6 items to check before reporting in the PVSyst manual

Table of Contents

• The significance of using the PVSyst manual for pre-report checks

• Are the input conditions and project assumptions consistent with the reported content?

• Are there any unexplained discrepancies between the meteorological data and the installation conditions?

• Do the system configuration and capacity conditions match the design documentation?

• Can you explain to the person you're reporting to the rationale for the loss settings?

• Have the interpretations of the result indicators been organized without any misunderstanding?

• Did you check the comparison cases and version control before generating the report?

• Common oversights in pre-report checks

• How to Leverage the PVSyst Manual for Internal Standardization

• Summary

The Significance of Using the PVSyst Manual for Pre-Report Checks

Consulting the PVSyst manual is not limited to simply checking how to operate the software. When using the results of a photovoltaic project study for internal meetings, customer proposals, documents for financial institutions, design reviews, or pre-construction checks, being able to explain under what conditions those results were produced is more important than the simulation results themselves. Energy production, PR, loss diagrams, monthly results, system capacity, meteorological data, azimuth, tilt, shading conditions, and so on—none of these is sufficient on its own. Before reporting, you need to confirm that each of these items is connected by consistent assumptions.

Because PVSyst’s result screens and reports summarize the parameters used in the simulation and the main results, it is important when reviewing before reporting to check not only the results but also the underlying assumptions. The official PVsyst documentation likewise states that simulation results are summarized as a printable report that includes a table of the parameters used and descriptions of the main results. In other words, the person responsible for preparing the report materials needs to be able to explain why the output numbers are what they are, rather than simply pasting the numbers as-is.

One point to pay special attention to is that PVSyst results are composed of technical numerical values. A superficial comparison that only notes whether the energy production is high or low does not lead to practical decisions. You must distinguish whether harsh weather conditions are the cause, whether orientation or tilt are having an effect, whether shading settings are significant, whether temperature losses are noticeable, or whether there are characteristic settings for inverter capacity or the DC/AC ratio. If the report recipient is a technician, they will require detailed justification; if they are a non-technical person, you need to explain the meaning of the numbers in plain language.

Therefore, the items you want to check in the PVSyst manual before reporting are more useful in practice if you treat them not as checks of operational procedures but as verification points to fulfill accountability. It is important not only to think about which screen to open or which button to press, but also to determine which input conditions affect the results, which losses are significant, and which figures should be adopted in the report.

1. Are the input conditions and project assumptions consistent with the reported content?

The first thing to check is whether the project assumptions entered into PVSyst match the project conditions described in the report materials. This may seem like a basic check, but it is a very common source of pre-reporting errors. If the project name, site, installed capacity, installation method, module type, inverter configuration, azimuth, tilt, assumed start of operation, grid connection conditions, and so on differ from internal design documents or customer-provided materials, the overall credibility of the results may be called into question later.

In PVSyst simulations, the conditions entered are directly reflected in the results. Therefore, before reporting, first open the assumptions section of the output report and verify that the project information matches the latest design proposal. For example, in initial studies you may simulate with a provisional capacity, and later the number of modules or the number of power conditioners may be changed. If you use the old simulation results directly in the report materials in that case, the energy production, specific yield, loss rates, PR, and so on will no longer match the design proposal.

Also, when confirming project assumptions, attention must be paid to how units are handled. Units such as kW, kWp, kWh, MWh, and kWh/kWp/year may look similar but have different meanings. In reporting materials, you should decide whether to present only annual generation, generation per unit of installed capacity, or monthly results. Especially when comparing multiple projects, looking only at simple annual generation can make larger-capacity projects appear more favorable. Checking indicators normalized by installed capacity as well makes it easier to compare projects with different conditions.

When checking input conditions, what’s important is that the materials viewed by the report recipient match the conditions written in the PVSyst report. For example, if the report materials state a tilt angle of 10 degrees while PVSyst used a 15-degree case, the consistency of the entire documentation breaks down even before the validity of the energy yield is considered. Similarly, it is important to confirm that azimuth, number of mounting surfaces, array configuration, string configuration, and equipment ratings do not deviate from the design documents.

Before submitting the report, check not only the final selected case but also whether any cases created during intermediate reviews have been mixed in. In PVSyst you may create and compare multiple variants, but if file names or case names are ambiguous, it becomes difficult to determine which is the final proposal. For cases used in reporting materials, assign names that indicate the date, conditions, purpose of the comparison, and reason for selection so they can be easily verified later.

2. Are there any discrepancies that cannot be explained by the meteorological data and installation conditions?

Next, I want to check the meteorological data and the installation conditions. In photovoltaic (PV) simulations, solar irradiance, air temperature, installation location, elevation, azimuth, tilt, topography, nearby shading, distant shading, and other factors greatly affect the results. When using the PVSyst manual to review before reporting, check which meteorological data were used, whether that data is appropriate for the project site, and whether it is consistent with the installation conditions.

Meteorological data is an important input that forms the basis of power generation estimates. When using data from nearby sites, the person you are reporting to may ask, "Why did you use data from that site?" Even if data for the project site itself are not available, you must be able to explain which type of data you adopted—nearby-site data, typical-year data, satellite data, measured data, etc. Simply saying "we used it because it could be imported into PVSyst" is not sufficient.

Also, if the site’s latitude, longitude, or elevation are incorrect, it can affect the treatment of solar altitude, temperature conditions, and solar radiation conditions. Before submitting a report, cross-check with maps and design documents to confirm the site is set correctly. In particular, for large-scale projects or projects in mountainous areas, topography and solar radiation conditions can vary even within the same municipality. If you use meteorological data from a location distant from the candidate site, organizing how you will account for those differences will make it easier to explain in the report.

Azimuth and tilt are also items you should always check before reporting. On design drawings expressions such as south-facing, southeast-facing, and east-west orientation are used, whereas in PVSyst they are entered as angles. If this conversion is done incorrectly, the results can change significantly. In particular, if you enter values without a clear understanding of the sign of the azimuth or the reference direction, east and west can be reversed, or calculations may be performed for a direction different from the design intent. Before reporting, it is important to verify by cross-checking not only the PVSyst screen but also the layout drawings and design plans.

Checks before reporting are also essential for shadow conditions. Whether near-field shading is considered, whether distant terrain is taken into account, or how mutual shading between arrays is treated will change how energy production and loss diagrams appear. If you report a case where no shading settings were applied, you must clearly state the basis for judging that shading effects are small and the assumption that they will be verified separately. Conversely, if shading has been modeled in detail, confirm that the shading model matches the site conditions and the design drawings.

Meteorological data and installation conditions are the foundation that supports the credibility of the results. If you carefully review these before reporting, you will be able to explain the magnitude of power generation not as a mere numerical comparison, but with explanations grounded in the conditions.

3. Do the system configuration and capacity conditions match the design documents?

The third thing to check is the system configuration and capacity conditions. PVSyst results vary depending on the modules, inverters, string configuration, DC capacity, AC capacity, the approach to oversizing, wiring, loss settings, and so on. Before reporting, you need to verify that the system configuration entered into PVSyst matches the design documents and the estimate/quotation conditions.

Particularly important is the capacity relationship between the DC side and the AC side. In solar power generation, the ratio of module capacity to inverter capacity affects output limiting, the occurrence of clipping, and how the generated power appears. In reporting materials, there are occasions to explain not only the annual energy generation but also why that capacity configuration was chosen. When the DC/AC ratio is high, it is necessary to clarify whether the aim is to improve operating rates under low irradiance or to accept limitations at peak times. Conversely, when the DC/AC ratio is low, be prepared to explain how you are considering the balance between equipment utilization and cost.

It is also necessary to confirm the module model and rated conditions. If the module capacity listed in the report differs from the module capacity selected in the PVSyst database, discrepancies will arise in the total capacity and in the power generation. If the model designation does not match exactly, an approximate model may be used, but in that case you need to decide how much of this to explain in the report. In practice, provisional equipment may be used during the initial study phase and replaced with the final equipment in the detailed design phase. Therefore, depending on the purpose of the report, it is important to clarify whether the conditions are provisional or final.

We also check the inverter’s capacity, number of units, input circuits, efficiency, operating voltage range, maximum input current, and so on. If the string design is not appropriate, the voltage range or current conditions may not match the assumptions. Before reporting, we review PVSyst to ensure there are no errors or warnings and that the design conditions are feasible. In technical review sessions, reviewers may confirm that the design is valid before evaluating the expected energy production.

Wiring losses and system losses also need to be consistent with the design documents. If assumptions about cable length or voltage drop differ significantly, they will affect the loss rates. In initial studies it is common to use standard loss values and then align them to the actual wiring plan during detailed design, but if you do not distinguish those differences in the report materials, you will later be asked, "Why was this loss value used?"

When checking the system configuration, it is important not to rely solely on the PVSyst screen. Cross-check against the single-line wiring diagram, layout diagram, equipment list, quotation documents, and internal design memos to verify that the simulation is being run under the same assumptions. Performing this task before reporting will improve not only the accuracy of the results but also the consistency of the design proposal.

4. Can you explain to the report recipient the basis for the loss settings?

The fourth thing to check is the loss settings. In PVSyst reports, the loss diagram allows you to see at which stages and by how much the energy production is reduced. The official documentation also states that the loss diagram helps quickly assess the quality of a photovoltaic system design and identify the main sources of loss. Therefore, before reporting, it is important not only to glance at the loss diagram but also to confirm that there is a rationale to explain each loss value.

Loss assumptions include various items such as soiling, IAM, temperature, mismatch, wiring, inverter, shading, degradation, downtime rate, transformer, and grid-side constraints. Which losses become significant varies by project. For example, projects with nearby buildings or trees may exhibit noticeable shading losses. In high-temperature regions, temperature losses can have a larger impact. For projects with long wiring distances, wiring losses may not be negligible. Before reporting, be prepared to explain why the major items in the loss diagram take the values they do.

One point to note is that smaller loss values are not always better. Setting losses to be small will make the estimated power generation look higher, but if they do not reflect realistic conditions, the credibility of the report will decline. For example, if soiling losses are estimated to be extremely small, the consistency with the operating environment and cleaning schedule may be questioned. If shading losses are not taken into account, you will need to explain whether the surrounding environment has been adequately checked. Before reporting, prioritize having reasonable assumptions over making the power generation figures look good.

In PVSyst, the effects of various losses can be checked in the simulation results and visually understood via loss charts. The official documentation on array and system losses also states that the impacts of losses are available as hourly, daily, and monthly values and can be visualized in loss charts. Before reporting, checking monthly loss trends as needed, in addition to annual values, makes it easier to explain seasonal factors.

When looking at a loss diagram, it is practical to separate losses that can be improved by design from those that must be accepted as environmental conditions. Shading losses can sometimes be improved by revising the layout or array spacing. Wiring losses can sometimes be improved by cable size or routing planning. Temperature-related losses are influenced by the installation method and ventilation conditions. On the other hand, parts attributable to weather conditions or regional characteristics cannot always be completely eliminated by design alone.

Before reporting, it is reassuring to organize the causes, validity, potential for improvement, and the approach you will take to explain particularly large items in the loss diagram.

Simply pasting the loss diagram as-is can appear to the report recipient as a mere list of numbers. It is important to supplement in words which losses affect power generation, which items are within design tolerances, and which items are issues for future consideration.

5. Are the result metrics organized so they can be interpreted without misunderstanding?

The fifth thing to check is how to interpret the result indicators. In PVSyst reports, multiple indicators appear, such as annual energy production, specific yield, PR, monthly energy production, incident irradiance, effective irradiance, array output, and grid-injected energy. If these are not correctly understood, you may inadvertently use misleading expressions in the report materials.

First, annual power generation is an easy-to-understand indicator, but when looked at on its own it may not be suitable for comparisons. For projects with different installed capacities, those with larger capacities will have greater annual generation. Therefore, when comparing multiple proposals, you also need to check the power generation per unit of installed capacity. Looking at generation per unit of capacity makes it easier to compare on an even basis despite differences in capacity.

PR is also a metric often used in reports. In the PVsyst official documentation, Performance Ratio is described as the ratio of the energy actually and usefully produced to the energy that would be obtained if the system operated continuously at its nominal STC efficiency. This indicator is useful for evaluating system performance while smoothing out the effects of installed capacity and irradiance conditions to a certain extent. However, it is dangerous to simply judge that a high PR means everything is excellent or that a low PR means everything is poor. It must be interpreted taking into account the influences of meteorological conditions, temperature, shading, design strategy, inverter configuration, and so on.

Monthly results are also important. Relying solely on annual generation makes it difficult to see seasonal biases or loss trends in specific months. Confirming whether generation is higher in summer, whether shadows have a stronger impact in winter, or what patterns emerge during the rainy or snowy seasons adds depth to the report. In particular, when explaining revenue estimates or the relationship with electricity demand, monthly fluctuations can be more important than the annual total.

When reporting performance indicators, clarify which value is treated as the final generated energy. In PVSyst, the energy at the array output stage and the energy injected into the grid have different meanings. The value to use in reporting documents depends on the purpose of the project. If explaining revenue from electricity sales or project economics, it is natural to emphasize the amount of electricity ultimately delivered to the grid. On the other hand, when explaining equipment design or loss analysis, it is also necessary to check the array output and the energy before and after losses.

Also, care is needed in how numbers are rounded. Reporting PVSyst's output values as-is with many decimal places can give an overly precise impression. In practical documents, values such as MWh, kWh/kWp, and percent are often rounded to a number of digits appropriate to the audience. However, be careful that rounding does not create inconsistencies in totals or comparative figures. When the same value appears in multiple places within a report, it is important to keep the units and number of decimal places consistent.

When reviewing outcome metrics, it's important not to select only the favorable numbers but to choose figures that can withstand explanation. Before reporting, decide which metrics will be primary, which will be supplementary, and which will be kept for internal review; doing so will make the entire document easier to understand.

6. Have you verified the comparison cases and version control before outputting the report?

The sixth item to check is the comparison cases and version management. In practical work using PVSyst, it is common to create multiple simulation cases for a single project. You compare several options depending on the study objectives—different orientations, different tilts, different capacities (system sizes), different equipment, with or without shading, different loss settings, different meteorological data, and so on. Before reporting, you need to confirm which case has been adopted and whether the comparison conditions are consistent.

A common problem in comparative cases is that some conditions have unintentionally changed. For example, even if you intend to compare different orientations, if only one case has different weather data or loss settings, you cannot correctly compare the effect of orientation. When comparing capacity differences, if module or inverter conditions have changed, the difference cannot be explained by simple capacity differences alone. Before reporting, it is important to confirm that all conditions other than the element you want to compare are consistent.

Naming cases is also important. In the early stages of work, people tend to use names like test, case1, new, or final, but when it comes time to report, it can become unclear which is the final version. This is especially problematic when there are multiple files named final, making it difficult to determine the most recent one. For cases used in reports, giving them names that include the date, the conditions, and the content of the review makes them easier to check later.

In version control, check the report output date and the simulation date and time in PVSyst. If the results included in the report materials do not match the contents of the PVSyst file you have on hand, it will cause confusion when rechecking later. If you change conditions after creating the report materials, confirm that the figures, tables, and numbers in the materials have also been updated. If you update only the simulation results while the loss diagram and monthly tables remain outdated, the consistency within the document will be compromised.

Also, before internal review or submitting to clients, it's advisable to organize the correspondence between PDF reports, working files, and reporting materials. Ensuring you can trace which numbers were quoted from which PVSyst case and which figures were used allows you to verify them quickly if questions arise later. This is particularly important for documents intended for financial institutions or for business feasibility assessments, where being able to trace the basis for figures is essential.

Comparison cases and version control may seem unrelated to the power generation itself. However, they are indispensable for supporting the credibility of the report. No matter how precise the simulation, if you report an outdated case or a case with different conditions, the value of the results will be diminished. Before reporting, always verify the consistency of the final case, the comparison conditions, the output materials, and the cited numerical values.

Common Oversights in Pre-Report Checks

Even when performing a pre-report check while referring to the PVSyst manual, several oversights tend to occur in practice. The most common is looking only at the result numbers and postponing verification of the input conditions. It’s easy to feel reassured when the energy production and PR are within the expected range, but if the input conditions are outdated or differ from the design documents, corrections may be required after reporting.

The next most common issue is insufficient interpretation of loss diagrams. Because loss diagrams are visually easy to understand, they are sometimes pasted directly into reports. However, for report recipients it can be hard to tell which losses are important, which losses are design-related issues, and which are caused by environmental conditions. When using loss diagrams, adding a brief explanation for each major loss item makes them easier to understand.

Also, judging solely by annual values without checking monthly results is another oversight. Even if the annual power generation looks reasonable, there may be months with extreme values. This can be caused by shading settings, meteorological data, snowfall, temperature conditions, downtime rates, input errors, and so on. Before reporting, review not only the annual values but also the monthly trends to confirm there are no unnatural peaks or drops.

Care must also be taken when different units are mixed. Mixing kWh and MWh, kW and kWp, or percent and ratio displays can confuse readers of the report materials. When transcribing PVSyst output values into documents, unify the units and convert them as necessary. In particular, when pasting tables or graphs into other documents, check that the units on axis labels and in legends are correct.

It is also common to present only the results without explaining the differences in conditions between comparison cases. For example, when showing the difference in power generation between case A and case B, the reader cannot judge unless it is made clear what differs between the cases. Explaining whether the orientation is different, the capacity is different, the shading conditions are different, or the loss settings are different conveys the meaning of the comparison results.

In pre-report checks, it is important to be mindful not only of the correctness of the numbers but also of whether readers might be misled. Because PVSyst results are highly specialized, the way they are explained can greatly affect the impression. Even if the results are technically correct, if the expressions in the materials are hard to understand, they will not be conveyed to the report recipients. Before reporting, review the material from both the technician’s perspective and the reader’s perspective.

Approach to Leveraging the PVSyst Manual for Internal Standardization

Using the PVSyst manual not only for reviewing individual projects but also to inform internal standard checks makes it easier to stabilize report quality. If each person uses different check items, the level of detail and the explanations in materials will vary even for similar projects. If the items that must be checked before reporting are standardized across the company, review efficiency improves and it becomes easier to prevent repeated mistakes.

The first thing we want to do for internal standardization is to establish a fixed pre-report checklist. Items such as input conditions, meteorological data, installation conditions, system configuration, loss settings, result indicators, comparison cases, and version control will be defined as a flow to be checked for each project. The person in charge will review PVSyst reports and screens according to that checklist and incorporate any necessary explanations into the documentation. This will reduce missed checks even for less experienced staff.

Next, we will standardize the terms and units used in reporting materials. If notations for annual energy production, specific yield, PR, loss rate, solar irradiation, installed capacity, etc. differ between documents, unnecessary checks will arise during internal reviews. Deciding in advance which parts should match PVSyst outputs and which should be formatted for readability as internal documents will improve the efficiency of preparing materials.

It is also effective to prepare standard explanatory texts in advance. For example, explanations of PR, how to read loss diagrams, handling meteorological data, and considerations for shading conditions do not need to be written from scratch for each project. By using standard text as a base and appending project-specific conditions, you can maintain the quality of explanations while reducing work time.

However, standardization is not enough if it is reduced to a mechanical checklist. The points that need to be checked for solar power projects vary depending on location, scale, installation method, surrounding environment, contractual conditions, and the stage of review. While using a standard checklist as the foundation, it is important to change the priority of items to be checked for each project. For example, for rooftop projects, orientation, shading, and loading conditions tend to be important, whereas for ground-mounted projects, terrain, array spacing, wiring, and site development conditions tend to be important.

The purpose of leveraging the PVSyst manual for internal standardization is not to constrain the work of responsible personnel, but to stabilize the quality of reporting. Ideally, it should ensure that, whoever prepares the report, minimum checks are performed and the rationale for important figures can be explained. On that basis, by adding project-specific judgment and technical review, the reports will be robust enough for practical use.

Summary

The six items to check in the PVSyst manual before reporting are input conditions, meteorological data and installation/site conditions, system configuration, loss settings, result indicators, and comparison cases and version control. These are not independent check items but are interconnected for correctly explaining results such as energy production and PR. Even a single discrepancy among them can affect the credibility of the entire report.

What’s important in pre-report checks is not to use PVSyst results as-is, but to be able to explain the conditions behind those results. By organizing why you used that meteorological data, why that azimuth and tilt, why those loss values, and why that case was chosen, you will be better able to respond to questions from the report’s recipients.

Also, by looking not only at the annual energy production but also at the specific yield, PR, monthly results, and the loss diagram together, you can grasp the meaning of the results more accurately. Because PVSyst reports contain a lot of information, rather than including everything in your materials as-is, it is important to select the key items according to the reporting purpose and organize them in an easy-to-understand way.

By making pre-report checks a habit, you can not only reduce input errors and condition mismatches but also improve the quality of internal reviews and explanations to clients. The PVSyst manual can be used not only to confirm operations but also as a checklist to ensure simulation results are communicated correctly in practice. Rather than stopping at producing generation figures, preparing them to the point where you can explain those numbers leads to reports that are trusted.