Where to Start with PVSyst? Introducing the First 7 Operational Steps

PVSyst is a specialized simulation software for predicting the power generation of photovoltaic systems and for checking design conditions and loss factors. For designers using it for the first time, the many screen items and technical terms can make it hard to know where to start. However, you don’t need to learn all the functions from the beginning. If you grasp the basic workflow for predicting power generation and enter the inputs in order, it becomes much easier to understand what PVSyst is used to check.

This article organizes and explains seven initial operational steps that practitioners searching for "What is PVSyst" should first handle. Rather than memorizing screen operations in detail, it is more important to understand which screen determines what, and how that input affects energy production and losses. From the way of thinking before starting to use PVSyst, through site selection, meteorological conditions, azimuth, tilt, system configuration, shading, losses, and result verification, this summarizes the flow beginners should grasp first.

Table of Contents

• PVSyst is software for entering design conditions in sequence to check energy production

• Step 1: First determine the project's objectives and the baseline case

• Step 2: Set the installation site and meteorological conditions

• Step 3: Enter azimuth and tilt to determine the irradiance on the panel surface

• Step 4: Set the system capacity and equipment configuration

• Step 5: Check shading and terrain conditions and incorporate them

• Step 6: Input loss parameters to bring the model closer to reality

• Step 7: Check the energy production using the results screen and reports

• Common issues that PVSyst beginners often stumble over in their first operations

• Practical ways to learn PVSyst operation

• Improve the accuracy of energy production forecasts by combining PVSyst with on-site information

PVSyst is software that allows you to input design conditions in sequence to verify the energy production

PVSyst is software for predicting the power generation of photovoltaic (PV) systems and for organizing the differences between design conditions and loss factors. In photovoltaic power generation, output is not determined solely by installed capacity. Solar irradiance at the installation site, ambient temperature, panel azimuth and tilt, shading from the surroundings, topography, wiring, equipment configuration, soiling, temperature rise, and various other conditions affect the power output. PVSyst is used to enter these conditions and to check annual generation, monthly generation, loss breakdown, performance ratio, and so on.

When first using PVSyst, what's important is not to look at the screens separately, but to understand them as the flow that determines the energy production. First create the project's assumptions, decide the installation site and meteorological conditions, enter the panel orientation and tilt angle, configure the system capacity and equipment layout, reflect shading and losses, and finally check the results. Once you understand this order, it's easier to grasp the meaning of the screen items.

Operating PVSyst is not a simple matter of just entering data and running calculations. You need to verify that the input conditions match the actual on-site situation, check for any anomalies in the generation results, and confirm that the way losses appear is reasonable. In particular, inexperienced designers tend to think, "it's finished once the calculation results are out," but in practice the ability to interpret the results is important. Whether the generation is higher or lower than expected, if you cannot explain why, the results become difficult to use for design decisions or for explaining to stakeholders.

The purpose of first using PVSyst is not to master all of its features, but to experience the basic workflow of energy yield prediction. Start by creating a single baseline case, then gradually change azimuth, tilt, system capacity, shading conditions, and so on, and compare the results so you can clearly see which inputs affect the energy yield. When first operating the software, prioritize understanding the relationship between input conditions and results over perfecting detailed settings.

Step 1: First determine the project's objective and the baseline case

When you begin using PVSyst, it is important to decide the purpose of the project first. If you start operating with the reason for the simulation unclear, it becomes difficult to know which conditions to input and which results to prioritize. Whether it is an initial feasibility study for a power generation project, a comparison of design proposals, a check of shading impacts, or an assessment of equipment capacity, the conditions you enter and the way you interpret the results will differ.

The first thing beginners should create is a baseline case. A baseline case is a case in which you enter the design conditions that are considered the most standard or realistic at that time. By entering the installation location, weather conditions, azimuth, tilt, system capacity, equipment configuration, shading, and loss conditions, it becomes a starting point for checking power generation. Having this baseline case makes it easier to compare how power generation and losses change when you later change the conditions.

In PVSyst, the approach of managing multiple design conditions within the same project is important. When creating cases with different orientations, different tilts, cases that account for shading, or cases that change system capacity, you need to keep each set of conditions clearly separated. If case names or notes are vague, you won't be able to tell later which conditions were used for a given calculation. Because similar cases tend to multiply during design studies, it is very important in practice to organize them from the outset.

When deciding the purpose of a project, it's also a good idea to consider how the results will be used. Whether it is for internal review, stakeholder briefings, design comparisons, or pre-construction verification will affect the required level of accuracy and the content of explanations. For initial studies it may be treated as a rough estimate, but when using it for detailed design or stakeholder briefings, you need to more thoroughly organize the basis for the input conditions.

In the initial steps, it is important not to advance through the screens merely for the sake of progressing, but to make clear which conditions will serve as the baseline. PVSyst’s results are predictions based on the input conditions. If the baseline case is well defined, subsequent comparisons and considerations for improvement become easier to understand. Conversely, if the baseline case remains ambiguous, no matter how many simulations you create, it will be difficult to explain the meaning of the results.

Operation Step 2: Set the installation location and weather conditions

The next step in PVSyst is to set the installation site and meteorological conditions. The electricity generation of a photovoltaic system is greatly influenced by the site's solar irradiance and ambient temperature. Even with the same system capacity, the annual energy production varies between regions with high and low irradiance. In addition, in regions with higher temperatures, module temperatures tend to rise, which can cause greater temperature-related output losses. The installation site and meteorological conditions are important inputs that form the foundation of energy production forecasts.

When setting the installation location, confirm that the candidate site's position is reflected correctly. If latitude, longitude, elevation, or regional characteristics are off, assumptions about the sun's position and local weather may be incorrect. This is especially true in mountainous, coastal, basin, snowy, or urban areas, where solar radiation and temperature patterns can differ even between nearby locations. Beginners should not treat the task of selecting weather conditions as mere screen input, but understand it as the process of determining the assumptions for power generation.

In meteorological assessments, power output is calculated from solar irradiance and air temperature data. Solar irradiance is the energy source for solar power generation, and air temperature is related to temperature losses. Higher solar irradiance tends to increase power output, but high air temperatures can cause panel temperatures to rise and reduce output. Therefore, instead of judging advantage or disadvantage based only on solar irradiance, it is necessary to consider air temperature and seasonal variations as well.

Once you have set the installation location and meteorological conditions, always verify on the results screen later whether those assumptions were reasonable. If the annual energy production seems too high or too low, the meteorological conditions may not match the actual site. For generation forecasts, you should not simply use the data selectable on the screen as-is; you need to consider how well it represents the local environment.

Also, in preliminary assessments, detailed on-site information may not yet be available. Even then, you can create a baseline case using provisional conditions. However, the results should be treated as a starting point for the study, not as the final power generation figure. Later, once on-site surveys and design conditions become more concrete, it is important to review the installation location and meteorological conditions and update the simulations.

Operation Step 3 Enter the azimuth and tilt to determine the solar radiation on the panel surface

After setting the installation location and weather conditions, next enter the panel's orientation and tilt. Orientation refers to the direction the panel is facing. Tilt refers to the angle at which the panel is installed relative to the horizontal plane. These two are important input parameters that determine how much solar radiation reaches the panel surface.

PVSyst calculates the solar irradiance reaching the panel surface based on the meteorological conditions at the installation site. The irradiance reaching a horizontal plane is not the same as the irradiance reaching an inclined panel surface. The orientation and tilt of the panels change the amount of irradiance received by season and by time of day. Therefore, the azimuth and tilt settings affect not only the annual energy yield but also the trends in monthly generation.

What novice designers should be careful about is not to decide orientation and tilt solely based on ideal values. In actual sites, roof orientation, land shape, racking installation constraints, surrounding shading, constructability, maintenance access paths, and other factors can prevent freely choosing orientation and tilt. Even if PVSyst indicates conditions that produce higher energy yields, those conditions cannot be adopted if they cannot be realized on site. PVSyst should be used to compare which conditions are reasonable within the range that can be implemented on site.

After entering the azimuth and tilt, you will learn more effectively by slightly changing the conditions and observing the results. By checking how power generation and monthly trends change when you alter only the azimuth or only the tilt, you can see the relationship between the input conditions and the results. However, when making comparisons, it is important not to change too many conditions at once. If you change multiple conditions simultaneously, it becomes difficult to determine which factor is responsible for the differences in power generation.

When adjusting azimuth and tilt, it is important to understand the concept of irradiance on the panel surface. In solar power generation, not only the regional irradiance itself but the irradiance that actually reaches the panel surface affects the power output. Setting azimuth and tilt is the process of determining how the panels receive energy from the sun. With this understanding, the fields on PVSyst's screens become visible not as mere numeric inputs but as important design conditions that influence power generation.

Operation Step 4: Set Equipment Capacity and Device Configuration

After entering the azimuth and tilt, next set the system capacity and equipment configuration. Here you organize the panel capacity, power conversion equipment capacity, connection conditions, and circuit configuration. In photovoltaic power generation, the DC power generated by the panels is converted and taken out as usable electricity. Therefore, the balance between panel capacity and power conversion equipment capacity affects generation output and losses.

The installed capacity is a basic parameter that indicates the scale of a power generation facility. While a larger capacity generally makes it easier to increase power output, simply making it larger is not always the right solution. If many panels are placed on limited land or a roof, inter-row shading may increase, maintenance access may be insufficient, and wiring distances may become longer. In PVSyst, after entering the installed capacity you can check how the generation output and losses will behave.

Balancing with the capacity of the power conversion equipment is also important. If the capacity of the power conversion equipment is smaller than the panel capacity, output may be curtailed during periods of strong solar irradiance. Such output curtailment will be reflected in the results as losses. On the other hand, increasing panel capacity to some extent can make it easier to secure generation during periods of weak solar irradiance. The important thing is not to judge solely by the size of capacities, but to check annual energy production, output curtailment, performance ratio, and the breakdown of losses together.

When setting up the equipment configuration, also check the circuit conditions. Depending on how the panels are connected and how the circuits are divided, the voltage and current conditions will change. If the conditions are not appropriate, the setup may fall outside the equipment’s operating range or the power generation efficiency may decrease. Beginners should not just confirm that no errors appear on the screen, but also be aware of how the configuration affects generated power and losses.

A common misconception in this procedure is the idea that increasing system capacity will always be advantageous for generation forecasts. While increasing capacity can raise total energy production, it can also worsen the balance with shading, wiring, output limits, constructability, and maintainability. In PVSyst, you can create multiple cases with different capacities and check the changes in generation and losses per unit capacity to make more realistic design decisions.

Step 5: Check and Incorporate Shadow and Terrain Conditions

After setting the system capacity and equipment configuration, check for shadows and terrain conditions. In photovoltaic power generation, shadows cast by surrounding buildings, trees, slopes, topographic undulations, equipment structures, and between panel rows affect energy production. Running simulations without accounting for the impact of shading can make estimated generation appear higher than actual. When using PVSyst in professional practice, verifying shading conditions is extremely important.

In shadow assessment, we consider not only whether shadows exist but also when, where, and to what extent they occur. Even in places with little shadow during summer daytime, the sun’s altitude is lower on winter mornings and evenings, causing shadows to stretch much longer. Even if surrounding obstructions are some distance away, if they are tall they may cast shadows depending on the season. A single site visit is not sufficient to judge the shadow impacts throughout the year.

To account for shading in PVSyst, you need to understand on-site obstacles and topography as accurately as possible. The positions and heights of buildings and trees, elevation differences across the site, the installation area, and the spacing between panel rows all affect the shading inputs. If this information remains unclear, PVSyst’s shading assessment will also be unclear. Before using the shading screen, it is important to organize which information is required.

For beginners, a recommended approach is to first create a case that does not account for shading, then create a case that does, and compare the two. This comparison lets you understand how much shading affects annual and monthly energy production. If including shading causes a large drop in generation, you should consider changing the layout, reassessing the installation area, or adjusting the spacing between rows.

When reflecting shading conditions, it is important not to make eliminating shading losses entirely the sole objective. Depending on site conditions, some shading may be unavoidable. What matters is identifying the causes of shading and separating shading that can be mitigated from shading that should be accepted. PVSyst's shading assessment is not intended to invalidate a design but to provide a more realistic estimate of energy generation and to serve as input for improving layout planning.

Step 6: Enter Loss Conditions to Make It More Realistic

After confirming shading and terrain conditions, next input the various loss parameters. In solar power generation, the energy received from the sun does not directly become the final electrical output. Various losses occur, such as reflection, soiling, temperature rise, wiring, equipment conversion, output limiting, and mismatch. In PVSyst, by setting these loss parameters you can perform a generation forecast that is closer to reality.

What you should understand first about loss conditions is that simply setting losses low is not the right approach. Reducing losses will increase the simulated power output, but if they do not match real-world conditions, the results become less reliable. Conversely, setting losses high without justification will lead to underestimating the true power output. What matters is choosing loss values that are reasonable for the site conditions and design parameters.

Temperature loss indicates a reduction in output caused by an increase in panel temperature. Even during periods of high solar irradiance, generation efficiency can decrease if ambient temperatures are high and panel temperature rises. Wiring loss refers to losses that occur in the process of transmitting the generated power. Because it varies with wiring distance and configuration, it is related to equipment layout and wiring routes. Soiling loss is the effect of dust and dirt accumulating on the panel surface, which makes it less able to receive solar radiation.

It is also necessary to check losses and output limitations caused by power conversion equipment. Conversion equipment has an efficiency, and a certain amount of loss occurs during the process of converting electrical power. In addition, depending on the balance between panel capacity and the capacity of the conversion equipment, output can be curtailed during periods of strong solar irradiance. PVSyst results allow you to verify how much these losses affect the energy yield.

When entering loss conditions, it's important to record the rationale so you can explain it later. If stakeholders ask for the basis of the projected energy production and you cannot explain which losses you assumed and how, the reliability of the simulation will be undermined. PVSyst's loss settings are not merely detailed screen inputs; they are a crucial step in bringing the energy production forecast closer to reality.

Step 7: Check power generation on the results screen and in the report

After entering all the main conditions, check the energy production on the results screen and in the report. What you should look at here is not just the annual energy production. By checking the monthly energy production, performance ratio, loss diagram, shading losses, temperature losses, wiring losses, output limitations, and so on together, you can interpret the reasons for the energy production. Reviewing PVSyst results is not simply a task of looking at numbers, but a task of verifying whether the input conditions and output results are consistent.

Annual energy production is the most straightforward result. It indicates how much electrical energy the generation equipment is expected to produce over one year. It is an important metric for business planning and design comparisons, but you cannot judge the quality of a design based solely on annual energy production. Larger installed capacity tends to increase production, and optimistic loss assumptions can make it appear higher. Treat annual energy production as an entry point for grasping the overall picture.

Monthly power generation is important for observing seasonal trends. If generation drops significantly in winter, you should check not only solar irradiation but also the effects of shading. If generation fails to rise as expected in summer, temperature-related losses or output limitations may be influencing performance. Examining monthly results reveals design characteristics that are not apparent from the annual total.

The performance ratio is a metric for checking how efficiently an installation converts the solar irradiance it receives into electricity. If the performance ratio is low, check for losses such as shading, temperature, wiring, equipment configuration, and soiling. Even when the performance ratio is high, you should verify whether the loss conditions are realistic and whether shading is being represented correctly. Do not assume a high value is unconditionally good; assess it together with the validity of the input conditions.

The loss diagram shows how much energy is lost at each stage, from solar radiation to the final power output. It may look difficult for beginners, but following the flow of energy from top to bottom makes it easier to understand. By checking which losses are large, you can identify candidates for design improvements. If shading losses are large, check the layout and obstructions; if wiring losses are large, review the wiring plan; if output limitations are large, check the capacity balance.

When reviewing a report, I re-read not only the results but also the input conditions. If you do not confirm that the installation location, meteorological conditions, azimuth, tilt, system capacity, shading, and loss assumptions match what was intended, you cannot judge the validity of the results. A PVSyst report is not a list of calculation results; it is a document for explaining the relationship between the design conditions and the energy production.

Common pitfalls for PVSyst beginners during initial operations

A common pitfall for PVSyst beginners is that filling in the screens in order becomes the goal. PVSyst has many input fields, but completing the fields themselves is not the objective. It is important to understand how the entered conditions affect energy production and to set assumptions that match the local site conditions. If you only proceed with screen operations, you will not be able to interpret the results correctly unless you understand the meaning of the input parameters.

Another stumbling block is using initial settings or common values as-is. Initial or standard values can serve as a starting point, but they do not apply to every site. Soiling, wiring, shading, temperature, equipment configuration, and the like can cause appropriate values to vary depending on site and design conditions. If you plan to use PVSyst results in practice, you need to be able to explain why you used those values.

Shadow settings are another aspect that beginners often stumble over. If shadows are present on site but shadow conditions are not reflected, the estimated power generation can appear higher than it actually is. Conversely, overestimating shadows can cause the power generation to be assessed lower than necessary. Since shadows change depending on the position and height of obstacles, the season, and the time of day, they need to be set carefully in combination with on-site verification.

Users also stumble over how to read the results screen. If you judge only by the annual energy production, you will not understand the reasons behind the generation. You need to check the monthly generation, the loss diagram, and the performance ratio to interpret which conditions are affecting the results. In particular, by looking at the loss diagram you can identify the impacts of shading, temperature, wiring, and power curtailment. The value of PVSyst lies not only in producing a number for energy production but in enabling you to explain the reasons for that number.

Also, when comparing multiple cases, it is common for management of the conditions to become unclear. If cases with changed azimuth, changed tilt, and changed capacity are mixed together, it becomes difficult to tell which result indicates what. When making comparisons, it is important to define a reference case, clearly specify the modified conditions, and organize the differences in the results.

Practical ways to learn PVSyst operation

To become familiar with operating PVSyst, it is more effective to create a simple reference case and learn the workflow than to tackle a complex project from the start. By going through the sequence of choosing the installation site, setting the meteorological conditions, entering the azimuth and tilt, configuring the system capacity and equipment configuration, and inputting minimal loss conditions to view the results, you can more easily grasp the overall picture.

Next, change one condition at a time and compare the results. For example, change only the azimuth, only the tilt, only the system capacity, compare before and after adding shading, or change the loss conditions—limit the items you modify and check them. Doing so lets you understand which inputs affect energy generation and losses. Changing many conditions at once makes it impossible to tell what caused the differences in the results, so it is not suitable for beginners.

When reviewing results, it's a good habit to check the annual energy production, monthly production, performance ratio, and loss diagram each time. Even if the numbers are hard to interpret at first, by comparing multiple cases you'll begin to see which losses increase when shading is introduced, how monthly production changes when the tilt is adjusted, and how output limitations appear when the capacity is changed. PVSyst becomes easier to understand by operating it and observing how the results change.

When using it in practice, practicing how to link on-site information with simulations is also important. Check the site’s orientation, tilt, obstacles, elevation differences, installation area, and wiring routes, and reflect these in PVSyst. By observing how energy production and losses change as a result, you connect the desk-based inputs with the actual site conditions. PVSyst is not something that is completed solely within the software; it should be used together with on-site surveys and design reviews.

At the end of the training, it is good to practice explaining the results. Explain in your own words why the energy production reached that figure, which losses are large, how shading and azimuth/tilt affect it, and which conditions could be changed to improve it. The ability to use PVSyst in professional practice is not just about being able to operate the software, but about interpreting the results and explaining them to stakeholders.

Improving power generation forecast accuracy by combining PVSyst and on-site information

PVSyst is simulation software used to predict the energy generation of photovoltaic systems and to verify design conditions and loss factors. When first using it, it is important to follow the workflow of deciding the project's objective, setting the installation site and meteorological conditions, entering azimuth and tilt, configuring system capacity and equipment layout, reflecting shading and losses, and checking the results screens and reports. By understanding these seven operational steps, the basic use of PVSyst becomes easier to grasp.

However, PVSyst's results depend on the input conditions. If the installation location, meteorological conditions, orientation, tilt, shading, losses, or system capacity differ from the actual site, the reported energy production may also deviate from reality. In particular, shading, terrain, installation area, the location of obstacles, and elevation differences can have a significant impact on energy production. It is important not only to learn how to operate the software but also to accurately obtain site information and reflect it in the input conditions.

To use PVSyst's energy production forecasts in practical work, you need to be able to explain not only the numerical results but also why those numbers were produced. Check the overall picture with the annual energy production, observe seasonal variations with the monthly production, identify causes of energy reduction with the loss diagram, and verify the overall system efficiency with the performance ratio. By repeatedly checking input conditions and results, you can enhance the simulation's reliability and its ability to be explained.

If you want to streamline on-site position checks, grasping the installation area, recording obstacles, and confirming orientation and elevation differences, using an LRTK (iPhone-mounted GNSS high-precision positioning device) is effective. By obtaining high-precision positional information on-site, it becomes easier to organize the basis for the installation area, shading conditions, and terrain conditions to be entered into PVSyst. By combining PVSyst power generation simulations with on-site information obtained by LRTK, even beginners can more easily bring design conditions closer to reality, improving the accuracy of power generation forecasts and the ability to explain them to stakeholders.