8 basics for using PVsyst in the field

Many practitioners researching how to use PVsyst are not merely looking for the order of screens; they want to know how to read the information necessary for planning, design, construction, inspection, and handover of a solar power plant, and how to translate that into on-site decisions. Energy yield simulations cannot be completed by desk calculations alone. If you do not understand site conditions, orientation, tilt, shading, equipment configuration, losses, and how to interpret the reports, discrepancies can arise with design drawings and construction plans.

This article organizes how to use PVsyst into eight fundamentals for on-site personnel and explains them so that even someone handling it for the first time can grasp the overall picture. Detailed parameter settings vary depending on project conditions and internal standards, but it focuses on the concepts you should commonly check at any site.

Table of Contents

• PVsyst is a tool to verify energy output under site conditions

• Basic 1: First, align the project conditions and the study objectives

• Basic 2: Confirm the meteorological data and the assumptions for the installation site

• Basic 3: Match the azimuth and tilt with the site drawings

• Basic 4: Enter the equipment configuration and reconcile capacities

• Basic 5: Check the impact of shading from the on-site perspective

• Basic 6: Review the loss conditions to ensure there are no omissions or excesses

• Basic 7: Organize the values to be checked on the results screen

• Basic 8: Use the report for site, design, and client explanations

• Summary: Convert PVsyst results into information usable on site

PVsyst is a tool for confirming energy production under site conditions

PVsyst is a specialized software used to simulate the power generation and loss factors of photovoltaic (PV) systems. In practical work it is used for preliminary estimates before constructing a plant, for checking expected energy production during the design phase, for comparing equipment configurations, for assessing the impact of shading, and for preparing submission documents. When learning how to use it, the important thing is not merely to fill in the input fields, but to be aware of how well the entered conditions reflect the actual site circumstances.

From a site perspective, the ability to read PVsyst reports is useful not only for design personnel but also for construction personnel, surveyors, power plant planners, and operations and maintenance personnel. This is because the simulation results include information related to site quality and post‑completion explanations, such as panel orientation, tilt, shading, losses, energy production, and performance ratio.

For example, even if a layout appears to be south-facing on the design drawings, assumptions about power generation can change depending on the actual site shape, the grading of earthworks, the orientation of the racking, and surrounding structures. Also, if trees, utility poles, neighboring buildings, slopes, fences, or the like cast shadows on site, desk-based conditions may not match the actual situation. When using PVsyst, you need to adopt an approach that links the input conditions shown on screen with the conditions observed in the field.

Power generation simulations do not guarantee the final amount of electricity sold or profitability. Weather conditions vary from year to year, and factors such as soiling after installation, aging, maintenance conditions, equipment downtime, and changes in the surrounding environment also have an impact. Therefore, PVsyst results should be treated as projections calculated based on these assumptions.

Avoid making overly definitive claims; clearly state the assumptions when sharing results with stakeholders—this is the first step to preventing practical disputes.

Basic 1: First, align the project conditions and the objectives of the review

Before you start using PVsyst, the first things to clarify are the project conditions and the objectives of the analysis. If you open the software and start entering data immediately, you may find that required information is missing partway through, or that the output differs from what stakeholders expect. When using it for on-site work, it is particularly important to decide the purpose of the simulation in advance.

There are several types of objectives. At the early planning stage, the focus is on checking how much capacity can be installed on the site and estimating the annual generation. At the design stage, orientation, tilt, row spacing, equipment configuration, and shading effects are reflected to verify a more realistic generation estimate. During construction, one may assess how design changes and differences in site conditions affect generation. Prior to handover, it is necessary to organize the assumptions into a report for submission and present them in a form that is easy to explain to the client and other stakeholders.

If the purpose remains vague, the level of detail in the inputs and the items that need to be checked will become inconsistent. Spending too much time on overly detailed settings for a rough estimate is inefficient, while conversely, if checks for shading or losses are too coarse for material intended for submission, you may have trouble explaining things later. When learning how to use PVsyst, it is important to always be aware not only of the sequence of operations but also what decisions this simulation will be used to inform.

As project requirements, we organize the installation location, site boundaries, equipment capacity, number of panels, mounting orientation, tilt angle, equipment configuration, connection conditions, assumed start of operation, and surrounding shading factors. These are confirmed from design documents, survey results, site photographs, layout drawings, and single-line wiring diagrams. If information has been obtained on site, it is necessary not to rely solely on desk-based materials but to verify them against actual conditions.

One point to pay particular attention to is that the assumptions in the design drawings and those on site do not necessarily match exactly. It is necessary to decide whether to reflect in the simulation items such as the ground elevation after earthworks, level differences with neighboring plots, structures that will remain during construction, and obstacles that will exist permanently rather than as temporary installations. If site personnel understand the input assumptions for PVsyst, they can request confirmation from the design team at an early stage, making it easier to reduce rework.

Basic 2: Verify assumptions about meteorological data and the installation site

In PVsyst, assumptions about the installation site and meteorological data have a major impact on the predicted energy output. In solar power simulations, solar irradiance, ambient temperature, solar altitude, azimuth, and other factors form the basis of the calculations. Therefore, if the region, coordinates, or weather conditions set initially are inaccurate, no matter how precisely you configure equipment and losses afterward, the reliability of the results will decline.

For on-site use, first confirm that the power plant’s location is correctly reflected. It is important to check not only the municipality name but also whether the conditions correspond to the actual site location. Even within the same region, weather conditions and shading can vary depending on whether the site is coastal, mountainous, in a basin, or at a different elevation. While it is difficult to reproduce every minor difference exactly, you should at least confirm that calculations are not being performed using conditions from a location that is far away.

Meteorological data are directly tied to projected annual power generation. If the solar irradiance is set high, the estimated generation will look large; if set low, it will look small. That is why, when using PVsyst results in submission materials or for internal decisions, you must be able to explain which meteorological conditions were used. Rather than simply accepting the numbers shown on the screen, confirm whether they are reasonable as assumptions to adopt for the project.

Also, the weather data are based on average conditions, and actual power generation will not be the same every year. In actual operation, variations occur in years with heavy rainfall, extreme heat, snow accumulation, or typhoon impacts. When explaining on-site, it is necessary to convey that the simulation values should not be treated as fixed guaranteed values, but are estimates based on weather conditions.

When configuring the installation location, you must avoid mixing up the region because it also affects calculations of time and solar position. In particular, when handling multiple projects, reusing settings from a past project for a different site can lead to a serious erroneous assumption. Even when using templates, make it a habit to review basic items each time — installation location, weather conditions, system capacity, azimuth, tilt, and so on.

Basic 3: Match orientation and slope to the site drawings

In evaluating the energy output of a solar power plant, panel orientation and tilt are important. One common point of confusion when using PVsyst is correctly matching the orientation shown on the drawings with the settings in the software. Site personnel must check the layout plan, survey map, racking drawings, and site development drawings to ensure that the azimuth and tilt entered match the actual project.

Azimuth indicates which direction the panels face. Generally, a direction that receives the most sunlight is preferred, but due to site shape, interconnection planning, relationships with roads and slopes, and terrain conditions, it may not be possible to achieve the ideal orientation. In PVsyst, differences in orientation affect annual energy production and hourly generation patterns. It is important not to confuse the north indicated on drawings, the orientation of coordinates, and the actual orientation on site.

The tilt angle is equally important. Changing the tilt alters how solar radiation is received and affects seasonal power generation patterns. At the same time, the tilt angle also influences racking height, row spacing, wind loads, constructability, and land-use efficiency. The tilt should not be decided based solely on energy yield; it must be determined together with the overall site conditions.

On site, measured values after construction may differ from the design values. Due to racking installation errors, ground unevenness, grading slope, or on-site adjustments during construction, the actual tilt and orientation may vary slightly from the design values. It is not always necessary to reflect every small difference in the simulation, but if the changes are large enough to affect power generation or explanatory materials, the conditions should be reviewed.

When you set azimuth and tilt in PVsyst, always verify them against the drawings. Instead of just checking the numbers on the screen, confirm that they match the planned layout, that you haven't swapped east/west or north/south, and that areas with different orientations are properly separated. In particular, if there are multiple generation blocks within the site with different orientations or tilts, summarizing the whole site under a single set of conditions can deviate from reality.

Azimuth and tilt are important prerequisites when reviewing PVsyst results. If energy production is lower than expected, you need to check not only equipment performance and losses but also whether the orientation and tilt conditions were appropriate. If on-site personnel understand this relationship, they can use PVsyst not just for checking numbers but to validate the soundness of the design.

Basic 4: Enter equipment configuration and reconcile capacities

When using PVsyst, you enter the equipment configuration, such as PV modules and inverters, and set up the plant capacity and connection conditions. For on-site personnel, the important thing is not to memorize all the specialized settings, but to verify that the equipment configuration listed in the design documentation matches the inputs in PVsyst.

In a solar power plant, the number of modules, the output per module, the number of modules in series, the number of parallel circuits, the number of inverters, and the installed capacity are all interrelated. If any one value deviates, it affects the total capacity and simulation results. For example, if the number of modules differs from the design drawings, the number of connection circuits differs from the actual plan, or the total capacity does not match the submitted documents, comparing or explaining power generation becomes difficult.

In PVsyst, operating conditions and losses are calculated according to the equipment configuration. Therefore, pay attention to the breakdown of the configuration, not just matching the total capacity. On site, design changes or material changes may occur. Module specifications may change, the number of modules may be adjusted for layout reasons, or connection units may be modified. If such changes occur, it is necessary to check whether the PVsyst input conditions also need to be updated.

When reconciling capacities, we compare multiple documents. We verify that the number of modules listed on the layout drawing, the number of circuits in the electrical design documents, the equipment capacity list, and the overview document to be submitted all match. If only the PVsyst report shows different figures, the client or reviewers may raise questions. If the on-site staff can detect discrepancies in advance, they can more quickly revise the explanatory materials and confirm with the design staff.

Also, when entering the equipment configuration, check whether the conditions are excessively favorable. Simulation results change depending on the assumptions. If you assume configurations that will not actually be adopted or layouts that cannot be implemented on site to produce high generation, the resulting document will be impractical. When using PVsyst, it is more important to accurately reflect conditions that can be realized on site than to make the power generation appear larger.

Points to check on site are not limited to capacity figures alone. Maintenance access, clearances, terrain, drainage, constructability, cable routing, and equipment placement locations also ultimately affect the final equipment configuration. PVsyst inputs are primarily focused on electrical simulation, but they rely on a layout that can actually be constructed on site. Linking desk calculations with on-site conditions increases the practical applicability of the simulation results.

Basic 5: Check the impact of shadows from an on-site perspective

One of the factors that affects the power output of a solar power plant is shading. In PVsyst you can evaluate the impact of shadows from distant terrain and nearby obstacles, but for on-site work it is important to determine which shadows should be accounted for. Shadows can arise from various sources such as surrounding buildings, trees, mountains, slopes, utility poles, fences, equipment, and adjacent panel rows.

The important thing when checking for shading is to distinguish between temporary and permanent sources. Temporary structures during construction and temporary material storage areas may not exist after operation begins. In contrast, neighboring buildings, existing trees, terrain, fences, electrical equipment, and slopes created by site development may continue to cast shadows throughout the power plant’s operational life. What should be reflected in PVsyst are the elements that will continuously affect power generation.

Shadows also change depending on the season and time of day. In winter the sun’s altitude is low, so shadows tend to be longer. Shadows tend to extend in the morning and evening, affecting areas different from those at midday. If you base your assessment only on shadows observed on a sunny day at the site, you may overlook seasonal variations. Using PVsyst makes it easier to check the impact of shadows throughout the year, but as a prerequisite you need to accurately identify what obstacles are present at the site.

Shading between rows is also important. When installing solar panels in multiple rows, the front row can cast shadows on the rows behind. Increasing the row spacing makes shading less likely, but it may reduce the number of panels that can be installed on the same site. Tightening the row spacing makes it easier to increase capacity, but it may increase losses due to shading. Thus, considering the balance between capacity and shading is important when evaluating layouts on site.

When dealing with shading in PVsyst, the accuracy of site information affects the results. If the height, position, distance, or azimuth of obstacles differ significantly, the shading calculations will deviate from reality. Even when creating a detailed three-dimensional model, it is necessary to confirm that the input shape matches the site. Although shading conditions are easy to judge visually, errors can easily be introduced when quantifying them, so it is desirable to utilize survey results and on-site verification.

If there is shading expected to reduce power generation, rather than simply treating it as a loss, consider whether design changes can improve the situation. There may be on-site measures such as shifting the layout, adjusting row spacing, avoiding areas subject to heavy shading, or revising maintenance aisles and equipment placement. PVsyst is useful not only for viewing results but also for comparing and evaluating these options.

Basic 6: Review loss conditions without omission or excess

In PVsyst simulations, various loss conditions that affect energy production are set. The loss conditions include multiple elements such as the effect of temperature, losses due to wiring, effects of soiling, losses associated with equipment conversion, and the consideration of variability and degradation. What is important for field personnel is not to memorize all the detailed theories of each loss, but to check that the settings are not unreasonable for the project conditions.

If loss assumptions are set low, estimated power generation tends to appear high. Conversely, if they are set high, estimated power generation appears low. It is not simply a matter of which is correct; it is important to use values that reflect the actual site conditions and design parameters. Overly optimistic loss assumptions become difficult to explain later when actual results differ significantly. On the other hand, being excessively conservative without justification can be disadvantageous for business decisions or design comparisons.

For example, losses due to soiling vary depending on the surrounding environment and maintenance plan. Sites near farmland or land development can be more affected by soil dust, and in coastal areas soiling that contains salt may need to be taken into account. In snowy regions, a region-specific perspective is necessary, such as considering reduced power generation caused by snow. These conditions should not be determined uniformly on paper but should be confirmed based on the site environment and maintenance policy.

Wiring losses also depend on the on-site wiring distances and configuration. At power plants with large sites, distances between equipment tend to be longer, and the wiring plan affects generation efficiency and construction costs. If the settings in PVsyst do not match the detailed design, the results may differ. If wiring routes are changed during the construction phase, they should be reviewed as necessary.

Temperature effects are also important in solar power generation. The more sunlight panels receive, the more they generate, but rising temperatures can sometimes affect output. Installation method, ventilation, ground-surface conditions, and local ambient temperatures all play a role. When the mounting height or installation environment changes on site, it is wise to confirm your approach to temperature conditions.

When reviewing loss assumptions, it is important to ensure consistency with internal standards and past projects. If you use significantly different loss values for projects with similar conditions, you must be able to explain the reason. When submitting a PVsyst report, you may be asked to justify the basis for your loss assumptions. In practice, recording not only the parameter values themselves but also why those assumptions were chosen is helpful.

Basic 7: Organize the key metrics to view on the results screen

When you run calculations in PVsyst, various results are displayed, such as annual energy production, monthly energy production, the performance ratio, and a breakdown of losses. Staff using it for the first time can be overwhelmed by the many figures and may not know where to look. For on-site use, it is important not to treat all items with equal weight, but to organize and check the figures necessary for practical decision-making.

First, what I want to check is the expected annual power generation. This figure is often used for overall project assessment and for explanations to the client. However, looking at annual generation alone does not reveal which conditions are affecting it. If the result is higher or lower than expected, check in order the solar irradiance conditions, orientation, tilt, shading, losses, equipment configuration, and so on. Generation is an outcome, and it is important to read the assumptions behind it.

Monthly generation is also an item that should be checked. Even if the annual total looks fine, output can drop significantly in specific seasons. By understanding seasonal trends—winter shading, snowfall, solar altitude, and irradiance conditions during the rainy season—you can see how they relate to site conditions. When explaining the operation of a power plant, it is easier to be understood if you communicate seasonal variations as well as the annual total.

The performance ratio is used as an indicator to understand the overall efficiency of a power plant. Simple generation output alone can make comparisons difficult due to differences in installed capacity and solar irradiance conditions. By looking at the performance ratio, it is easier to see how efficiently a plant generates power under the same irradiance conditions. However, because the performance ratio is also influenced by underlying assumptions and conditions, it should not be judged solely on its absolute value; rather, it should be evaluated by comparing it with similar projects and design conditions.

The breakdown of losses is also important. The results from PVsyst allow you to see at which stage and to what extent losses are expected. Depending on whether losses from shading are large, temperature effects are significant, or losses due to wiring and equipment configuration stand out, the direction of improvement will differ. When on-site personnel can read this breakdown, it becomes easier to propose improvements to layout and installation conditions rather than merely checking a report.

When reviewing results, it's also important to consider the possibility of input errors. If the generation is extremely high or low, the monthly trends look unnatural, or the relationship between capacity and generation doesn't add up, you need to check the configuration settings. Common points to check include a swapped installation location, incorrect orientation entry, errors in the tilt angle setting, a mismatch in the number of panels, omission of shading conditions, and excessive or insufficient loss settings.

The ability to read the results screen is one of the most practically valuable aspects of using PVsyst. If only the operator understands the results, explanations to the site and the client become dependent on that individual. By determining which figures stakeholders should commonly review and organizing them clearly within the documentation, the transparency of decision-making is improved.

Basic 8: Use reports to explain to site staff, designers, and clients

The PVsyst report is an important document for sharing simulation results with stakeholders. For on-site use, it is important not to treat the report as a mere output but to organize it as supporting documentation that explains the design conditions, construction conditions, and expected power generation.

What should be checked first in a report are the basic details such as the project name, installation location, system capacity, azimuth, tilt, equipment configuration, meteorological conditions, and loss assumptions. If these do not match the actual project conditions, the generation results may look plausible at first glance but will be insufficient as submitted documentation. Common oversights in practice include leaving the name of a past project, keeping the capacity from an outdated design, or retaining conditions from before a layout change.

When explaining to a client, it is important to describe the assumptions used in the calculations as well as presenting the annual generation figure. If you can explain how you treated meteorological conditions, orientation, tilt, shading, and losses, the meaning of the simulation results will be easier to understand. Conversely, presenting only the generation figure without describing the assumptions may lead to misunderstandings later regarding discrepancies with actual performance.

When sharing with the design team, you can use PVsyst results to verify the validity of the layout and equipment configuration. If there are areas with significant shading losses, this can prompt consideration of layout changes or adjustments to row spacing. By comparing a proposal that increases capacity with one that mitigates shading, it becomes easier to make decisions that take into account practical energy generation and constructability rather than simply maximizing capacity.

For construction personnel, it is important to verify that the conditions described in the report match the assumptions that must be followed on site. Changes in orientation, tilt, layout, or equipment configuration can lead to discrepancies between the simulation results and the as-built conditions. If changes occur during construction, this provides the basis for deciding whether a recheck under the revised conditions is necessary.

Also, the report can be used for in-house quality control. As a pre-submission check, confirm the consistency of input conditions, the validity of the results, the items required for explanation, and the presence of any typographical errors. In particular, when multiple people are working together, it is effective for the PVsyst operator, the designer, and the on-site personnel to each review from their respective perspectives. The operator should verify the settings, the designer should confirm consistency with the drawings, and the on-site personnel should check for discrepancies with actual site conditions.

PVsyst reports are not complete simply by being generated. By including supplementary materials so readers can understand, explaining important assumptions in the main text, and presenting the report together with design drawings and site photographs, the document becomes practical and easy to use in real-world work. For on-site use, it is essential to treat the report as a common language among stakeholders.

Summary: Converting PVsyst Results into On-site Usable Information

When organizing the use of PVsyst for field personnel, the key is less the operational steps themselves and more matching the input conditions to the actual site conditions and converting the results into a form suitable for practical decision-making. If you check the installation location, meteorological conditions, orientation, tilt, equipment configuration, shading, losses, and how to read the report in that order, even someone using it for the first time will find it easier to grasp the overall picture.

Power generation simulations do not fully guarantee the actual output after completion. However, by clarifying the assumptions, accurately reflecting site information, and carefully interpreting what the results mean, it becomes easier to improve the accuracy of planning and design. In particular, shadows, terrain, construction conditions, and layout constraints that are not evident from drawings can affect power generation on site. Rather than taking PVsyst results at face value, it is important to make judgments in combination with on-site verification.

To prevent failures in practical work, it is important to first decide the purpose of the study, organize the project conditions, and document the rationale for input values. Next, check not only the power generation but also monthly trends, the performance ratio, and the breakdown of losses. And before submitting the report, verify consistency with design drawings, site conditions, and explanatory materials. If you make this workflow a habit, PVsyst can be used not just as calculation software but as a basis for decision-making that connects the field and design.

In a solar power plant, not only simulations but also on-site surveying, verification of pile positions, layout planning, construction management, and post-completion records are important. By linking the expected power generation obtained from PVsyst with on-site positional information and construction data, it becomes easier to improve accuracy from planning through construction to handover. When using PVsyst on site, it is important to cross-check the software’s calculation results with facts that can be confirmed on site and to prepare materials so that stakeholders can make decisions based on the same assumptions.