5 Points to Check in the PVSyst Manual When an Error Occurs

Table of Contents

• Concepts to Keep in Mind Before Proceeding with Error Handling in the PVSyst Manual

• Verify the consistency of input conditions first when an error occurs

• Mismatches Likely to Occur Between Meteorological Data and Location Settings

• How to Review Module, Inverter, and Wiring Settings

• Points to check when errors occur in shadow analysis or 3D models

• How to interpret warnings displayed in calculation results and report outputs

• Practical management methods to prevent the recurrence of errors

• Using the PVSyst Manual to Stabilize Analysis Quality

Key concepts to keep in mind before proceeding with error handling in the PVSyst manual

Understanding the five points to check in the PVSyst manual when errors occur makes it easier to calmly isolate the cause if you get stuck in photovoltaic system design or energy yield simulations. PVSyst is software in which many settings — weather data, installation conditions, modules, inverters, wiring, losses, shading analysis, report output, and so on — interact to produce results. Therefore, when an error or warning appears, trying to judge based only on the wording displayed on the screen can lead you to misidentify the cause.

PVSyst errors are not just critical bugs that simply stop the software. They are displayed at various stages: when inputs are missing, when settings contradict each other, when the system configuration is not viable, or when the calculation has completed but the reliability of the results requires caution. In practice, not only the red errors but also the yellow warnings and attention messages are important. Rather than assuming there is no problem because the calculation proceeded, you should take the stance of checking why the warning was issued.

Especially when using PVSyst for the first time or when creating a new project by reusing past project data, previous settings can remain. If the region, azimuth, tilt angle, number of modules, string configuration, number of inverters, loss conditions, etc., do not match the new project, errors may occur during calculation or the results after calculation may diverge significantly from reality. The purpose of reading the PVSyst manual is not simply to learn where the buttons are, but to understand how each setting affects the overall analysis.

What’s important in error handling is not to immediately start changing numbers to try things, but to separate and consider which area the problem is occurring in. By isolating whether it’s an issue with input conditions, meteorological data, system design, shadow analysis, or report output, you can reduce unnecessary corrections. If you go through the five points to check when errors occur in the PVSyst manual in order, even beginners will find it easier to organize the causes, and practitioners will be able to produce data that is easier to review.

Consistency of input conditions to check first when an error occurs

When an error occurs in PVSyst, the first thing you should check is the consistency of the input conditions. The site information, system type, mounting configuration, azimuth, tilt angle, and installed plant capacity that are set when creating the project form the basis for subsequent calculation conditions. If there are omissions or contradictions here, the entire analysis can become unstable even if the module and inverter settings have been entered correctly.

One of the most common input-condition errors is proceeding with required fields left blank. For example, you might think you have set the project's location, but the linkage to the meteorological data may not have been completed. You may also select installation conditions and then change settings on a different screen, leaving related values unchanged. Because many settings in PVSyst are interrelated, if you change conditions partway through you need to review the related items as well.

Entering azimuth and tilt angles can also cause errors or mismatches in results. Even if the numeric values can be entered, if the angles are set differently from the intended orientation, the calculated energy production can change significantly. This is especially true for roof-mounted or multi-surface installations: because each surface may have a different azimuth and tilt, trying to represent the whole system with a single condition can fail to match the actual equipment configuration. It is important to consult the PVSyst manual and, before entering data, clarify whether the project’s installation surfaces are a single simple surface, multiple surfaces, or include nearby shading.

Also, you need to be careful about how units are handled. For input fields such as area, length, capacity, voltage, current, and loss rate, a specific unit is assumed for each field. Even if you enter similar numbers, using the wrong unit can make the calculation results extreme. In some cases it will stop with an error, but other times it may not raise an error and will simply produce unrealistic results. For example, entering a wiring length or loss rate larger than the actual value will cause the power generation to be too low.

When checking the consistency of input conditions, it is important to compare the project summary with the settings in PVSyst. Verify that the installed capacity, installation location, installation method, roof or ground‑mount conditions, azimuth, tilt, and grid‑connection assumptions match the design documents. Rather than only looking at the error screen, review whether the case information is correct as an analysis target in the first place; by doing so you can detect fundamental mistakes at an early stage.

When copying and reusing past projects, you need to verify the input conditions more carefully. If previous project names, locations, weather data, loss conditions, or report notations remain, the project may look like a new one on the surface but actually carry over the conditions of another project. If an error occurs in this state, it becomes difficult to identify which setting is the cause. For new projects, confirming the basic conditions first and then proceeding to the system configuration is the quickest way to reduce errors.

Common inconsistencies between weather data and location settings

Among the five points to check for errors in the PVSyst manual, meteorological data and site configuration are particularly important. In photovoltaic simulations, conditions such as solar irradiance, air temperature, wind speed, latitude, longitude, elevation, and time zone greatly affect power output. If these are off, calculations may still run, but the reliability of the results will decrease.

A common error with meteorological data is when the project site and the meteorological data site do not match. For example, if the actual installation is in a mountainous area but you use meteorological data from a nearby urban area, the solar radiation and temperature trends may differ. It may not be possible to obtain meteorological data for exactly the same location, but even in that case you should be able to explain which location’s data you used and why you chose that data.

Also, be careful if the format or period of the meteorological data do not match. Monthly data, hourly data, long-term average data, etc., affect analysis accuracy and how the data should be used. If the imported data contain missing values, or if the solar irradiance field differs from what was expected, PVSyst may display errors or warnings. When an error occurs, don't judge only by the filename or data format; it is important to check which fields are actually being read.

When setting the site, you must be careful not to confuse latitude and longitude. If you enter numbers into the wrong fields or get the sign for east/west/north/south wrong, the installation location may be treated as an entirely different area. While such mistakes are often noticeable in domestic projects, sign errors in coordinates are more likely to be overlooked in overseas projects or those covering multiple regions. You should check the PVSyst manual and verify that the coordinate input format matches the position on the map.

Settings for time zone and elevation should not be overlooked. Because they affect solar position calculations and the time handling of meteorological data, a mismatch between the site conditions and the data conditions can impact shading analysis and power generation calculations. When using time-series data in particular, it is important to confirm whether the timestamps in the data are local time or standard time, and whether daylight saving time is accounted for.

To isolate errors in meteorological data, a useful method is to first check whether calculations can be performed with standard data, and then switch to the project-specific data. If calculations work fine with the standard data but errors occur only with the data you imported yourself, it is likely that the cause lies in the data format or the mapping of fields. On the other hand, if the same error occurs with any meteorological data, the problem may be in the location settings or the system configuration.

In practical work, it is also important to document the rationale for selecting meteorological data. Not only during error handling, but also when explaining to clients or in internal reviews, which data were used is always checked. By using the PVSyst manual to understand not only how to import meteorological data but also how it influences the results, you can act not just as an operator but as someone who can manage analysis quality.

How to Review Module, Inverter, and Wiring Settings

Typical areas where PVSyst reports errors or warnings are the module, inverter, and wiring settings. Photovoltaic systems have interdependent parameters such as the number of modules, the number in series, the number in parallel, inverter capacity, input voltage range, maximum current, oversizing ratio, and wiring losses. Therefore, correcting only a single value will not resolve an error if it conflicts with other conditions.

First, what you should check is the module and inverter combination. Module open-circuit voltage, operating voltage, short-circuit current, maximum output current, and so on change with temperature conditions. Because voltage rises in cold conditions and falls in hot conditions, you need to confirm that they fall within the inverter's input range. If PVSyst issues warnings about the voltage range, it is important not only to change the number of strings but also to review the assumptions about the minimum and maximum temperatures.

If the number of modules in series is too high, the low-temperature voltage can exceed the inverter's allowable range. Conversely, if the number of modules in series is too low, the operating voltage at high temperature may be insufficient, creating conditions where the system cannot generate adequate power. Even if calculations indicate it will operate under some conditions, you must confirm that the configuration allows stable operation throughout the year. While checking the relevant settings in the PVSyst manual, comprehensively review the voltage range, current range, and MPPT configuration.

The balance between inverter capacity and module capacity can also cause errors and warnings. In plant design, a certain amount of oversizing is sometimes considered, but connecting an excessively large DC capacity can increase clipping losses and trigger configuration warnings. Conversely, having an inverter capacity that is too large may not be appropriate from the perspectives of equipment cost and operational efficiency. Warnings in PVSyst do not necessarily mean that a design is infeasible, but you should be able to explain why you chose that configuration.

In the wiring settings, verify cable length, conductor cross-sectional area, voltage drop, resistance, wiring loss rate, and other parameters. If wiring losses are excessively large, power generation will be lower than expected. Even if this does not trigger an error, you should reassess the wiring conditions when the results screen shows large losses. In particular, confusing DC-side and AC-side losses in the inputs, or counting the same loss multiple times, can cause the results to be underestimated.

Care is required even when using module or inverter databases. Even if items appear to be from the same manufacturer or the same series, electrical characteristics can differ with only a slight change in the model number. If you proceed with an analysis using a similar model number as a placeholder, it may later fail to match the final design. While referring to the PVSyst manual, it is important to cross-check the database selection, model numbers, rated values, temperature coefficients, and other parameters against the design documentation.

When addressing errors, rather than viewing module settings, inverter settings, or wiring settings individually, confirm that the system as a whole is consistent. For example, if you increase the number of modules, it will affect the string configuration, inverter inputs, wiring length, losses, equipment capacity, and how things are presented in reports. Understanding how a single change is reflected across other screens lets you not only superficially clear errors in PVSyst but also produce analysis data that stands up in practice.

Points to Check When Errors Occur in Shadow Analysis or 3D Models

When dealing with shading analysis or 3D models in PVSyst, the causes of errors and warnings become even more complex. Depending on how fully you represent shading conditions — ground-mounted, roof-mounted, surrounding buildings, trees, mountain shadows, racking, inter-row shading of modules, etc. — the information that must be entered changes. Among the five points to check in the PVSyst manual when an error occurs, shading analysis is an area prone to user operation mistakes and misunderstandings of design conditions.

The first thing to check in shadow analysis is whether the 3D model’s geometry accurately represents the real installation conditions. If the heights, positions, distances, or orientations of buildings and obstacles are off, the way shadows fall can change significantly. Even deviations that look small in the model can have a large effect during periods of low solar altitude. For roof-mounted projects in particular, you need to decide how much to include—such as roof slope, ridge orientation, level changes, parapets, and equipment.

Errors in 3D models can be caused by overlapping objects, face orientation, or non-closed geometry. Even if they appear to be placed correctly, they may not be recognized as valid faces in the calculations. If shadow calculations in PVSyst are not proceeding correctly, simplify the complex model and check at which object addition the error occurs — this makes it easier to identify the cause.

Also, it is important not to confuse the handling of near shading and far shading. Near shading deals with shadows caused by objects near the installation, such as surrounding buildings, mounting structures, and module rows. Far shading, on the other hand, deals with shadows caused by distant obstacles such as the horizon or mountains. Both affect power generation, but they differ in where they are set and in the way they are considered. Checking the PVSyst manual and clarifying whether the shading at issue in a project is near or far will help avoid errors.

When dealing with shading between module rows, row spacing, tilt angle, racking height, clearance from the ground, and array layout are important. If the row spacing is set too narrow, shading losses can increase and warnings may appear in the results. In actual designs, row spacing may be reduced due to site constraints, but in such cases you need to evaluate it with an understanding of why losses increase. Widening row spacing solely to eliminate errors or warnings will make the layout inconsistent with the actual design.

In shading analysis, over-detailing can become a problem. Complex 3D models may look realistic, but they can lead to input errors, increased computational load, and make reviews more difficult. In practice, it is necessary to prioritize modeling the elements that have a large impact on analysis results and simplify details that have little effect. When addressing errors in PVSyst, considering the balance between precision and reproducibility is important.

If the results of a shading analysis are unreasonably large or small, check not only the 3D model but also the azimuth, tilt, meteorological data, and time zone. Because shading calculations depend on the sun's position, if the site settings are off, the way shadows appear will change. In other words, what looks like a shading analysis error may actually stem from the site settings or input conditions. Understanding how the screens relate to each other in the PVSyst manual makes it easier to deal with such complex issues.

How to interpret warnings in calculation results and report output

In PVSyst, even after the calculation itself has finished, warnings may appear on the results screen or during report generation. If these warnings are ignored, they can become a problem later during design reviews or client presentations. As the fifth and final item among the five points to check for errors in the PVSyst manual, it is important to emphasize checking warnings after calculations and when producing reports.

The first thing to look at in the calculation results is the breakdown of losses. Verify that items such as irradiance loss, temperature loss, wiring loss, mismatch loss, inverter loss, shading loss, and clipping loss are not larger than expected. Even if there are no error messages, if a particular loss item is excessively large, the input conditions may be incorrect. In particular, if you feel the power generation is too low, do not simply conclude that the weather conditions are poor; it is important to check the loss breakdown in order.

Warnings in report output can point to issues such as unfilled items, conditions outside recommended ranges, or settings that are insufficiently documented. A PVSyst report is not merely a printout but an important document for explaining analysis conditions and results to third parties. Warnings and notes displayed in the report may relate to the assumptions underlying the analysis. Therefore, before submission always check the warning section and notes, and review settings as necessary.

Be careful when power generation is higher than expected. Generally low power generation is considered problematic, but results that are too high can also be dangerous. There is a possibility the results are more optimistic than reality for reasons such as shading losses not being correctly reflected, temperature conditions being too lenient, wiring losses not being included, different assumptions about system capacity, or inappropriate meteorological data. While consulting the PVSyst manual, it is important to review whether each loss item matches the actual design conditions.

On the other hand, if the power output is too low, watch out for overlapping loss settings. For example, if you enter wiring losses separately and also add a loss of the same nature on another screen, it can be double-counted. Likewise, if shading losses are calculated with a detailed model but you still add a large fixed loss separately, the results will be underestimated. Even if no error is reported, you should verify that loss treatments are not duplicated.

When generating reports, we also verify the entries for project name, site name, system capacity, module model number, inverter model number, installation angle, meteorological data, loss conditions, and so on. In practice, it is important not only that the calculation results themselves are correct, but also that the conditions stated in the report match the design documentation. If an incorrect project name or an outdated model number remains, the reliability of the entire analysis will be questioned. This check is especially essential when copying from past projects.

When reviewing PVSyst result screens, it is important not to rely on a single indicator. Check a combination of annual energy production, specific yield, performance ratio, loss diagram, monthly energy production, shading losses, inverter behavior, and so on. If any one part appears unusual, the cause may lie in the surrounding settings. By carefully reviewing post-calculation warnings and any inconsistencies, you can improve the validity of the analysis results rather than merely dismissing errors.

Practical management methods to prevent errors from recurring

PVSyst's error handling is not finished by resolving the issue on the spot. To avoid repeating the same mistake in the next project, it is important to establish procedures for verifying settings. To translate the five points to check in the PVSyst manual into practical work, you need to make the checklist shareable within the team rather than relying solely on individual experience.

One effective practice is to keep a record of the input conditions for each project. Organize location information, meteorological data, modules, inverters, string configuration, wiring losses, the scope of shading analysis, and other loss conditions separately from the analysis data. If you confine information only to the PVSyst file, it becomes difficult to understand which decisions led to particular settings when you review the project later. Leaving a brief justification for each setting makes it faster to isolate causes when an error occurs.

Next, it is important to establish rules for copying and using projects. Reusing past projects is efficient, but there is a risk that outdated conditions will remain. After copying, make it standard practice to review the project name, site, weather data, equipment capacity, model numbers, loss conditions, and report notation. Companies with many similar projects are especially prone to mistakes from reuse. Rather than fixing errors after they appear, a mechanism to verify things at the point of reuse is necessary.

Also, keeping a record of how you handled errors and warnings can be helpful. If you note which screen displayed the message, what the message said, and which settings you changed to resolve it, future responses will be faster. If know-how exists only in the heads of people who are familiar with operating PVSyst, the same troubles will recur when the person in charge changes. It is important to combine the manual with internal memos to create reproducible procedures for responding.

A review process is also indispensable. If a PVSyst analysis is completed solely by the person who entered the data, mistakes caused by assumptions can be overlooked. Simply having another person check the input conditions, meteorological data, system configuration, losses, shading analysis, and the report can prevent many errors and anomalous results. In reviews, rather than merely checking that values have been entered, confirm that they are consistent with the design documentation and that the assumptions are ones that can be explained to the client.

Version control is also important in practical work. Depending on the version of PVSyst and the update status of its database, the display and calculation results may differ even for the same project. When multiple people in the company analyze a project, standardizing the version used and how the database is handled can reduce differences in results. When recording error handling, leaving a record of the environment used also makes it easier to trace the cause later.

To prevent errors from recurring, it is effective to establish a fixed order for checks. Standardize a flow in which you first check the project's basic information, then the meteorological data, then the modules and inverters, then the wiring and losses, then the shading analysis, and finally the results and report. By checking in this order, even if an error appears on a downstream screen, it will be easier to trace the cause from upstream settings. When reading the PVSyst manual, keeping this flow in mind also makes it easier to understand the relationships between the various functions.

Using the PVSyst Manual to Stabilize Analysis Quality

The five points to check in the PVSyst manual when an error occurs are: input conditions, meteorological data, modules, inverters and wiring, shading analysis, and calculation results and reports. By checking these five in order, you can avoid ad hoc fixes when an error occurs and logically narrow down the cause. Because PVSyst is a feature-rich software, the source of an error is not necessarily confined to a single screen. Assuming multiple settings interact, it is important to check the overall consistency.

What you should avoid most when handling errors is changing settings solely for the purpose of clearing warnings. Even if the displayed errors disappear, if you enter values that differ from the actual design conditions, the meaning of the analysis results is lost. PVSyst’s errors and warnings are clues for reviewing the design. By understanding why the message appeared and which conditions are problematic, and by making the necessary corrections, you can improve the reliability of the results.

For beginners, it is more important to check settings in order from the basic conditions than to try to understand all the settings at once. Verify that the site and meteorological data are correct, that the module and inverter configuration is valid, that wiring losses are realistic, that the shading analysis is neither over- nor under-configured, and that no unnatural warnings remain in the report. By repeating this process, the contents of the PVSyst manual will become easier to understand in connection with practical work.

For practitioners, handling PVSyst errors directly affects the quality of analysis. Simulation results for solar power generation systems are used for system design, financial planning, customer explanations, and internal approvals. Small input mistakes or overlooked warnings can lead to major rework in later stages. That is why it is important to establish verification procedures not only when errors occur but also as part of routine analyses.

When using the PVSyst manual, it is important to be aware not only of how to operate the software but also of the meaning of each item and its impact on the results. If you have the five key points to check when an error occurs, you can respond calmly when problems arise and increase your ability to explain analysis results. Using PVSyst not merely as a calculation tool but as a practical tool to verify design conditions and confirm the validity of the expected energy production leads to more stable simulations.