5 Tips to Reduce Simulation Time in the PVSyst Manual

Table of Contents

• Time-Saving Concepts to Grasp Before Reading the PVSyst Manual

• Main causes of increased simulation time

• Measure 1: Organize input conditions to reduce the number of recalculations

• Tip 2 Determine meteorological data and site conditions first

• Tip 3: Narrow down 3D scenes and shadow settings to what is necessary and sufficient.

• Measure 4: Clarify the purpose of case comparisons and reduce the number of calculation patterns

• Measure 5 Standardize procedures for reviewing and revising reports

• Operational approaches to embed time-saving practices in day-to-day work

• Summary

Time-saving concepts to grasp before reading the PVSyst manual

Many practitioners searching for a PVSyst manual do not merely want to know how to operate the software; they want to carry out project assessments and verify design conditions in the shortest possible time. In photovoltaic system simulations there are numerous items to check, such as meteorological data, azimuth, tilt, system capacity, string configuration, loss conditions, shading conditions, and report output. Therefore, simply opening screens sequentially and entering data often leads to losing track of what certain settings mean or having to recalculate repeatedly after changing assumptions, which tends to take more time than anticipated.

Reducing simulation time isn't just about rushing the calculations themselves. In practice, you need to shorten the overall work time by covering everything from organizing information before the calculation, confirming input values, creating comparison cases, and the order in which results are reviewed, to the format for sharing within the company. When reading the PVSyst manual, rather than trying to learn every feature comprehensively, it's more effective to identify the parts that are consuming time in your projects and prioritize understanding those first.

For example, if you frequently find yourself uncertain about which meteorological data to select, you should first clarify the site conditions and your approach to data selection. If configuring shadows is taking too long, you need to decide in advance how detailed the 3D scene should be. If you are repeatedly recalculating due to string design or capacity-ratio adjustments, it is important to limit the conditions you compare in advance and avoid adding unnecessary cases.

PVSyst is highly versatile, so if you want to get into the details you can dig into the settings as much as you like. However, in practical work you always have limited time, and you need to balance the level of accuracy required for decision-making with explanations you can provide. In other words, saving time is not cutting corners; it is designing the workflow to concentrate on settings that influence decisions and to avoid getting stuck on aspects that are unlikely to significantly affect the results.

In this article, we outline five tips that practitioners consulting the PVSyst manual should keep in mind to reduce simulation time, presented in the sequence of pre-calculation, input, shading settings, case comparison, and report review. This content provides an opportunity to review workflow not only for those using PVSyst for the first time but also for existing users who still find their tasks time-consuming.

Main causes of long simulation times

The reason work time in PVSyst becomes long is not just the software’s calculation speed. Rather, in many cases starting work while the preconditions before input are still ambiguous is what causes rework. If you begin simulations when the system capacity may still change, panel layouts are undecided, there are multiple candidate PCS units, terrain and shading conditions are uncertain, or your company’s criteria for selecting meteorological data have not been established, you will find yourself having to go back and modify settings more often.

It is especially time-consuming when you repeatedly create similar cases for comparison but it isn’t clear what you want to compare. For example, if you simultaneously increase cases that change azimuth, cases that change tilt, cases that change the DC/AC ratio, and cases that change the loss rate, it becomes difficult to determine which condition affected the results. As a result, you end up needing to create additional cases, and only the number of simulations increases.

Also, 3D scene and shadow settings influence the amount of work required. If you develop detailed models without first deciding how much to reflect the site's topography, surrounding buildings, trees, racking rows, array spacing, etc., both the data-entry and review tasks become burdensome. If you treat projects that require precise modeling and those that are sufficient for a conceptual review at the same level of detail, you'll end up spending more time than necessary.

Furthermore, the fact that there is no defined procedure for checking after report generation also contributes to longer processing times. Simulation results contain many numerical values, loss factors, monthly results, PR, energy generation, specific yield, and so on. If the order in which these items should be checked is not defined, reviewers will have to jump back and forth between screens and reports looking for points of concern, which increases the likelihood of overlooking settings that need correction.

To use the PVSyst manual efficiently, it is important to first understand where your working time is increasing. Depending on whether input is taking time, recalculations are taking time, interpreting results is taking time, or internal sharing and the preparation of explanatory materials are taking time, the items you should review will differ. The first step to reducing time is not to speed up every operation, but to identify where rework is occurring.

Optimization 1 Organize input conditions to reduce the number of recalculations

The most fundamental way to reduce simulation time is to organize the input conditions before opening PVSyst. If you proceed while reading the PVSyst manual, you can check the required items on each screen, but in practice it is far more efficient to compile candidate input values in advance than to think about numbers on the spot.

First, what you should organize are the basic project conditions. Before running a simulation, compile the site location, system capacity, assumed module, PCS, orientation, tilt, installation method, grid-connection conditions, regional characteristics such as snowfall or high temperatures, and whether any expected obstructions are present. If you start work with these unclear, you will not only be confused by the input screens but also find it difficult to know what to change later when conditions are modified.

Next, it is important to separate confirmed values from provisional values. Few projects have all information finalized from the outset. Therefore, you should distinguish numbers that are confirmed at this point, numbers that use internal standard values, and numbers that are provisional and expected to be reviewed later. When using provisional values, make a note explaining why you chose those values so it will be easier to make judgments when reviewing the results later.

A typical cause of increased recalculations is overlooking related settings after changing a single setting. For example, changing the module type can affect capacity, string configuration, the combination with the PCS, temperature conditions, and loss conditions. Changing tilt or azimuth also relates to irradiance conditions, shading effects, and the appropriateness of array spacing. Listing input conditions makes it easier to track the related items that should be checked when changes are made.

When consulting the PVSyst manual, you will be more efficient if you not only follow the on-screen procedures but also pay attention to how each input affects the results. Prioritizing your understanding of items that have a large impact on energy production, items reflected in the loss diagram, and items that will need to be explained in the report will help prevent you from spending too much time on fine details.

It's also effective to create input templates for each project. Certain conditions tend to be standard depending on the project type—roof-mounted, ground-mounted, sloped land, low-voltage, high-voltage, self-consumption, power sales–oriented, etc. Rather than thinking through the conditions from scratch each time, organizing checklist items by project type can shorten the initial input time.

What matters is not rushing the data-entry work, but reducing rework. The more time-consuming the projects in PVSyst are, the more time is spent on changing conditions and rechecking them rather than on the screen operations themselves. By organizing the conditions up front and clarifying which values are final and which are provisional, you can greatly reduce the number of recalculations.

Tip 2: Confirm meteorological data and site conditions first

In PVSyst simulations, the meteorological data and site conditions form the foundation of the results. If you proceed with other settings while there is uncertainty here, you may need to review everything later when you change the data. Therefore, if you want to reduce simulation time, it is important to finalize the meteorological data and site conditions as much as possible at the start.

When selecting meteorological data, you should not simply pick the nearest site. You must judge based on regional characteristics such as the distance to the project site, elevation difference, whether it is coastal or inland, whether it is mountainous or on a plain, and whether snow or fog have an impact. When reading the PVSyst manual, it is important to pay attention not only to the data import procedures but also to the rationale for how to choose a site.

Those who take longer tend to put off entering meteorological data. If you enter the layout and equipment configuration first and review the meteorological data last, the appearance of monthly generation, PR, and losses will change, forcing you to redo the comparisons. This is especially true when dealing with multiple candidate sites at the proposal stage: increasing the number of cases while leaving site conditions vague weakens the basis for later comparisons.

When confirming site conditions, organize the site's coordinates, elevation, time zone, nearby meteorological observation conditions, and the type of solar irradiance data to be assumed. Depending on the project, elevation differences and the effects of terrain may not be negligible. Even when dealing with distant topography or nearby shading, if the site conditions are inaccurate, they can affect the assessment of solar irradiance and shadows.

Also, defining adoption criteria for the meteorological data commonly used within the company will speed up decision-making for each project. For example, you could use a fixed standard dataset for preliminary assessments and verify data that are closer to the project site or have been adjusted for detailed design. Conducting detailed analyses for every project from the outset takes time, but conversely, handling everything only at the preliminary level can lead to difficulties when explaining matters later.

When using the PVSyst manual, it is useful in practice to consider not only the format of meteorological data and the import methods, but also how to describe the data you have selected. When sharing reports internally or with clients, it is important to be able to explain why that meteorological data was used, how it relates to the project site, and whether it is appropriate for the study phase.

Locking in the meteorological data and site conditions up front stabilizes subsequent simulations. Rather than repeating calculations while leaving conditions that could change significantly later, preparing the foundation from the start will reduce the overall amount of work time.

Tip 3 Limit 3D scenes and shadow settings to what is necessary and sufficient

One of the tasks that tends to take time in PVSyst is creating the 3D scene and configuring shadows. In photovoltaic systems, shadows from buildings, trees, surrounding structures, terrain, and between arrays affect power generation. Therefore, for projects where shadow conditions cannot be ignored, creating the 3D scene and setting up obstructing objects is important. However, if you model details more finely than necessary, both data entry and verification take longer, and the overall simulation becomes heavier.

To save time, you first need to determine how important shadow settings are for the project. If it is a preliminary assessment with no tall buildings or trees nearby and array spacing is sufficiently maintained, the priority of developing a detailed 3D scene may not be high. On the other hand, for roof-mounted projects, urban projects, projects in mountainous or sloping terrain, or projects with utility poles or adjacent buildings, you need to carefully assess the effects of near-field shading.

When reading the PVSyst manual you will encounter sections on creating 3D scenes and configuring shadows, but it is not always necessary to reproduce every obstruction exactly as it appears on site. In practice, you should prioritize obstructions that are likely to affect power generation and simplify those with minor impacts. Rather than spending time on detailed shapes, it is more practical to identify the times of day, seasons, and the arrays that will experience shading.

Shadows between arrays are also important from a time-saving perspective. If you adjust a 3D scene while changing tilt angles and row spacing repeatedly, the number of calculation patterns increases. By first deciding on a range of candidate tilt angles and row spacings and narrowing the comparison conditions before inputting them, you can reduce unnecessary recalculations. Especially when the layout is not yet finalized, it is more efficient to understand the trend of the shadow’s impact using representative cases than to perform detailed shadow calculations again and again.

Also, the accuracy of on-site information affects the work time. If you create a 3D scene without having organized site photos, quick surveys, drawings, aerial imagery, terrain information, etc., you will later need to correct the positions and heights of obstructions. If you record, during the site inspection, the objects likely to cast shadows, their orientation, distances, and approximate heights, data entry into PVSyst will be faster.

A 3D scene is not necessarily better the more detailed it is. Adding detail can sometimes increase the reliability of results, but if you elaborate details while the basis for input values remains unclear, you end up with a model that looks precise yet is difficult to justify. To balance time savings and reliability, it is important to decide up front what to represent in detail and what to simplify.

When learning shading settings using the PVSyst manual, you need to be conscious not only of the operating procedures but also of creating project-specific decision criteria. For projects where near shading is a primary concern, configure settings carefully; for projects where shading effects are limited, keep the granularity to what is necessary and sufficient. Once you can make this distinction, simulation time can be greatly reduced.

Tip 4: Clarify the purpose of case comparisons to reduce calculation patterns

The main reason work time increases in PVSyst is creating too many comparison cases. When you want to slightly increase energy production, reduce losses, find the optimal capacity ratio, or examine differences in azimuth and tilt, you tend to want to run simulations under many different conditions. However, if you add cases while the objectives remain unclear, organizing the results takes time and making decisions becomes difficult.

Before conducting case comparisons, you should first clarify what decision the comparison is intended to inform. For example, the conditions you should vary differ depending on whether you are comparing to decide module capacity, PCS capacity, tilt angle, or the effectiveness of shading countermeasures. If you change multiple conditions at once, it becomes difficult to determine which factor influenced the results.

To reduce time, the basic rule is to change only one main condition per comparison. If you are comparing orientations, keep all conditions other than orientation as fixed as possible; if you are comparing tilt, keep all conditions other than tilt fixed. When comparing DC/AC ratios, you need to standardize equipment configuration and loss conditions. By rigorously applying this approach, you can keep the number of cases down while making the meaning of the results easier to interpret.

When consulting the PVSyst manual, it is important not only to learn the operations for creating cases and managing variants, but also to adopt a comparative-design mindset. Running more simulations does not necessarily bring you closer to the correct answer. In fact, the more aimless calculations you perform, the more complex the comparison tables become and the more time it takes to prepare explanatory materials.

In practice, it is effective to first decide on a single baseline case. A baseline case summarizes the conditions that are considered most reasonable at the present time. Based on that, create derived cases for each point you want to examine. When the baseline case is clear, it is easier to explain the differences from the derived cases. Conversely, if you create multiple patterns without a baseline case, it becomes unclear which one should be adopted.

Also, when comparing cases, it is important to decide in advance which indicators to examine. The scope of checks required varies depending on whether you look only at annual generation, monthly generation, PR, loss diagrams, or constraints at peak times. If the purpose is for proposal materials, you should prioritize indicators that are easy to explain. If it is for detailed design, you need to examine loss factors and electrical constraints more carefully.

Reducing the number of comparison cases does not mean making the analysis less thorough. It means cutting cases that do not directly inform necessary decisions and focusing on meaningful comparisons. With simulation tools like PVSyst, precisely because there are many things you can calculate, deciding what not to calculate leads to time savings.

Tip 5 Standardize the procedures for reviewing and correcting reports

An often-overlooked way to reduce simulation time is standardizing report review and correction procedures. PVSyst outputs a large amount of information as calculation results. Because there are many items to check—annual energy production, monthly production, PR, loss diagrams, system configuration, meteorological conditions, shadowing effects, breakdowns of various losses, etc.—it takes time if there is no established order for reviewing them.

The first thing to confirm is whether the input conditions have been reflected as intended. Before looking at the numerical results, verify that the location, meteorological data, system capacity, azimuth, tilt, modules, PCS, string configuration, and loss settings match your expectations. If you miss an input error at this stage, you may incorrectly interpret the energy production or losses.

Next, check the major trends in annual energy production and monthly energy production. Look to see whether the results are excessively high or low given the region and system conditions. If the monthly energy production is unnaturally skewed, there may be items to check in the weather data, azimuth, tilt, shading settings, or loss conditions.

After that, check the loss diagram. The loss diagram helps you understand where energy is being lost. Check temperature losses, mismatch, wiring losses, shading losses, PCS-related losses, and so on, and look for any values that seem anomalous given the project conditions. If you do not understand the meaning of the losses, you cannot judge the results even if numbers are provided. When reading the PVSyst manual, it is important to be aware not only of the names of the loss items but also of how they relate to site conditions and design conditions.

One reason report reviews take a long time is that whenever you spot something worrying you go back to the input screen, make a correction, recalculate, and then return for another part, repeating that cycle. To prevent this, it is effective to collect all proposed corrections at once and then recalculate. Even if there are items you want to fix immediately, first review the entire report, identify the points that need fixing, and then apply them together.

When multiple people within a company use PVSyst, it is also important to share the verification procedures. If the order in which reviewers check things and their decision criteria differ by person, the points raised will change with each review and the number of corrections will increase. By standardizing the minimum items to check, the criteria for judging anomalous values, the conditions that require recalculation, and the comments that should be included in the report, you can shorten review time.

The PVSyst manual is useful for understanding how to operate the software, but in practice the post-operation verification procedures determine the quality of the deliverables. By deciding the order in which you review the report and standardizing the input conditions, energy yield, losses, comparison results, and the items to be transcribed into explanatory materials, you can greatly reduce the time required after the simulation.

Operational approach for embedding time-saving practices in daily work

To reduce simulation time in PVSyst, there are limits to relying only on individual operating speed. In practice, you can shorten the entire team's working time by organizing project-specific assumptions, input templates, verification procedures, review methods, and the documentation workflow.

First, clarify the purpose of the simulation at the start of the project. Whether it is for a rough estimate proposal, for detailed design, for revenue estimation, or for internal comparison will change the required level of accuracy and the items to be checked. Entering inputs at the same granularity as detailed design during the rough estimate stage takes too much time. Conversely, if only rough-estimate-level conditions are considered during the detailed design stage, major rework will occur later.

Next, creating a standard workflow for each project type is effective. For rooftop-mounted projects, emphasize confirming building geometry and nearby shading, while for ground-mounted projects prioritize terrain, array spacing, azimuth, tilt, and PCS configuration—decide the priority items for each project in advance. Rather than reviewing every item to the same depth each time, it is important to shift where you spend time according to the nature of the project.

Also, it is effective to keep a record of common configuration mistakes. If you turn past errors into checklist items—such as selecting the wrong meteorological data, confusing units, omitting the capacity input, inconsistencies in string configuration, leaving loss settings at their default values, failing to apply shading settings, or case differences when exporting reports—you can avoid repeating the same rework.

When using the PVSyst manual for in-house training, it is more effective to have trainees learn the necessary items according to the actual workflow than to make them read every chapter in order. For beginners, first teach the basics of project creation, meteorological data, system configuration, loss settings, and result verification. For intermediate users, focus on case comparison, shading setup, report interpretation, and how to detect anomalies. Dividing the material to read according to each person's proficiency also shortens the learning time.

Furthermore, the way results are saved and the naming rules must not be overlooked. If you don't know which case is the most recent, under what conditions it was calculated, or whether it has been reviewed internally, you'll spend more time searching later. It is important to manage the project name, analysis date, condition name, and version clearly, and to be able to trace the relationship between the baseline case and the comparison cases.

Time savings should not be a one-off tweak but must be established as an operational practice. If the same hesitation occurs every time you use PVSyst, it is not an individual problem but likely a sign that procedures and decision criteria are not well established. Rather than just learning operations by reading the manual, creating standard procedures tailored to your company’s projects will continuously reduce the time required for tasks.

Summary

To reduce simulation time in PVSyst, simply learning the operations quickly is not enough. In practice, many of the causes of time consumption are insufficient organization of conditions before input, uncertainty about meteorological data and site conditions, overelaborate 3D scene modeling, case comparisons without clear objectives, and a lack of established procedures for checking reports. By reviewing these items one by one, you can reduce the number of calculation runs and revisions and make result verification more efficient.

The initial measure is to organize input conditions to reduce recalculations. Separate fixed values from provisional ones, and by identifying related items that should be checked when changes occur, you can prevent rework. Next, it is important to finalize meteorological data and site conditions first. Once the simulation’s foundation is stable, comparisons and explanations in later stages will proceed smoothly.

The third measure is to limit 3D scenes and shadow settings to what is necessary and sufficient. By distinguishing between projects that require detailed reproduction and those that can be simplified, you can reduce input time while ensuring the accuracy needed for decision-making. The fourth is to clarify the purpose of case comparisons and avoid increasing the number of calculation patterns too much. By establishing a baseline case and changing only one main condition per comparison, the meaning of the results becomes easier to interpret.

The fifth is to standardize the procedures for report review and correction. Decide the order in which to check input conditions, power generation, loss diagrams, monthly results, and comparison results, and by compiling candidate corrections before recalculating you can reduce the time spent on review and rework. When multiple people in the company use it, aligning review criteria and naming rules is also effective.

PVSyst is a convenient simulation tool that can model many different conditions. However, precisely because you can configure so many detailed settings, using it without a clear purpose can be time-consuming. To put the PVSyst manual to practical use, it is important not to try to learn every feature to the same depth, but to prioritize understanding the items necessary for project decision-making.

Reducing simulation time does not mean making the analysis sloppy. Rather, it is a practical skill for focusing on the important conditions, reducing unnecessary rework, and producing results that are easy to explain. By organizing inputs before entry, finalizing meteorological data, optimizing shading settings, narrowing down comparison cases, and standardizing report checks, project evaluations using PVSyst can become faster, clearer, and more reproducible.