly reliable simulation results, increasing the importance of design know-how. In practice, there have been cases where optimistic design forecasts led to generation falling short of plan, or overlooked shading caused problems, so acquiring proper design and simulation knowledge is increasingly crucial. Against this backdrop, attention has turned to the globally used software PVsyst, and interest in learning solar design know-how through Japanese translations and explanatory materials has been growing.

Overview of PVsyst and the Benefits of Japanese Translations

PVsyst is a world-standard simulation software widely used for designing solar power systems and predicting energy yield. By inputting system size and configuration, you can obtain detailed reports such as annual and monthly energy forecasts and breakdowns of losses. Its high functionality has made it popular among experts, mainly overseas, but the language barrier was an issue for Japanese users. This is where PVsyst Japanese translations become useful. Although the software itself is primarily in English, key terms translated into Japanese and explanatory materials have become more comprehensive, creating an environment where users can understand operations and results in Japanese. Using Japanese-language explanations helps engineers who are not comfortable with English to master PVsyst more easily, reducing misunderstandings and oversights and enabling accurate simulations. It also facilitates information sharing within teams and explanations to clients in Japanese, so the benefits of PVsyst Japanese translations are considerable. Domestically, PVsyst simulation results are increasingly used in business planning for large-scale projects like utility-scale solar farms, and its high reliability has made it an industry-standard tool.

Common PVsyst Terms and Their Japanese Translations

Here are some key terms to know when working with PVsyst and their translations.

• Irradiation / Irradiance: Terms that refer to the amount of solar radiant energy. For example, "Global Horizontal Irradiation" is the annual solar irradiation on a horizontal plane and indicates the potential of a site.

• Tilt Angle / Azimuth : The tilt angle of a solar panel (angle from horizontal) and the installation direction (azimuth, with true south = 0° as the reference for east–west). Proper tilt and azimuth settings are key to capturing the maximum solar radiation.

• Shading : Shadows that block sunlight. In PVsyst you can consider near shading from nearby buildings or trees as well as distant shading from terrain or the horizon. Shading significantly affects energy output, so it is analyzed in detail.

• Losses : A general term for various losses occurring within the system. Examples include wiring losses due to cable resistance, temperature losses from module temperature rise, soiling losses from dirt, mismatch losses from module variability, and initial degradation like LID. PVsyst lets you set and review each loss factor individually.

• Performance Ratio : An indicator of system performance expressed as the percentage ratio of actual energy produced to the ideal energy under reference conditions. A higher PR means the overall system is more efficient and experiences fewer losses. (For large-scale projects, the first-year PR typically settles around 80%.)

• Meteo Data : Data sets of irradiation, temperature, and other meteorological inputs for simulations. PVsyst can use various weather data sources such as Meteonorm, NASA, or domestic datasets like NEDO irradiation data. Choosing appropriate data directly affects accuracy.

• Simulation Report : The detailed output report generated by PVsyst, including annual and monthly energy, breakdowns of different losses, performance ratio, and statistical achievement probabilities (P50/P90 values). Japanese-language documentation that explains these outputs can help interpret them correctly.

Understanding these terms helps in reading simulation results. Japanese-language explanations of PVsyst output reports are also available, and consulting them as needed can deepen understanding.

Design Considerations: Irradiation, Shading, and Loss Factors

To achieve high-accuracy simulations and practical designs, pay attention to the following aspects. Irradiation: Accurately knowing the site’s irradiation is the starting point. Use reliable meteorological data and accurately understand annual irradiation and local weather conditions. For example, compare multiple data sources (domestic NEDO data and international databases) to select irradiation values closer to measured data. Different datasets can differ by several percent in annual irradiation, and that difference directly affects energy yield predictions. Also consider impacts like winter snowfall or region-specific weather patterns if applicable. Shading: Because shadows can drastically reduce module output, thoroughly identify shading sources. Check not only near shading from nearby buildings, trees, or adjacent panel rows but also terrain-induced shading from mountains or ridges on the horizon. For instance, if a plant falls into a mountain’s shadow during winter mornings or evenings, you should predict those generation losses in advance and plan countermeasures. PVsyst enables creation of 3D models including surrounding objects to simulate shading-related generation losses over a year. Understanding shading effects at the design stage and adjusting layout, ensuring sufficient row spacing, or considering tree removal are important countermeasures. Loss Factors: It is also crucial to include all various loss factors that occur system-wide. Longer cable runs increase resistance losses, and high temperatures reduce module output. Over long-term operation, soiling and aging will reduce output. PVsyst allows you to set values for each loss item. Reference empirical values or manufacturer-provided figures and input loss rates that reflect actual conditions as much as possible. Some loss factors can be mitigated at the design stage—for example, choosing appropriately sized cables reduces wiring losses, and scheduling regular cleaning reduces soiling losses. Avoid overly optimistic estimates and include a reasonable margin (safety factor) to minimize the gap between predicted and actual performance.

Oversizing (DC/AC ratio) design: These days it’s common to oversize the DC array relative to inverter capacity, but it’s necessary to weigh the pros and cons. Oversizing can increase inverter utilization on sunny days and boost annual generation, but excessive oversizing increases clipping losses (energy lost due to inverter saturation) during peak periods. PVsyst calculates losses due to inverter output limits, so review simulation results and determine the optimal oversizing ratio.

Tips to Improve Energy Yield Simulation Accuracy

To improve design simulation accuracy and bring predicted generation closer to reality, keep the following points in mind.

• Use high-quality input data: Use the latest, most reliable meteorological data and equipment characteristics. Select long-term weather data from locations close to the site, and check not only manufacturers’ nominal performance values for panels and inverters but also measured values and temperature coefficients. If you have site-specific measured irradiation data from installed instruments, incorporating it can further improve accuracy.

• Conduct detailed shading analysis: Perform detailed shading simulations when possible. PVsyst’s 3D shading simulation feature can reproduce shading movements by time of day and season. This is particularly effective for rooftop or mountainous projects, where detailed shading analysis improves accuracy beyond simple calculations.

• Set appropriate loss values: Adjust values for cable wiring losses, conversion efficiency, downtime, etc., to match the project reality. Setting soiling levels and maintenance frequency based on the actual site rather than generic standard values will make predictions more realistic.

• Compare multiple scenarios: To account for uncertainty, run multiple simulation cases. For example, comparing best-case and worst-case scenarios or varying irradiation by a few percent helps understand result variability. PVsyst can calculate statistical indicators like P50 (median) and P90 (conservative estimate), which are useful for risk assessment. Scenario comparisons help grasp generation uncertainty during planning and create feasible business plans.

• Cross-check with measured data: If you have operating data from similar systems, use them as references. Comparing simulation results with actual generation and analyzing discrepancies reveals model adjustment points. Tweaking PVsyst input values based on historical data improves new project prediction accuracy. Repeatedly aligning the model with actual performance refines the simulation and benefits future project forecasting.

Bridging Design and Site Using LRTK (Point Clouds, AR, Surveying)

To reliably realize desk-based designs on-site, it’s important to implement measures that connect design and the field. Key to this is leveraging digital technology, and one noteworthy tool is LRTK. LRTK is a compact surveying device used with a smartphone that offers centimeter-level RTK-GNSS positioning and LiDAR scanning. With this single device you can perform high-precision site positioning and surveying, obtain 3D point cloud data, and even project design drawings via AR (augmented reality). Even carefully simulated PVsyst designs won’t deliver their full value unless they reflect actual site conditions. For example, a layout that was optimal in simulation might be impossible to install as planned due to subtle ground undulations or unexpected obstacles. By using LRTK, you can walk the site before construction and scan the terrain and surrounding structures into a 3D point cloud to incorporate them into the PVsyst design. This allows you to accurately model shading sources and ground slopes, further improving simulation accuracy. Moreover, LRTK’s AR functionality lets you visualize the completed design plan on-site. By overlaying planned solar panel layouts onto the real scenery through a smartphone screen, you can intuitively detect discrepancies between drawings and the site. This is useful for final pre-construction checks and for positioning during construction. For instance, on a large site, LRTK’s coordinate guidance can help accurately mark panel row endpoints and equipment locations according to the design, enabling efficient reproduction of the planned layout. Tasks that formerly required experienced surveyors and significant time—surveying and marking—can be performed efficiently by one person using LRTK. The ability to perform surveying, point cloud measurement, and marking in a single, short, and simple workflow—previously requiring multiple instruments and skilled personnel—is a significant advantage. LRTK does not require special advanced skills, enabling both labor savings and higher on-site accuracy. In short, combining PVsyst digital design with LRTK-driven site digitalization bridges the gap between design and construction and helps deliver the planned generation performance.

Conclusion: Naturally Introduce LRTK Use within a Practical On-Site Workflow

Designing solar power systems requires not only desk-based planning but also consideration of whether the system will deliver the expected performance on-site. This article reviewed design know-how and points to note using PVsyst Japanese translations, covering key factors such as irradiation, shading, and losses, and tips for improving simulation accuracy. We also showed how combining advanced tools like LRTK makes it possible to bridge digital design and on-site construction, minimizing gaps between simulation and actual performance. The crucial point is that these insights and tools are only meaningful when applied on-site. By performing precise yield forecasts in PVsyst, identifying risks at the design stage, and then smartening up site surveys and construction with LRTK, you can achieve integrated quality control from planning through commissioning. As solar deployment continues to grow, knowledge gained from PVsyst Japanese translations together with LRTK utilization will form a powerful combination for anyone seeking high-quality design and reliable construction. Incorporate the latest technologies and build a practical, efficient workflow for solar design and construction. An integrated approach using digital technologies will become increasingly important, and leveraging modern tools will further enhance the efficiency and reliability of solar power projects.