【How to Use Near Shading in PVSyst｜7 Essentials to Learn First】

Table of Contents

• What does the Near Shading feature check?

• Item 1 Decide the purpose of shadow analysis first

• Item 2 Understand the concept of a 3D scene

• Item 3 Enter target objects and obstructions separately

• Item 4 Check for azimuth and height misalignments

• Item 5 Distinguish linear shading from electrical effects

• Item 6 Interpret shading results as losses

• Item 7 Improve Near Shading accuracy with on-site survey data

• Common mistakes and checkpoints in Near Shading

• Summary

What does the Near Shading feature check?

PVSyst's Near Shading is a feature that incorporates into generation simulations the effects of shadows cast by nearby buildings, trees, slopes, rows of racking, fences, equipment, and surrounding structures on a photovoltaic installation. A solar installation's energy production is influenced by many factors — irradiance, panel orientation, tilt angle, temperature, equipment specifications, wiring, soiling, and degradation over time — but shadows from nearby objects are easy to overlook in practice. Especially on rooftops, developed sites, mountainous areas, factory premises, land converted from agricultural use, and locations with many existing structures, even slight shading can have a large impact on annual and monthly energy yields and on output during the morning and evening.

The purpose of using Near Shading is not merely to create the appearance of shadows. It is used to assess the validity of design proposals, quantify shading losses, and, when necessary, review panel placement, row spacing, racking height, installation area, azimuth, and tilt angle. In other words, Near Shading is not a drafting tool but a practical function for visualizing power generation risk at the design stage.

What beginners commonly struggle with at first is over-detailing the 3D scene. There are many objects on an actual site, but it is not necessary to reproduce all of them precisely. Prioritize inputting objects that may cast shadows on the power-generating surface, those likely to have an impact throughout the year, and those required as justification for power generation assessments or internal explanations. Conversely, modeling small distant objects that have little impact or decorative elements unrelated to design decisions will only increase work time and make verification more difficult.

To use Near Shading correctly, you need not only to input the sources of shading but also to understand the positional relationship with the power-generating surface, azimuth, height, terrain elevation differences, the specific time, seasonal variations, and the method for calculating shading. In particular, at low solar elevations in the morning and evening, distant objects can cast long shadows. Conversely, at midday or in summer their impact may appear small. Therefore, rather than making a judgment based on a single moment’s view on the screen, it is important to verify shading losses over the course of the year.

In this article, aimed at practitioners beginning to use PVSyst's Near Shading, we lay out the first seven items you should learn, in order. Rather than a simple operations guide, it explains why each setting is necessary, what kinds of mistakes can affect energy yield estimates, and how to incorporate on-site information into the design.

Item 1 Decide the purpose of the shadow analysis first

Before opening Near Shading, the first thing to decide is the purpose of the shading analysis. If you begin creating a 3D scene while the purpose is unclear, you won’t be able to determine what to input and to what extent, which can lead to excessive work or oversights. Shading analysis can serve multiple purposes, such as comparisons in the early design stage, risk checks before detailed design, providing the basis for energy yield predictions, internal explanations, customer explanations, and checks for post-construction discrepancies.

In the early design stage, it is more important to understand the broad effects of buildings, trees, and adjacent panel rows than to create an exact detailed geometry. At this stage, the goal is to compare multiple layout options and to avoid early areas that are likely to experience significant shading losses. For example, if there is a tall structure to the south, that can inform decisions such as reducing the number of panel rows near it, shifting racking positions, or changing the installation area.

On the other hand, in detailed design and in studies for submitting power generation estimates, the accuracy of shadow inputs becomes more important. This is because differences in the height, position, orientation, tilt, and ground elevation of objects directly affect loss calculations. At this stage, it is necessary to input the shadow-casting elements as realistically as possible based on site survey data, drawings, current-condition photographs, point cloud data, coordinate information, and so on.

Also, the results you should look at vary depending on whether the purpose of the shading analysis is "deciding on design changes" or "explaining power generation." For deciding on design changes, it is important to know where shadows will occur, when their impact is greatest, and how much improvement can be achieved by changing the layout. For explaining power generation, the focus is on checking the annual loss rate, monthly losses, time-of-day impacts, and the positioning in loss diagrams.

The biggest thing to avoid when using Near Shading is letting the input work itself become the objective. It is more important to appropriately reflect the shading effects needed for the energy yield assessment than to make the 3D scene look nice. Therefore, if you first decide "what do I want to judge with this shading analysis?" before starting work, it will become clear which objects need to be input and which can be omitted.

Item 2 Understand How to Think About 3D Scenes

In Near Shading, the power generation equipment and surrounding obstructions are placed in 3D space to calculate the effects of shadows according to the sun’s position. This 3D scene is like creating a model of the site. However, its purpose differs from that of precise 3D models used in architecture. What matters is not visual fidelity but reproducing how shadows fall on the power-generating surface.

When creating a 3D scene, you first need to understand the concept of the reference coordinate system. If it's unclear where to set the origin, which direction to align the orientation, or which reference to use for entering heights, the scene may to look plausible on screen but the positions of shadows will be shifted from reality. In particular, misalignment in orientation has a significant impact on shadow analysis. Even if the entire installation is off by only a few degrees, the way shadows fall in the morning and evening changes, and the appearance of losses can be altered.

Next, an important consideration is how the ground surface is treated. It is relatively simple for flat roofs or prepared level ground, but on sloping sites or sites with steps or level changes, not only the height of obstructions but also the elevation difference relative to the installation surface affects shading. For example, even structures of the same height will produce different shadow lengths and affect different areas depending on whether they are positioned above or below the generation surface. In mountainous areas or sites with slopes, ignoring this elevation difference can lead to underestimating or overestimating shadow losses.

In a 3D scene, the panel surface is treated not as a mere plane but as a light-receiving surface with azimuth and tilt. Therefore, it is important to verify that the panel orientation, tilt, row arrangement, and racking height are correctly represented. Even if you meticulously model only the surrounding obstructions, if the crucial power-generating surface’s position or tilt is incorrect, the results of the shadow analysis will be difficult to trust.

Beginners tend to try to input complex terrain and fine details from the start, but it is recommended to first understand the movement of shadows using simple shapes. Treat buildings as rectangular prisms, fences as thin, elongated planes, and trees as obstructions with approximate height and width, and observe how shadows are cast. Then, by detailing only the parts that have a significant impact, you can more easily balance work efficiency and the reliability of the results.

The 3D scene for Near Shading is not finished once it has been created. You should review the results to confirm whether the obstructions you entered are actually affecting shading losses, whether there are too many unnecessary elements, or conversely whether you have overlooked important obstructions, and make corrections as necessary. In practice, treating the workflow as an iterative cycle of input, review, correction, and recalculation repeated several times will bring you closer to a high-accuracy shading analysis.

Item 3 Enter target objects and obstructions separately

When using Near Shading, it is important to distinguish between the object used for power generation and the obstructions that create shadows. The object used for power generation refers to the surface or array where the solar panels are installed. Obstructions are buildings, trees, steps, parapets, equipment, surrounding structures, adjacent racking rows, and so on, that cast shadows on the power-generating surface. If these two are confused, it becomes difficult to determine which shadow is affecting which power-generating surface.

In solar power plants, not only surrounding buildings and trees but also the generation equipment itself can cast shadows. In particular, with ground-mounted systems, front-row panels can cast shadows on the rows behind them. On roofs as well, parapets, equipment foundations, rooftop units, and upstand sections can create shadows. These self-shading effects directly affect layout and row-spacing considerations.

When inputting the target object, you must accurately reflect the panel installation area, number of rows, tilt angle, azimuth, and the height of the mounting structure. When inputting obstructions, the relative position to the power-generating surface, height, width, and depth are important. It is not necessary to fully reproduce the shape of an obstruction, but you should model and input it in a way that does not substantially change the shadow outline or the effect of its height on the power-generating surface.

Care must be taken when dealing with trees. Trees are not rigid rectangular solids like buildings; the density of branches and leaves and seasonal variations change the darkness of their shadows. However, when performing power generation assessments in PVSyst, in practice the area and height that cast shadows are often treated as representative values. The presence or absence of leaves, plans for felling, room for growth, and whether the trees are outside the site and cannot be managed also affect the interpretation of results. If future growth could increase shading, it is safer to consider conservative conditions as well as the current state.

For buildings and structures, it is important to check their height relationship to the power-generating surface, not just the dimensions on the drawings. Roof parapets may appear as thin lines on plan views, but they can cast long shadows in the morning and evening. Equipment such as cubicles and ventilation units can also affect specific strings or panel rows depending on where they are installed. Even small obstructions can have a significant electrical impact depending on where their shadows fall.

Making a habit of entering objects and obstructions separately makes it easier to compare design proposals later. For example, it becomes easier to evaluate cases such as changing only the panel layout while keeping obstructions fixed, changing only the racking height while keeping the panel layout fixed, or comparing cases with and without trees. Near Shading is not something you enter once and finish; it is a feature for comparing impacts as you change design conditions. Therefore, keeping inputs organized from the initial stage greatly affects the efficiency of subsequent processes.

Item 4 Check for orientation and height deviations

Representative factors that affect the results of Near Shading are azimuth (orientation) and height. Both are misalignments that are hard to notice on screen, but they can make a big difference in shading analysis. If the azimuth is off, the times and directions when shadows occur will change. If the height is off, the length of shadows and how they fall on the power-generating surface will change. In particular, when design drawings, site surveys, manual data entry, and 3D scene creation are performed separately, the reference can become inconsistent somewhere.

When checking orientation, be mindful of true south and true north. The upward direction on a drawing is not necessarily north. Also, the sense of direction observed on site may not match the orientation in coordinates. Even if panels are arranged to fit the shape of a roof or site, if the actual orientation differs by a few degrees, it can lead to differences in annual power generation and in how shading losses occur.

When checking heights, organize not only the height of obstructions themselves but also the height of the power-generating surface, the ground surface height, and how reference heights are taken. For example, if the building height is entered from the ground while the power-generating surface is referenced to the roof surface, the relative height relationships can become misaligned. On sloping ground, even when referring to the same ground, the elevation differs depending on location. Ignoring these conditions can make shadows appear shorter than they actually are, or conversely lead to overestimating their impact.

When dealing with height in Near Shading, the relative height relationship between the power-generating surface and obstructions is more important than absolute elevation. Of course, elevation information is useful when accurately dealing with the entire terrain, but what to check first in shading analysis is how much higher the obstructions are than the power-generating surface and how far away they are. If you know the height and distance, it becomes easier to assess the times of day and seasons when shading is likely to have an impact.

In practice, it is important not to rely solely on on-screen appearance when checking orientation and height. Cross-reference site photos, survey measurements, layout plans, cross-sections, and topographic data to confirm that input values match field conditions. In particular, in areas with many existing structures, heights measured on site can differ from those shown on drawings. Exercise caution when using old drawings or when dealing with roofs after renovation.

Deviations in azimuth and height are mistakes that even people familiar with using Near Shading can easily make. That’s why, after finishing a 3D scene, it’s important not to look at the results immediately but to first go through a step of checking the reference direction, height, distance, and the tilt of the installation surface. Simply making this check a habit will greatly improve the reliability of shadow analysis.

Item 5 Distinguish linear shading from electrical effects

An important point in understanding Near Shading is to distinguish between linear shading and electrical effects. Linear shading is a way of geometrically assessing how much of the power-generating surface is shaded. For example, it is the perspective that at a given time a portion of the panel surface is obstructed and the solar irradiance it receives is reduced. By contrast, electrical effects consider how shading impacts the output of a panel or a string.

Even if only part of a solar panel's surface is shaded, the electrical impact can be greater than the shaded area alone would suggest. This is because how the shadow falls, the arrangement of cells within the panel, the string configuration, circuit conditions, and the operation of equipment all affect how output losses manifest. Therefore, you cannot simply conclude that a small shaded area will have only a small impact.

In Near Shading, shadow occurrence is checked using a 3D scene and reflected in loss calculations, but practitioners need to distinguish between the shadows shown on the screen and their impact on power generation. For example, even shadows with the same area can have different design implications: a shadow that briefly falls on the edge of a panel, versus a shadow that repeatedly falls across multiple rows of panels in the morning and evening. Also, even if the annual loss rate appears small, there can be cases where a drop in output during specific months or certain times of day becomes problematic.

Checking linear shading is effective for understanding where and when shadows will occur. By seeing which obstructions cast shadows on which panel surfaces in which seasons, you can identify directions for design changes. For example, if shadows occur only in the morning and have a limited impact on power generation, they may be acceptable. On the other hand, if shadows persist for long periods on winter mornings, they can affect not only annual energy yield but also expected output and operations planning.

When considering electrical effects, it is important to review panel layout and circuit configuration together. Even if only part of the area is shaded, if that shading affects multiple panels on the same circuit, losses can be significant. Conversely, if shaded panels can be separated in the layout or areas with heavy shading can be avoided, design mitigation becomes easier.

What’s important in using Near Shading is not just finding shadows, but determining how significant those shadows are from a design standpoint. Shadows can make you uneasy, but eliminating all shadows is not realistic. What matters is to comprehensively evaluate annual losses, monthly losses, the times when shadows occur, the area affected by the shadows, and the potential electrical impacts, and to separate shadows that are acceptable from those that require mitigation.

Item 6 Interpreting Shadow Results as Losses

After creating a 3D scene with Near Shading, you need to interpret the shadow results as losses. What matters here is not how prominent the shadows appear on screen but how much they affect power generation. Even if a shadow looks large visually, if it occurs when the sun elevation is low and its contribution to generation is small, its impact on annual losses may be limited. Conversely, a shadow that appears small but recurs during periods of strong solar irradiance can become a non‑negligible loss.

When evaluating shading losses, it is important not to judge based only on annual values. The annual loss rate is convenient for getting an overall picture, but it can hide monthly or time-of-day impacts. For example, even if losses are small on an annual basis, in projects where winter generation is important, winter shading can be a problem. Also, when demand or operations place emphasis on morning or afternoon output, it is necessary to examine the impacts by time of day.

When explaining Near Shading results in practical work, it is important not only to state the magnitude of the losses but also to be able to explain their causes. Organizing which obstructions are the primary contributors, which panel areas are affected by shading, and which times of year the impact is greatest makes it easier to explain to internal teams and customers. Simply saying "the shading loss is X percent" makes it difficult to determine whether design changes are necessary or appropriate.

When comparing design proposals, it is important to calculate Near Shading under the same conditions. If meteorological conditions, panel specifications, equipment configuration, installed capacity, azimuth, tilt, or other loss conditions differ, it becomes difficult to compare the impact of shading alone. If you want to evaluate the effectiveness of shading countermeasures, change only the conditions related to shading as much as possible and keep the other conditions fixed for comparison. This makes it easier to see the effects of changes in panel layout, adjustments to row spacing, distancing from obstructions, changes in racking height, and so on.

When interpreting shading losses, consider not only the magnitude of the numbers but also whether mitigation is feasible. If the shading can be improved by changing the on-site layout, it is worth examining the effects of design changes. Conversely, if the shading is caused by off-site buildings or trees whose positions cannot be changed, power generation forecasts and project feasibility assessments must be conducted on the assumption of that shading. In practice, the decision is not whether shading can be eliminated but how to deal with it.

Also, the results of Near Shading depend on the accuracy of the input conditions. If the positions or heights of obstructions are uncertain, uncertainty will remain in the resulting losses. Therefore, for important projects it is useful to record the basis for the input values. If you clarify whether a value was measured on site, read from drawings, or assumed, it will be easier to make judgments when reviewing the results later.

Item 7 Enhancing the Accuracy of Near Shading Using On-site Survey Data

On-site survey data is extremely important for improving the accuracy of Near Shading. No matter how carefully you build the 3D scene in PVSyst, if the input positions or heights deviate from reality, the shading analysis results will also be off. Especially at sites with many existing buildings, trees, level changes, slopes, rooftop equipment, and surrounding structures, field-measured information dictates the reliability of the shading analysis.

The information to confirm during an on-site survey includes the position of the power-generating surface, the locations of obstructions, the heights of obstructions, ground and roof elevations, orientation, the boundaries of the installation area, and surrounding obstacles. Organizing these as coordinate and elevation information makes them easier to reflect in a 3D scene. In particular, in locations where multiple obstructions overlap or on sloped terrain with elevation differences, it is difficult to judge the effects of shading from plan views alone, so a three-dimensional on-site assessment is effective.

For rooftop projects, the heights of parapets and equipment, the slope of the roof surface, and the dimensions of the installable area are important. For ground-mounted projects, ground undulation, surrounding trees, adjacent structures, post-development elevation, and elevation differences between racking rows have an impact. If this information is lacking, the Near Shading inputs will have to rely on assumptions. The more assumptions there are, the more care is needed when explaining the results.

On-site photographs are useful, but photos alone can make it difficult to accurately determine heights and distances. While photos are convenient for confirming the presence of obstructions and for explanatory materials, shadow analysis requires input values such as coordinates, dimensions, and heights. Combining on-site photos with survey data makes it easier to check for input errors and to explain findings to stakeholders.

In practical work on Near Shading, there are cases where the designer cannot visit the site. In such cases, it is important to share in advance what information the on-site surveyor should collect. It is necessary not only to take photos of the site, but to obtain information that shows the position and height of objects that may cast shadows, their distance to the power-generating surface, and their orientation. If necessary information is lacking at the survey stage, a re-survey may be required later, leading to rework of the entire design.

Using iPhone-mounted GNSS high-precision positioning devices like LRTK makes it easier to utilize position information acquired on site in design studies. If you can link and manage the installation area of power generation equipment, the positions of obstructions, the locations where site photos were taken, point cloud data, and so on with high-precision positional information, it becomes easier to grasp the current conditions needed for input into Near Shading. In particular, at large outdoor sites or sites where there is a large discrepancy between drawings and actual conditions, being able to obtain accurate coordinates on site is a major advantage.

Common Mistakes and Checkpoints in Near Shading

One common mistake in Near Shading is to feel reassured simply by inputting obstructions. Placing buildings or trees in a 3D scene can make you feel as if you have performed a shadow analysis, but what matters is verifying that the input values match reality, that the positional relationship to the power-generating surface is correct, and that the results are reasonable. In particular, azimuth, height, distance, and the tilt of the installation surface are difficult to judge by appearance alone, so caution is required.

A common mistake is over-modeling objects that have no impact. In Near Shading, you should prioritize entering obstructions that affect power output. Modeling in detail low structures that are far away or objects that cast almost no shadow along the sun’s path increases the time required and makes checking the model more difficult. In practice, it is efficient to enter the most impactful items first and then refine the necessary areas while reviewing the results.

Conversely, there are also obstructions that are easy to overlook: small rooftop equipment, parapets, railings, lightning protection equipment, piping, adjacent racking rows, trees near the site boundary, and local changes in elevation. These may not be noticeable on plan drawings, but they can cast shadows when the sun is low. In particular, checking shadows in winter and at dawn and dusk can reveal elements you had overlooked.

Care must also be taken in how trees are handled. Trees grow, and their foliage changes with the seasons. Even if the impact is small at the time of the site survey, shadows may become larger in a few years. If there are plans for felling or pruning, it is necessary to confirm whether those actions will definitely be carried out and who is responsible for maintenance. In shadow analysis, it is practically important to consider not only the current situation but also future operations.

Furthermore, there are cases where the conditions are not consistent when comparing design proposals. In one proposal an obstruction is entered while in another it is not, or the azimuth or installed capacity may have changed; if you compare only the shading losses under those circumstances, you may reach an incorrect conclusion. If the purpose of the comparison is shading countermeasures, it is fundamental to align as many non-shading conditions as possible.

When explaining the results of Near Shading to colleagues or customers, it is important not only to present the numbers but also to clarify the assumptions. Organizing which obstructions were entered, which data were used to set heights, how trees and future structures were treated, and whether on-site surveying was conducted makes it easier to explain the reliability of the results. Power generation simulations will change if input conditions change. That is why recording the basis for inputs in Near Shading is important.

Summary

Near Shading in PVSyst is an important feature for reflecting the impact of shadows cast by nearby obstructions on energy yield simulations for photovoltaic installations. The first thing to remember is not to create a neat 3D scene, but to correctly organize the shadowing conditions required for the energy yield assessment. By deciding the purpose of the shading analysis, separating the objects of interest from the obstructions, checking azimuth and height, distinguishing linear shading from electrical effects, and interpreting the results as losses, Near Shading becomes a practical basis for decision making.

Particularly important is the basis for the input conditions. If the height or position of obstructions is uncertain, no matter how precisely you set them, uncertainties will remain in the results. Combining site photographs, drawings, survey measurements, point cloud data, coordinate information, and other sources to capture the site’s condition as accurately as possible leads to improved accuracy in shadow analysis. In the early design stage it is practical to perform rough comparisons, and in the detailed design stage to reflect site information and increase accuracy — a phased approach is practical.

By mastering Near Shading, you can treat shading losses not merely as a source of concern but as material for design improvement. If you can understand where, when, and to what extent shadows occur, it becomes easier to consider panel layout, row spacing, racking height, installation area, and site management. It also makes it easier to explain the basis for power generation forecasts to internal teams and customers.

To perform simulations that accurately reflect on-site conditions, obtaining high-precision positioning in the field is indispensable. As an iPhone-mounted GNSS high-precision positioning device, LRTK makes it easier to handle on-site location information, photos, and point clouds, and supports the design review and site condition verification of solar power installations. If you want to assess the impact of shadows more accurately in Near Shading, creating an environment that can record on-site obstructions and installation areas with high precision is the first step toward improving the reliability of simulation results.