7 Items to Understand the Meaning of Settings in the PVSyst Manual

Table of Contents

• Get an overview of the settings before reading the PVSyst manual

• Meteorological data settings determine the assumptions for power generation.

• Azimuth and tilt angles affect annual energy production and seasonal variations.

• System capacity and the DC/AC ratio change how system size is viewed

• The configuration values of the module and PCS are directly linked to the reliability of the calculation results.

• Loss settings are the items that break down and examine the reasons why power generation decreases.

• Shading settings should take into account not only the shaded area but also the electrical effects.

• Report indicators are reviewed to confirm the validity of the configured values.

• Confirmation procedure to make configuration settings easier to share within the company

• Summary

Get an overview of the settings before reading the PVSyst manual

When checking configuration values in the PVSyst manual, the first thing to keep in mind is not to view each item as an isolated input field. PVSyst is software for the design, sizing, and data analysis of photovoltaic systems, and it covers multiple applications such as grid-connected, stand-alone, pumping, and DC grid. Because it is structured to examine combinations of meteorological data, component databases, and various PV system conditions, changing a single configuration value will interactively affect annual energy production, the loss diagram, PR, monthly results, and even the appearance of proposal documents.

If you proceed without understanding the meaning of the settings, even when the simulation on the screen shows as complete you will often find yourself unable to explain the results. For example, if the energy yield is lower than expected, you cannot distinguish whether that is due to the choice of meteorological data, the effect of the tilt angle, constraints of PCS capacity, or the impact of shading conditions. The purpose of reading the PVSyst manual is not just to learn the operational procedures, but to understand which calculations each setting affects.

Especially in practical work, simply transcribing PVSyst results directly into internal or proposal documents is insufficient. The simulation results become persuasive only when you can explain the basis for the energy production, the breakdown of losses, the differences caused by changes in settings, and the validity of the assumptions. For that reason, rather than filling in the input screens from top to bottom, it is important to read and organize the roles of the settings in the sequence: weather, layout, equipment, losses, shading, and result indicators.

In this article, I organize into seven items the settings in the PVSyst manual that you should particularly understand. Replacing screen names and technical terms that beginners are likely to stumble over with language easier to use in practice, I explain which settings to check to improve design accuracy and the persuasiveness of your materials.

Meteorological data settings determine the assumptions for power generation

The first settings you should check in the PVSyst manual are those related to meteorological data. In photovoltaic simulations, solar irradiance, ambient temperature, wind, and time-step variability are the assumptions underlying energy production. No matter how accurately you configure the modules and the PCS, if the meteorological data assumptions do not match local conditions, the annual energy yield forecast can be significantly off.

The official PVSyst tutorial also covers meteorological data management, importing, synthetic data generation, and quality checks. This is because meteorological data are not merely supplementary information but foundational information that determine the reliability of simulations.

Representative settings to check in meteorological data are location, data source, temporal resolution, type of solar radiation, temperature data, and the handling of missing or anomalous values. Location relates to the power plant’s latitude and longitude and the distance to nearby observation points. Data sources differ and can include measured values, typical-year data, external data, and synthetic data. Temporal resolution can be monthly, hourly, or at finer time steps, and it affects the reproducibility of shading and output variability.

What’s important for understanding the meaning of settings is not to judge meteorological data solely as “right or wrong.” In practice, you need to explain which data were used, why that data was adopted, and how large the differences are compared with alternative data. When reading the PVSyst manual, it is also important to grasp not only the operation of input fields but also the approach to checking and comparing data quality.

For example, even on the same site, solar irradiance and temperature trends differ between mountainous areas, coastal areas, urban areas, and snow-prone regions. In regions with high temperatures, module temperature rises and power output losses can be greater. Conversely, in regions with low temperatures and good irradiance conditions, higher energy yield can be expected from the same installed capacity. When reading meteorological data settings, it is necessary to check not only the annual irradiance but also monthly distribution biases and temperature conditions.

Also, in proposal documents and internal reviews, the source of the meteorological data is an item that is likely to be questioned. When explaining the energy production calculated in PVSyst, being able to answer "which meteorological data for this site were used, and what period or representative year is assumed" will reduce rework from reviews. When reading the meteorological data settings section in the PVSyst manual, it is important not simply to memorize the import procedure, but to understand it as the screen that defines the assumptions for the energy production.

Azimuth and tilt angles affect annual energy production and seasonal variation

The next important settings are the azimuth and tilt angles. The orientation and tilt of the solar panels directly affect the amount of solar radiation they receive. When viewing the azimuth and tilt screens in the PVSyst manual, you should not treat them merely as inputs for “south-facing,” “east–west-facing,” or “how many degrees to tilt,” but read them as conditions that affect annual energy production, seasonal generation, morning and evening generation trends, and how shading develops.

Azimuth is the setting that indicates which direction the array is facing. In general, the closer it is to facing south, the easier it is to secure annual energy production, but the optimal direction varies depending on site shape, roof shape, the timing of electricity demand, feed-in tariff rates, and shading conditions. For east- or west-facing layouts, the timing of generation peaks shifts, so it is important not only to consider annual energy production but also how to evaluate output in the morning and evening.

The tilt angle indicates how much the module surface is tilted relative to the ground. Increasing the tilt makes the array more exposed to winter solar radiation, but it affects the installation area, wind loads, mounting-structure costs, array spacing, and shadow length. Decreasing the tilt can make it easier to increase installation density, but you need to consider impacts on energy production, soiling, drainage, and snowfall. When checking tilt angle settings in the PVSyst manual, it is practical to understand their meaning not only for energy production but also in terms of construction and maintenance conditions.

A common mistake with azimuth and tilt angles is looking only at the result of changing the settings and not checking why it changed. For example, if annual energy production changes by a few percent, you need to examine monthly results and time-of-day trends to see whether the difference appears in spring and autumn production, in winter, or in the morning and evening. Although it may appear as a single parameter on the PVSyst screen, it actually represents a condition that alters the entire generation curve.

Furthermore, in projects where multiple orientations and multiple tilts coexist, the meaning of the settings becomes even more important. In rooftop projects, the orientation and tilt can differ for each roof surface. Even for ground-mounted installations, grading or slope conditions may cause the tilt to differ between arrays. In such cases, you should consult the PVSyst manual for the treatment of multiple sub‑arrays and multiple orientations, and make clear which input corresponds to which array.

Azimuth and tilt angles may look like simple numbers, but they can greatly affect simulation results. When reading the PVSyst manual, check not only the input values themselves but also how those values relate to solar energy capture, seasonal variation, layout density, shading, and the proposed strategy.

System Capacity and the DC/AC Ratio Change the Way You View System Size

When trying to understand the meaning of the settings in the PVSyst manual, system capacity and the DC/AC ratio are also essential. In solar power projects, module capacity, PCS capacity, array configuration, number of strings, and the concept of overloading are intricately linked. If you only look at the equipment capacity numbers, you can overlook why output limits or losses are occurring in the simulation.

Module capacity is the total of the nominal outputs of the photovoltaic modules to be installed. It is generally expressed as kW DC or kWp and indicates the scale of the plant’s DC side. Meanwhile, PCS capacity relates to the upper limit of output that can be converted on the AC side. The DC/AC ratio is a concept that shows the relationship between the module capacity on the DC side and the PCS capacity on the AC side, and it serves as a basis for judging the appropriateness of oversizing design and the likelihood of output curtailment.

When setting the system capacity in PVSyst, it is not sufficient to simply enter the number of modules and the number of PCS units. The number of modules in series, the number in parallel, the input range per PCS, the MPPT configuration, voltage range, current limits, and so on are involved. If these settings do not match the actual design, the reported energy production and losses in the report may deviate from the actual equipment configuration.

Raising the DC/AC ratio makes it easier to use the PCS efficiently during periods or seasons of low solar irradiance; however, during periods of strong irradiance, clipping losses due to the PCS limit may occur. Conversely, if the DC/AC ratio is too low, the module capacity may be small relative to the PCS capacity, and the energy generation relative to capital investment may be insufficient. When reading the capacity-related settings in the PVSyst manual, it is not simply a matter of increasing capacity—you need to see where constraints will arise.

What’s important in practice is not just to present the DC/AC ratio as a number, but to explain which losses will increase and which indicators will improve as a result. For example, when oversizing, annual energy production may increase, but curtailment losses during peak hours can also rise. You need to check whether those losses are within an acceptable range, whether there is a benefit in terms of return on investment, and whether this contradicts the grid interconnection conditions or the assumptions for output control.

When reading the PVSyst manual, it is important not to view the system capacity screen merely as the place to enter the size of the installation. Capacity settings are a central configuration that links equipment selection, energy production, losses, costs, and proposal conditions. Understanding the meaning of the set values makes it easier to explain differences in energy production and to compare design proposals.

Module and PCS settings are directly tied to the reliability of the calculation results

PVSyst performs simulations using databases of modules and PCS. In PVSyst’s official documentation, the component database is presented as an element involved in defining the components of a photovoltaic power generation system. Therefore, the configuration values for modules and PCS are not merely a selection of equipment names but an important premise that supports the reliability of the calculation results.

Items to check in the module settings include nominal power, open-circuit voltage, short-circuit current, maximum power operating voltage, maximum power operating current, temperature coefficients, cell configuration, bypass diodes, degradation rate, and so on. These affect output calculations when irradiance or temperature change, string voltage, compatibility with the PCS, and behavior under shading. If the manufacturer's datasheet and the values registered in PVSyst do not match, the basis for the calculation results becomes weak.

Items to check in PCS settings include the rated output, input voltage range, maximum input current, number of MPPTs, conversion efficiency, behavior under overload, and temperature conditions. The PCS is a device that converts direct current (DC) power to alternating current (AC) power and acts as a constraint on the entire system. Even if the module-side design is good, if it does not match the PCS’s input range or current limits, design mismatches and losses may occur.

When reading module and PCS settings in the PVSyst manual, it is important not to trust equipment data blindly. Rather than assuming that a database entry is correct, you must verify that it matches the actual model number, datasheet, drawings, and string configuration to be used. Differences in model number, output rating, generation, and specification variations within the same series are particularly easy to overlook.

Also, the temperature coefficient is a setting that beginners tend to overlook. Because a solar module’s output decreases as temperature rises, temperature conditions have a greater impact in hot regions and for rooftop installations. Understanding how temperature-related losses are calculated in PVSyst makes it easier to explain reduced energy production in summer and the month-by-month results.

Module and PCS settings are closely related to string design. If the number of series-connected modules is too high, the voltage rise at low temperatures can become problematic, while if it is too low it can be disadvantageous for the PCS’s MPPT range. When the number of parallel strings is high, input current and the requirements of protective devices also need to be checked. The PVSyst manual notes that it is important not only to read these settings as device-specific screens but to understand them together with the string design.

In practice, even when the module and PCS settings are not directly visible in the final report, they provide the basis that supports the validity of the results. When asked to explain the generation output, being able to state which model numbers were used and which specification values were assumed helps ensure reliable PVSyst operation.

Loss settings are the items used to break down and examine the reasons for reduced power generation

A common stumbling block for beginners in the PVSyst manual is the loss settings. If you look only at the word "loss," you may be inclined to enter it as small as possible, but in practice this setting is meant to appropriately reflect the actual reductions in energy generation that occur. Underestimating losses will lead to an overestimation of generation and can undermine the credibility of proposals and revenue estimates. Conversely, overestimating them can make project evaluations unnecessarily strict.

Loss settings include various items such as temperature loss, wiring loss, mismatch loss, soiling loss, IAM loss, PCS conversion loss, and availability-related losses. Each of these losses is an element deducted as the generated energy moves from the theoretical value toward the actual output. In PVSyst results, they are often represented as a loss diagram and serve as important material for explaining where and by how much energy generation is reduced.

Temperature losses represent the reduction in output caused by an increase in module temperature. While stronger solar irradiance increases energy production, it also tends to raise module temperature. Rooftop installations often have poorer ventilation conditions and may be more affected by temperature rise than ground-mounted installations. When reading temperature-related settings in the PVSyst manual, you should interpret them in the context of site conditions, mounting structure, ventilation, and local ambient temperatures.

Wiring losses indicate power lost due to cable resistance. Because they vary with cable length, conductor cross-sectional area, current, and wiring route, it is important to verify consistency with the design drawings. Standard values may be used at the estimation stage, but as you approach detailed design, the actual wiring conditions need to be reflected. If wiring losses in PVSyst are large, it may be necessary to review cable lengths and cross-sectional areas.

Mismatch loss is the loss that arises from variations between modules and differences between strings. It is related to differences in module performance, differences in irradiance conditions, temperature differences, soiling, and the effects of shading. Soiling loss reflects reductions in power generation caused by dust, pollen, bird droppings, snow accumulation, and the surrounding environment. It is important to consider this together with local environmental conditions and cleaning schedules.

The most important thing when understanding loss settings is not to treat each loss simply as an "adjustment value" that reduces energy production. Each loss has its own physical, equipment-related, and operational significance. When reviewing loss items in the PVSyst manual, clarify why each loss occurs, which design or operational measures can reduce it, and whether it is something that should be explained when making a proposal.

Also, when looking at the loss diagram, you need to understand that the final energy yield is determined not by focusing only on the single largest loss but by the accumulation of multiple losses. If you learn to read the loss settings properly, you can use PVSyst’s results not as mere numbers but as design information that reveals opportunities for improvement.

Shading settings should consider not only the shaded area but also electrical effects

One item to pay particular attention to in the PVSyst manual is the shading settings. Shading is the phenomenon where sunlight is blocked by buildings, trees, racking, adjacent arrays, mountains, surrounding terrain, and similar obstructions. The official PVSyst documentation states that shading calculations are applied, on a time-step basis, to the beam, diffuse, and albedo components. For near-field shading, you need to consider both losses as a reduction in irradiance and losses arising from the electrical response of series-connected modules or parallel strings.

A common misconception among beginners regarding shading settings is to assume that a small shaded area implies small losses. In solar power generation, because modules and cells are connected in series, partial shading can cause electrical mismatch and affect output more than it appears. PVSyst’s help also explains that electrical shading losses are caused by the mismatch that occurs when shaded and unshaded modules are interconnected.

Shading can be broadly divided into far-field shading and near-field shading. Far-field shading refers to elements such as mountain ranges and distant buildings that affect periods when the sun is low in the sky. Near-field shading refers to the effects of relatively close obstacles on or around the site—such as on-site and neighboring buildings, trees, fences, transformer/substation equipment, and adjacent arrays. When reading the PVSyst manual, you should not lump these together as a single type of shade; instead, you need to consider separately which obstructions affect which times of day, which seasons, and which arrays.

In proximity shielding, creating or importing a 3D scene is important. If the positions, heights, shapes of buildings and obstacles and the distances to the array are inaccurate, shielding loss calculations will also be inaccurate. Especially for ground-mounted projects, array spacing, post-construction terrain, surrounding embankments, slopes, fences, and utility poles can have an impact. For rooftop projects, a key consideration is how extensively to model parapets, equipment, roof penthouses, and adjacent buildings.

The important point in shading settings is that the goal is not to model every detail. You don't need to input every small obstacle in detail. It is practical to prioritize obstructions that affect energy production and to distinguish between those with minor and major impact. When reading the shading-related settings in the PVSyst manual, you need to understand not only the steps for creating the 3D model but also the criteria for deciding which obstructions should be included in the calculation.

Furthermore, shading settings are closely related to the accuracy of the on-site survey. If obstacle heights and positions are judged solely from desk drawings, there may be discrepancies in how shadows actually fall. Organizing coordinates, elevations, obstacle positions, photos, point clouds, and survey data obtained on site before reflecting them in PVSyst will make the simulation assumptions clear. Using tools that make it easy to acquire on-site positional and terrain information—such as the LRTK, an iPhone-mounted GNSS high-precision positioning device—also helps clarify assumptions about shading and layout.

Shading settings have a major impact on power output, yet they are a parameter that is difficult to explain. For that reason, when reading the PVSyst manual you should not just look at the shape of the shading, but also understand it in terms of irradiance components, electrical losses, string configuration, and consistency with on-site surveys.

Report metrics are read to verify the validity of configured values

The final thing you should grasp in the PVSyst manual is how to read the report indicators. PVSyst outputs information as simulation results such as annual energy production, monthly energy production, loss diagrams, PR, Specific Yield, and energy balance. These not only show the results but also serve as checks to verify whether the input settings were appropriate.

Annual energy production is the metric that most often draws attention. However, looking only at the annual production does not allow you to judge whether the settings are good or bad. Even with the same annual production, the design may be strong in summer or in winter, generation may be concentrated in the mornings or evenings, or losses may be concentrated in different areas. When checking how to read the report in the PVSyst manual, it is important to consider not only the annual values but also the monthly values and the breakdown of losses.

PR is a representative indicator that shows how efficiently a power generation system converted the solar irradiance it received into electricity. A high PR does not necessarily mean a good design, nor does a low PR necessarily mean a bad design. It is influenced by weather conditions, temperature conditions, system configuration, loss settings, shading, PCS capacity, and other factors. When evaluating PR, you need to compare the value with the loss diagram and configuration settings to understand why it is at that level.

Specific Yield is used as an indicator to assess the energy generated per unit of installed capacity. It is useful when comparing projects with different capacities, but simply comparing projects with different meteorological or installation conditions can be misleading. When sharing PVSyst results internally, make sure the comparison targets have the same underlying assumptions even when using the same indicator.

Loss diagrams are especially useful for verifying the meaning of settings. This is because they let you break down how weather data, azimuth and tilt, equipment characteristics, temperature, wiring, soiling, shading, PCS constraints, and so on affected the final energy production. If any loss items are larger than expected, you need to go back and check those settings. For example, if shading losses are large, review the 3D scene, obstacle conditions, and string configuration. If wiring losses are large, check cable lengths, cross-sectional area, and layout planning. If temperature losses are large, review the installation method and ventilation conditions.

The purpose of reading report indicators is not to make the results look neat; it is to verify that the input settings align with the site and design conditions. When reading the report screens in the PVSyst manual, do not use the output numbers as they are; instead, treat them as an entry point to go back and check the settings.

Confirmation procedure to make configuration values easier to share internally

Once you understand the meaning of the settings in the PVSyst manual, the next important step is to organize them in a format that is easy to share within the company. In practice, if only the person who operated PVSyst understands the contents, reviews and approvals are likely to result in rework. To ensure that design, sales, construction, maintenance, and business-viability assessment staff can all review the results with the same assumptions, it is necessary to record the meanings of the settings and the reasons they were adopted.

First, what needs to be clarified is the purpose of the simulation. The required level of accuracy in the settings will vary depending on whether it is a rough estimate, for proposal materials, a study close to detailed design, or intended for explanations to financial institutions or external stakeholders. Standard values may be used at the conceptual stage, but at the detailed design stage alignment with equipment specifications, wiring plans, shielding conditions, and on-site data becomes more important.

Next, document the reasons for adopting the main setting values. Organize which location and data source were used for the meteorological data, which drawings or site conditions the azimuth and tilt angles were based on, which model numbers were selected for the modules and PCS, whether the loss settings are standard values or project-specific values, and which site information the shading conditions reflect. Keeping these records makes it easier to track differences when changing conditions and recalculating later.

A common mistake when sharing settings is to share only the PVSyst output report and omit an explanation of the input conditions. The report contains important information, but it may not fully convey why those settings were chosen. In internal reviews, it is important to share not only the numerical results but also the assumptions and the reasoning behind the decisions.

Also, when comparing multiple cases, you need to make clear which setting values were changed. If cases with different azimuth angles, PCS capacities, added shading conditions, and revised loss settings are mixed together, it will be impossible to understand the reasons for the differences in results. By clarifying the purpose of the comparison and organizing the changes one by one, the PVSyst results become easier to use for design decisions.

It's also important to verify things before recalculation. In PVSyst, even small changes to settings can alter the results, so before recalculating, record which items you modified and the conditions before and after the change. This is especially important when using the results in proposal materials or revenue estimates—if you later can't determine which conditions produced the results, the credibility of the documents will suffer.

To make settings easier to share internally, rather than explaining the PVSyst manual’s screen layout as-is, it is effective to replace it with decision-making units used in practice. Organizing it as meteorological conditions, layout conditions, equipment conditions, loss conditions, shading conditions, and result indicators makes it easier to communicate to people who do not operate PVSyst directly.

Summary

To understand the meaning of the settings in the PVSyst manual, simply filling in the input fields in order is not sufficient. Meteorological data determine the assumptions for energy production, the azimuth and tilt affect solar irradiation capture and seasonal variation, and the system capacity and DC/AC ratio indicate the scale of the installation and its constraints. Module and PCS settings directly influence the reliability of the calculated results, and loss settings are the items used to break down the reasons for reduced energy production. In shading settings, you need to consider not only the shaded area but also the electrical effects and the string configuration. Finally, by reading the report indicators you can verify whether the settings you entered were appropriate.

When using PVSyst in a professional setting, the important thing is not merely producing simulation results, but being able to explain those results. If you understand which input settings affect which numbers when looking at annual energy production, PR, loss diagrams, and monthly results, you will be more persuasive in internal reviews and proposal documents.

If you do not understand the meaning of the parameter values, you will not be able to explain why the numbers changed, and rework will occur every time recalculations or document revisions are made. On the other hand, if you organize the parameter values according to the flow of meteorology, layout, equipment, losses, shielding, and result indicators, it becomes easier to explain differences in conditions between projects and the impact of design changes.

Especially for projects involving shading and terrain conditions, the accuracy of on-site information greatly affects the assumptions used by PVSyst. Rather than relying on drawings alone, it is important to accurately capture the site’s location, elevation, obstructions, and terrain, and to reflect that information in the simulation settings. Using an iPhone-mounted GNSS high-precision positioning device such as LRTK can streamline site verification and coordinate management, making it easier to improve the accuracy of the assumptions handled by PVSyst.

The PVSyst manual is not merely a document for checking operational procedures. It can be used as a practical guide to interpret the meaning of settings, explain the rationale behind predicted energy yields, compare design proposals, and produce materials that are convincing both inside and outside the company. Start by using the seven items introduced here as a framework to check which results each setting affects, and apply PVSyst’s outputs to make more reliable design decisions.