【How to Configure Shading in PVSyst｜5 Basics for Beginners】

Table of Contents

• What the shading settings in PVSyst do

• Basic 1: Understand the difference between near shading and far shading

• Basic 2: Recreate the causes of shadows in the 3D scene

• Basic 3: Check the shading between module rows

• Basic 4: Set electrical losses due to shading

• Basic 5: Check the impact of shading in the results screen and reports

• Common points where beginners are likely to fail in shading settings

• The importance of on-site verification and surveying to improve accuracy in practice

• Summary

What Does Configuring Shading in PVSyst Do?

Shading settings in PVSyst refer to the process of reflecting elements that cast shadows on a photovoltaic installation in the simulation to make annual energy production, monthly energy production, and losses closer to reality. In solar power generation, even in regions with the same irradiance, energy output can vary greatly depending on the duration and extent of shading on the module surface. In particular, low solar altitude in the morning and evening, long shadows in winter, partial shading from adjacent objects, and shading between rows of modules are factors that are difficult to correct later if overlooked during the design phase.

Shadows handled in shading settings can be broadly divided into those cast by objects near the power generation facility and those produced when the horizon or distant mountain ranges block the sun. Shadows from nearby objects often fall on part of a module and can lead not only to a simple reduction in solar irradiance but also to electrical losses at the string or array level. In contrast, shadows from distant mountains or terrain create periods when the sun itself is not visible, affecting power generation mainly in terms of the presence or absence of solar irradiance.

What beginners should understand first is that shading settings are not just the task of "drawing shadows." In PVSyst you set up a 3D scene and horizon information to calculate the areas and times that receive shade, but it is also important how you reflect that in generation losses. For example, if part of a module surface is shaded, the power output does not necessarily decrease in proportion to the shaded area. Actual losses vary depending on wiring layout, module orientation, string configuration, the behavior of bypass diodes, and so on. For that reason, it becomes easier to understand shading settings if you think of them as the work that connects layout design, electrical design, and understanding of site conditions.

In practice, the purpose of setting shading configurations varies by project. At the preliminary assessment stage, the goal is to determine whether there are large obstacles nearby, whether the module row spacing is reasonable, and how much winter shading will affect performance. For detailed design, internal approvals, client explanations, and materials for financial institutions, it is important to be able to explain losses caused by shading. For post-completion power generation assessment and troubleshooting, it is necessary to confirm that actual site conditions match the simulation conditions.

To use PVSyst's shading settings correctly, it is important first to clarify "what the shading is being set for." Rather than simply filling in input fields, ensuring you can interpret which shadows affect energy production, which times of day they impact, and whether they can be improved through design changes will broaden the ways the simulation results can be used.

Basic 1: Understanding the Difference Between Near Shadows and Far Shadows

The first step in shading setup is to distinguish between near-field shadows and far-field shadows. Near-field shadows are those cast by buildings, trees, utility poles, fences, substation equipment, adjacent racking rows, parapets, rooftop protrusions, and the like located close to the photovoltaic (PV) installation. These can cast shadows on only part of the module surface, and the shadow position moves over time. In particular, cases where only the lower edge of a module is shaded, only part of a row is shaded, or rooftop equipment casts shadows only during specific times of day should be treated as localized losses.

On the other hand, distant shading refers to shading caused by mountains, hills, elevated terrain on the horizon, distant structures, and the like, which affects the times when the sun rises above or sets below the horizon. Because distant shading creates periods during which sunlight does not reach the entire power generation facility, it is treated more as a binary condition of whether the sun is visible or not, rather than as nearby shading where only part of a module is shaded. In mountainous areas, valley terrain, or plants surrounded by slopes, distant shading can significantly affect annual power generation.

If you proceed with shading settings without understanding this distinction, not only will the input work become more complex, but the interpretation of the results will also become ambiguous. For example, in a project with a mountain behind the site, trying to model the mountain's shape in fine detail as a near-field shadow in 3D can make the workload excessively large. In such cases, it is more practical to treat it as a horizon profile. Conversely, if you simplify buildings or rows of racks that are very close by as if they were far-field shadows, the exact locations on the module surface where shadows fall will not be represented, and losses from partial shading cannot be adequately evaluated.

Beginners should first organize the causes of shading into "objects close to the power generation equipment" and "objects far away that change the apparent position of the sun." Simply adopting the idea that close objects are entered into the 3D scene while distant objects are treated as horizon information significantly reduces uncertainty in the settings. Of course, actual projects will also have obstacles at intermediate distances. In those cases, it is practical to judge based on whether the shadow falls on part of the module surface or affects the entire installation in the same way.

Also, the scope of measures that can be taken by design changes differs between near shadows and distant shadows. Widening the spacing between rack rows, changing module layout, moving modules away from obstacles, and avoiding equipment placement are measures against near shadows. On the other hand, distant shadows caused by surrounding terrain are basically accepted as inherent site conditions, or their impact is reduced by changing placement positions within the site. If you classify the types of shadows in the simulation, it becomes easier later to organize "which shadows can be improved by design" and "which shadows should be explained as site conditions."

Basic 2: Reproducing the Cause of Shadows in a 3D Scene

When evaluating near shading, PVSyst uses a 3D scene to recreate the module surface, rows of racking, and surrounding obstacles in three dimensions. For beginners the 3D scene may look difficult, but you do not need to model every detail perfectly from the start. What’s important is to prioritize entering the elements that affect energy production and not to spend too much time on small shapes that do not cast shadows.

First, the inputs to enter are the position, orientation, tilt angle, and row spacing of the module surface. In ground-mounted projects, the height of the racking rows, front-to-back spacing, number of rows, and east–west alignment are directly linked to shadow formation. In rooftop projects, the roof slope, parapet height, locations of rooftop equipment, and heights of adjacent buildings are important. To evaluate the impact of shadows, the relative positions of the modules and the objects that cast shadows are the most important.

Next, place obstacles that cast shadows. For buildings, reflect their height, width, depth, distance from the generation equipment, and azimuth (orientation). Trees are difficult to model precisely because foliage changes seasonally, but at minimum including approximate tree height and position lets you understand shadow patterns. Utility poles and narrow structures may have a limited impact on annual energy production because their shadows are narrow, but if they repeatedly cast shadows on the module surface at close range they cannot be ignored.

When creating a 3D scene, prioritize dimensions and spatial relationships over visual realism. A common practical mistake is focusing too much on neatly reproducing building shapes while leaving critical heights and distances ambiguous. The length and reach of shadows are determined by an object's height, the solar altitude, and its distance to the module. In other words, rather than fine appearance details, the height and position of the upper edge that casts the shadow are what matter. Rooftop equipment is also better represented as simple shapes with representative height and width for casting shadows than as intricately modeled forms, as this provides a better balance between work efficiency and ease of explanation.

After creating a 3D scene, always check the movement of shadows by changing seasons and times of day. Examining mornings and evenings around the winter solstice, periods of the year when the sun’s altitude is low, and mornings and evenings during seasons with high energy production makes it easier to identify which obstacles affect power output. In particular, when shadows fall long across the lower edge of modules or extend over multiple rows, they can represent non-negligible annual losses. Conversely, when shadows occur only for a short time in the early morning or late evening, they may look significant but have a limited impact on annual energy production.

Beginners should proceed on the assumption that they will adjust the 3D scene several times while reviewing the results, rather than creating it once and finishing. In practice, it is effective to first create a rough model, identify the elements that have the largest impact on shadows, and then refine the dimensions only where necessary. Rather than making everything detailed, accurately modeling the elements that affect power generation will increase the reliability of the simulation.

Basic 3: Check for shadows between module rows

In shading settings, shadows between module rows are particularly important. When multiple racking rows are arranged facing the same direction, as with ground-mounted and flat-roof installations, the shadow of the front row can fall on the modules in the rear rows. This is sometimes referred to as self-shading, mutual shading, or inter-row shading. During winter and in the morning and evening when the solar elevation is low, shadows from the racking rows extend further, so if the row spacing is narrow the rear rows are more likely to be shaded.

When checking for inter-row shading, what you should look at is not simply whether shading exists or not. It is important to see in which season, at what time of day, on which row, and on which part the shading occurs. For example, if shading affects only a small portion during the early morning in winter, the impact on annual energy production may be limited. On the other hand, if shading persists into daytime hours or occurs over a wide area during seasons when significant generation is expected, a redesign of the system may be necessary.

Inter-row shading is strongly influenced by the relationship between the racking tilt angle and row spacing. In general, increasing the tilt angle can be advantageous for solar energy capture in winter, but it tends to lengthen the shadows cast on the rear rows. Widening the row spacing can reduce the impact of shading, but it may decrease the capacity that can be installed on the same site. In other words, assessing inter-row shading is a task of balancing power generation, installed capacity, land-use efficiency, and constructability.

What beginners often overlook is judging the impact of inter-row shading solely by annual energy production. Even if the difference in annual output looks small, losses can be concentrated in specific months or time-of-day periods. Depending on feed-in or self-consumption conditions, output control, and demand patterns, when you can generate power can be crucial. Therefore, if possible, you should also check monthly, time-of-day, and seasonal trends, and avoid making decisions based only on a simple annual value.

Inter-row shading is also related to electrical design. When a shadow falls on some modules within the same string, the losses can be greater than what a simple area ratio would suggest. Whether modules are mounted in landscape or portrait, which direction the strings are arranged, and how modules that receive the same shading are grouped all affect the impact of shading. In PVSyst's shading settings, you need to be aware of not only the geometric shading but also the electrical impacts.

When evaluating inter-row shading, comparing multiple layout options can also be effective. Prepare variants with slightly increased row spacing, modified tilt angles, and different numbers of rows, and compare each option's power generation, losses, and installed capacity to facilitate design decisions. In practice, completely eliminating shading is not always optimal. It is important to decide how much shading to tolerate based on site conditions and the project's economics.

Basic 4: Set electrical losses due to shading

What often confuses beginners in shading settings is the difference between geometric shading and electrical losses. Geometric shading refers to the physical shadow—i.e., which parts of the module surface are shaded and by how much. Electrical loss, on the other hand, indicates how much the entire power-generation circuit is affected by that shading. In photovoltaic systems, even shading of only part of a module can reduce the output of the entire string. Therefore, there are cases where the shaded area and the reduction in power generation do not simply correspond proportionally.

For example, if a long, narrow shadow falls across part of a module surface, the shadow’s area alone might appear small. However, if that shadow falls unfavorably with respect to the direction of cell strings or submodules, the electrical loss can be large. Conversely, the same shadow area can cause comparatively small losses depending on the module configuration and wiring orientation. If a simulation is run without understanding this difference, the effect of shadows may be underestimated or overestimated.

In PVSyst, to make shading losses more realistic, settings are made that take into account module layout, string configuration, and electrical effects. Beginners should first check the geometric shading calculation results and then consider how to handle electrical losses. Rather than jumping straight into a detailed electrical model, it is first important to understand which shadows fall on which arrays, when the shadows occur, and whether the shadows are concentrated in part of the array or are widely distributed.

When setting electrical losses, it is important to align the simulation conditions with the actual wiring plan. If the string orientation, number of connections, the extent connected to the same input, or the modules' placement orientation differ from reality, the electrical effects of shading will also diverge from actual behavior. For example, losses manifest differently when shaded rows and unshaded rows are mixed within the same circuit compared with when modules with similar shading conditions are grouped together. If design drawings or single-line wiring information are available, it is advisable to verify them together with the shading settings.

In practical work for beginners, it's important not to make things excessively detailed at first. Trying to assess shading effects precisely by making detailed assumptions about wiring that hasn't been finalized on site or about undecided equipment configurations can actually make explanations more difficult. In preliminary studies, a practical approach is to grasp the general tendencies of shading using a standard configuration and then review them in the detailed design stage based on the actual wiring information.

Also, when evaluating shading losses, simultaneously check for opportunities to improve the design. If shadows are concentrated on specific rows or parts of a string, simply changing the layout slightly can reduce losses. Avoid placing modules near rooftop equipment, arrange modules in separate groups, separate circuits that are prone to shading, or adjust row spacing—design changes like these can reduce the impact of shading. Simulations can be used not only to produce results but also to explore potential improvements.

Basic 5: Check the impact of shadows on the results screen and in reports

After setting up shading, check the impact of shadows on the results screen and in the report. The important point is not to stop at just looking at total energy production. Annual energy production is an easy-to-understand metric, but to understand the effects of shading you need to review the loss categories, monthly trends, and the breakdown of losses caused by shading.

First, you should look at how much shading losses account for in the total losses. On an open site with no shadows, shading losses should be small. Conversely, if there are many surrounding buildings or trees, the spacing between racking rows is narrow, there is shading from mountains, or the system is installed on a complex roof, losses due to shading can become non‑negligible. Comparing shading losses before and after changing design conditions makes it easier to explain the improvement.

Next, check the monthly energy production and losses. The impact of shading varies significantly by season. In winter, the sun’s altitude is low and shadows tend to be long, so inter-row shading and shadows from surrounding obstructions become more noticeable. Conversely, in summer the sun’s altitude is high and shadows from the same obstructions are shorter, so the effect of shading can be reduced. However, rooftop equipment or nearby structures can still cast shadows during certain times of day in summer. By examining monthly trends, you can determine whether shading is a year-round issue or concentrated in particular seasons.

When checking the results, comparing before-and-after settings is effective. For example, by separating and comparing cases such as no shading, only distant shadows, including near shadows, and including electrical losses, you can see how much each setting affects the results. Beginners who try to look only at the final result from the start will find it difficult to understand which factors are reducing power generation. Comparing step by step also makes the findings easier to use as explanatory material.

When reviewing a report, check not only the shading loss figures but also whether the input conditions can be explained. It is important to have a basis for explaining to internal teams and customers the dimensions and positions of obstacles that cast shadows, terrain conditions, row spacing, tilt angle, orientation, and so on. Simulation results depend on the input conditions. No matter how readable the report is, if the on-site conditions and the input conditions are misaligned, the reliability of the results will be reduced.

Also, when shading losses are large, rather than submitting the results as-is, it is desirable to consider improvement proposals. If the shading is caused by column spacing, you can create cases that adjust the row spacing or the tilt angle. If surrounding obstacles are the cause, you can consider options such as relocating the layout or reducing the number of modules in the shaded area. If distant shadows are significant, you may also check whether conditions improve at another location within the site. The results screen should be used not merely as a place for verification but as material for design decisions.

Common Pitfalls Beginners Encounter in Shading Settings

There are several points in PVSyst’s shading settings where beginners tend to make mistakes. The most common is trying to input every single cause of shading in detail, which brings the work to a halt. In a 3D scene, you can model buildings and terrain as finely as you like. However, reproducing details that have almost no effect on energy output has little practical value. What matters is correctly capturing the height, position, distance, and azimuth of the objects that cast shadows. Prioritize factors that affect energy output over visual fidelity.

Another common mistake is setting site dimensions while they are still ambiguous. If the heights of surrounding buildings, the positions of trees, the height of mounting structures, the spacing between module rows, or the heights of rooftop equipment are inaccurate, the extent of shadows will also be off. In particular, underestimating an object's height tends to lead to underestimating the impact of shadows, while overestimating it tends to lead to overestimating them. Even at the conceptual estimate stage, it is important to distinguish whether the dimensions entered are assumptions, values from drawings, or on-site measurements.

Also, attention is needed when handling orientation. Even a slight shift in module orientation or the relative positions of obstacles changes how shadows fall in the morning and evening. Even when entering data while looking at a plan, you need to confirm that the north direction on the drawing, the on-site orientation, and the coordinate direction in the software are all aligned. In particular, for rooftop projects or narrow sites, an orientation error of a few degrees can affect shadow evaluation. For beginners, it is safer not to enter orientation by feel; verify it based on drawings and on-site measurements.

Judging shading losses based solely on annual values can also lead to failure. Even if the annual loss appears small, large losses may be concentrated in the mornings and evenings during winter, or shadows may occur during time periods that are important for self-consumption. In practice, it is important to check, in addition to annual generation, the monthly and time-of-day breakdowns and the locations where shadows occur. In particular, when deciding on design changes, you need to evaluate not simply by comparing annual values, but also consider capacity, layout, constructability, and operating conditions.

Moreover, there are cases where focusing only on geometric shading causes the electrical effects to be overlooked. If part of a module is shaded, judging losses solely by the shaded area can lead to underestimating the actual drop in power output. The impact of partial shading varies with string configuration and wiring direction. In the detailed design phase, it is important to review electrical design and shading settings together rather than treating them separately.

Finally, one point to avoid is locking in shading settings after creating them only once. In photovoltaic system design, layout, capacity, equipment configuration, and site conditions can change during the design process. If you continue to use shading conditions created at an early stage, the final design and the simulation conditions may diverge. When the design is updated, it is important to make a habit of reviewing the shading settings as well.

The Importance of On-site Verification and Surveying for Improving Accuracy in Practice

The reliability of PVSyst’s shading settings depends greatly on the accuracy of the on-site conditions you input. No matter how carefully you construct the 3D scene in the software, if the actual locations of buildings, the heights of trees, ground undulation, or the planned mounting positions differ from reality, the simulation results will diverge from the real world. In particular, on sites with complex terrain or many existing structures, there can be shading factors that cannot be discerned from drawings alone.

During the site inspection, start by identifying objects around that might cast shadows. Check buildings, retaining walls, slopes, trees, utility poles, fences, rooftop equipment, adjacent structures, and the like, and understand their positional relationship to the power generation equipment. Next, consider the sun’s movement and estimate during which time periods—morning, midday, or evening—shadows are likely to occur. If possible, record not only photographs but also location and height information, as this will make it easier to reflect in PVSyst later.

In ground-mounted projects, terrain undulation is also important. If the site is not flat, the way inter-row shading occurs changes depending on the relative heights of the racking rows and the slope of the ground surface. When the ground elevation of the front and rear rows differs, the impact of shading changes even with the same row spacing, so entering the site simply as flat can lead to errors. For projects that include sloped land, developed or regraded sites, or earthworks such as embankments and cuttings, it is necessary to consider how much the existing topography and the planned ground level should be reflected.

For rooftop projects, the roof slope, parapet height, locations of rooftop equipment, and the heights of adjacent buildings are important. Even if existing drawings are available, the actual equipment layout may differ from the drawings. Small obstacles such as HVAC equipment and ducts, handrails, lightning protection equipment, and inspection walkways can cast shadows. However, it is not necessary to enter everything in detail. In practice, prioritize checking items that are likely to cast shadows on the power-generating surface, those that are nearby, and those that are tall.

To improve the accuracy of shading settings, positioning and surveying methods that can efficiently obtain on-site location information are helpful. If the positions of obstacles, site boundaries, planned racking locations, ground elevations, and the positional relationships of surrounding structures can be captured with high precision, the input conditions for a 3D scene can be made clearer. In particular, in photovoltaic (PV) design, because the relative positions of objects that cause shading and the module surfaces are important, it is effective to link coordinates and elevation information obtained on-site with the design data.

What’s useful here is an iPhone-mounted GNSS high-precision positioning device such as LRTK. If you can obtain high-precision position information on site and record points within the site, obstacles, boundaries, and terrain feature points, it becomes easier to organize on-site conditions as a preliminary step before inputting data into PVSyst. In shading settings, not only the operations performed in the software but also how accurately you can identify local shading factors will affect the results. By reconciling design drawings, layout plans, and 3D scenes based on the position information obtained on site, you can enhance the explanatory power of the power generation simulation.

Summary

PVSyst's shading settings are essential for making a photovoltaic system's energy yield estimates more realistic. For beginners, elements like the 3D scene, near shading, far shading, electrical losses, and result verification may seem numerous. However, once you grasp the basic concepts, it becomes easier to understand what to prioritize in practice.

First, it is important to consider near-field shadows and far-field shadows separately. Shadows from buildings, trees, and rows of mounting racks should be treated as near-field shadows in the 3D scene, while shadows caused by mountains and the horizon should be organized as far-field shadows. Next, in the 3D scene, prioritize correctly entering the height, position, distance, and azimuth of the objects that cast shadows rather than focusing on visual detail. For shadows between module rows, verify the row spacing, tilt angle, season, and time of day, and compare multiple scenarios as necessary.

Also, in shading settings, attention must be paid not only to the shaded area but also to electrical losses. Partial shading affects energy production differently depending on string configuration and module layout. As you approach detailed design, it becomes important to verify geometric shading together with the electrical design. In the result screens and reports, check not only annual energy production but also monthly trends, loss components, and comparisons before and after the settings, and use them for design decisions and explanatory materials.

The accuracy of shading settings ultimately depends on understanding on-site conditions. Rather than relying solely on drawings, confirm on-site obstacles, terrain, orientation, and relative heights, and obtain high-precision location information as needed to increase the reliability of the input conditions. Mastering PVSyst is not just about memorizing the software’s operating procedures. It is important to understand the entire workflow: what to measure on site, what to enter, and how to interpret the results.

In solar PV design and energy yield assessment, accurately capturing the effects of shading is a major factor in enhancing a plan’s reliability and explanatory power. During site surveys, using an iPhone-mounted high-precision GNSS positioning device like LRTK enables efficient recording of on-site position, height, and obstacle information, making it easier to organize the baseline data needed for shading settings in PVSyst. If you want to improve simulation accuracy, reassessing not only the settings in PVSyst but also how you acquire accurate on-site positional data is a significant practical step.