Introduction to the PVSyst Manual｜5 Basic Steps for Energy Yield Calculation

Table of Contents

• An overview of power generation calculations you should understand before reading the PVSyst manual

• Step 1 Set the site conditions and meteorological data correctly

• Step 2 Decide the configuration of the solar panels and power conditioner

• Step 3 Reflect the effects of azimuth, tilt angle, and shadows

• Step 4 Organize loss conditions and adjust the estimated power generation to be closer to reality

• Step 5 Interpret simulation results and use them to inform design decisions

• Terms and interface concepts in the PVSyst manual that commonly cause confusion

• Common Mistakes and Checkpoints in Power Generation Calculations

• Learning sequence for beginners to use PVSyst in professional practice

• Summary

Overview of Power Generation Calculations You Should Grasp Before Reading the PVSyst Manual

PVSyst is one of the representative analysis software programs used to simulate the energy production of photovoltaic (PV) systems. It is used in a wide range of situations, including the planning stage of power plants, design studies, explanations to financial institutions and project owners, validation of energy production forecasts, and comparisons of multiple proposals. However, for first-time users the interface contains many on-screen items and the meaning of the numerical inputs can appear technical, so even after reading the manual it is easy to be unsure where to start.

When reading the PVSyst manual, the first thing to keep in mind is that you are not expected to memorize every operation. First, it is important to understand the order in which the energy production calculations are carried out. Simulating a photovoltaic system is not simply a matter of entering the solar panel capacity and producing an annual energy estimate. It is a process of building up, one by one, the factors that affect energy output: the site’s irradiance, temperature, panel orientation, tilt angle, shading, equipment configuration, wiring losses, temperature losses, soiling, degradation, system downtime, inverter efficiency, and so on.

A major reason beginners get confused with PVSyst is that they look at input items in isolation. For example, selecting meteorological data, registering module data, pairing inverters, configuring nearby shading, entering loss rates, and reviewing reports are each performed on separate screens. In reality, however, all of these are connected within the flow of the energy production calculation. If the meteorological data changes, the incident solar irradiance changes; if the tilt angle changes, the irradiance reaching the panel surface changes; if temperature conditions change, the output degradation changes. If the equipment configuration is not appropriate, even when the theoretical irradiance is sufficient, electrical losses or constraints can prevent achieving the expected energy production.

To read the PVSyst manual efficiently, it helps to be aware of the stages at which energy output decreases. The first is the irradiance on the horizontal plane that falls at the site. From there, it is converted to irradiance on the panel surface according to the panel's tilt and azimuth. Next, the usable irradiance is reduced by shading, reflection, soiling, and so on. Furthermore, the DC-side power output changes due to the photovoltaic modules' temperature rise and equipment characteristics. Finally, after passing through the cables, the inverter, transformer equipment, and grid-side constraints, it is evaluated as AC-side power output.

In other words, the energy production calculation carried out in PVSyst follows the sequence of entering the natural conditions, entering the system conditions, entering the loss conditions, and validating the results. If you understand this overall picture before reading the manual, the meaning of each screen becomes apparent not merely as an operational procedure but as an element for design decision-making. In practice, it is important not only to present the energy production figures but also to be able to explain which assumptions led to those figures. As much as memorizing PVSyst’s screen operations, you need the ability to interpret the rationale behind the calculation results.

This article explains, in five basic steps, the workflow of energy-yield calculations for readers approaching the PVSyst manual for the first time. Rather than covering every detailed function, it organizes the key concepts and checkpoints needed to begin practical energy-yield simulations.

Step 1 Correctly set the site conditions and meteorological data

The first step when starting energy-yield calculations in PVSyst is to configure the project's site conditions and meteorological data. The electricity generation of a photovoltaic system varies greatly depending on where it is installed. Even with the same solar panels and the same installed capacity, annual irradiance and temperature conditions differ between Hokkaido, Tohoku, Kanto, Chubu, Kansai, Kyushu, and Okinawa. Furthermore, even within the same prefecture, conditions change in coastal areas, mountainous areas, basins, snowy regions, and high-wind regions. Therefore, for the initial inputs in PVSyst it is very important to specify the installation site's latitude, longitude, elevation, time zone, and selection of meteorological data.

Weather data are the foundation of power generation calculations. If solar irradiation is estimated to be high, the calculated generation will be high; if solar irradiation is estimated to be low, the calculated generation will be low. Weather data include global horizontal irradiance, direct irradiance, diffuse irradiance, ambient temperature, wind speed, and other parameters. In PVSyst, these data are used to calculate how much solar irradiation reaches the surface of the solar panels. Therefore, treating the selection of weather data lightly will reduce the reliability of the entire simulation.

Beginners often get confused about which meteorological data to choose. In PVSyst you can handle multiple meteorological data sources, and for some locations you may use nearby-station data or satellite-derived data. In practice, you need to define a clear data-selection policy according to the project’s purpose. For preliminary assessments, standard data may be acceptable, but for uses close to investment decisions or contractual documentation, more careful data verification is required. It is advisable to compare multiple datasets and check the annual solar irradiation, monthly trends, and the presence of any anomalies.

When evaluating site conditions, elevation and surrounding topography are also items that are easy to overlook. Elevation affects temperature conditions, and temperature influences the output of solar panels. Because solar panels' output decreases as temperature rises, locations with simply higher solar irradiance are not always advantageous. In hot regions, even where irradiance is high, temperature-related losses can be large; in cold regions, even if there are periods with low irradiance, cooler temperatures can be beneficial for efficiency. PVSyst can incorporate these relationships between climatic conditions and equipment characteristics into its simulations.

Also, it is important to examine monthly trends in meteorological data. Even if the annual power generation looks acceptable, looking by month can reveal issues for equipment planning—such as output drops due to high temperatures in summer, extremely low solar radiation in winter, or generation during the rainy season being lower than expected. In particular, for self-consumption solar power systems, generation patterns by time of day and by season can be more important than the annual total. Understanding meteorological data is indispensable for confirming when generated power can be used and whether the peaks of demand and generation align.

When reading the PVSyst manual, first review the weather-data-related screens and terminology and make sure you understand what each value represents, as this will make subsequent steps easier. In particular, terms such as global horizontal irradiance, plane-of-array (tilted) irradiance, diffuse irradiance, direct irradiance, and ambient temperature are fundamental to energy-yield calculations. If you proceed while these remain unclear, it will be difficult to judge which losses are significant when you review the report.

The purpose of Step 1 is to establish the assumptions about the solar energy incident at the site. The conditions set here will affect all subsequent calculations. Therefore, carefully checking the location and meteorological data at this initial stage is the first step to improving the accuracy of energy yield calculations using PVSyst.

Step 2 Decide the configuration of solar panels and power conditioners

Once the site conditions and meteorological data are set, the next step is to determine the configuration of the solar panels and power conditioners. In PVSyst, you set module capacity, number of modules, number of modules in series, number in parallel, inverter capacity, MPPT configuration, voltage range, oversizing ratio, and so on, and verify the electrical consistency of the entire system. This process is an important step directly linked to both power generation calculations and design review.

When configuring photovoltaic panels, you should first check the specifications of the module you will use. Representative items include nominal maximum power, open-circuit voltage, short-circuit current, maximum power operating voltage, maximum power operating current, and temperature coefficients. PVSyst provides a module database, but in practice you must confirm that the specifications of the actual model to be deployed match the registered data. Because even models with similar part numbers can differ in output and temperature coefficients, it is important not to use the registered data as-is but to verify it against the specification sheet.

When configuring the inverter, check the input voltage range, maximum input current, rated output, maximum efficiency, number of MPPTs, and allowable string configurations. Because solar panels’ voltage and current change with irradiance and temperature, they do not always operate under constant conditions. Open-circuit voltage rises at low temperatures, and operating voltage falls at high temperatures. Therefore, when determining the number of panels in series per string, verify that the maximum voltage at low temperature does not exceed the inverter’s allowable range and that the operating voltage at high temperature does not fall below the MPPT range.

What beginners often struggle with in PVSyst is judging the configuration based only on the total capacity. For example, there are cases where they look only at the ratio between the total capacity of the solar panels and the inverter capacity and conclude there is no problem. However, in reality, if the number of modules in series, the number of parallel strings, the input voltage, the input current, and the MPPT allocation are not appropriate, warnings can appear in the simulation or the configuration may be unworkable as an actual installation. In the PVSyst manual, the screens that check these electrical compatibility aspects are important.

Additionally, in photovoltaic power generation, panel capacity is sometimes designed to be larger than inverter capacity. This approach takes into account the characteristic of solar panels that they do not always generate at their rated maximum output, and it is intended to use the inverter more efficiently. However, if panel capacity is increased excessively, clipping losses will increase because the inverter limits output at peak times. PVSyst allows you to check the balance between the increased energy production from such oversizing and the clipping losses.

In the design phase, it is common to compare several configuration options. For example, for the same site you might compare an option that increases the number of panels, an option that changes the inverter capacity, an option that alters the string configuration, and an option that changes the tilt angle. The advantage of using PVSyst is that it allows you to evaluate not only simple capacity comparisons but also losses, PR, and monthly energy production. Rather than simply choosing the option with the highest annual energy yield, it is necessary to make a decision that considers equipment constraints, constructability, maintainability, grid constraints, and cost considerations.

When deciding the configuration of modules and inverters, it is important to take future operation into account. On site, partial shading, soiling, faults, replacements, and aging occur. If string configurations are too complex, identifying the root cause during maintenance can become difficult. PVSyst's energy yield calculation is the entry point for design studies, but by considering the configuration with actual plant operation in mind, the simulation becomes more practical.

The goal of Step 2 is to create a configuration that can properly convert the DC power produced by the solar panels into AC power through the inverter. When reading the PVSyst manual, it is important to understand the relationship between modules, strings, inverters, and MPPTs as a single electrical system, rather than simply filling in the input fields.

Step 3 Reflect the effects of azimuth angle, tilt angle, and shadows

Another important factor is the installation angle of the solar panels and the effect of shading. In PVSyst's energy production calculations, azimuth and tilt are set to calculate how much solar irradiance reaches the installation surface. The azimuth indicates which direction the panels face, and the tilt indicates how steeply they are inclined relative to the ground. These conditions affect not only the annual energy production but also seasonal and hourly generation patterns.

In general, solar power generation tends to produce more annual energy when installed facing south. However, in practice it is not always possible to install panels in the ideal south-facing orientation. Constraints such as roof shape, site layout, land development conditions, racking layout, surrounding structures, grid interconnection location, and maintenance access can lead to east–west or southeast/southwest orientations. PVSyst can compare expected energy production while accounting for these conditions.

The tilt angle is also important. A larger tilt angle can be advantageous for the lower solar altitude in winter, but it is not necessarily optimal for the higher solar altitude in summer. A smaller tilt angle makes it easier to receive summer solar radiation, while it can affect winter energy production and the ease with which dirt is washed away. In snowy regions, the tilt angle also changes how easily snow slides off and the outlook for winter power generation. In PVSyst simulations, it is important to judge the effect of angle by looking not only at the annual total but also at monthly energy production.

Shading configuration is a part that beginners often find particularly difficult. In solar power generation, surrounding buildings, trees, utility poles, mountains, fences, substations and transformer equipment, and panels in adjacent rows create shadows. Shading does not simply reduce solar irradiance. Because solar panels are made up of multiple cells and strings, partial shading can cause disproportionately large electrical losses. Especially in the morning and evening and during winter, when the sun elevation is low and shadows lengthen, they can have a non-negligible impact on annual power generation.

PVSyst distinguishes between far shading and near shading. Far shading deals with the effects of distant terrain, such as mountains or the horizon, that block the sun. Near shading concerns the effects of obstacles around the power generation equipment, such as buildings, trees, rows of racks, and equipment. When reading the PVSyst manual, understanding this difference makes it easier to know what to configure on each screen.

When configuring shadows, it is important to avoid both underestimation and overestimation. If shadows are not included, estimated power output tends to be higher, but actual operation is more likely to fall below expectations. Conversely, if obstacles that in reality have a limited impact are set too conservatively, power generation can be underestimated unnecessarily. The effect of shadows varies with the object’s position, height, distance, the sun’s path, and the season, so it is important to set them based on on-site conditions as much as possible.

In ground-mounted systems, mutual shading caused by row spacing is also important. If the spacing between panel rows is narrow, shadows from the front rows fall on the rear rows during winter and in the morning and evening. Widening the row spacing reduces shading, but may decrease the number of panels that can be installed on the same site. In other words, there is a trade-off between increasing installed capacity per site and reducing shading losses. By using PVSyst, you can compare energy production and losses for each layout option, allowing you to design not simply to maximize the number of panels but to balance that with generation efficiency.

On roof-mounted systems, rooftop equipment, parapets, adjacent buildings, antennas, and air-conditioning equipment are sources of shading. Especially for buildings in urban areas, the height and distance of surrounding buildings can have a large impact on power generation. When handling rooftop projects in PVSyst, it is desirable to not only rely on drawings and site photos but, if possible, verify the dimensions and positional relationships of on-site obstacles and reflect them in the shading settings.

The objective of Step 3 is to bring the theoretical solar irradiance closer to the irradiance actually received by the solar panels. The PVSyst manual contains many items related to azimuth, tilt, and shading settings, but all of these serve a single purpose: how to evaluate the solar irradiance reaching the panel surface.

Step 4 Organize loss conditions and adjust the estimated power generation to be closer to reality

When performing energy yield calculations in PVSyst, the loss conditions determine the final energy yield. In photovoltaic power generation, even if solar irradiance reaches the panels, not all of it can be used directly as electricity. Generation is reduced by many factors such as reflection, soiling, temperature rise, wiring, mismatch, inverter conversion, equipment downtime, and degradation. In PVSyst, these losses are set item by item to perform simulations that are closer to reality.

First, what you need to understand is temperature loss. Solar panels generate electricity when exposed to sunlight, but at the same time the panel temperature also rises. Most solar panels have the characteristic that output decreases as temperature increases. Therefore, even in summer when solar irradiance is high, if the panel temperature is too high, power generation efficiency decreases. In PVSyst, output reduction due to temperature is evaluated based on ambient temperature, wind speed, mounting method, and the thermal characteristics of the panels. Because the way panel temperature rises differs between installations mounted flush to the roof and ground-mounted racks with adequate ventilation, differences in mounting method also affect energy yield.

Another important factor is losses due to soiling. When sand and dust, pollen, bird droppings, fallen leaves, salt, volcanic ash, snow, and other contaminants accumulate on the surface of solar panels, solar irradiance has a harder time reaching the panel interior. The impact of soiling varies greatly depending on the region and the environment. In some locations rain will naturally wash it away easily, while in dry regions, around factories, near agricultural areas, and along coastlines soiling may tend to persist. PVSyst allows you to set soiling losses, but in practice, rather than simply entering a uniform value, it is important to consider the local environment and maintenance plan together.

Wiring losses must not be overlooked. In the DC wiring from the solar panels to the inverter and the AC wiring from the inverter to the power receiving and transformer equipment, losses occur due to current flow. Losses increase under conditions such as long cable length, small cable cross-sectional area, and large current. In PVSyst, you can set wiring losses for both the DC side and the AC side and have them reflected in the energy yield. While approximate values may be used at the basic design stage, as the design approaches the detailed stage it becomes necessary to verify based on the actual wiring routes and cable specifications.

Mismatch loss is the loss that occurs because of output differences between solar panels. Even panels of the same model will not all produce exactly the same output due to manufacturing variations, temperature differences, differences in soiling, and differences in how shadows fall. If some panels in a string have lower output, this will affect the overall output. PVSyst can account for losses caused by such variations. In particular, you should be careful about mismatch effects when you combine shaded areas or surfaces with different orientations into the same input.

Inverter losses occur when converting DC power to AC power. Inverters have a conversion efficiency that can vary with the load factor. If an inverter is undersized relative to the system capacity, output clipping during peak times increases; conversely, if an inverter is oversized, efficiency at low loads can become a concern. In PVSyst, conversion losses can be evaluated based on the inverter’s efficiency curve and input conditions. Here too, it is important not to judge solely by the capacity ratio, but to look at the power generation pattern over the course of the year.

Reflection losses also affect energy production. When sunlight strikes the surface of a panel, part of it is reflected depending on the angle. During times when the angle of incidence is large—such as in the morning and evening or in winter—losses due to reflection can increase. PVSyst includes an item that accounts for incidence-angle losses, which is related to the panel surface characteristics and the installation angle. Although this factor is not usually given much attention, examining the breakdown of annual energy production shows that it has a measurable impact.

Conditions related to equipment downtime and availability are also important in practice. A power plant does not always operate ideally. Inspections, faults, communication failures, output curtailment, grid-side constraints, the operation of protection devices, and so on can cause the plant to be offline during times when it would otherwise be able to generate power. In PVSyst’s basic energy production calculations, it is necessary to organize in advance how to handle these factors. When using it for investment decisions, it is important to consider not only the theoretical energy output but also the extent of real operational risks to be expected.

A common mistake beginners make regarding loss conditions is proceeding with the default values without thinking deeply about the numbers. Default values are not always wrong, but they are not necessarily optimal for every project. For rooftop installations, ground-mounted systems, agrivoltaics, snowy regions, coastal areas, high-temperature regions, and mountainous areas, the way to think about loss conditions changes. When reading the PVSyst manual, it is important to understand the meaning of each loss item and consider which items are likely to have a strong impact on the energy production for your project.

The purpose of Step 4 is to bring the power generation estimated under ideal conditions closer to reality. To make PVSyst simulation results convincing, you must be able to explain the loss assumptions. Rather than presenting only the power generation figures, organizing which losses were assumed under which premises makes it easier to build a shared understanding among designers, project owners, contractors, and operators.

Step 5 Interpret the simulation results and apply them to design decisions

When you input the conditions and run the simulation, PVSyst outputs a report that includes the energy production and a breakdown of losses. Beginners tend to focus first on the annual energy production figure. However, what truly matters in practice is interpreting whether that figure is reasonable. PVSyst is a tool that produces results, but it is up to the user to judge what those results mean.

First, what I want to check are the annual generation and the generation per unit of installed capacity. When comparing projects with different installed capacities, it can be difficult to judge based only on the total annual generation, so we sometimes look at the generation per 1 kW. This makes it easier to compare system design efficiency and regional characteristics. However, a higher generation per installed capacity does not necessarily mean the design is optimal. It is necessary to make a judgment that also considers site conditions, costs, demand patterns, maintainability, grid constraints, and so on.

Next, an important metric is PR. PR stands for Performance Ratio, and it indicates how efficiently a photovoltaic (PV) system converts the solar irradiance it receives into electrical energy. PR is not a measure of how much solar irradiance a region receives, but rather reflects system losses and efficiency, so it is useful for verifying the soundness of a design. If PR is extremely low, there may be significant losses somewhere, such as shading, temperature effects, wiring, mismatch, inverter limits, or soiling. Conversely, if PR is unnaturally high, you should check whether loss conditions have been underestimated.

In PVSyst reports, checking the loss diagram is extremely important. By looking at the loss diagram, you can see the flow from irradiance on the horizontal plane to plane-of-array irradiance, reductions due to shading and reflection, DC generation at the module level, temperature losses, wiring losses, inverter losses, and the final AC energy output. Rather than looking only at the final generation figure, confirming how much is lost at each stage reveals the points that should be improved.

For example, if shading losses are large, there may be room to review the layout, row spacing, and how obstacles are handled. If temperature losses are large, it is necessary to check the mounting method, ventilation conditions, and module selection. If inverter clipping losses are large, reconsider the overloading ratio (DC/AC ratio) and inverter capacity. If wiring losses are large, check the cable routing, conductor cross-sectional area, and collection/combiner configuration. PVSyst results can be used not just as a simple energy yield forecast but as guidance for design improvements.

Checking monthly power generation is also essential. Even if the annual generation is as expected, there can be unevenness when viewed by month. For example, you may see trends such as higher generation in summer but greater temperature-related losses, lower solar irradiance and larger shading effects in winter, and reduced generation during the rainy season. For self-consumption systems, it is important whether the seasons of high demand coincide with seasons of high generation. Even for systems that sell electricity to the grid, understanding seasonal generation trends makes it easier to forecast revenues and plan maintenance.

Also, when using simulation results as submission materials, it is important to explain the input conditions. PVSyst reports contain many figures, but the reader may not understand all of them. You need to organize and explain which meteorological data were used, what the system capacity is, how the panels and inverters are configured, how the loss conditions were set, and the extent to which shading was considered. Presenting the assumptions together with the generation figures enhances credibility compared to showing only the generation numbers.

When comparing multiple options, it is important to compare them under the same assumptions. If the meteorological data or loss conditions differ between Plan A and Plan B, you will not be able to tell whether a difference in energy production is due to differences in equipment configuration or to differences in input conditions. When comparing design proposals in PVSyst, make the conditions as consistent as possible except for the element you want to compare. If you only want to compare tilt angle, keep the equipment configuration and loss conditions the same. If you want to compare inverter capacity, keep the panel layout and meteorological conditions the same. Following this basic rule makes interpreting the results easier.

The goal of Step 5 is to turn simulation results into design decisions. Mastering PVSyst is not simply about producing reports. It means being able to read the results, understand the losses, devise improvements, and explain them to stakeholders. When reading the PVSyst manual, learning with an awareness of how you will ultimately use the result screens and reports makes that knowledge more applicable in practice.

Terminology and Screen Concepts in the PVSyst Manual That Often Cause Confusion

A common stumbling block for beginners when working through the PVSyst manual is the technical terminology. If you are not familiar with photovoltaic system design and analysis, you may not understand what the on-screen items mean and thus cannot assess the reasonableness of the values you input. Here, we summarize the concepts that are particularly important for understanding PVSyst.

First, some terms related to solar irradiance. Horizontal plane irradiance indicates the solar energy that falls on a horizontal surface. However, because solar panels are installed at an incline, the irradiance incident on the panel surface is what actually matters. In PVSyst, horizontal-plane irradiance is converted into irradiance on the panel surface by taking azimuth and tilt angles into account. Because of this conversion, energy production can vary with installation angle even within the same region.

The difference between direct and diffuse solar radiation is also important. Direct solar radiation is the radiation that arrives directly from the sun, while diffuse solar radiation is radiation that reaches the surface after being scattered in the atmosphere. Under clear-sky conditions, direct radiation has a greater influence, whereas under cloudy conditions the proportion of diffuse radiation increases. These differences are relevant when considering the effects of shadows and terrain. In PVSyst calculations, the solar radiation components included in the meteorological data are used to evaluate the incident radiation on the panel surface.

Next is the metric called PR. PR is a representative indicator of a power plant’s performance, but its meaning differs somewhat from simple efficiency. PR is an indicator that shows how effectively the system was able to extract power under irradiance conditions. Even in regions with high irradiance, PR will fall if losses are large, and in regions with low irradiance, PR can appear relatively high if the system design is appropriate. By looking at PR, you can more easily assess the design quality of the system independently of the region’s irradiance conditions.

The concept of Specific Yield is also commonly used in practice. It indicates the amount of power generation per unit of installed capacity and is useful when comparing projects. Looking only at total annual generation can make larger-capacity installations appear more favorable, but examining generation per unit of capacity makes it easier to compare design efficiency and site conditions. However, this should not be judged in isolation; it needs to be considered together with the breakdown of losses and equipment conditions.

PVSyst's screens may seem complicated at first, but broadly they can be organized into a screen for setting project conditions, a screen for deciding the system configuration, a screen for setting shading and losses, and a screen for checking results. When reading the manual, being aware of which of these categories the screen you're looking at falls into will make it easier to understand. Rather than trying to memorize every item with equal weight, it's important to place them in the context of the energy production calculation flow.

Especially for beginners, we recommend viewing the report screen early. Rather than understanding all input items before looking at the results, run a simulation once with simple conditions and check where each input is reflected in the results — this will improve learning efficiency. For example, see how changing the tilt angle affects plane-of-array irradiance and monthly energy production, how changing the soiling loss affects the final energy output, and how changing the inverter capacity affects clipping losses; doing so makes the meaning of the on-screen items easier to grasp.

The PVSyst manual is effective not only for checking operating procedures but also for understanding the concepts behind power generation calculations. When you encounter unfamiliar terms, read while organizing which category—solar irradiance, equipment characteristics, losses, or result evaluation—the item relates to; doing so makes it easier for the knowledge to become practical for use in the field.

Common Mistakes and Points to Check in Power Generation Calculations

In power generation calculations using PVSyst, input errors and insufficient clarification of assumptions can reduce the reliability of the results. Not only beginners but also experienced practitioners are more likely to overlook things as project conditions become more complex. Here, we outline common mistakes and checkpoints.

One of the most common mistakes is proceeding without thoroughly checking the meteorological data. Even if you think data from a nearby location is acceptable, differences in elevation, terrain, and coastal versus inland conditions can change trends in solar irradiance and temperature. Also, if multiple data sources show differences in annual insolation, those differences directly affect power generation. When presenting simulation results, it is advisable to clearly state which meteorological data were used and, if necessary, compare multiple datasets.

Next, a common mistake is confusing module and inverter model numbers. Even similar model numbers can have different outputs or voltage ranges, and the database entries may not match the actual specifications. In particular, if the selected equipment was changed during the design process, the settings in PVSyst may remain outdated. Before issuing the final report, be sure to verify the module model numbers and quantities, the inverter model numbers and number of units, and the string configuration.

Care must also be taken to avoid mistakes in azimuth settings. When the north direction on drawings, true north, magnetic north, and the handling of coordinate systems are mixed, azimuths can be entered incorrectly. In roof projects and on complex sites, multiple surface azimuths may exist, so it is necessary to correctly organize the conditions for each surface. Because errors in azimuth input affect energy production and monthly trends, it is important to cross-check the drawings with the PVSyst settings.

Shadow settings often do not fully reflect on-site conditions. If nearby buildings or trees are overlooked, power generation tends to be overestimated. Conversely, if obstacles that actually have only a limited impact are modeled too conservatively, power generation will be underestimated. Because shadows change with the seasons and time of day, it is important to check their impact over the course of a year. In particular, during winter mornings and evenings, when the solar altitude is low, shadow effects tend to be greater.

Continuing to use the loss conditions at their default values is also a common mistake. PVSyst’s default values are convenient for learning and rough estimates, but for real projects you need to review them to match the site and design conditions. Soiling losses, wiring losses, temperature conditions, mismatch losses, downtime rate, and similar items are assumptions that should be clarified for each project. Loss conditions that you cannot explain the rationale for will become weaknesses when stakeholders ask about them later.

When checking results, a common mistake is judging solely by annual energy production. Instead of assuming there is no problem because the annual production is close to expectations, you need to check the loss diagram, PR, monthly energy production, clipping losses, shading losses, and temperature losses. If significant losses are overlooked by looking only at annual energy production, you will miss opportunities to improve the design.

Also, there are cases where the assumptions are not aligned when comparing multiple scenarios. If meteorological data, loss conditions, shadow handling, and equipment data differ between scenarios, you cannot make a fair comparison. In comparative evaluations, it is important to keep all conditions identical except for the one you want to change and to clarify the cause of any differences. PVSyst is a tool that makes it easy to examine multiple scenarios, but if you design the comparison incorrectly you can misinterpret the meaning of the numbers.

The checkpoints for verifying energy production calculations can be organized into three stages: input, calculation, and results. In the input stage, check the location, meteorological data, system capacity, equipment configuration, tilt/angle, shading, and losses. In the calculation stage, check for warnings or inconsistencies and for any electrical constraints. In the results stage, review the annual energy production, monthly generation, PR, and the breakdown of losses. Making this workflow a habit helps stabilize the quality of simulations performed with PVSyst.

Learning Path for Beginners to Use PVSyst in Professional Practice

To learn PVSyst efficiently, it is important not to try to understand all of its functions at once. PVSyst has many configuration items, but what beginners should learn first is the basic workflow for power generation calculation. Set the site conditions, select the meteorological data, decide the system configuration, reflect the installation angle and shading, input the loss conditions, and read the results. Experiencing this flow once through should be the initial goal.

At first, practicing with a simple ground-mounted model makes it easier to understand. If you start with a project that has a complex roof shape, multiple azimuths, and detailed shading conditions, it becomes hard to tell which conditions are influencing the results. First run simulations with a single azimuth, a single tilt, no shading, and basic loss conditions, and review the results report. After that, change one condition at a time—such as the tilt angle, the azimuth angle, soiling loss, or inverter capacity—to observe the impact and deepen your understanding.

Next, it is important to learn how to read the report. The value of PVSyst is not just in calculating energy production from the input conditions. Its worth lies in being able to look at the loss breakdown and identify which factors are reducing generation. Beginners should focus on four items: annual energy production, monthly energy production, PR, and the loss diagram. If you can understand these, you will be able to explain the overall results of the simulation.

After that, you learn how to configure shading. Shading has a major impact on power generation, yet it is a difficult parameter to set. Near shading, far shading, inter-row shading, building shading, and other factors to consider vary depending on the project. Initially, set simple obstacles to check how power generation changes with and without shading. Next, change the row spacing and racking layout to assess the balance between shading losses and system capacity. At this stage, you can use PVSyst not just as a calculation tool but as a design evaluation tool.

Furthermore, for practical use, managing the input conditions is important. The meaning of PVSyst results changes depending on which assumptions were used for the calculations. If you do not organize meteorological data, equipment model numbers, loss conditions, shading settings, system capacity, simulation dates, and scenario names, you will not be able to interpret the results when you review them later. Especially when multiple people are working on the design or when preparing materials to submit to the client, tracking the history of input conditions is indispensable.

At the end of your training, it's a good idea to compare multiple design options under conditions close to those of real projects. For example, create options that vary the tilt angle, the number of panels, the inverter capacity, and the row spacing, and compare annual energy production, PR, loss breakdown, and monthly energy production. Through this exercise, you'll develop a feel for applying PVSyst results to design decisions.

The PVSyst manual can be used like a dictionary to consult when you encounter an unfamiliar screen, but in the early stages of learning it is effective to use it as a guide to review the flow of power generation calculations. Rather than merely following the operating steps, reading while considering where each input item affects the power generation makes it easier to apply in practice.

Summary

For someone reading the PVSyst manual for the first time, the number of screen items and technical terms can be a major hurdle. However, if you understand the basic flow of the energy production calculation, you can learn to operate PVSyst in an organized way. The important thing is the following five steps: set the site conditions and meteorological data, decide the configuration of the photovoltaic panels and the power conditioner, account for azimuth, tilt, and shading, organize the loss conditions, and interpret the simulation results.

In Step 1, the installation site and meteorological data form the foundation for power generation calculations. Properly handling irradiance, temperature, elevation, and local characteristics increases the reliability of the simulation. In Step 2, verify the electrical compatibility between the modules and the inverter. It is important to consider not only capacity but also string configuration, voltage range, MPPT, and the oversizing ratio. In Step 3, account for azimuth, tilt angle, and shading effects. By evaluating how much irradiance actually reaches the panel surface, you approach a generation estimate that is closer to reality.

In Step 4, organize loss conditions such as temperature, soiling, wiring, mismatch, reflection, inverter conversion, and equipment downtime. Loss conditions should not remain at their initial values; it is important to review them according to the environment and design conditions of each project. In Step 5, check not only annual generation but also PR, monthly generation, and loss diagrams, and use them for design improvements and explanations to stakeholders.

PVSyst is not software that simply outputs the energy yield automatically and that’s the end of it. Only by interpreting how the input conditions were set, what losses are included in the results, and where there is room for improvement does it become a tool useful in practical work. When reading the manual, it is important to treat it not as mere operational steps but as material for understanding the methodology behind energy-yield calculations.

Beginners should start by completing a simulation once under simple conditions and reviewing the results report. Then, by changing meteorological data, angle, shading, losses, and equipment configuration one at a time, check how energy production and the breakdown of losses change. By repeating this process, you will be able to understand the contents of the PVSyst manual as practical material for decision-making.

To master PVSyst, you don't need to memorize all of its features at once. Grasp the five basic steps of energy yield calculation and be able to explain the relationship between input conditions and the results. From there, depending on the type and objectives of the project, expand your learning into areas such as shading analysis, comparison of multiple scenarios, self-consumption assessment, and the detailed specification of loss conditions, and PVSyst can be used as a powerful evaluation tool in solar power system design.