How far can PVSyst be used in professional practice? 7 things to know before adoption

Table of Contents

• What is PVSyst used to determine in practical work?

• Item 1 to know before introduction: Use cases for energy yield simulations

• Item 2 to know before introduction: The scope for comparing and evaluating design conditions

• Item 3 to know before introduction: What can be checked with shading analysis and 3D scenes

• Item 4 to know before introduction: Points where practical differences emerge in loss settings

• Item 5 to know before introduction: What can be observed in battery storage and self-consumption models

• Item 6 to know before introduction: Using it for report creation and internal presentations

• Item 7 to know before introduction: How to compensate for discrepancies with on-site conditions

• Precautions when implementing PVSyst in practice

• Summary: Linking desk studies and field information for practical use

What is PVSyst used to assess in practical work?

PVSyst is used in various practical situations as simulation software for the design review and energy production forecasting of photovoltaic power generation systems. It is used not only to simply calculate annual energy production but also to organize and numerically compare many conditions related to power generation projects and system design, such as meteorological conditions, installation orientation, tilt angle, module configuration, PCS capacity, shading effects, various losses, batteries, and self-consumption.

Many practitioners who search for "How to use PVSyst" want to know not only how to operate it but also how much they can trust it in actual projects, which stages it can be used in, and which results they should look at. Designing a photovoltaic system involves many pieces of information: drawings, site conditions, equipment specifications, electrical design, contractual terms, and operational policies. PVSyst does not automatically make all of those judgments, but it is very effective for entering assumptions, comparing multiple design options, and understanding trends in energy yield and losses.

On the other hand, introducing PVSyst does not automatically improve design quality. If the meteorological data entered are inappropriate, the results will be affected, and if shadow modeling is coarse, the assessment of shading losses will also be coarse. If the site's topography, site development status, racking layout, obstacles, surrounding buildings, snowfall, soiling, maintenance conditions, and so on are not adequately reflected, discrepancies will arise between actual operational results and the simulation. In other words, PVSyst is a powerful tool to support professional judgment, but it assumes that site information and design intent are correctly organized and applied.

This article explains, in seven items you should know before implementation, to what extent PVSyst can be used in practice. Assuming scenarios ranging from beginners learning how to operate the software to designers using it for internal and client presentations, we clearly organize PVSyst's practical role.

Item 1 to Know Before Implementation: Use Cases for Power Generation Simulations

The central purpose of PVSyst is to simulate the energy production of photovoltaic installations. You can check annual energy production, monthly production, system losses, performance ratio, available solar irradiation, temperature effects, limitations imposed by the PCS, and losses due to shading, allowing you to understand how much generation performance the planned installation will have. What you should understand before deployment is that PVSyst is not "a tool that delivers the one correct energy production value in a single shot," but rather "a tool to organize conditions and produce a reasonable estimate of energy production."

In practice, expected power generation is required at various stages such as initial studies, basic design, detailed design, investment decisions, internal approvals, customer briefings, explanations to financial institutions, and post-construction performance comparisons. In the initial study, you grasp the rough generation potential of candidate sites and judge whether the project appears commercially viable. In basic design, by varying orientation, tilt, layout, capacity, and PCS configuration, you determine which option offers the best balance between generation and constructability. In detailed design, you reflect shading and loss conditions more concretely to bring the power generation forecast closer to an explainable, verifiable estimate.

PVSyst's strength is that it lets you track the breakdown of energy production step by step. Rather than simply displaying "the annual energy production is this value," it allows you to inspect the process by which energy output decreases — for example, the conversion from horizontal plane irradiance to tilted plane irradiance, optical losses, temperature-related losses, losses due to module characteristics, wiring losses, mismatch losses, PCS losses, and shading losses. This makes it easier to determine whether a low energy yield is caused by irradiance conditions, angular conditions, shading, temperature, oversizing, or PCS limitations.

However, power generation simulations are highly sensitive to the input conditions. For example, even with the same installed capacity, results can vary depending on the meteorological data used, the installation angle, module temperature conditions, soiling losses, wiring conditions, and the method used to model shading. Therefore, when using PVSyst results in practice, you should not only look at the final energy yield but always check which assumptions were used for the calculation.

At the pre-installation stage, rather than thinking of PVSyst as "software just for calculating energy yield," viewing it as "software for organizing the design conditions that affect energy yield" makes its practical use clearer. Being able to explain not only the magnitude of the energy yield but also why that result occurred is a major value of using PVSyst.

Things to Know Before Implementation 2: Range Available for Comparing Design Conditions

PVSyst is well suited for tasks that compare multiple design conditions. In solar power design, various layout proposals can be considered even for the same site. Changing module orientation, tilt angle, row spacing, racking height, array configuration, PCS capacity, oversizing ratio, string configuration, and installed capacity will affect energy production, shading losses, constructability, maintainability, and equipment utilization. Using PVSyst, you can compare these conditions in simulation and use the results to inform design decisions.

For example, increasing the tilt angle can increase solar radiation capture during certain seasons, but it may also increase inter-row shading and require consideration of wind loads and racking costs. Conversely, decreasing the tilt angle can make it easier to place more modules on a site, but it can affect soiling, drainage, and seasonal variation in energy production. In PVSyst, you can compare changes in energy production and losses while varying these conditions.

It can also be used when considering the balance between DC capacity and AC capacity. In designs where module capacity is larger than PCS capacity, output limiting can occur during periods of strong irradiance, while generation during mornings, evenings, and cloudy conditions may be boosted. PVSyst allows checking clipping losses due to oversizing and the impact on annual energy yield, so rather than judging solely by capacity ratios, it can be examined as an annual generation characteristic.

It is also useful for examining string design. By considering the number of modules in series and in parallel, the PCS input conditions, the voltage range, and temperature conditions, you can verify whether the system configuration is feasible. In practice, detailed confirmation of the electrical design is required separately, but entering the array configuration into PVSyst makes it easier to check consistency in the simulation.

On the other hand, PVSyst is not construction drawing software. It does not automatically produce mounting structure component quantities, foundation layouts, detailed construction procedures, cable rack arrangements, site delivery plans, or similar deliverables. While it is useful for comparing design conditions, constructability, structural analysis, and compliance with laws and standards must be verified through a separate design process.

Therefore, when using PVSyst in professional practice, it is effective to position it as a comparative tool for narrowing down design options. Final design decisions should be made through a comprehensive assessment that considers not only power generation but also constructability, maintainability, terrain conditions, equipment specifications, electrical constraints, and project viability. PVSyst plays the role of quantitatively indicating generation performance and the loss structure within that assessment.

Item 3 to Know Before Introduction: Shadow Analysis and What Can Be Checked in 3D Scenes

One of PVSyst's important features for practical use is shading analysis. In photovoltaic systems, solar irradiation can be blocked by surrounding buildings, trees, utility poles, fences, slopes, mountain shadows, adjacent array rows, and so on, which affects power generation. Especially for ground-mounted and rooftop installations, the presence or absence of shading can have a significant impact on annual and monthly energy production.

In PVSyst you can create 3D scenes to model module surfaces and surrounding obstacles and to calculate losses from nearby shading. This makes it easier to capture shading effects in simulations that are difficult to discern from a simple planar layout alone. For example, you can check how much winter shading losses increase when row spacing is reduced, how much a building’s shadow affects the site in the morning, and how annual losses change when surrounding obstacles are taken into account.

Shadow analysis is also useful for early-stage layout design. When comparing a plan that maximizes site area to increase capacity with a plan that widens row spacing to reduce shading losses, differences appear that cannot be judged by installed capacity alone. Increasing capacity can lead to larger shading losses, resulting in less-than-expected energy generation. Conversely, by slightly revising the layout, shading losses can be reduced and annual energy yield and performance ratio can improve.

However, the accuracy of the 3D scene depends on the accuracy of the input model. If the on-site building heights, positions of obstacles, ground elevation, racking heights, or module layout differ from actual conditions, the results of the shadow analysis will also deviate from reality. This is especially true on sloped sites or sites where the terrain changes before and after earthworks, where a planar layout alone may not be sufficient. It is important to verify the positions and heights of surrounding obstacles on site and, when necessary, model them using survey data or point cloud data.

Also, the effect of shading relates not only to energy production but also to electrical connections. Even the same shading can have different actual impacts depending on which string is shaded and whether the shading is partial or widespread. PVSyst can evaluate shading losses with a consistent model, but the results need to be interpreted together with the on-site wiring design and the approach to string grouping.

In practice, you should not assess shadow-analysis results based solely on the single figure of "what percentage the shadow loss is"; it is important to check when, where, and why shadows occur. Even if shadows are unavoidable, their impact can often be mitigated by changing the layout, adjusting row spacing, reviewing rack height, or optimizing the string configuration. PVSyst is an important basis for conducting those evaluations.

Pre-implementation Item 4: Points Where Loss Settings Lead to Differences in Practice

When using PVSyst in practice, loss settings are extremely important. In energy production simulations, the final output is determined not only by solar irradiance and system capacity but by the accumulation of various losses. Temperature losses, soiling losses, wiring losses, mismatch losses, losses related to module quality, incidence-angle losses, PCS losses, shading losses, degradation rate, and many other settings are involved.

A common pitfall for beginners using PVSyst is to simply use the initial values or the settings from past projects as they are. Of course, having company standard values and standard conditions for each project type is practically useful. However, if you reuse loss settings without thoroughly checking them despite differences in site conditions and equipment specifications, it becomes difficult to justify the validity of the results.

Temperature losses are influenced by the installation environment and the type of mounting structure. When the module's rear side is well ventilated versus when it is close to the roof surface and heat tends to accumulate, the way the module temperature rises differs. Because higher temperatures reduce power generation efficiency, the temperature loss setting affects annual energy yield. In practice, it is necessary to verify the settings taking into account the installation method, surrounding environment, and ventilation conditions.

Soiling loss is also an item that tends to vary by site. Soiling conditions differ in regions with heavy rainfall where natural washing occurs, areas with high dust, locations near farmland or land development, sites affected by bird fouling, and coastal areas prone to salt exposure. Because it also changes depending on cleaning schedules and maintenance policies, an explanation that takes the local environment into account is necessary rather than a simple uniform setting.

Wiring losses depend on cable length, cross-sectional area, current, voltage, wiring route, and other factors. In the initial stages it is sometimes acceptable to use approximate values, but in detailed design it is desirable to make them closer to the actual wiring plan. Underestimating wiring losses can result in an overestimation of power generation, while overestimating them can lead to an incorrect evaluation of a design proposal.

Mismatch losses are related to module-to-module variations, variability between strings, partial shading, aging over time, and other factors. In practice, settings are checked while considering module specifications and layout, the presence or absence of shading, and the string configuration. At sites with shading, it is important not to rely on a simple loss setting alone, but to verify it together with shading analysis and the electrical configuration.

In PVSyst reports, losses are displayed step by step, which makes them useful for explaining results. If the power generation is lower than expected, you can check which losses are large and look for opportunities to improve the design. Once you can handle loss settings carefully, PVSyst becomes not just calculation software but an analysis tool for design improvement.

Item 5 to Know Before Installation: Observations in Battery Storage and Self-Consumption Models

In recent years, there has been a growing number of projects that not only simply sell electricity from solar power generation systems but also involve self-consumption on the customer side or combinations with storage batteries. In PVSyst, you can create models that take self-consumption and storage batteries into account and examine how much of the generated electricity is used, how much surplus is produced, and how battery charging and discharging change the situation.

In a self-consumption model, what matters is not just the amount of generation but also its overlap with demand patterns. Solar power generates during the daytime, but the self-consumption rate can vary greatly depending on whether a facility’s electricity use is higher during the day or at night and how it changes between weekdays and weekends. Even if annual generation is the same, surplus increases if the timing of demand and generation do not align. Conversely, facilities with high daytime demand can more easily use the generated power on site.

In PVSyst, you can use load data and demand conditions to assess self-consumption trends. This allows you to evaluate whether increasing system capacity would create an excessive surplus, how much utilization improvement can be expected by adding batteries, and whether the balance between generation and demand is appropriate. At the pre-installation stage, it is advisable to check not only generation forecasts intended for selling electricity but also whether the results can be used for proposals to electricity consumers.

In battery storage models, capacity, charging/discharging conditions, efficiency, and operational policies affect the results. Installing a battery does not necessarily produce benefits. If excess generation is small, the battery may not be able to be used effectively. Conversely, in projects with significant excess generation, a battery may be able to shift daytime excess to other time periods. However, actual implementation decisions also involve factors beyond the simulation, such as equipment costs, operational policies, contract terms, electricity prices, uses for disaster preparedness, and peak shaving.

PVSyst only shows energy flows based on the conditions you set. If the demand data is coarse or actual operation differs from the settings, the results will also change. For example, the picture you get differs when you examine only monthly estimated demand versus when you use hourly demand data. If you handle self-consumption or battery storage in practice, it is important to prepare demand data that is as close as possible to measured values within constraints and to clarify the assumptions.

Thus, PVSyst can be used to evaluate battery storage and self-consumption, but it should not be relied on alone to make the final decision on equipment installation. It is practical to use it as a tool to organize generation, demand, surplus, and charging/discharging trends and to feed those findings into other commercial feasibility assessments and operational design.

Pre-implementation Item 6: Leveraging for Report Preparation and Internal Briefings

PVSyst is also well suited to practical work because it can organize calculation results into reports. In designing and proposing solar PV systems, you need to explain the basis for projected energy production to stakeholders both inside and outside the company. Simply reporting the annual energy yield without clarifying why that figure is reached, under which assumptions it was calculated, and which losses were assumed will be unconvincing. PVSyst’s reports provide the foundation for these explanations.

The report organizes project conditions, meteorological data, system configuration, module and PCS conditions, installation angle, power generation, loss diagrams, monthly results, and so on. This makes it easier to share the calculation assumptions with team members other than the design staff. Sales personnel, construction personnel, maintenance personnel, business planning staff, customer representatives, and others each have different points of focus, but being able to discuss things based on the same report is a major advantage.

In internal briefings, it is important first to confirm that the calculation conditions align with the project's assumptions. Check that equipment capacity, installation location, azimuth, tilt, equipment configuration, and loss settings match the current design proposal. Next, review the energy generation and the performance ratio to see whether there are any major discrepancies compared with past or similar projects. Furthermore, examine the loss diagram to determine whether any specific loss is excessively large or whether there is room for design improvements.

When explaining to customers, rather than simply listing technical terms, you should translate the meaning of the results into easy-to-understand language. For example, explain "temperature loss" as "the effect of reduced efficiency when the module becomes hot," "shading loss" as "the effect of solar radiation being blocked by surrounding objects or by inter-row shadows," and "wiring loss" as "the portion lost during the process of transmitting electricity" to make them easier to understand. It is important not to just hand over the PVSyst report as-is, but to supplement it with explanations of the project's key points.

Reports can also be used for comparative evaluation. By organizing the results of multiple proposals and comparing power generation, shading losses, limitations due to overcapacity, equipment capacity, and operational considerations, it becomes easier to determine the design policy. Rather than simply choosing the proposal with the highest power generation, the report can be used as material for decision-making that also takes constructability, maintainability, and site constraints into account.

However, just because a report looks well formatted doesn't mean its contents are correct. If the input conditions are wrong, the report will likewise be based on incorrect assumptions. It is important to establish internal checklists before implementation. By creating procedures to verify the consistency of meteorological data, location, azimuth, tilt, system capacity, equipment conditions, loss settings, shading models, and output results, you can stabilize the quality of PVSyst's practical use.

Item 7 to Know Before Deployment: How to Compensate for Discrepancies with On-Site Conditions

When using PVSyst in practice, the thing to pay most attention to is the mismatch between the simulation and on-site conditions. PVSyst performs calculations based on the conditions entered. That means if the actual site conditions are not correctly reflected, the results will deviate from the real situation. If you are considering "what can be achieved with PVSyst" before implementation, you must also consider "how accurately you can enter on-site information."

Site conditions include the site shape, ground elevation, slope/gradient, slope faces, surrounding buildings, trees, utility poles, fences, existing equipment, surrounding topography, roads, and neighboring site conditions. For rooftop installations, roof pitch, roofing material, parapets, air-conditioning equipment, piping, lightning protection equipment, and adjacent buildings can have an impact. For ground-mounted installations, site development plans, ground undulations, row spacing, racking height, drainage, and maintenance access routes are also relevant.

It is not easy to reproduce all of these perfectly in PVSyst. However, elements that have a large impact on energy yield and shading losses need to be represented as accurately as possible. In particular, in shading analysis the way shadows fall can change if the position or height of obstacles is even slightly different. On sloped sites, array height relationships and inter-row shading differ from those on flat ground, so on-site terrain information is important.

In practice, we combine on-site surveys, measurements, photographic records, drawing checks, point cloud acquisition, and stakeholder interviews to establish the basis for input conditions. Photographs alone can leave heights and distances ambiguous, and old drawings may not reflect current obstacles. Planned drawings made before site development can differ from the actual terrain after development. To conduct high-accuracy analyses with PVSyst, organizing on-site information before simulation is extremely important.

Also, care is required when comparing simulation results with actual operational performance. Actual power generation is affected by weather, equipment downtime, output curtailment, soiling, failures, maintenance status, and grid-side constraints. If the power generation predicted by PVSyst differs from the actual performance, you should not immediately conclude that the simulation is wrong; instead, check the meteorological conditions, operational status, downtime, output limits, and the consistency of the measurement data.

PVSyst is not a tool for measuring the site directly. It only becomes a simulation usable in actual practice when the site is properly understood and that information is organized as design conditions. Before implementation, it is important to establish internally the workflow from on-site surveys through the creation of input conditions, not just how to operate the software.

Considerations when implementing PVSyst in practice

When introducing PVSyst, it is necessary to clarify who will use it, at what stage, and for what purpose. Whether it is only to produce a rough estimate of generation, to use for design comparisons, to prepare materials for submission to clients, or to create documentation for financial institutions will change the required input accuracy and the items to be checked. If you begin using it while the purpose is unclear, the handling of results will also become ambiguous, making it difficult to apply them to practical decisions.

First, it is important to establish standard input rules within the company. Organizing items such as how to choose meteorological data, the approach to setting losses, temperature conditions, soiling losses, wiring losses, mismatch losses, degradation rate, criteria for performing shadow analysis, and the checklist when generating reports will reduce variability among staff. Especially when multiple people use PVSyst, operational rules are indispensable to prevent results from differing significantly between personnel even when calculating the same project.

Next, it is also important to establish a checking system. While PVSyst is highly functional, it has many input fields, so it is prone to input errors and configuration omissions. Mistakes that can occur in practice include the wrong site being selected, an incorrect sign for the azimuth, entering the wrong tilt angle, the installed capacity not matching the latest plan, an outdated shading model, or loss settings left as they were for past projects. Before issuing a report, it is reassuring to put in place an operation in which another team member verifies the assumptions.

Also, it is important not to over-rely on PVSyst results. Simulations are, after all, computational models and do not perfectly reproduce actual power generation. In particular, local weather variability, snow, soiling after typhoons, changes in the surrounding environment, vegetation growth, equipment outages, and output curtailment may not be fully captured at the time of simulation. When using the results, you should explain the assumptions and the uncertainties together.

On the other hand, when PVSyst is used correctly, it can make a significant contribution to improving design quality. Rather than subjectively judging that “this layout seems good,” you can compare power generation, losses, and the effects of shading numerically. It also makes it easier to present the rationale for decisions to customers and internal stakeholders. It becomes easier to check the impact of design changes and to consider whether to increase capacity, avoid shading, change the tilt angle, or review PCS capacity.

When getting started, there is no need to try to master all features at once. First, create a basic grid-connected model and learn meteorological data, azimuth, tilt, array configuration, PCS configuration, basic losses, and how to read the reports. After that, gradually expand the scope of use to shading analysis, detailed loss settings, self-consumption, batteries, and multi-scenario comparisons to make it easier to adopt in practice.

Summary: Connect and leverage desk-based analysis and on-site information

PVSyst is a simulation software widely used in practical photovoltaic power system work for energy yield prediction, design comparison, shading analysis, loss analysis, self-consumption and battery studies, and report generation. What you should know before adopting it is that PVSyst is not an all-purpose automatic design tool, but a tool to assist design decisions based on the input conditions.

The practical value in real-world work is not just in producing a number for annual energy generation. It lies in being able to clarify why that generation occurs, which losses are the largest, what would improve if design conditions are changed, where shading effects manifest, and how the balance between demand and generation will behave. By using PVSyst, you can convert intuitive judgments into numerical values and present them in a form that is easy to explain to stakeholders.

On the other hand, the reliability of simulations depends heavily on the accuracy of on-site conditions and input parameters. If meteorological data, installation tilt, array configuration, loss settings, shading models, topographical conditions, or obstacle information are inaccurate, the results will deviate from reality. Therefore, when implementing PVSyst, it is important to establish business workflows that cover not only operation procedures but also site surveys, surveying, drawing verification, utilization of point cloud data, and systems for checking input parameters.

In particular, for layout studies that consider shadow analysis and terrain, accurate on-site location information is highly important. If you can correctly understand the positions of surrounding obstacles, the installation positions of the racking, ground elevation, and the relationship with existing structures, analyses in PVSyst will be closer to reality. Conversely, if on-site dimensions and heights remain ambiguous, no matter how carefully you operate the software, the explanatory power of the simulation results will be weak.

Therefore, to make desktop studies using PVSyst useful in practice, it is effective to combine them with accurate location information obtained on site. LRTK, as a high-precision GNSS positioning device that can be attached to an iPhone, can streamline coordinate acquisition and position recording in the field. If the planned site of a solar power installation can record the installation area, obstacles, racking positions, existing terrain, and verification points with high accuracy, it becomes easier to improve the reliability of the assumptions entered into PVSyst.

PVSyst is a tool for numerically evaluating design conditions, while LRTK is a tool for accurately capturing on-site positional information. By linking desktop simulations with measured on-site data, the credibility of power generation forecasts and shading analysis is increased, making it easier to make decisions in the design, construction, and explanation stages. If you introduce PVSyst into practical work, rather than completing everything within the software settings, considering how to accurately acquire site information and how to reflect it in the design conditions will lead to more practical use.