Getting Started with PVsyst｜7 Steps for Your First Simulation

PVsyst is simulation software used to examine the energy yield and loss factors of solar power systems. During the planning stage of a power plant, expected energy production is checked while organizing many conditions such as the site’s meteorological conditions, orientation, tilt angle, module capacity, inverter configuration, shading effects, and wiring losses. By using PVsyst, you can input these conditions and more easily check annual energy production, monthly energy production, and breakdowns of losses.

On the other hand, for practitioners using the software for the first time, it can be unclear where to start entering data, which items to decide first, and which parts of the result report to look at. This article explains the flow of conducting an initial simulation in seven steps for those researching how to use PVsyst. Since detailed numerical settings vary depending on project conditions, design policies, and internal standards, the aim here is to first grasp the overall picture and to cover the checkpoints that are easy to get confused about in practice.

Table of Contents

• Things to understand before running your first PVsyst simulation

• Step 1: Organize the project conditions and the purpose of the simulation

• Step 2: Create the project and set the installation location

• Step 3: Select meteorological data and prepare the assumptions for energy production calculations

• Step 4: Input the system configuration and installation conditions

• Step 5: Set shading, losses, and operational conditions

• Step 6: Run the simulation and check the results

• Step 7: Interpret the report and use it to guide improvements for next time

• Points to be aware of when using PVsyst in practice

• Summary: For the first time, prioritize mastering the framework for organizing conditions rather than achieving perfect accuracy

Things to understand before running your first simulation in PVsyst

What’s important when learning to use PVsyst is not trying to understand every setting perfectly from the start. Simulating solar power generation is not simply a task of calculating energy output. It is the process of organizing at which site, what kind of equipment, in what orientation, and to what degree of losses the system will be installed, and then checking the expected energy production based on those assumptions. In other words, organizing the input conditions is as important as operating the software.

In the initial simulation, you should first clarify what the calculation is intended to verify. For example, if you want a rough estimate of annual energy production as an early review of a business plan, versus if you want to compare differences before and after a design change, the required level of detail for input conditions and the results to be checked will differ. In preliminary studies you may use coarse conditions to capture overall trends, but documents used before placing orders or for explaining to stakeholders may require justification of input values and explanations of loss settings.

In PVsyst you configure the installation site, meteorological data, module surface orientation, system capacity, equipment configuration, shading effects, and various losses. Because these are interrelated, adjusting only a single value makes it difficult to assess the validity of the results. For example, even if the annual energy production appears high, if the azimuth or tilt angle differs from the actual design, those results are hard to use for practical decision-making. Similarly, if loss settings are underestimated the apparent energy yield will increase, but the simulation may no longer reflect real site conditions.

Therefore, for the first time, it is safer to focus on being able to explain later which conditions you entered rather than on pressing the correct buttons. Gather the project documents before inputting data, and record which conditions were used after the calculation so that recalculation and comparison become easier. PVsyst allows for detailed investigation, but because it has many settings, diving too deeply into the details from the outset can make it easy to lose sight of the overall flow. First, it is important to gain experience by going through the sequence of organizing the project conditions, entering the basic settings, and viewing the result report.

Step 1: Organize project conditions and simulation objectives

Before opening PVsyst, first organize the project parameters. A common mistake in first-time simulations is realizing after entering the interface that required information is missing and ending up with vague settings midway through. In solar PV calculations, the installation location, system capacity, mounting method, azimuth, tilt angle, and assumed operating conditions all influence the results. By compiling these in advance, data entry becomes smoother and it is less likely you'll become confused when reviewing the conditions later.

The first thing to confirm is the installation site. Power output is affected by factors such as solar irradiance and ambient temperature, so setting the location is one of the basic conditions. If you know the address or latitude and longitude, specify a point as close as possible to the actual installation site. You can proceed with only a general region name, but weather conditions can differ in mountainous, coastal, and inland areas. Even in an initial study, results may change if you later replace the location information, so it is important to record which site conditions were used for the calculation.

Next, decide on the purpose of the simulation. If the purpose remains vague, it will be difficult to judge whether the results are good or bad. For example, if it’s an initial project feasibility check, the focus will be on confirming annual power generation, trends in equipment utilization, and monthly variations in power generation. If the purpose is design comparison, it’s important to look at the differences when changing tilt angle, orientation, or capacity configuration. If you want to examine the effects of shading, the key point is how much to reflect conditions such as surrounding obstructions and array spacing.

Also, organize the basis for input values in advance. Having design drawings, layout plans, equipment specifications, on-site survey records, and information about the surrounding environment on hand stabilizes the inputs to PVsyst. If detailed materials are not yet available, clearly state that the conditions are provisional and ensure they can be replaced with formal conditions later. In practice, the results of the initial simulation may become the starting point for internal review or explanations to clients. Therefore, it is essential to distinguish whether the figures are provisional or based on design documentation.

In the initial phase, it is more important to identify gaps in the conditions than to have perfect conditions. During the process of entering data into PVsyst, missing information may become apparent. In such cases, rather than making definitive judgments, manage them as provisional settings, under review, or scheduled to be replaced later. By organizing things this way, the recipients of the simulation results will find it easier to judge the level of precision with which they should interpret them.

Step 2: Create a project and set the installation location

Once you've organized the project conditions, create a new project in PVsyst. A project is the unit used to collectively manage the installation location and simulation conditions. For the first entry, give it a name that makes the project name, study stage, creation date, and so on clear, so it will be easier to compare multiple calculation results later. If the name is ambiguous, when files for the same project multiply with changed conditions, you may not be able to tell which one is the latest.

When creating a project, you set the installation site. In site settings, latitude, longitude, elevation, and regional information form the basis for power generation calculations. In particular, latitude affects solar altitude and insolation conditions, so calculating with an incorrect site will impact the results. Even when choosing a nearby location based on an address, check that it is not significantly distant from the actual installation site. If you use a broad-area candidate site, take into account differences in local weather conditions and treat the results with caution.

After setting the site location, also check the time zone and regional settings. These are usually set in conjunction with the site information, but if you import data or reuse past projects, unintended settings may remain. For the initial simulation, rather than copying and using an existing file, create a new project and verify the basic conditions one by one; this makes it easier to learn the workflow.

At the stage of creating a project, the conditions for calculating power generation are not yet all in place. What is being done here is building the foundation for those calculations. In solar power generation simulations, the site settings lead to the subsequent selection of meteorological data and the power generation calculations. If the initial site settings are ambiguous, you won’t be able to tell which site conditions apply to the power generation when you review the results later.

In practice, when the installation site has not yet been decided, multiple candidate sites may be compared. In such cases, either separate projects by candidate site or manage them within the same project using names that indicate the different conditions. It is important to ensure you can distinguish whether differences in power generation are due to site differences or to differences in equipment configuration or tilt angle. Establishing a management framework from the outset makes subsequent assessments easier.

Step 3: Select meteorological data and establish assumptions for power generation calculations

Next, select the meteorological data. In PVsyst simulations, meteorological conditions such as irradiance and ambient temperature affect the calculation of energy production. Because photovoltaic systems convert solar irradiance into electricity, the choice of meteorological data has a significant impact on the results. Even when you are learning how to use the software for the first time, meteorological data should be treated not as mere initial settings but as the assumptions underlying energy production.

When selecting meteorological data, check whether the data are from near the installation site and whether the period and representativeness match your purpose. In general preliminary assessments, representative data that show long-term trends are often used, but depending on the project you may want to check on-site observations or data for a specific period. Because results can vary depending on which data are used, it is important that, when using them in reports or internal documents, you are able to describe the type of meteorological data used and the site conditions.

In the initial simulation, before making detailed corrections to the meteorological data, we first select the basic data that allow the calculation to be performed. What is important here is to verify that the data are not significantly different from the installation site and are not clearly unrealistic values. For example, if coastal conditions are reflected in an inland project, data from a location with a large elevation difference are being used, or a location with different regional characteristics has been selected, caution is required when interpreting the results.

Weather data affect not only energy generation but also monthly trends. Even if the annual generation looks similar, whether a system tends to perform better in summer or suffers larger drops in winter changes what to focus on for equipment planning and financial assessments. Because PVsyst’s results allow you to check monthly generation, after setting the weather data you should pay attention not only to the annual values but also to monthly patterns.

When you choose meteorological data, make a note of the assumptions under which you will proceed using that data. In practice, you may later compare what happens when calculations are performed with different meteorological data. In such cases, if the initial calculation conditions are not known, it becomes difficult to trace the causes of the differences. If you develop the habit from the first time of managing the location, meteorological data, creation date, and purpose of the analysis as a set, it will be easier to explain the reliability of the simulation.

Step 4: Enter system configuration and installation conditions

After setting the meteorological data, enter the system configuration for the photovoltaic installation. Here you configure module capacity, circuit layout, inverter capacity, and the azimuth and tilt angle of the mounting surface. Many people find this system configuration a stumbling block when using PVsyst. Because there are many configuration items and an understanding of the equipment layout and design conditions is required, it is important to proceed while reviewing the documentation in advance.

First, enter the orientation and tilt angle of the mounting surface. Orientation indicates which direction the module surface faces. The tilt angle indicates how much it is inclined relative to the horizontal plane. Because these directly affect how solar irradiance is received, they influence power generation. For rooftop installations, they are often matched to the roof pitch and building orientation, while for ground-mounted installations they are typically determined by the racking design. In the initial assessment, verify the values shown on design drawings and layout plans and avoid entering estimated values.

Next, configure the modules and inverters. The important point here is that the equipment specifications you enter match the system configuration under consideration. If capacity, number of modules, number in series, number in parallel, etc., deviate from the actual plan, the simulation results will diverge from reality. For the initial run, proceed by confirming that the basic capacity balance is established rather than aiming for detailed optimization. If warnings or caution messages appear in the software, do not simply clear them; it is important to check why they were displayed.

In the system configuration, pay attention to the relationship between the module-side capacity and the inverter-side capacity. In solar power generation, the two capacities are not necessarily the same. The capacity ratio may be set based on planning considerations. However, excessive settings or inputs without justification make interpreting the results difficult. For the initial simulation, set them within ranges consistent with internal standards and design policies, and ensure you can explain why that configuration was chosen.

When entering installation conditions, consider whether to treat the entire installation as a single simple surface or to divide it into multiple surfaces. If the roof has multiple orientations or there are sections with different tilt angles, it can be more realistic to set the conditions separately. However, making it too complex from the start increases the chance of operational errors, so it is practical to first run calculations using representative conditions and then split them as needed.

Step 5: Set Shadows, Losses, and Operating Conditions

After entering the system configuration, set the shading and various loss conditions. PVsyst's results can be viewed not as simple ideal generation but as reflecting the loss conditions you entered. In real installations, multiple factors reduce generation output—shading effects, temperature-related losses, wiring losses, soiling, equipment downtime, and variability in module characteristics. For the initial simulation, it is more important to understand which loss items are included in the results than to specify every detail.

In shadow settings, surrounding buildings, trees, terrain, and shading between rows of mounting racks may be taken into account. Because the effects of shading vary with time of day and season, they can affect not only annual power generation but also generation in specific months and during mornings and evenings. While initial assessments may proceed with simplified settings, projects with significant shading require analyses that reflect layout planning and the surrounding environment. In particular, at locations where shadows occur during periods of low solar altitude, the impact on power generation may not be negligible.

When setting losses, it is important not to enter overly optimistic values. If losses are underestimated, estimated power generation will be higher, but the results may not match actual operation. Conversely, entering large losses without justification will make equipment evaluations excessively strict. At the initial stage, confirm the standards commonly used within the company and the approaches taken in past projects, and determine whether any adjustments are necessary for each project.

Operating conditions also affect the results. For example, how extensively you account for shutdowns due to regular inspections and maintenance, equipment soiling, and performance degradation with age depends on the purpose of the simulation. Standard conditions may be acceptable for initial comparisons of power generation, but when assessing long-term project viability you need to check assumptions including operation and maintenance. However, because future operating conditions are uncertain, it is important not to treat them as definitive and to state them clearly as assumptions.

Settings for shading and losses are among the parts of using PVsyst that most often require practical judgment. Entering numbers into the software interface itself isn't difficult, but whether those numbers are appropriate depends on the project conditions. Initially, prioritize clarifying which losses have been considered and which losses have not been reflected, rather than finely adjusting the settings to produce a favorable result.

Step 6: Run the simulation and check the results

After entering the basic conditions, meteorological data, system configuration, and loss conditions, run the simulation. On the initial run, rather than rushing to look only at the numerical results, check before running whether any warnings or unset items remain. In PVsyst, warnings may be displayed when there are inconsistencies in input conditions or items that require confirmation. Although the calculation may proceed even when warnings are issued, advancing without understanding their meaning makes it difficult to assess the reliability of the results.

When you run the simulation, you can check the annual generation, monthly generation, and breakdown of losses. The first thing to check is whether the annual generation is extremely large or small relative to the project size. On an initial run it may be difficult to make a detailed validity assessment, but verify that the relationship between installed capacity and generation does not seem inconsistent. If extreme values appear, there may be an input error in the location, weather data, azimuth, tilt, capacity settings, or loss settings.

Next, we look at monthly power generation. Solar power generation varies with the seasons. By examining the monthly results, you can identify differences between summer and winter, periods when the rainy season or snowfall are likely to affect output, and times when shading effects are more likely to occur. Monthly results reveal trends that are not visible from annual values alone. In practice, documents sometimes present only annual generation figures, but during the evaluation stage it is easier to explain later if you confirm the monthly patterns.

The breakdown of losses is also important. In PVsyst, based on the input conditions, you can check at which stages and what kinds of losses occur. If there are items with large losses, verify their causes. If shading losses are large, you may need to reconsider the layout and the surrounding environment. If losses related to wiring or temperature are large, you need to recheck the design conditions and input values. At the initial stage, it is more important to understand the components that make up the results than to try to fine-tune the loss breakdown.

When you review the simulation results, don't immediately treat the calculated power output as final. The initial result is a first estimate to verify that the input conditions are correct. In practice, you adjust conditions and compare multiple scenarios to arrive at results that are easier to explain. Once results are produced, save the input conditions together with the output so they can be reproduced.

Step 7: Read and interpret the report, and use it to guide improvements for the next time

After running a simulation, review the report. PVsyst's report compiles the project conditions, meteorological data, system configuration, installation conditions, energy production, and a breakdown of losses. For first-time use, it's important to read the report not as submission-ready results but as reference material to verify the input conditions. By examining the report, you can objectively confirm under which conditions you performed the calculations.

First, check the project information at the beginning of the report. Verify that the project name, installation site, meteorological data, and simulation conditions are as intended. If the site or meteorological data are incorrect here, it becomes difficult to judge the subsequent power generation results. Next, check the orientation and tilt angle of the installation surface, the system capacity, and the equipment configuration. Cross-reference with the design documents to ensure there are no data entry errors.

When examining power generation results, look not only at the annual value but also at monthly values, generation trends per unit of capacity, and the flow of losses. Annual generation is an easy-to-understand indicator, but by itself it does not reveal the context behind the results. Looking at monthly values lets you grasp seasonal variations, and checking the breakdown of losses lets you confirm where generation is declining. On the first review, prioritize understanding where and what is written in the report rather than judging whether the numbers are good or bad.

After reviewing the report, organize the points to be corrected for the next improvement. For example, improvements to consider include making the installation site more accurate, comparing meteorological data under different conditions, entering shadow conditions in more detail, confirming the basis for loss settings, and aligning the design capacity with the latest drawings. The initial simulation is not the final deliverable but a starting point for organizing the conditions. A practical approach is to identify missing information while reviewing the report and increase accuracy in the next calculations.

When sharing a report with stakeholders, always include the assumptions. The same power generation figures can mean very different things depending on whether they were calculated under provisional assumptions or based on design drawings. Especially for initial simulations, which often contain uncertain conditions, explicitly stating what has been incorporated and what remains unverified will help prevent misunderstandings.

Points to keep in mind when using PVsyst in practical work

As you become familiar with using PVsyst, you will be able to run simulations in a short time. However, in practice what matters is not just producing results quickly. It is important that anyone who looks at the numerical results can understand the underlying assumptions and can explain the reasons for any differences when conditions change. Simulations change when input conditions change. That is why managing the conditions is more important than the operation.

A particular point to watch is when reusing files from past projects. Even if the projects are similar, copying and using a previous file can leave elements such as the site location, meteorological data, capacity, loss conditions, and shading conditions unchanged. Even if it appears to be a new project on the surface, if the internal conditions remain outdated it can lead to incorrect results. When reusing files, be sure to check the basic conditions in order and record which parts you changed and which you left unchanged.

Next, it is also important not to be overly definitive about the results. PVsyst simulation results are estimates based on the input assumptions. Actual energy production can vary due to year-to-year weather variability, equipment condition, maintenance status, and changes in the surrounding environment. Therefore, it is not appropriate to present the figures in the report as if they will necessarily equal that amount of generation. In practical documents, it is safer to treat them as estimates based on certain conditions or as simulation results under assumed conditions.

It is also important to match the granularity of input conditions to the purpose. Simple conditions may be sufficient for an initial study, but more accurate inputs are required when using the results for detailed design or for explanations to stakeholders. Conversely, if you refine details at a stage when the design is not yet fixed, you will need to recalculate if the conditions change later. Decide how detailed the inputs should be according to the purpose of the simulation.

When multiple people in the company use PVsyst, sharing input rules helps stabilize quality. Standardizing how project names are assigned, how meteorological data is selected, how loss settings are determined, how reports are saved, and how comparison patterns are managed makes it easier to track results even if the person in charge changes. Simulations tend to be person-dependent, so being mindful from the first run about how to keep records helps prevent future problems.

Also, do not forget to verify consistency with on-site conditions. The orientation, tilt angle, and shading conditions entered at the desk may not match the actual site. Surrounding obstacles, terrain, existing equipment, maintenance routes, and the installable area may only become apparent through on-site inspection. To bring PVsyst results closer to real-world practice, it is important to organize on-site information and, where necessary, reflect it in the simulation conditions.

Summary: On the first attempt, prioritize learning the approach to organizing conditions over accuracy

When first learning how to use PVsyst, it is more important to go through the flow of an initial simulation once than to memorize every detailed setting. Organize the project conditions, create the project, set the installation site and meteorological data, enter the system configuration and loss conditions, run the simulation, and review the report. If you understand this flow, it becomes easier to see what to modify in subsequent evaluations.

PVsyst is a convenient software that allows you to check power generation and losses based on the conditions you enter, but the reliability of the results depends on how well those input conditions are organized. If you perform calculations while the installation site is ambiguous, the assumptions behind the meteorological data are unclear, or the loss settings have no rationale, the results will not be easy to explain in practical work. From the first run, it is important to record which conditions were entered, which ones are provisional, and which need to be reviewed later.

For practitioners, PVsyst is not just a calculation tool but also a means to verify and organize the planning conditions of solar power generation facilities. Rather than only looking at the generation figures, confirming why those results occurred, which losses are large, and which conditions change the outcome makes it easier to use for design reviews and explanations to stakeholders.

In the initial simulation, it’s okay not to try to produce highly polished results right away. Rather, it’s important to check each input condition one by one, read the results report, and organize which items to improve next. By mastering this basic workflow, you’ll be better prepared to handle larger projects or to compare multiple scenarios.

Also, to leverage results obtained from PVsyst in on-site work and design studies, grasping the on-site conditions is indispensable. Confirm shadows, installation area, surrounding environment, maintenance access routes, and other factors that cannot be determined from drawings alone, and reflect the necessary information in the simulation conditions so that the study is closer to practical work. When learning how to use PVsyst, be sure to treat not only software operation but also condition organization, recordkeeping, and on-site verification as a single, integrated workflow.