8 Common Configuration Mistakes Beginners Often Make in the PVSyst Manual

Table of Contents

• Prerequisites You Should Understand Before Reading the PVSyst Manual

• Configuration mistake 1: Not aligning the project type with the objective

• Configuration Error 2: Proceeding without checking location information and weather data

• Setting mistake 3: Confusing the tilt angle and the azimuth angle

• Configuration mistake 4: Deciding module and inverter combinations based on intuition

• Configuration mistake 5: Grouping multiple faces or multiple arrays under a single condition

• Configuration mistake 6: Confusing distant shadows with nearby shadows

• Configuration mistake 7: Continuing to use the detail loss at its default value

• Misconfiguration 8: Evaluating the results report solely by power output

• Order of checks when using the PVSyst manual in practice

• Summary

Prerequisites to Keep in Mind Before Reading the PVSyst Manual

Many people searching for the PVSyst manual want to start simulating solar photovoltaic systems, but they are unsure which screen to use for which settings and which values have the greatest impact on the results. PVSyst is software for designing, sizing, and analyzing solar power systems, and it is said to handle applications such as grid-connected, stand-alone, pumping, and DC grid systems. Because it provides extensive weather data, equipment databases, and functions for evaluating energy production and losses, it is convenient, but beginners in particular tend to feel "there are too many fields to fill in."

In PVSyst, the important thing is not to fill the screens in order but to understand the workflow as a connected sequence: project, site, meteorological data, orientation, system configuration, shading, losses, and result verification. In the official manual, Project design and Simulation is likewise described as the overall project scope of consideration, including selection of meteorological data, system design, shading assessment, loss settings, and economic evaluation. Simulations are run on a time-step basis throughout the year and produce detailed result reports, so an initial input mistake will propagate through to the final evaluation.

Beginners tend to get tripped up not so much by the operation itself as by moving on to the next step without fully checking the meaning of the settings. Small oversights—failing to check why a red or orange warning has appeared, misreading the sign of the azimuth, omitting shading input, or leaving losses at their default values—can greatly reduce the reliability of the results. This article narrows down eight configuration mistakes that beginners reading the PVSyst manual are especially likely to make, and organizes, from a practical perspective, what to check to reduce failures.

Configuration Mistake 1: Project Type Not Aligned with Objective

A common early mistake is selecting a project type in PVSyst that does not match the intended purpose of the power generation system under study. You might be evaluating a grid-connected power plant but enter data with an off‑grid‑oriented approach. You might want to include self‑consumption and batteries, but proceed on the assumption of a simple feed‑in-to-grid project. Such mismatches will lead you to misinterpret the results themselves, even if you later carefully correct module and inverter settings.

When reading the PVSyst manual, you should first articulate what kind of project you want to evaluate. The settings you need to configure will differ depending on whether you want to look at annual energy production, self-consumption rate, battery charge/discharge, or output curtailment due to grid constraints. PVSyst explains a structure in which a project contains basic definitions such as site information and meteorological data, and on top of that you create variants that contain the system details for simulation. In other words, if you confuse the roles of the project and the variant, you will not be able to correctly separate the conditions you want to compare.

For example, if you want to compare a south-facing option and an east–west option on the same site, it is more natural to keep the location and meteorological data the same as project conditions and compare by creating variants that differ in orientation and system configuration. On the other hand, if you treat projects that use a different region or different meteorological data on the same comparison axis, differences in meteorological conditions will be mixed into the results rather than differences in orientation or equipment. Beginners tend to focus on filling in the input fields on the screen, but in PVSyst it is important to decide first “what to fix and what to compare.”

To avoid this mistake, before running the simulation, put in writing the project name, location, purpose, the design options you want to compare, the conditions to keep fixed, and the conditions to vary. Even when working with the PVSyst manual, if you are unsure on the initial screen, do not start entering data right away; instead, confirm the relationship between the project and its variants. If you proceed while this is unclear, you will later be unable to explain, when looking at the report, why a particular option’s energy yield is higher.

Configuration Mistake 2: Proceeding without verifying location information and weather data

The second mistake is using site location information and meteorological data without thoroughly checking them. In PVSyst, the latitude, longitude, elevation, and type of meteorological data for the simulation site affect the energy yield. Beginners tend to feel reassured when a place-name search returns candidates, but if the selected candidate is offset from the actual site or if meteorological data from a nearby city are used as-is, the assumptions behind the simulation results are undermined.

The official manual explains that when creating a geographic site you can import data based on coordinates from weather-data providers such as Meteonorm, PVGIS, Solcast, Solar Anywhere, and Solargis. It also explains that users must evaluate which weather data are most suitable for the project. In other words, the ability to import data automatically is not the same as the data being optimal for the project.

Particular attention should be paid to projects in mountainous areas, coastal areas, heavy-snow regions, high-temperature regions, and rooftop projects. Even meteorological data from nearby locations can show different solar radiation and temperature trends due to differences in elevation, sea breezes, snowfall, localized cloud formation, and surrounding topography. While this may not be a major problem when roughly estimating annual power generation, if the data are to be used for business feasibility assessments or for examining guaranteed values, you should be able to explain the source and validity of the meteorological data.

A common mistake beginners often make is feeling reassured after selecting a single weather dataset and then not revisiting the weather conditions section of the report. When using the PVSyst manual, check not only the weather data selection screen but also, in the result report, which location, which data source, and which period or representative year’s data were used. If the energy yield seems higher or lower than expected, the first thing to suspect should not be equipment settings alone. Reviewing whether the assumptions behind the weather data match the project is the first step toward a correct simulation.

Configuration error 3: Confusing the meanings of tilt angle and azimuth angle

The third mistake is swapping the tilt angle and azimuth angle inputs. This is a very common setup error among beginners. Even if you can enter the tilt angle by looking at the roof pitch or racking angle, getting the sign or reference direction of the azimuth wrong will cause the simulation to treat the solar panels as facing a completely different direction.

In the PVSyst manual, the tilt angle is described as the angle between the collecting surface and the horizontal plane, and the azimuth angle is described as the angle between the collecting surface and the equatorial direction. In the Northern Hemisphere, it is indicated that south is treated as 0 degrees, west as 90 degrees, north as 180 degrees, and east as -90 degrees. For projects in Japan, if an east-facing roof is entered as +90 degrees and a west-facing roof as -90 degrees, the east–west orientation will be reversed.

This mistake can be hard to notice if you only look at generation output. When conditions are such that swapping east and west does not drastically change annual generation, the numbers in the result report alone may not feel off. However, there are large differences in morning and evening generation trends, compatibility with self-consumption, how shading occurs, and the assessment of peak time periods. In particular, for projects considering self-consumption systems or battery integration, the difference between east-facing and west-facing is not merely an orientation issue but concerns the temporal alignment with power demand.

The preventive measure is to always verify the orientation on a plan or an aerial photograph before inputting, and to convert it into PVSyst's azimuth convention prior to entry. Even if site documents state "southwest-facing" or "east-southeast-facing", do not enter them based on intuition; you must convert them into an angle. If there are multiple roof surfaces, do not consolidate them into a single representative orientation; consider the handling of multiple surfaces described later. When reading the PVSyst manual, do not skim the Orientation screen's description—be sure to confirm the sign convention.

Configuration Mistake 4: Choosing Module and Inverter Combinations by Intuition

The fourth mistake is choosing the combination of a solar module and an inverter based only on the capacity ratio. Beginners tend to focus on the ratio of panel capacity to inverter capacity, but in PVSyst the number of modules in series, the number of parallel strings, MPPT inputs, voltage range, current limits, and temperature conditions all affect system behavior. Even if the capacity ratio looks fine at first glance, problems can arise such as the open-circuit voltage at low temperatures being close to the upper limit, the operating voltage in summer easily falling outside the MPPT range, or the number of parallel strings being too large for the input current.

In PVSyst’s Project design, the workflow that supports PV array design for the inverters and equipment chosen by the user—including the number of series and parallel strings—is explained. At the system definition stage, it is important not only to select equipment but also to verify the compatibility between devices. The official documentation also explains that parameter consistency is checked: orange warnings indicate a condition that is acceptable but requires caution, while red warnings are treated as problems that prevent simulation.

A common mistake beginners make is assuming “if the simulation runs, it’s fine” even when warnings appear. Orange warnings are not necessarily fatal, but they indicate conditions that need to be explained as part of the design. Red warnings, of course, will prevent you from proceeding, but if you leave orange warnings unaddressed and move on to the final report, you will have trouble explaining the results to a third party later. Capacity ratios, voltage ranges, input current, and MPPT assignments must always be checked as design conditions.

To avoid this mistake, once you have selected the modules and inverter, first read the warning messages, then check whether the string configuration matches the actual construction plan. On site, you may be forced to change the number of modules connected in series for each roof surface, or you may need to separate MPPTs to avoid shading effects. A configuration that works in PVSyst does not necessarily match the actual switchboard configuration and wiring plan. It is important to consider simulation not as a substitute for design but as a tool to verify design conditions.

Configuration Mistake 5: Combining multiple surfaces or multiple arrays into a single condition

The fifth mistake is grouping multiple roof surfaces or multiple racking rows into a single orientation, a single tilt, and a single array condition. For small-scale estimates it may be acceptable to use representative values, but if you want detailed results in PVSyst, forcing different orientations or tilts into one condition will make the assessment of energy production and losses less precise.

For example, if a factory roof has a mix of south-, east- and west-facing surfaces, the solar irradiation conditions and peak times differ for each. South-facing surfaces are strongest around midday, east-facing ones generate more in the morning, and west-facing ones generate more in the afternoon. If you aggregate these into a single southerly orientation, the annual generation estimate may be similar, but the evaluation of generation by time of day and the self-consumption rate will be skewed. Especially for projects that need to be compared with demand curves, oversimplifying the treatment of multiple surfaces reduces the value of the simulation.

PVsyst 8 explains the flexibility of project customization, such as combinations of multiple orientations, trackers, and fixed surfaces. It provides features to handle conditions that are difficult to represent with a simple single-surface model, including nearby shading, layout, and the treatment of electrical shading losses. For that reason, beginners need to judge which conditions warrant splitting surfaces and which can be consolidated.

The criteria for judgment are whether the orientation, tilt, shading, the MPPT to which they are connected, module type, installation height, row spacing, and surrounding obstacles differ significantly. If these factors differ greatly, it is closer to reality to treat them as separate conditions even if they are part of the same system capacity. Conversely, if they share the same racking angle, are aligned in the same orientation, have the same shading conditions, and fall under the same MPPT design, they can in some cases be treated together.

To prevent this mistake, decide which areas will be treated under the same conditions before entering data into PVSyst, referring to the plan and single-line wiring diagrams. Beginners tend to try to organize things later within the software, but it is safer to sort out multiple surfaces before input. When reading the PVSyst manual, don’t view Orientation, System, Module Layout, and Near Shadings as separate screens; understand them as definitions of the same design conditions from different angles.

Configuration Mistake 6: Confusing Distant Shadows with Nearby Shadows

The sixth mistake is confusing distant shadows with near-field shadows. In PVSyst, the approach differs between distant shadows such as the horizon or mountains and near-field shadows caused by buildings, parapets, trees, adjacent racks, and so on. Distant shadows are treated largely as whether the sun is visible or not, whereas near-field shadows involve shadows falling on part of the solar panel and even concern which areas within the plane are shaded.

The official documentation describes far shadows using the horizon line, explaining that they are caused by sufficiently distant objects that affect the entire PV field. Conversely, near shadows are described as shadows cast visibly onto the PV field by nearby objects, and require a complete PV system and a detailed 3D description of the surrounding environment. Furthermore, near shadows are regarded as one of the more difficult aspects in PVsyst, and a tutorial is provided.

A common mistake beginners make is treating all shadows from surrounding buildings as horizon shading, or attempting to model even distant mountain shadows as 3D near shading. Shadows from nearby objects need to be considered separately from a simple reduction in irradiance, because electrical losses vary depending on which modules or strings receive the shading. In PVSyst, two approaches to near shading are described: a method that looks only at the loss of irradiance, and a method that handles the electrical effects based on module layout and stringing.

It's also dangerous to be complacent just because you've created a 3D scene. If the number, orientation, area, and module arrangement of PV surfaces in the 3D scene do not match the module count and azimuth conditions defined on the System side, the simulation's consistency will break down. The official manual also explains that the PV module area and number of modules in the 3D scene should be close to those in the system definition. Furthermore, Module Layout is described as a feature for precisely specifying each module's position and string connections and for handling mismatch losses due to shading with high accuracy.

To prevent this mistake, first distinguish the types of shading. Consider whether mountains, terrain, and distant clusters of buildings should be handled as horizon, and whether parapets, rooftop equipment, adjacent buildings, trees, and mutual shading between racking rows should be handled as near shadings. After setting up the shading, check the loss plot in the results report to see how much shading loss is occurring. Even if you think you have entered shading, it will not affect the results if you forget to select the setting that applies it to the simulation. Treat creating the shading screen and evaluating shading loss as separate tasks.

Configuration Mistake 7: Continuing to Use the Detail Loss at Its Default Value

The seventh mistake is to keep using the detailed losses at their default values. Because PVSyst can run simulations with default settings, beginners tend to think, "As long as results come out, that's fine." However, losses such as soiling, temperature, wiring, mismatch, IAM, equipment quality, and downtime rate vary depending on project conditions. Using results without checking these can lead to an evaluation that is either more optimistic or more pessimistic than reality.

In PVSyst project design, it is explained that Detailed losses can be modified from the System screen, and that this covers soiling, IAM, module temperature parameters, wiring resistance, module quality, mismatch, downtime rate, and so on. The official grid interconnection manual also explains that while reasonable initial values are entered for the first simulation, there are parameters that should be adjusted to system-specific conditions to achieve greater accuracy.

For example, soiling losses vary with rainfall, the surrounding environment, cleaning frequency, agricultural land or factories, coastal areas, and regions with high dust levels. Temperature losses depend on roof-mounted systems, ground-mounted systems, rear-side ventilation, installation height, and local ambient temperature. Wiring losses are affected by cable length, voltage, conductor cross-sectional area, and the distance to the junction box or PCS. Mismatch is related to module variability, string configuration, and the pattern of shading. IAM is described as an optical effect in which the irradiance reaching the cell surface is reduced for oblique incidence.

A common pitfall for beginners is to regard detailed losses as "fine-grained items for experts" and hardly touch them. However, in projects where even a few percent difference in power generation can significantly affect the project viability assessment, loss settings are important. Even when using initial/default values, you need to be able to explain why you judged those defaults to be acceptable. Conversely, stacking overly strict losses without justification will lead to excessively conservative results.

To prevent this mistake, review the Detailed losses one by one and separate the items that should be changed for each project from those that can remain at their default values. You don’t need to set everything perfectly, but you should pay special attention to soiling, temperature, wiring, mismatch, and downtime rate. When reading the PVSyst manual, it’s important to understand not only how to operate the settings screens but also what each loss represents physically.

Configuration mistake 8: Judging the results report solely by power generation

The eighth mistake is judging the results report solely by annual energy production. When looking at PVSyst results, attention tends to go to the final energy production and specific yield. However, to verify the validity of the simulation, you need to look at the loss diagram, PR, monthly variations, shading losses, temperature losses, wiring losses, inverter losses, grid constraints, unused energy, and so on.

In PVSyst's result variables, the irradiance incident on the collector surface, after horizon correction, after near-shadings correction, after IAM correction, after soiling correction, and the irradiance finally effectively reaching the PV cell surface are organized step by step. In other words, the result report is not simply for seeing "how many kWh were generated," but for tracking at which stage which losses occur.

One thing beginners often overlook is that a setting error can occur even when the results look "too high." If you forgot to include shading, set soiling losses too low, assumed temperature conditions that are more favorable than reality, over-optimized the orientation, or made wiring losses too small, the results will appear good. However, the more favorable the results look, the more you must verify their basis; otherwise the outputs become difficult to use in practice.

Conversely, if the results are low, you should not immediately conclude that the design is bad. The azimuth sign may be reversed, the meteorological data location may be shifted, shading settings may be applied twice, electrical losses from nearby shading may be overestimated, or inverter limits may be set too strictly—these configuration issues can reduce the energy yield. When using the PVSyst manual, reading the report should be treated as part of the operating procedure.

To prevent this mistake, after a simulation always review "Input conditions", "Warnings", "Loss diagram", "Monthly results", and "Key indicators" in that order. In particular, for comparative analyses it is important that the conditions changed in each variant are made clear one by one. If it is unclear whether the difference between Option A and Option B is orientation, capacity, shading, or losses, the comparison of results becomes less meaningful. A report is not only a conclusion but also documentation to verify whether the input settings were appropriate.

Order of Checks When Using the PVSyst Manual in Practice

To use the PVSyst manual efficiently, it is important not to try to understand all features from the start. What beginners should aim for is not to cover all features, but to check items in the order in which errors are most likely to occur. First check the project type and the purpose of the assessment, then check the site and the meteorological data. After that, review azimuth and tilt, modules and inverters, the arrangement of multiple surfaces, shading, detailed losses, and the results report in that order to make it easier to understand the connections between inputs.

The official documentation explains that within PVsyst you can access the relevant online help via the F1 key or the help icon. If you encounter a screen you don’t understand while operating, rather than relying solely on a search engine, open the help directly from that screen to more easily reach explanations corresponding to the current settings.

In practice, it is more effective to use the PVSyst manual as a "dictionary to check the meaning of settings" rather than as a document to read from start to finish. For example, if you are unsure about the azimuth, check the explanation under Orientation. If you are confused about shading, check the difference between Horizon and Near Shadings. If the energy production does not match expectations, check Detailed losses and Results. Developing the habit of returning to the manual for the specific screen where a question arises will make it less likely that you repeat the same mistakes.

Also, in the initial simulation, it’s important not to try to create perfect conditions. First create a coarse variant, run it once without warnings to obtain a result, and then progressively refine shadows, losses, multiple surfaces, and the layout so it’s easier to trace which settings affected the results. The official documentation also presents the workflow of first making a coarse variant with default values and then applying the necessary detailed settings.

Summary

The configuration mistakes that beginners commonly struggle with in the PVSyst manual are not mere input errors but issues related to how they understand the assumptions of the simulation. Not matching the project type to its purpose, failing to verify site information and meteorological data, confusing tilt angle and azimuth, choosing module and inverter combinations by feel, over-consolidating multiple surfaces into one, mixing up far-field and near-field shading, leaving detailed losses at their default values, and judging the results report solely by energy production—these eight mistakes are especially likely to occur among people who are new to using PVSyst.

The important point is not to view PVSyst as "software that produces answers simply by entering numbers." Simulation results are built on the assumptions you input. If those assumptions are vague, no matter how polished the report, it will not be material you can use to explain things in practice. Conversely, if you verify the meaning of each setting one by one and clarify which conditions were fixed and which were compared, PVSyst’s results can become useful material for design reviews and energy yield assessments.

Beginners should first use these eight items as a checklist. Before running a simulation, check the project type, site, meteorological data, azimuth, equipment configuration, multiple surfaces, shading, and losses; after the simulation, review warnings, loss diagrams, monthly results, and key indicators. If you make this process a habit, time spent reading the PVSyst manual will become practical work to reduce configuration errors and strengthen the credibility of your results, rather than merely looking things up.