6 Settings You Should Know Before Reading the PVSyst Manual

Table of Contents

• Why you should grasp the overall settings before reading the PVSyst manual

• Setting 1: Organize the project conditions first

• Setting 2: Understanding the Approach to Meteorological Data

• Setting 3: Determine the azimuth and tilt angles correctly

• Setting 4: Check the conditions of the module and the power conditioner

• Setting 5: Bring loss conditions closer to reality

• Setting 6: Decide in advance how to interpret the simulation results

• Practical considerations when using the PVSyst manual

• Summary

Why You Should Grasp the Overall Settings Before Reading the PVSyst Manual

When you begin reading the PVSyst manual, what tends to confuse you at first is not the operational procedures themselves but the overall picture of why each setting is being entered. PVSyst is specialized software used for simulating the energy production and conducting design studies of photovoltaic installations, and the interface requires you to enter many items in sequence. However, simply filling in the fields will not produce analysis results that are useful in practice. What matters is reading the manual with an understanding of how each setting connects to energy production, losses, system efficiency, comparative evaluations, and proposal documents.

Many people who search the PVSyst manual are those who will be operating it for the first time, those who have used it a little in the past but are unclear about the meaning of the settings, or staff members responsible for calculating power generation within their company. Sometimes they only want to know which button to press on the screen, but in reality they face concerns such as “Is this value okay?”, “Are the results reasonable?”, and “What should be aligned when comparing design proposals?” Therefore, before reading the manual, it is important to organize the basic way of thinking about the settings that should be understood at a minimum.

PVSyst analyses are built on the accumulation of input conditions. Meteorological conditions, site location, azimuth, tilt, modules, power conditioners, wiring, shading, soiling, temperature, and degradation over time, among other assumptions, all affect energy production. The result is not determined by any single setting alone. Conversely, a seemingly small input error can influence the assessment of annual energy production and loss rates.

Also, because the PVSyst manual describes functions individually, it does not necessarily align perfectly with the order of considerations in actual practice. If you simply read the manual from top to bottom, it can be difficult to tell which settings are necessary for your project and which can be checked later. For this reason, if you first clarify "what to decide before you operate," "what you want to compare," and "which results you will use in your report," you will be able to understand the manual more quickly.

In this article, we explain six settings you should know before reading the PVSyst manual. Rather than focusing on detailed screen operations, we emphasize the decision criteria that tend to cause uncertainty in practical work. This serves as a useful basic overview for those who are just starting to use PVSyst, as well as for anyone who wants to be more confident in their energy production simulation results.

Setting 1: Organize the project conditions first

Before reading the PVSyst manual, the first thing you should confirm is the project conditions. Project conditions refer to the basic information of the photovoltaic system to be analyzed. These include the installation site, the scale of the power plant, whether it is ground-mounted or roof-mounted, whether it is fixed or tracking, whether it is grid-connected or intended for self-consumption, and whether it includes battery storage.

In PVSyst you create a project and then proceed to detailed system design, but if the project’s purpose is unclear at this stage, later settings can easily become inconsistent. For example, even for the same photovoltaic installation, the items to verify differ between a project that aims to maximize annual energy production assuming electricity sales and a project that wants to evaluate the self-consumption rate according to a factory’s or facility’s power use. Before reading the PVSyst manual, it is important to first clarify the results you want to obtain.

An especially important aspect of project conditions is how the installation site is handled. The installation site relates to meteorological data, solar irradiance, temperature, solar altitude, the effects of shading, and so on. If the location changes, power generation will change even with the same installed capacity. Rather than assuming it is acceptable because locations are close at the prefectural level, you should be conscious of setting conditions as close as possible to the actual installation site. Differences in the surrounding environment are particularly likely to be reflected in the results in mountainous areas, coastal areas, snowy regions, and high-temperature regions.

Next, clarify the purpose of the installation. The required level of accuracy and depth of analysis will vary depending on whether you want to produce a rough estimate of energy production, compare design proposals, or prepare explanatory materials for financial institutions or the client. A rough estimate may be sufficient in preliminary studies, but as you approach detailed design you will need to check equipment specifications and loss assumptions in greater detail. When reading the PVSyst manual, being aware of which stage of analysis you are in will make it less likely that you overlook necessary items.

Also, whether you analyze a single scenario or compare multiple scenarios is important. For example, when comparing scenarios that change the tilt angle, the azimuth, the module capacity, or the power conditioner capacity ratio, you should keep all other conditions as consistent as possible. If the reference conditions are not aligned, it will be difficult to determine which setting is causing the differences in power generation.

If you start reading the manual without organizing the project conditions, you may understand the on‑screen descriptions but not know how to apply them to your own project. Conversely, if you first summarize the project conditions on paper or in a note, the manual’s explanations are easier to connect to practical work. As preparation before using PVSyst, organizing the project name, installation location, system capacity, installation method, purpose of the study, the scenarios you want to compare, and the intended use of the output documents will make operating the software much easier.

Setting 2: Understanding Meteorological Data

In PVSyst power generation simulations, the configuration of meteorological data is critically important. Solar power output is heavily influenced by solar irradiance. Not only solar irradiance, but also ambient temperature, wind speed, seasonal variations, and regional characteristics affect energy production. Therefore, before reading the PVSyst manual, it is essential to understand that meteorological data is not mere background information but the foundation of the simulation results.

Weather data include site-specific solar irradiance and temperature, among other variables. In PVSyst, available weather data are imported to run simulations under conditions close to the installation site. However, weather data are not without limitations. The meaning of the results changes depending on whether the data are measured values, long-term averages, satellite-based, or interpolated. When reading the manual, it is important not only to think about which data to choose as the “correct” one, but also to adopt an attitude of understanding the nature of the data you select.

In practice, a nearby meteorological station may be used. However, even a nearby station can show different solar radiation and temperature trends if elevation, terrain, or distance from the sea differ. This is especially true in mountainous areas, basins, and snowy regions, where judging based solely on simple distance is risky. Before reading the PVSyst manual, it is important to understand the surrounding environment of the installation site and be mindful of how well the meteorological data represents the project.

When selecting meteorological data, attention should be paid not only to annual power generation but also to monthly trends. Even if annual values are similar, sites that perform strongly in summer, weakly in winter, or are susceptible to the rainy season or snowfall will have different seasonal distributions of generation. For self-consumption systems, monthly and time-of-day generation patterns affect how well they align with electricity demand. In power-sale projects, there are also situations where seasonal generation needs to be explained. Therefore, the choice of meteorological data is not a mere initial setting but an important process that influences the reliability of analysis results.

Also, temperature data should not be overlooked. Solar panels tend to lose output as their temperature rises. Even in areas with high irradiance, high ambient temperatures can lead to large temperature-related losses. In PVSyst, temperature conditions affect the energy production calculations, so the validity of the temperature values contained in the meteorological data is another point to verify. For high-temperature regions and rooftop installations, considering the ventilation conditions on the module’s rear side will make the analysis closer to reality.

What to be careful about when configuring meteorological data is not to become fixated solely on fine-tuning the numbers. Actual weather varies from year to year. Simulations do not perfectly predict future power generation; they are intended to capture the expected power output based on certain assumptions. Therefore, when selecting meteorological data, it is important to record which assumptions were adopted and be able to explain them later.

When reading the PVSyst manual, be aware not only of how to import meteorological data and operate the settings screens, but also of how the selected data can affect the results. Even if generation figures are produced, if the assumptions about the meteorological conditions are unclear, those figures become difficult to use for comparison or explanation. Meteorological data are the basic conditions whose reliability should be verified first in PVSyst analyses.

Setting 3: Correctly determine the azimuth and tilt angles

One of the settings you should definitely grasp before reading the PVSyst manual is the azimuth and tilt angles. The direction the solar panels face and the angle at which they are installed directly affect the amount of solar irradiance they receive. Azimuth and tilt are fundamental parameters that determine a design's energy yield, and input errors or differences in approach can be reflected strongly in the results.

Azimuth indicates the direction a solar panel faces. Generally, south-facing is often considered advantageous, but the optimal orientation varies depending on site shape, roof shape, mounting configuration, surrounding shading, and the time-of-day distribution of electricity demand. For example, facilities with high morning power demand may favor an eastward orientation, while those with high evening demand may favor a westward orientation. It is important to consider not just annual energy production, but when the generation occurs.

The tilt angle indicates how much solar panels are tilted from the horizontal plane. When the tilt angle changes, seasonal generation patterns change. Increasing the tilt can make panels more likely to receive winter solar radiation, but it also affects summer generation output, rack spacing, wind loads, ease of installation, snow accumulation, and maintainability. A low tilt angle can make it easier to increase installation density, but issues such as soiling and drainage, snow sliding during snowy conditions, and reflection conditions must also be considered.

In PVSyst you can set the azimuth and tilt angle for simulations, but in practice it is essential to verify that those values match the design drawings and on-site conditions. Angles on the drawings, the designer's intent, and the actual construction conditions can differ. Especially for rooftop installations, you may not be able to freely choose the ideal angle because you must match the roof's pitch and orientation. For ground-mounted systems, layout is also constrained by the shape of the land, site development conditions, roads, neighboring property boundaries, and the need to secure maintenance access.

When considering azimuth and tilt angles, you should not search for optimal values in isolation; you also need to consider shadow effects and their relationship with row spacing. Increasing the tilt angle can lengthen shadows on the rows behind. Widening row spacing can mitigate shadow impacts, but it may reduce the number of modules that can be installed on the same site. As a result, even if power generation efficiency per unit of capacity increases, the conclusion for total site generation or project economics may be different.

Before reading the PVSyst manual, understand that setting the azimuth and tilt angles is not merely entering numbers but a design decision. Even if the manual shows how to input them, which angles to adopt depends on the project conditions. Rather than fixing a single angle from the start, it is important to compare multiple options and evaluate the balance between energy yield, constructability, land-use efficiency, and maintainability.

Also, in comparative studies, it is easier to identify the cause if you consider separately the cases where only the azimuth angle is changed, only the tilt angle is changed, and where both are changed. If you change multiple conditions at once, it becomes difficult to determine which factor is responsible for differences in power generation. To master PVSyst, not only the simulation results but also how you set up the comparisons is important.

Setting 4: Verify the conditions of the modules and power conditioners

When calculating power generation in PVSyst, the settings for modules and power conditioners play a central role. The PV modules’ output characteristics, temperature characteristics, number of modules, series count, parallel count, and the power conditioner’s input range, capacity, and conversion efficiency all influence the system’s overall generation performance. Before reading the PVSyst manual, understanding what these equipment settings mean will make it easier to grasp the contents of the interface.

When configuring solar modules, it is important not to focus solely on nominal output. Even modules with the same rated capacity can differ in temperature coefficient, voltage, current, low-irradiance characteristics, size, and cell configuration. In simulations, these characteristics are reflected in the calculations of energy production and losses. When selecting modules using the manual, make sure the information matches the equipment that will actually be used in the project.

When configuring a power conditioner, the capacity ratio and input conditions are important. Depending on how the power conditioner’s capacity is sized relative to the total capacity of the solar modules, considerations regarding lost generation and equipment costs will change. Even if module capacity is increased, if the power conditioner imposes output limits, generation above a certain level may be curtailed. Conversely, since maximum output is not always achieved, determining the appropriate capacity ratio requires design judgment.

In PVSyst, verifying the string configuration is also important. If the number of modules in series is not appropriate, the string voltage may fall outside the power conditioner's input voltage range. Because voltage increases at low temperatures and decreases at high temperatures, the configuration must allow safe and efficient operation throughout the year. Before reading the manual, you should understand that string design is not merely a module count calculation but a verification process based on temperature conditions and equipment specifications.

Additionally, the combination of modules and power conditioners affects not only power generation but also constructability and maintainability. As the number of strings increases, the approach to wiring and junction boxes changes. The number and arrangement of power conditioners influence cable lengths, voltage drop, and the ease of inspection work. Some factors are difficult to express numerically in PVSyst, but in practice it is necessary to verify the overall consistency of the design.

When selecting equipment data, even when using registered data, verify that the model number and specifications match the actual design. Using a similar model number or equipment with a similar capacity as a placeholder is acceptable during initial assessments, but leaving it unchanged in final documents can cause misunderstandings. Pay particular attention to items related to output, efficiency, voltage range, and temperature conditions, as they are likely to affect the results.

The PVSyst manual explains the procedures for equipment selection and system configuration, but in practice simply choosing according to the manual is not sufficient. It is important to be able to explain why you selected that module, why you chose that power conditioner capacity, and why you adopted that string configuration. When sharing analysis results internally and externally, if the rationale for the equipment conditions is clear, the reliability of the simulation will be higher.

Setting 5: Make Loss Conditions More Realistic

When running energy yield simulations in PVSyst, the configuration of loss conditions determines how realistic the results are. A photovoltaic system cannot use all incoming solar irradiation as electricity. Various factors—temperature rise, soiling, wiring, mismatch, shading, equipment efficiency, degradation, downtime, and grid constraints—reduce the energy yield. Before reading the PVSyst manual, recognize that loss conditions are not "minor adjustments" but important settings to bring simulations closer to actual energy production.

First, the main thing to understand is temperature loss. Solar modules produce more power as solar irradiance increases, but their output decreases as temperature rises. Temperature losses can be especially large in summer, on rooftop installations, or in poorly ventilated environments. In PVSyst, temperature-related settings are configured taking into account the installation method and ventilation conditions. When reading the manual, it is important not to simply use the default values, but to consider whether they suit the project's installation environment.

Next are losses due to soiling. When dust, pollen, bird droppings, fallen leaves, sand, or residual deposits after snowfall adhere to the module surface, the amount of light received decreases. The impact of soiling varies by region, installation tilt angle, rainfall conditions, and the surrounding environment. In installations with a low tilt angle, dirt may not wash off easily. On agricultural land, near factories, along roads, and in coastal areas, the effects of dirt and salt need to be considered. If soiling losses are underestimated, projected energy production tends to be overly optimistic, so caution is required.

Wiring losses are also important. In the DC wiring from the modules to the power conditioner and in the AC wiring from the power conditioner to the receiving equipment, losses occur depending on distance, current, and cable size. In early-stage studies approximate values may be used, but in projects with large system sizes or long cable routes the impact of losses can be non-negligible. When reading the PVSyst manual, you should not treat the wiring loss input field as a mere form entry, but view it as an item connected to the design drawings and electrical design.

Losses due to shading are a concern for many people when using PVSyst. Surrounding buildings, trees, utility poles, mountains, rooftop equipment, and shading between rows of mounting structures all affect power generation. Shading settings may be treated as a simple percentage, or they may involve 3D models and near-field shading assessments. How detailed the settings should be depends on the project stage, but underestimating the impact of shading can result in a large discrepancy from actual power generation.

Mismatch losses and equipment efficiency losses should not be overlooked. Variations between individual modules, temperature differences, variability in soiling, and differing conditions between strings all reduce actual generation compared with the theoretical output. The conversion efficiency of the power conditioner (inverter) is not constant and can change depending on the load. PVSyst can simulate these losses, but even if you adopt the initial/default values as-is, it is important to be able to explain them later.

A common mistake in loss assumptions is adopting only optimistic values to make the expected power generation look better. Since simulations are used for proposals and business decisions, overly optimistic results can lead to problems later on. Conversely, being excessively conservative can unfairly depress the asset’s valuation. What’s important is to set assumptions that are reasonable given the project conditions and to document the rationale for them.

When using the PVSyst manual, understand the meaning of each loss item and document which values were set and for what reasons. Once you can properly handle loss conditions, you will not only view PVSyst's results but also be able to explain why the predicted energy production turned out as it did. This is a key point in progressing from a beginner to a practical practitioner.

Setting 6: Decide how to interpret simulation results

Before reading the PVSyst manual, it's surprisingly important to decide in advance how you will view the simulation results. PVSyst can output many results: annual energy production, monthly energy production, breakdown of losses, performance ratio, generation curves, system efficiency, output clipping, effects of shading, and more. However, if you wait until you open the results screen to decide what to look at, it's easy to become overwhelmed by the sheer number of figures.

First, what you should check is the annual power generation. How much generation can be expected over a year is the clearest indicator in many projects. However, judging something solely by the annual generation is insufficient. Even with the same annual generation, the evaluation changes depending on whether it is concentrated in summer, stable in winter, or matches self-consumption demand. The annual figure is an entry point and should be considered the starting point for more detailed verification.

Next to check is the monthly power generation. By looking at monthly trends, it becomes easier to identify the effects of weather conditions, orientation, tilt, temperature losses, snow, and the rainy season. For example, if solar radiation is strong in summer but generation does not increase as much as expected, temperature losses or output limitations may be having an impact. If winter generation is low, it becomes a cue to check solar radiation conditions, tilt angle, shading, snow, and so on.

The breakdown of losses is also important. PVSyst's results let you see at which stages and to what extent losses occur. By understanding whether temperature losses are large, shading losses are large, wiring losses are large, or limitations at the power conditioner are prominent, you can identify opportunities for improvement. Rather than simply concluding that generation is low, it is important to interpret which factors are acting as bottlenecks.

The performance ratio is another indicator you should check. The performance ratio serves as a guideline for how efficiently a system is generating power compared to ideal conditions. However, you should not judge the quality of the installation by the performance ratio alone; it needs to be evaluated together with meteorological conditions, design conditions, and loss factors. If the energy yield is high but the performance ratio is low, there may be large losses in the system. Conversely, even if the performance ratio is high, the total energy generation may be insufficient due to installed capacity or solar irradiation conditions.

When reviewing simulation results, decide on the criteria for comparison in advance. When comparing multiple options, conclusions can change depending on which metrics you prioritize. Clarifying beforehand whether you emphasize annual energy production, energy production per unit capacity, self-consumption rate, or minimizing shading effects will help ensure the interpretation of the results remains consistent.

Also, when using a PVSyst report as submission material, you should supplement it with explanations so that readers can easily understand it. Simply providing technical numbers as-is can make it difficult for clients or internal stakeholders to make judgments. If you can briefly explain the annual energy production, the major losses, the assumptions adopted, the differences between alternative scenarios, and any points to note, it will be easier to apply the PVSyst results in practice.

The PVSyst manual is also useful for understanding the meaning of output results. However, simply reading the terms written in the manual may not easily lead to practical decisions. By first deciding the purpose for reviewing the results and identifying the necessary metrics before reading the manual, it becomes clear which items are important. The goal of simulation is not to produce numbers, but to obtain information that can be used for design and business decision-making.

Practical considerations for using the PVSyst manual

When using the PVSyst manual, it's important to treat operation procedures and design decisions separately. The manual helps you understand what to configure on each screen. However, deciding which values to adopt, which option to choose, and whether a result is reasonable must be based on project conditions and practical experience. Reading the manual does not automatically enable all decision-making.

Beginners often stumble over whether it is acceptable to use the initial default values as-is. PVSyst provides standard values and general settings, but they are not necessarily optimal for every project. In preliminary studies you may use standard values to produce rough estimates, but at stages closer to proposal documents or detailed design, it is necessary to verify the validity of each setting. In particular, meteorological data, loss conditions, equipment specifications, and shading effects are items that tend to show significant differences from project to project.

Also, it is important not to place too much reliance on PVSyst results. Simulations are calculations based on the assumptions entered. If the assumptions change, the results will change. Future weather, equipment degradation, maintenance conditions, and actual operational constraints cannot all be predicted perfectly. Therefore, when reviewing the results, you should explain the assumptions, the expected ranges, and the risk factors together.

On the other hand, the value of using PVSyst is very high. Because you can numerically compare different design proposals, you can make judgments that are not based solely on intuition. By comparing differences in azimuth and tilt angles, equipment configuration, and loss conditions, you can identify which factors are affecting power generation. This is useful for explanations to clients, internal review, design improvements, and business feasibility assessment.

When reading the PVSyst manual in professional practice, it is also important not to try to understand everything perfectly from the outset. PVSyst has many features, and it is not easy to grasp all of them when you are using it for the first time. First, focus on the basic workflow—project creation, meteorological data, azimuth and tilt, equipment configuration, loss conditions, and result review—and then proceed to shadow analysis, detailed loss settings, and economic evaluation to make understanding easier.

It's also important to make a habit of recording configuration settings. To ensure anyone can reproduce the same conditions, keep a record of the meteorological data used, equipment specifications, loss conditions, differences between comparison scenarios, the update date, and the purpose of the analysis. When reviewing results later, being able to trace why those figures were produced will make internal reviews and explanations to clients run smoothly.

Furthermore, when multiple people use PVSyst, it is also effective to organize internal configuration rules. If each person selects different loss conditions or meteorological data, it becomes difficult to compare projects. By establishing a standard input policy and operating so that exceptions for each project are recorded, it becomes easier to align the quality of the results.

The PVSyst manual is more effective when read as a document that supports practical decision-making than when read merely as an operational guide. Rather than just memorizing on‑screen procedures, reading it while being aware of how each setting affects energy production and losses will allow you to make more accurate use of the simulation results.

Summary

The six settings you should know before reading the PVSyst manual are project conditions, meteorological data, azimuth and tilt angles, modules and power conditioners, loss conditions, and how to interpret simulation results. These are the basics for getting started with PVSyst and are important factors that determine the reliability of power generation simulations.

PVSyst is a feature-rich software, but to obtain correct results you must enter the correct assumptions. Of course, reading the manual and learning the operating procedures is important, but before that it is essential to understand what each setting means and how it affects the results. If you understand the meaning of the settings, you will be less likely to be confused by the input fields on the screen and it will be easier to assess the validity of the results.

Especially beginners tend to focus only on the annual energy production figure. However, in professional practice it is important to be able to explain which assumptions led to that figure. By checking whether the meteorological data are appropriate, whether the azimuth and tilt angles match the design conditions, whether the equipment specifications are correct, whether the loss assumptions are realistic, and whether the interpretation of the results matches the intended purpose, PVSyst analyses become more practical.

To use the PVSyst manual efficiently, first clarify the project's objectives, understand the required settings, and decide how you will use the results before you begin reading. Doing so will let you apply generation simulations to design decisions and proposals rather than merely learning the software's operations. If you understand the six settings covered in this article before you start using PVSyst, you should be able to relate the manual's content more directly to practical work.