PVSyst: Summary of Solar Design Know-how and Precautions Learned from the Japanese Translation

Introduction: Why Solar Design Is Attracting Attention Now

In recent years, as efforts toward achieving carbon neutrality by 2050 and the need to improve energy self-sufficiency have accelerated the shift to renewable energy, the design of solar power generation systems has been attracting particular attention. New projects are increasing domestically and internationally, from utility-scale mega-solar to residential installations, and design choices at the planning stage greatly affect generation efficiency and investment returns. Where practices once relied on experience and simple calculations, precise generation simulations and the use of digital tools are now indispensable. Especially as projects grow larger, financial institutions and project owners demand reliable simulation results, raising the importance of design know-how. In practice, there have been cases where optimistic predictions at the design stage led to actual generation falling short of planned values, or where overlooked shading caused problems, making the acquisition of proper design and simulation knowledge increasingly critical. Against this backdrop, attention has turned to the globally used software PVsyst, and learning solar design know-how through Japanese translations and explanatory materials has become more active.

Overview of PVsyst and the Benefits of Using Japanese Translations

PVsyst (pronounced "Pee-Vee-Syst") is a world-standard simulation software widely used for designing solar power generation systems and forecasting energy production. By inputting system scale and configuration, you can obtain detailed reports such as annual generation, monthly generation forecasts, and breakdowns of losses. Because of its high functionality, it is popular among experts, especially overseas, but the language barrier has been an issue for Japanese users. This is where PVsyst Japanese translations are useful. Although the software itself is primarily in English, major term translations into Japanese and explanatory materials have become more available, creating an environment where users can understand operations and results in Japanese. By using Japanese explanations, engineers who are not strong in English can more easily master PVsyst, reducing misunderstandings and oversights and enabling accurate simulations. Also, sharing information within teams and explaining results to clients in Japanese becomes smoother, so the advantages of PVsyst Japanese translations are significant. Domestically, PVsyst simulation results are increasingly used in business planning for large-scale projects like mega-solar, and its high reliability has made it a de facto industry standard.

Common PVsyst Terms and Their Japanese Translations

Here are some key terms you should know when working with PVsyst, along with their Japanese translations.

• Irradiation / Irradiance（照度・日射量）: Terms referring to the amount of solar radiant energy. For example, "Global Horizontal Irradiation" denotes the annual irradiation on a horizontal plane and indicates the potential of the design location.

• Tilt Angle（傾斜角）・Azimuth（方位角）: The tilt angle of the solar panel (angle from horizontal) and the installation direction (east-west direction with true south = 0° as the reference). Proper tilt and azimuth settings are key to receiving the maximum solar irradiance.

• Shading（影・遮蔽）: Shadows that block sunlight. In PVsyst you can account for both near shading caused by nearby buildings or trees and distant shading caused by terrain or the horizon. Because shading can greatly affect generation, it is analyzed in detail.

• Losses（損失）: A collective 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 due to module variability, and initial degradation such as LID. PVsyst allows you to set and review each loss factor individually.

• Performance Ratio（性能比, PR）: An indicator of system performance expressed as the percentage ratio of actual generation to the generation under ideal conditions. A higher PR indicates better overall system efficiency and lower losses. (In typical large-scale projects, the first-year PR generally settles around 80%.)

• Meteo Data（気象データ）: The dataset of irradiation, temperature, and other weather parameters used as simulation inputs. PVsyst can utilize various meteorological datasets such as Meteonorm, NASA data, and domestic datasets like NEDO irradiation data. Proper selection of data directly affects accuracy.

• Simulation Report（シミュレーションレポート）: The detailed result reports that PVsyst outputs. These include annual and monthly generation, breakdowns of various losses, performance ratio, and statistical achievement probabilities (P50/P90 values). By referring to documents translated into Japanese, you can correctly interpret these contents.

Understanding these terms helps in reading simulation results. Additionally, materials that explain PVsyst output reports in Japanese are available and can deepen your understanding when consulted as needed.

Design Considerations: Irradiation, Shading, and Loss Factors

To perform high-accuracy simulations and practical designs, pay attention to the following aspects. Irradiation: Knowing the precise irradiation at the design site is the starting point. Accurately understand the site’s annual irradiation and weather conditions and use reliable meteorological data. For example, compare multiple data sources (such as domestic NEDO data and international databases) and select the irradiation dataset closest to actual measurements. Different datasets can vary by several percent in annual irradiation, and that difference directly affects generation forecasts. Also consider the impact of seasonal snow in winter or region-specific weather patterns when applicable. Shading: Since shading on PV modules drastically reduces output, thoroughly identify shading factors. Check not only near shading from nearby buildings, trees, or adjacent panel rows, but also terrain-based shading (such as mountains or high ground on the horizon). For instance, if a plant is located where it will be in the mountain’s shadow during winter mornings and evenings, you can predict generation losses for those times in advance and plan countermeasures. PVsyst can create 3D models including surrounding objects and simulate how much generation loss due to shading occurs over the year. Understanding shading impacts during the design stage and considering layout adjustments, appropriate spacing, or tree removal are important measures. Loss Factors: It is also important not to overlook the various loss factors that occur across the entire system. For example, longer cable lengths increase resistive losses, and high-temperature environments reduce module output. Over long-term operation, soiling and aging will also invariably reduce output. PVsyst allows you to set values for each loss item. Refer to empirical values or manufacturer-provided figures and input loss rates that reflect actual conditions as much as possible. Some loss factors can be mitigated in the design phase—for example, choosing appropriate cable sizes to reduce wiring losses or planning regular cleaning to reduce soiling losses. Avoid overly optimistic estimates and include reasonable margins (safety factors) to minimize discrepancies between predictions and actual performance.

Overloading (DC/AC ratio) Design: Recently, it has become common to install more modules relative to inverter capacity (overloading), but you need to weigh its advantages and disadvantages. While overloading can increase inverter utilization on sunny days and boost annual generation, excessive overloading increases clipping losses (unproduced energy due to inverter saturation) at peak times. PVsyst calculates losses from inverter output limitations, so review simulation results and consider the optimal overloading ratio.

Tips to Improve the Accuracy of Generation Simulations

To increase the accuracy of design simulations and make generation forecasts closer to actual performance, keep the following points in mind.

• Use high-quality input data: Use the latest and most reliable meteorological data and equipment characteristics as the basis. Choose long-term weather data from points close to the site, and verify not only manufacturers’ nominal values for panels and inverters but also measured values and temperature coefficients. For example, if you have irradiation data measured on-site with installed instruments, reflecting that data will further improve accuracy.

• Conduct detailed shading analysis: Perform detailed shading simulations where possible. Using PVsyst’s 3D shadow simulation feature reproduces shading movement by time of day and season. Particularly for rooftop or mountainous projects, detailed shading analysis improves accuracy compared to simple calculations.

• Set appropriate loss values: Adjust values for cable wiring losses, conversion efficiencies, downtime, and other parameters to match the project’s actual conditions. For instance, rather than using generic standard values, setting loss rates based on the actual degree of soiling and maintenance frequency will make forecasts more realistic.

• Compare multiple scenarios: Considering uncertainties, it is useful to run multiple simulation cases. For example, examine best-case and worst-case scenarios or assess the impact of changing irradiation by a few percent to understand result variability. PVsyst provides statistical indicators such as P50 (median) and P90 (conservative estimate), which you can use for risk evaluation. Scenario comparisons help grasp generation uncertainty at the planning stage and build realistic business plans.

• Cross-check with measured data: If similar systems are already operating, using their generation performance as a reference is effective. Comparing simulation results with actual generation and analyzing differences reveals tuning points for the model. Adjusting PVsyst input values based on past data will improve forecasts for new projects. Repeatedly reconciling simulations with actual performance refines the simulation model and helps improve prediction accuracy for future projects.

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

To reliably realize desk-based designs on site, measures that bridge design and the field are also important. A key to this is leveraging digital technology, and one device to note is LRTK. LRTK is a compact surveying device used with a smartphone and is equipped with centimeter-level RTK-GNSS positioning (half-inch accuracy) and LiDAR scanning. With this single device, you can cover high-precision on-site positioning and surveying, acquisition of 3D point cloud data, and even projection of design drawings via AR (augmented reality). Even carefully simulated designs in PVsyst cannot demonstrate their full value unless they accurately reflect on-site conditions. For example, a layout that appears optimal in simulation may not be installable as planned due to minor terrain undulations or unexpected obstacles. By using LRTK, you can walk the site before construction, scan the terrain and surrounding structures into a 3D point cloud, and reflect that data in the PVsyst design. This allows you to accurately model shading sources and ground slopes, further enhancing simulation accuracy. Moreover, LRTK’s AR function lets you visualize the completed design plan on site. By overlaying the panel layout onto the actual landscape through a smartphone screen, you can intuitively detect discrepancies between drawings and the site. This is useful for final checks before construction and for stakeout tasks during construction. For instance, even on a vast site, LRTK’s coordinate guidance can accurately mark panel row endpoints and equipment installation positions on the ground according to the design, enabling efficient reproduction of the planned layout. Tasks that previously required experienced technicians and significant time for surveying and stakeout can be handled efficiently by a single person using LRTK. The ability to perform surveying, point cloud measurement, and stakeout in a short time with simple operation—tasks that formerly required multiple instruments and specialist personnel—is a major advantage. Without requiring special advanced skills, LRTK simultaneously reduces labor and increases accuracy on site. In short, combining PVsyst digital design with LRTK-driven site digitalization bridges the gap from design to construction and enables achieving the planned generation performance.

Conclusion: Naturally Introducing LRTK into a Practical Workflow That Works on Site

Designing solar power generation systems requires not only desk planning but also consideration of whether expected performance can be achieved in the field. This article reviewed design know-how and cautions using PVsyst Japanese translations as a foundation, covering key points such as irradiation, shading, and losses, and tips for improving simulation accuracy. We also saw that combining advanced tools like LRTK makes it possible to bridge digital design and on-site construction, minimizing gaps between simulations and actual performance. The crucial point is that these insights and tools are meaningful only when applied on site. By performing refined generation forecasts in PVsyst, identifying risks at the design stage, and smartening on-site surveys and construction with LRTK, you can achieve consistent quality control from planning to commissioning. As solar deployment continues to expand, acquiring knowledge through PVsyst Japanese translations and utilizing LRTK will form a powerful combination for anyone aiming to perform high-quality design and reliable construction. Incorporate the latest technologies and build a practical, efficient solar design and construction workflow. Integrated approaches that leverage digital technologies will become increasingly important, and through using the latest tools you can further enhance the efficiency and reliability of solar power projects.