What is PVSyst useful for? Explaining use cases in power generation projects

Table of Contents

• PVSyst is analysis software that produces decision-making information for power generation projects

• Reasons why PVSyst is needed in power generation projects

• Estimate expected energy production in the initial project planning phase

• Assess profitability and feasibility by comparing design conditions

• Understand the impacts of shading and terrain and apply them to layout planning

• Organize loss factors and explain the causes of reduced power generation

• Facilitate consensus-building with stakeholders through report preparation

• Reduce discrepancies between the plan and the site through pre- and post-construction checks

• Identify improvements by comparing actual performance after operation begins

• Points to note for leveraging PVSyst in power generation projects

• Improve project accuracy by combining PVSyst with on-site information

PVSyst is analysis software that creates decision-making materials for power generation projects

PVSyst is a specialized analysis software used to simulate the energy production of photovoltaic power systems and to organize design conditions and loss factors. In solar power projects, installing equipment does not guarantee it will generate electricity as expected. Various conditions affect energy production, including the solar irradiance at the installation site, panel orientation, tilt angle, presence or absence of shading, terrain, ambient temperature, wiring, system configuration, soiling, and aging. PVSyst helps by allowing these conditions to be input and by assisting in checking annual and monthly energy production, loss breakdowns, and performance indicators.

The reason PVSyst is emphasized in power generation projects is not simply that it can calculate energy production. When considering solar power generation as a business, energy production affects everything: revenue from electricity sales, investment decisions, equipment sizing, financing, design comparisons, construction planning, and operations management. In other words, energy production forecasts are the figures that form the assumptions for the entire project. If those assumptions are decided only by intuition or simple calculations, they may seem viable during the planning stage but could end up diverging significantly from reality during actual operation.

Using PVSyst, you can verify step by step why a given amount of generation is produced. You can understand how much solar irradiance is available, how much of it reaches the panel surface, how much is lost due to temperature, shading, wiring, conversion, and so on, and ultimately how much electrical energy is produced. In power generation projects, it is important not only to have the generation figures themselves but also to be able to explain those figures. The more stakeholders involved—project developers, designers, installers, financial parties, landowners, and government officials—the greater the value of evidence-based explanatory documentation.

For beginners trying to understand PVSyst, it is good to start with the understanding that it is "software that predicts power generation." However, you should not stop there; it is important to regard it as "software that creates decision-making material to realistically validate power generation project plans." PVSyst does not automatically determine whether a design is good or bad; it presents results based on the input conditions and is a tool for people to interpret and judge those results. To make it useful for power generation projects, understanding the meaning of the input conditions, how to read the results, how to interpret losses, and cross-checking with local information are indispensable.

Why PVSyst Is Necessary in Power Generation Projects

In power generation projects, there are many uncertainties during the planning stage. It is necessary to examine the solar irradiation conditions at candidate sites, whether the shape of the land is suitable for generation equipment, how much surrounding shading will affect performance, how much installed capacity can be secured, whether the annual energy production will be at a level sufficient to support the project plan, and what kinds of losses are likely to occur in future operations. PVSyst helps to organize these assessments numerically.

In solar power projects, power generation forecasts are central to business decision-making. Higher generation typically leads to greater profitability, but if plans are based on overly optimistic forecasts, discrepancies between expected and actual performance after operations begin can become problematic. Conversely, overly conservative forecasts can cause potentially viable projects to be passed over. PVSyst allows you to verify generation while reflecting installation conditions and loss factors, making it easier to assess the validity of a plan.

In power generation projects, there are often many situations where multiple design options must be compared. When evaluating changes such as panel orientation and tilt, layout, system capacity, power conversion equipment capacity, or wiring plans, it is necessary to compare numerically which option is more advantageous for energy yield. By using PVSyst, you can verify differences in energy yield and losses when conditions are changed, enabling design decisions based on evidence rather than intuition.

Furthermore, accountability to stakeholders is also important in power generation projects. In a variety of situations—internal approvals, financing, land-use coordination, review of construction plans, and the development of operation plans—the basis for projected power generation is required. PVSyst reports can organize and present the input conditions and output results, making them useful materials for creating a shared understanding among stakeholders. In particular, being able to show a breakdown of losses is effective for explaining why actual generation is lower than the ideal.

Another reason PVSyst is needed is that power generation projects are long-term endeavors. Solar power installations are not finished once they are installed. During operation, variations in weather conditions, soiling, equipment degradation, changes in the surrounding environment, and maintenance and management practices all affect power output. If you use PVSyst in the planning stage to organize your assumptions, it becomes easier to compare with actual performance after operations begin and identify where differences arise. A major role of PVSyst is to provide decision-making data that can be used from the project’s outset through the operational phase.

Forecasting Power Generation in the Initial Business Plan Review

The first stage where PVSyst proves useful in power generation projects is the early-stage project planning. Once a candidate site has been identified, it is necessary to determine how much electricity can be expected from that land. Simply looking at land area alone does not tell you whether a power generation project will be viable. You need to consider comprehensively factors such as solar radiation conditions, orientation, topography, shading, available installation area, equipment capacity, grid connection conditions, and maintenance access routes.

In the initial assessment, you first assume a rough system capacity and installation conditions and check the outlook for annual power generation. At this stage it does not need to be as precise as detailed design, but if calculations are based on assumptions that are too far from reality, significant rework may be required in later stages. By using PVSyst, you can check the irradiance reaching the panel surface and the expected power generation based on the solar radiation conditions of candidate sites. This makes it easier to assess a site's potential at an early stage.

In power generation projects, the accuracy of initial assessments affects subsequent decisions. If you proceed with a project plan while overestimating power generation, profitability may decline later, requiring design changes or plan revisions. Conversely, if you assume excessive constraints from shading or terrain at an early stage, you may overlook potentially viable candidate sites. PVSyst allows you to review multiple cases while varying conditions, helping you make flexible decisions in the early stages.

Also, in a business plan, not only the annual power generation but the trends in monthly power generation are important. By understanding how generation changes seasonally, it becomes easier to organize income forecasts and operational considerations. In locations where shading has a strong impact in winter, looking only at annual generation may make the problem seem small, but generation can drop significantly in certain seasons. By checking PVSyst's monthly results, you can grasp these seasonal variations at the planning stage.

When using PVSyst in preliminary studies, it is also important to understand the coarseness of the input conditions. At stages where accurate surveying of candidate sites and detailed design have not yet been completed, the input conditions necessarily include certain assumptions. Therefore, initial simulation results should be treated not as final values but as rough estimates for assessing project viability. As on-site information and design conditions become concrete in later stages, the PVSyst input conditions should be updated and the expected power generation reconfirmed.

Assess Profitability and Feasibility by Comparing Design Conditions

PVSyst is also highly useful for comparing design conditions. In power generation projects, multiple design proposals can be considered even for the same site. Changing panel azimuth and tilt, layout spacing, system capacity, circuit configuration, capacities of power conversion equipment, and wiring routes can alter energy production, losses, constructability, and maintainability. By using PVSyst, you can quantify how much these design differences affect energy production.

When comparing design conditions, it is important to recognize that the option with the highest energy output is not necessarily the optimal one. For example, increasing installed capacity may raise generation, but you must also consider land use, constructability, maintenance access routes, increased shading, cable run distances, and the balance with equipment capacity. Pursuing generation alone can lead to systems that are difficult to operate or that increase construction burdens. PVSyst can provide data for comparing the generation and losses of each option, but the final decision should also take site conditions and business policy into account.

Comparing azimuth and tilt is something whose effects can be easily checked in PVSyst. When a panel’s orientation or angle changes, not only the annual energy yield but also the monthly distribution of generation changes. A given tilt may produce a higher annual total, while another tilt may be advantageous in specific seasons. Which generation pattern should be prioritized depends on the project’s objectives and the intended use of the electricity. By comparing multiple cases in PVSyst, you can identify characteristics that aren’t apparent from simply looking at maximum generation.

The balance between installed capacity and the capacity of power conversion equipment is also important in designing a power generation project. The ratio of panel capacity to conversion-equipment capacity affects the amount of energy produced and how output limitations manifest. Increasing panel capacity relative to conversion-equipment capacity can increase operation during low irradiance, but may lead to curtailed output during high irradiance. In PVSyst, these differences in conditions can be identified as losses, making it easier to evaluate the validity of capacity design.

PVSyst is also useful for wiring planning and comparing electrical losses. In a power generation system, losses occur in the process of transmitting power from the panels to the conversion equipment and then to the receiving equipment. When wiring distances are long, wiring capacity is insufficient, or the configuration is inefficient, part of the generated power is lost. By comparing design proposals while checking losses in PVSyst, it becomes easier to plan with awareness not only of energy production but also of the overall system efficiency.

Understand the impacts of shadows and terrain and apply them to site layout planning

In solar power generation projects, shadows and terrain significantly affect power output. If there are buildings, trees, slopes, embankments, transmission towers, or other facility structures around the candidate site, panels can be shaded depending on the time of day and season. In particular, when the solar altitude is low in the mornings and evenings and during winter, shadows tend to extend longer and can reduce power generation more than expected. PVSyst is useful for power generation simulations that take these shadow effects into account.

What is important in shading assessment is not just whether a shadow exists, but when, where, and to what extent it occurs. Even short-duration shadows can lead to significant losses depending on the circuit configuration and equipment characteristics. In addition, the length and direction of shadows cast by the same obstacle change with the seasons. By setting shading conditions in PVSyst, you can confirm the impact of shading on energy production as losses and use that information to improve layout planning.

Terrain effects should not be overlooked. While layout is relatively easy to evaluate on flat land, actual candidate sites often have elevation differences and slopes. Undulating terrain affects panel installation height and orientation, inter-row shading, drainage, constructability, and maintenance access routes. To reflect terrain and shading conditions in PVSyst, it is important to accurately capture the site's topography. If on-site information remains coarse, shading assessment will also be uncertain.

In layout planning, you need to consider the balance between energy production and installed capacity. Placing panels densely may increase installed capacity, but it can increase inter-row shading and reduce generation efficiency. Conversely, widening the spacing can reduce shading, but the capacity that can be installed on the same land may decrease. Using PVSyst lets you check the energy production and shading losses when layout conditions are changed, allowing evaluation that includes generation efficiency as well as simple area efficiency.

Assessment of shading and terrain also relates to risk management for power generation projects. If, after project commencement, unexpected shading is discovered to be the cause of reduced power output, it can be difficult to remedy. Buildings and terrain cannot be easily changed, and there may be restrictions on tree management. Therefore, during the planning stage it is important to understand shading and terrain as accurately as possible and to check their impact on energy production using PVSyst. If shading risks can be identified early, measures such as layout changes, revising the installation area, or adjusting equipment configuration can be considered.

Organize loss factors and explain the causes of reduced power generation

One of the main reasons PVSyst is useful for power generation projects is that it can break down loss factors. In solar power generation, the energy received from the sun does not directly become electrical energy. Various losses occur due to conditions affecting what reaches the panel surface, conditions affecting conversion to electricity in the panels, conditions as the energy passes through wiring and equipment, and output constraints. PVSyst lets you inspect these losses step by step, making it easier to explain how the system's energy output was determined.

In power generation projects, presenting only the generation figures is not enough. It is important to be able to explain why that level of generation occurred, which conditions are reducing generation, and whether there is room for improvement. For example, if the annual generation appears lower than expected, you need to differentiate whether the solar irradiance conditions are poor, shading is significant, temperature losses are large, wiring losses are high, or whether there are constraints in the equipment configuration. PVSyst’s loss diagram and loss breakdown are useful for this kind of diagnosis.

Organizing the loss factors makes it easier to see the priorities for design improvements. If losses from shading are large, revising the layout and installation area should be considered. If wiring losses are large, you may need to review wiring distances and configurations. If temperature-related losses are large, it makes sense to check the installation method and ventilation conditions. If losses due to output limitations are large, there may be room to reconsider capacity balance. In this way, the loss breakdown is not just a presentation of results but a starting point for improvement.

However, it is not possible to reduce all losses to zero. In solar power generation, there are unavoidable losses such as output reduction due to temperature, reflection, wiring, and conversion. The important thing is not to view the mere existence of losses as a problem, but to judge whether those losses are within a reasonable range, appropriate for the local conditions, and possible to improve. Using PVSyst, you can review the magnitude of each loss and distinguish between losses that should be accepted and those that should be improved.

In power generation projects, there are many occasions when stakeholders need to be presented with forecasts of expected power output. If loss factors are not well organized at that time, the rationale behind the projected output becomes unclear. Using PVSyst results to explain the flow from solar irradiance to final generated power improves the transparency of the project plan. In particular, for investment decisions and design approvals, the persuasiveness of the documentation is greatly affected by whether losses are explained.

Advancing consensus with stakeholders in report preparation

PVSyst also helps build consensus among stakeholders involved in power generation projects. In such projects, many parties are involved, including project developers, designers, construction contractors, maintenance personnel, landowners, financiers, and government authorities. Because they do not necessarily share the same technical knowledge, materials that clearly explain expected energy production and design conditions are necessary. PVSyst reports can be used as the basic documentation for that purpose.

The report allows input conditions and output results to be reviewed in a single flow. Installation location, installed capacity, orientation, tilt, meteorological conditions, loss conditions, annual generation, monthly generation, performance indicators, and so on are organized, making it easier to share the planning details of a power generation project. Having stakeholders discuss while looking at the same materials reduces discrepancies in understanding. In particular, when comparing multiple design proposals, it is important to clearly separate the conditions from the results.

In consensus-building, it's important to share the assumptions as well as the results. If you present only the annual generation figures, it will be unclear under what conditions those figures were calculated. If the meteorological data, shading conditions, loss settings, or system configuration change, the generation will change as well. When using a PVSyst report, you should explain which conditions were assumed for the results and, where necessary, prepare supplementary materials that document the site conditions and the basis for design decisions.

Reports are useful not only for approving project plans but also for handing over to later stages. If records remain of what conditions were assumed during the planning stage, what losses were anticipated, and which design option was adopted, the rationale behind decisions can be checked during construction and operation. Power generation projects run for long periods, so personnel may change. Properly managing PVSyst reports makes it easier to trace back the assumptions made during planning.

When presenting a report to stakeholders, it is also important to explain technical terms. Words such as performance ratio, losses, solar irradiation, output limitations, and temperature losses can be difficult for people unfamiliar with photovoltaic power generation to understand. Rather than simply listing the numbers from PVSyst, explaining the points that affect business decisions in an easy-to-understand way will make it easier to build consensus. PVSyst is specialized analysis software, but, depending on how it is used, it can become a common language among stakeholders.

Reduce discrepancies between plans and the site through pre- and post-construction verification

PVSyst is useful not only at the planning stage but also for verification before and after construction. In power generation projects, the conditions on the design drawings do not always perfectly match the actual site conditions. Detailed pre-construction checks may reveal that terrain or obstacles differ from what was assumed, and during construction the layout or cable routing may be adjusted. Re-simulating with PVSyst is effective for determining how much these changes will affect energy production.

Before construction, it is important to review the input conditions based on the detailed design. Layout, equipment capacity, shading conditions, and wiring conditions that were approximate in the initial assessment become more concrete prior to construction. If you update PVSyst input conditions at this stage, you can confirm the generation that is close to the plan as actually constructed. By comparing with the initial assessment results, you can also understand the impact of design changes on generation.

During construction and after completion, it is important to reflect changes that occur on site. For example, due to ground conditions or construction constraints, the panel layout may be partially altered. If the wiring route changes, wiring losses may also change. The installation area may be adjusted because of surrounding obstacles or maintenance space. By reflecting these changes in PVSyst, you can confirm the differences between the original plan and the as-built condition in terms of power generation.

During post-construction verification, it is important to confirm that the completed installation aligns with the assumptions used in the simulation. If orientation, tilt, installation area, shading conditions, equipment configuration, and wiring conditions are as planned, it will be easier to compare actual performance after operations begin. Conversely, if there are discrepancies between the plan and the site, failing to record those differences will make it difficult to analyze the causes if power generation after start-up differs from expectations.

Using PVSyst for pre- and post-construction verification clarifies the link between planning, design, construction, and operation. Rather than leaving the simulation created at the planning stage fixed, updating it to reflect actual site conditions produces power generation forecasts that are closer to real-world practice. In power generation projects, it is important to minimize the difference between planned and actual values. To do so, it is essential to carefully incorporate on-site information from before and after construction and bring PVSyst’s assumptions closer to reality.

Identify areas for improvement by comparing actual performance after operations begin

PVSyst is also useful after a power generation system begins operation. The energy production forecast created during the planning stage serves as a baseline for comparison with actual post‑operation performance. If actual energy production differs significantly from the forecast, analyzing the causes can provide clues to identify equipment faults, soiling, changes in shading, equipment performance issues, and maintenance-management challenges.

When comparing post-operation performance, it's important not to simply compare annual energy production, but to examine monthly and seasonal trends. If performance is significantly lower in a particular month, factors such as weather during that period, shading, soiling, equipment outages, or equipment malfunctions may be responsible. Even if the annual total does not show a large difference, a monthly view can reveal that problems are concentrated in specific periods. Comparing PVSyst's monthly forecasts with actual performance makes it easier to identify these trends.

However, just because the measured values and PVSyst’s predicted values do not match, it does not immediately mean the simulation is wrong. Actual weather varies from year to year. In years when solar irradiance is below the long-term average, power generation will also be lower. Conversely, in years with favorable solar conditions, generation can exceed the prediction. Therefore, when comparing actual performance to predictions, you should also verify the actual solar irradiance and the equipment’s operating status.

To make effective use of PVSyst during the operational phase, it is important to properly document the assumptions made during the planning stage. If you do not know which meteorological conditions were used, which losses were anticipated, how shading conditions were set, or what the system configuration was, you cannot correctly analyze deviations from actual performance. Keeping the PVSyst planning report and input conditions organized will make post-operation evaluation easier.

Comparing actual performance can reveal areas for improvement. If a reduction in power output due to soiling is suspected, a review of the cleaning schedule may be warranted. If shading has a greater impact than anticipated, it is necessary to check for changes in the surrounding environment and the management of trees. If there are frequent equipment shutdowns, the maintenance framework and monitoring methods need to be reviewed. PVSyst does not directly resolve issues after operation, but by comparing against predicted values it provides a benchmark for identifying where attention should be focused.

Considerations for leveraging PVSyst in power generation projects

To use PVSyst in power generation projects, there are several points to keep in mind. The most important is that the input conditions have a large influence on the results. PVSyst is a high-functionality analysis software, but if the conditions entered do not match the actual situation on site, the resulting energy output will also be difficult to trust. Location, meteorological data, orientation, tilt, shading conditions, system configuration, and loss settings should be entered with as much justification as possible.

A common pitfall for beginners is treating simulation results as an absolute truth. PVSyst’s results are merely predictions based on the assumptions you set. Actual energy production will vary depending on weather, construction accuracy, operation and maintenance, changes in the surrounding environment, equipment condition, and so on. Therefore, PVSyst’s figures do not fully guarantee future generation and should be treated as a reasonable projection for business decision-making.

It is also important not to set loss assumptions overly optimistically. If you reduce factors such as soiling, shading, wiring, temperature, and equipment losses below reality just to make generation appear higher, the credibility of the business plan will suffer. The figures may look good in the short term, but if actual performance fails to materialize after operations begin, it will damage trust with stakeholders. The purpose of using PVSyst is not to produce convenient results, but to support business decisions with realistic assumptions.

Conversely, care must be taken not to set parameters that are overly conservative. If losses are overestimated, projected power generation may be undervalued and the project's economic viability can appear diminished. While it is important to account for risks in power generation projects, applying overly strict conditions without justification can lead to assessments that are detached from reality. What matters is neither optimism nor pessimism, but making reasonable assumptions based on site conditions and design parameters.

Also, it is important not to make business decisions based solely on a PVSyst report. Power generation projects involve many considerations, such as land conditions, legal procedures, constructability, maintainability, grid connection conditions, surrounding environment, and project schedule. PVSyst is very useful for evaluating energy yield and losses, but it alone does not determine the overall success or failure of a project. The energy yield simulation should be positioned as one of the key reference materials, and decisions should be made in conjunction with other operational information.

Enhancing project accuracy by combining PVSyst with on-site information

PVSyst is analysis software that helps with energy yield forecasting, design comparison, loss analysis, report generation, and performance comparison in power generation projects. In the early stages of project planning it can be used to assess the generation potential of candidate sites. During the design phase it is useful for comparing differences in orientation, tilt, layout, equipment configuration, and wiring conditions to choose the most appropriate design option. Before and after construction it can be used to check discrepancies between the plan and the field, and after operation begins it can serve as a basis for analyzing deviations from actual performance.

To use PVSyst effectively in power generation projects, it is important not to focus solely on annual energy production. By examining monthly energy production, performance indicators, the breakdown of losses, the impact of shading, and the validity of input conditions together, you can understand the reasons behind the energy production. The true value of PVSyst is not simply producing numbers, but breaking down the elements that make up the energy production and presenting them in a way that can be explained to stakeholders.

On the other hand, the accuracy of PVSyst is heavily dependent on the quality of on-site information. If the site orientation and tilt, land elevation differences, surrounding obstacles, causes of shading, installation area, wiring routes, and so on are inaccurate, the simulation results are likely to deviate from the actual situation. In power generation projects, it is important not to separate desk calculations from on-site conditions, but to reflect information obtained from field surveys in the design parameters and to verify those conditions with PVSyst.

Especially at candidate sites for power generation projects, a site that appears flat may have subtle elevation differences, and surrounding structures or trees can cast shadows depending on the season. If you proceed with a design without accurately capturing such information, you may later need to change the layout or revise the estimated power output. To perform a reliable analysis in PVSyst, it is essential to obtain the site’s location and shape information as accurately as possible and to clearly document the basis for the input conditions.

Therefore, when using PVSyst in power generation projects, it is important to also establish mechanisms to improve the accuracy of on-site verification. If position information and positioning data acquired on site can be reflected in design studies, it becomes easier to assess shading, layout, and installation boundaries, and the input conditions for PVSyst will be closer to reality. By utilizing an iPhone-mounted high-precision GNSS positioning device such as LRTK, on-site position checks and surveying tasks can be streamlined, making it easier to organize the field information needed for planning, design, and construction verification of power generation projects. By combining power output simulations from PVSyst with the high-precision position information obtained on site, you can further enhance the decision-making accuracy and explanatory power of power generation projects.