Getting Started with the PVSyst Japanese Translation: A Primer on Solar PV Planning for Local Governments

Introduction: Why Are Local Governments Now Being Called Upon to Plan for Solar Power?

Against the backdrop of climate change mitigation and rising energy prices, promoting renewable energy has become an urgent task for local governments as well. Aiming for carbon neutrality by 2050 (net zero greenhouse gas emissions), the Japanese government has set a target to source about 40% of the power mix from renewables by 2030. Accelerating the deployment of solar PV across the country is indispensable to achieve that. In fact, the Ministry of the Environment in 2024 set installation targets (kW values) by facility type for solar panel deployment on facilities owned by local public bodies to encourage stronger efforts. Some municipalities have also begun moves to make solar panel installation mandatory on new buildings. For example, Tokyo will require major housing developers to install panels on new homes from April 2025, and other jurisdictions such as Kawasaki City and Sagamihara City plan to enact similar ordinances. In this context, local governments are expected to take the lead in formulating and implementing plans to install solar PV systems on public facilities, thereby driving regional decarbonization.

Moreover, introducing solar PV to public facilities contributes to cost reductions through local production and consumption of energy and enhances resilience during disasters. If schools or municipal offices install solar systems with battery storage, they can secure emergency power during blackouts and strengthen their role as disaster-response hubs. For municipalities, solar PV planning is therefore an important measure that can deliver environmental benefits as well as fiscal and disaster-preparedness advantages.

Overview of PVsyst and the Value of “PVSyst Japanese Translation”

Tools that can simulate generation forecasts and design are indispensable when planning solar PV systems. A leading example is PVsyst. PVsyst is a professional solar PV simulation software developed in Switzerland and used by designers and engineers worldwide:contentReference[oaicite:0]{index=0}. By entering panel and inverter specifications, meteorological data for the installation site, shading conditions, and so on, PVsyst can calculate yearly generation, breakdowns of losses, and performance indicators (PR) in detail. It is useful across a wide range of cases from large-scale mega-solar to rooftop installations at schools, and it is powerful for visualizing and optimizing solar PV plans.

However, because PVsyst was originally provided in English, some municipal staff and engineers in Japan found it challenging. This is where the “PVSyst Japanese Translation” becomes noteworthy. Fortunately, recent versions of the software allow menus and screen displays to be switched to Japanese:contentReference[oaicite:1]{index=1}. In addition, materials explaining PVsyst simulation reports and terminology in Japanese have appeared. For example, guides to interpreting simulation reports in Japanese and bilingual glossaries of key technical terms are being developed. Learning supports through these Japanese translations make PVsyst more accessible to those not comfortable with English and help with capacity building within municipalities. By using PVsyst that can be learned in Japanese, staff can run generation simulations themselves and reflect results in plans, improving planning accuracy and reducing reliance on external parties.

Key Terms Used in PVsyst and Their Japanese Equivalents

To master PVsyst, understanding technical terms is essential. Below are frequently appearing terms in the software and reports, explained with their English equivalents.

• Solar panels / modules: The panel devices used for solar power generation. In English they are called PV modules or panels. The power capacity per module is on the order of several hundred W, and multiple modules are combined to form a system.

• Inverter (power conditioner): A device that converts direct current (DC) to alternating current (AC). Since electricity from PV is DC, it is converted to AC that can be used in homes and facilities, and any surplus can be exported to the grid. It is sometimes abbreviated as “power con” or “inverter.”

• Rated output (kW) and energy generation (kWh): Rated output (system capacity) is the maximum output the system can deliver, measured in kilowatts (kW). Energy generation is the actual energy produced, measured in kilowatt-hours (kWh). For example, even a 10 kW system will produce varying amounts of energy depending on sunlight conditions; on a sunny day it might generate roughly 50 kWh in a single day.

• Irradiation: The total amount of solar energy. It is the accumulated solar radiation at a location, usually expressed in units such as kWh/m². It is related to irradiance, but the latter refers to instantaneous irradiance (W/m²). PVsyst uses meteorological data such as annual or monthly average irradiation as the basis for generation calculations.

• Azimuth: The direction the panels face, expressed as an angle. In PVsyst for the Northern Hemisphere, true south is 0°, west is positive, and east is negative:contentReference[oaicite:2]{index=2}. In Japan, south-facing panels are standard, but roofs may face east or west, in which case generation is somewhat lower than south-facing installations.

• Tilt: The installation angle of the panels relative to the horizontal plane. 0° is horizontal (flat), and 90° is vertical. At Japan’s latitudes, a tilt of roughly 30–35° is said to maximize annual generation. However, roof shapes and structural constraints often prevent achieving the optimal tilt, so PVsyst is used to evaluate how different angles affect energy yield.

• Shading: Shadows cast by surrounding buildings, trees, or terrain. Shade on solar panels significantly reduces output, so understanding shading at the installation site is crucial. PVsyst can model both near shading (from nearby objects) and horizon shading (from terrain), and simulate losses due to shading.

• Losses: A collective term for factors that reduce actual generation from the theoretical maximum. These include temperature losses due to panel heating, electrical losses in wiring and transformers, soiling and degradation of panels, and more. PVsyst outputs a “loss breakdown” diagram in the simulation results, quantifying losses at each stage from incident light to final output.

• Performance Ratio (PR): Short for “Performance Ratio,” a quality indicator for a PV plant. It shows how much of the energy expected under ideal conditions is actually produced:contentReference[oaicite:3]{index=3}. For example, a PR of 80% means the plant is producing 80% of the ideal energy. The fewer the losses, the higher the PR; typical outdoor PV systems achieve PR values around 70–85%.

Considerations When Designing Solar PV for Public Facilities and Communities

When municipalities design solar PV systems for schools, municipal buildings, idle lands, and other sites, the following points should be kept in mind.

• Minimize shading impacts in the plan: As noted above, shading on panels greatly reduces generation. It is important to survey shading conditions on site in advance and design the layout to minimize shading. For building rooftops, shadows from outdoor air-conditioning units or rooftop water tanks may be problematic; for idle land, shadows from surrounding trees or structures are concerns. Consider removing or trimming obstructions or adjusting panel spacing as needed. PVsyst’s 3D simulation functions can visualize shadow movements by season and time of day, helping design layouts that minimize shading effects.

• Optimize azimuth and tilt: In Japan, south-facing panels at an appropriate tilt are the norm, but site conditions impose constraints. When roofs face east–west, panels will be placed east- or west-facing, resulting in lower generation around midday compared with south-facing systems, but making effective use of morning or evening sun. Regarding tilt, installing panels at the roof pitch often deviates from the optimal angle. Flat roofs allow the use of mounting frames to set the angle, but excessive tilt increases wind loads and construction costs. Use PVsyst to test various tilt and azimuth patterns and balance generation performance with structural safety and cost.

• Account for local climatic conditions: Climate characteristics vary by region and affect performance. Irradiation differs markedly between the Pacific side and the Sea of Japan side, and north–south latitude differences produce variance in annual generation. PVsyst can incorporate meteorological datasets for different areas (for example, NEDO regional irradiation data), so always simulate with data that matches the site. In snowy regions, countermeasures against generation loss from snow are important: steeper tilt to shed snow or planning for snow removal may be necessary. In salt-damage-prone or typhoon-prone areas, select weather-resistant equipment and robust mounting methods; in short, design according to local environmental risks.

• Regulations and safety: Installing solar PV on public facilities requires compliance with various regulations and ensuring safety. This includes filings for structures under the Building Standards Act, confirmation of compliance with electrical equipment technical standards, and checks for waterproofing and load-bearing capacity for rooftop installations. For schools, ensure evacuation routes remain clear and take measures against falling objects. Identifying such constraints during planning and consulting relevant departments and experts can prevent problems during construction.

Tips to Improve Generation Simulations and Design Accuracy

Improving the accuracy of solar PV planning requires meticulous planning using simulations. The following points help enhance generation forecast accuracy.

• Choose appropriate meteorological data: Simulation results are heavily dependent on the irradiation data entered. Select reliable data sources and use meteorological conditions that closely reflect the site. Domestic options include NEDO and JMA datasets; internationally, there are global datasets based on satellite observations. As estimated irradiation values differ among sources, it is advisable to run simulations with multiple datasets where possible and compare results.

• Conduct detailed shading simulations: To accurately estimate shading impacts, create and verify a 3D site model. Input buildings and trees into PVsyst’s 3D editor and reproduce seasonal shading to account for partial morning/evening shading that simple calculations might miss. Drone surveys or laser scanning can produce precise models, but if that is difficult, supplement with site photos and sun-path charts.

• Set loss coefficients appropriately: PVsyst allows customization of various loss parameters such as wiring resistance-induced voltage drop, panel temperature characteristics, and soiling rates. Use manufacturer datasheets and past performance data to set realistic values. Temperature-related output declines significantly affect summer generation, so set temperature coefficients according to site conditions. Detailed parameter tuning reduces discrepancies between desk-based plans and real-world operation.

• Compare multiple scenarios: In the early design stage, run multiple simulation scenarios to prepare for uncertainties. For example, simulate “south-facing 15° tilt,” “south-facing 30° tilt,” and “east–west 5° tilt” and compare generation against construction difficulty. Also, factor in panel degradation and potential changes in irradiation due to climate change to create a plan with margins for risk management.

• Cross-check with measured data: If possible, obtain generation records from existing PV installations or short-term irradiation measurements on site and compare them with simulation outputs. If simulations align with local measured data, the settings are likely reliable. If there are large discrepancies, recheck input data and parameter settings. Utilizing on-site data like this further improves design accuracy.

From Design to Construction: The Role of Local Governments and Process Flow

When a municipality implements a solar PV project itself, there are many steps from planning through construction and operation. Here is an outline of the main flow and the role of the municipality.

• Feasibility study and goal setting: First, investigate the feasibility of solar deployment on municipal facilities such as office buildings and schools, or suitable sites in the region. Identify roof area, orientation, solar access, electricity consumption, and estimate the potential installation scale. At the same time, set municipal renewable energy introduction targets (e.g., introducing XX kW on public facilities by 2030) to determine the plan’s direction.

• Preliminary design and generation simulation: For candidate sites, use PVsyst or similar tools to estimate generation and benefits. Estimates of how many kW mounted on which facility will generate how many kWh annually and how much electricity cost can be reduced serve as decision-making material for project implementation. Rough estimates of installation costs and financial projections are also prepared at this stage to evaluate return on investment.

• Budget securing and stakeholder coordination: If simulations indicate feasible benefits, next secure funding. Utilize national subsidies and grants, or coordinate budget allocation within the municipality. It is necessary to present the budget proposal to the council and obtain approval. At the same time, coordinate with stakeholders such as the board of education or school principals for school installations and engage local residents for understanding and cooperation. If self-funding is difficult, consider the use of the third-party ownership model (PPA), wherein a private entity installs and owns the system and the municipality pays for electricity usage, allowing zero initial investment. The Ministry of the Environment promotes PPA introduction for public facilities and has published guidance.

• Detailed design and procurement: Once the budget is confirmed, move to the detailed design phase. Select specialist design offices and contractors (through procurement if required), conduct detailed site surveys and structural checks, and finalize system designs. When panel layout drawings, wiring routes, equipment specifications, and construction schedules are finalized, sign construction contracts. As the procuring entity, the municipality should check that the design meets the original plan objectives and issue correction instructions if necessary.

• Construction management and inspection: During construction, monitor progress with attention to safety and quality management. Municipal staff should regularly inspect the site and coordinate with contractors. Upon completion, perform prescribed inspections to confirm that construction complies with the design documents and that the generation system operates correctly. Grid connection procedures with the power utility should also be completed at this stage in preparation for commissioning.

• Operation start and monitoring: After commissioning, implement generation monitoring and regular inspection and maintenance. Track generation performance and verify deviations from simulations to feed back into future planning improvements. The generated electricity not only contributes to facility energy savings but can also be used as educational material for community environmental learning or incorporated into emergency power drills, expanding post-installation benefits.

As described above, municipal-led solar PV projects require integrated management from planning through construction and operation. Although specialized knowledge is required at each stage, leveraging simulation tools like PVsyst and relevant guidelines will be key to steady progress and project success.

Conclusion: Bridging Planning and Construction with Simple Surveying Using LRTK

To ensure successful solar PV projects, it is important to bridge planning and on-site construction smoothly. A useful tool for this is simple surveying technologies that leverage the latest advancements. For example, LRTK is a solution that enables high-precision surveying using a smartphone, allowing detailed site dimensions and coordinates to be obtained quickly without specialized equipment. Incorporating LRTK survey data in the planning stage helps refine PVsyst-based designs to match actual site conditions. Conversely, during construction, using LRTK for stakeout based on design data helps align the on-paper layout with on-site installation without discrepancies.

By utilizing simple surveying with LRTK, municipalities can manage the entire flow from planning to construction more seamlessly. Linking thorough simulation-based planning with field-data-driven precise construction improves the accuracy of generation and schedule forecasts and reduces project issues. Be sure to incorporate new technologies like LRTK from the planning stage to lead municipal solar PV projects to success.