6 Fundamentals of Array Design from the PVSyst Manual

Table of Contents

• Why Learn Array Design from the PVSyst Manual

• Basic Item 1: Array design is the foundation of power generation simulations

• Basic Item 2: Module conditions should match the actual equipment specifications and the design intent

• Basic Item 3: Azimuth and tilt angle affect annual power generation and seasonal characteristics

• Basic Item 4: The number of series and parallel connections is determined by matching voltage, current, and capacity

• Basic item 5: Do not judge the combination with the inverter solely by the overloading rate

• Basic Item 6: Verify design quality including shadows, losses, and margin conditions

• Practical workflow for advancing array design using the PVSyst manual

• Common Pitfalls and Checkpoints in Array Design

• Summary

Why Learn Array Design from the PVSyst Manual

In solar power generation simulations, not only meteorological data and site conditions but also the approach to array design have a major impact on the results. The purpose of reading the PVSyst manual is not simply to learn how to operate the interface; it is to understand which input items relate to energy production, losses, electrical matching, system capacity, and design comparison, and to build simulations based on sound evidence.

Array design is the process of determining the orientation and tilt of solar modules, how many to connect in each string, and which inverter to pair them with. At first glance it may seem like a matter of layout on drawings and equipment selection, but in PVSyst it becomes the actual calculation parameters for energy yield. Module count, string configuration, array orientation, tilt, inverter capacity, shading effects, and voltage changes due to temperature all interact with one another and are reflected in the final simulation results.

One thing beginners often trip over is thinking that entering the numbers shown on PVSyst’s screen means the work is done. However, in array design, proceeding without understanding the meaning of input values can result in overestimated energy production, string configurations that are difficult to realize in practice, or overlooking inverter-side constraints. By using the PVSyst manual, you can verify the meaning of each setting and reduce the gap between design conditions and analysis conditions.

This article organizes and explains the fundamentals of array design taught in the PVSyst manual into six points. Not only first-time PVSyst users, but also those with prior experience can, by revisiting the principles of array design, create simulations that are easier to explain, easier to compare, and more practical for use in the field.

Basic Item 1: Array design is the foundation of power generation simulations

When performing energy production simulations with PVSyst, the first thing to be aware of is that the array design forms the basis of the calculations. In solar power generation, even when using the same location, the same meteorological data, and the same modules, changes in array orientation and tilt, connection methods, or inverter configuration will affect the annual energy yield and how losses occur. Therefore, array design should not be treated as a mere input item but considered a premise for the entire simulation.

When reading the PVSyst manual, it's important to first clarify "which screen decides what." For example, the project's location and meteorological data set the assumptions for solar irradiance and temperature. Meanwhile, array design determines on which surfaces that irradiance is received, which modules convert it into electrical power, and which inverters convert it to AC. In other words, while meteorological conditions are inputs from the external environment, array design is an input describing the power generation equipment itself.

In array design, the first thing to confirm is the purpose of the simulation. Whether it is a rough project feasibility study, a comparison at the basic design stage, or a verification close to detailed design will change the required input accuracy and the items to be examined. At the rough estimation stage, comparisons may be made using representative module specifications and general loss conditions, but as you approach detailed design, you need to reflect specific details such as the specifications of the equipment to be adopted, string configuration, layout conditions, shading effects, and wiring losses.

What beginners often overlook is that creating an array in PVSyst is not the same as having a feasible real-world design. Just because PVSyst does not report an error does not mean the design is optimal from the perspectives of on-site construction, maintenance, or electrical engineering. Conversely, even if PVSyst issues a warning, understanding what it means allows you to distinguish between cases that are acceptable in design and those that should be reviewed.

The foundation of array design is consistency among input values. If the number of modules, installed capacity, number of modules in series, number of parallel strings, number of inverters, number of MPPTs, number of mounting surfaces, azimuth angle, and tilt angle are determined inconsistently, it becomes difficult to explain the simulation results. By consulting the PVSyst manual and being aware of which calculations each setting affects, you can use PVSyst not just as a series of screen operations but as a tool for design decision-making.

Also, array design affects downstream processes. Energy production reports, loss diagrams, monthly energy production, Performance Ratio, inverter losses, clipping losses, temperature losses, shading losses, etc., are all tied to the conditions of the array design. Therefore, rather than judging solely by the results, it is important to first confirm that the entered array design is appropriate.

Basic Item 2: Align module conditions with actual hardware specifications and design intent

At the core of array design are the specifications of the photovoltaic modules. In PVSyst, you select the module model and its electrical characteristics, and based on that it calculates energy production, voltage, current, temperature effects, and so on. When checking module settings in the PVSyst manual, it is important not to simply choose a similar product from the database, but to verify how closely it matches the specifications of the equipment that will actually be used.

Particularly important module specifications are nominal maximum output, open-circuit voltage, short-circuit current, maximum power operating voltage, maximum power operating current, temperature coefficient, cell configuration, and whether it is bifacial. These relate not only to energy yield but also to string design and inverter compatibility. For example, open-circuit voltage and temperature coefficient are related to checking the maximum voltage at low temperatures. The maximum power operating voltage is related to determining whether it falls within the inverter’s MPPT voltage range. Short-circuit current and operating current relate to input current constraints and considerations for the number of parallel strings.

In practice, people sometimes judge modules as "more or less the same" by looking only at differences in output. However, even modules in the same output range can require different string configurations depending on whether they are voltage-type or current-type, on differences in cell count or internal construction, or on differences in temperature coefficients. When selecting modules in PVSyst, you should not rely solely on the manufacturer and model number; you need to cross-check the key values on the datasheet.

Module specifications should also be aligned with the design intent. For example, in roof-mounted installations where available area is limited, the design may use high-output modules to secure the required capacity. In ground-mounted installations where racking pitch and constructability are prioritized, module dimensions and layout efficiency can become important. In snowy or high-temperature regions, not only output but also load-bearing capacity, temperature characteristics, and their relationship with installation angle should be considered.

When using the PVSyst manual, it is helpful to understand which screens the module settings are used for energy production calculations and which screens they are used for electrical consistency checks. Module selection is not a standalone setting; it is linked to array capacity, string configuration, inverter selection, loss settings, and shading analysis. In particular, if you change the module model later, you must recheck whether the numbers of series and parallel connections can remain the same.

What you should be aware of is that the information in the PVSyst database does not necessarily fully match the latest actual equipment specifications. In practice, you may cross-check against manufacturers' datasheets, design drawings, estimate specifications, and the models planned for procurement, and, as needed, create user-defined data or explicitly state that the conditions are approximate. When explaining simulation results internally or externally, it is important to record which module conditions were used.

Module conditions are the starting point for energy yield simulations. If these remain unclear, no matter how detailed the loss settings or shading analysis are, the reliability of the results will not improve. Aligning module specifications with the design intent, while referring to the PVSyst manual, is the basic principle of array design.

Basic Item 3: Azimuth and Tilt Angles Affect Annual Energy Production and Seasonal Characteristics

The next important factors in array design are the azimuth angle and the tilt angle. In PVSyst you enter the direction and the angle at which the photovoltaic modules are installed. Because this setting is directly related to the solar irradiation received, it has a major impact on annual energy production, monthly output, and seasonal generation trends. When reviewing the array surface settings in the PVSyst manual, it is important to understand the relationship between installation conditions and generation characteristics, rather than simply entering angle values.

The azimuth indicates which direction the module surface faces. Generally, in many regions the closer a module is to facing south, the higher its annual energy production tends to be, but south-facing is not necessarily optimal for every project. For self-consumption solar PV systems, east- or west-facing generation may be prioritized to match morning or afternoon demand. For rooftop installations, constraints from the building’s shape and the roof plane’s orientation may require setting multiple arrays that are not south-facing.

The tilt angle indicates how far the module is inclined from the horizontal plane. Changing the tilt angle alters the amount of solar radiation received throughout the year. A lower tilt angle can sometimes increase generation in summer, while a higher tilt angle can make it easier to receive sunlight in winter. In snowy regions, the tilt angle may be chosen taking into account snow shedding and the impact on winter generation. Conversely, for roof-mounted installations, the angle cannot always be freely chosen because it must match the roof pitch.

One thing to be careful about in PVSyst is when there are multiple installation surfaces. For example, in projects where the east and west faces, the south and north faces, or each roof surface have different tilt angles, treating them as a single array surface can lead to discrepancies with reality. While checking the PVSyst manual, it is necessary to understand how to represent systems with multiple orientations and tilts. Since each surface has different power generation characteristics, allocation to inverters and MPPTs must also be considered.

Azimuth and tilt angle are also related to shading effects. For ground-mounted installations, as the tilt angle increases, the shadows between arrays become longer, which may require widening the racking pitch. For rooftop installations, shadows from parapets, ridgelines, adjacent buildings, HVAC equipment, chimneys, antennas, and so on can fall onto the array surface. Optimizing angles solely based on annual irradiance can, in practice, be disadvantageous due to shading losses and constraints on the number of modules that can be installed.

Also, azimuth and tilt angles affect not only the total energy production but also the shape of the generation curve. South-facing systems tend to have generation peaks around midday, east-facing systems skew toward the morning, and west-facing systems toward the afternoon. For self-consumption projects, a design that aligns generation times with demand can be more advantageous even if annual generation is slightly lower. In PVSyst array design, it is important to check not only annual energy production but also monthly and hourly trends.

Azimuth and tilt angles are parameters that designers should set deliberately. By referring to the PVSyst manual and, rather than simply entering "standard angles," setting them with consideration of land conditions, roof conditions, demand conditions, shading conditions, and construction conditions, the explanatory power of the simulation results is increased.

Basic Item 4: Series and parallel counts are determined by matching voltage, current, and capacity

When learning array design from the PVSyst manual, one of the most practically important items is the number of modules in series and the number of modules in parallel. In photovoltaic power generation, multiple modules are connected in series to form a string, and those strings are connected in parallel and fed into the inverter. If this configuration is not appropriate, not only can power generation decrease, but the inverter's input conditions may be violated and electrical design problems may arise.

When determining the number of modules in series, the main thing to check is voltage. When modules are connected in series, their voltages add. Therefore, the more modules in series, the higher the string voltage. What becomes important here are the open-circuit voltage at low temperatures and the operating voltage at high temperatures. At low temperatures, module voltage increases, so you need to ensure it does not exceed the inverter’s maximum input voltage. Conversely, at high temperatures the operating voltage decreases, so you must check that it does not fall below the MPPT’s operating voltage range.

When determining the number of parallel strings, the main thing to check is the current. When strings are connected in parallel, their currents add. Therefore, the current flowing into the inverter increases as the number of parallel strings increases. Inverters have an upper limit for input current, and there may be constraints per MPPT or per input terminal. Even if you can configure it in PVSyst, it is essential to confirm that the actual device specifications present no issues.

Capacity matching is also important. The DC-side capacity is determined by the number of modules and their output, which sets the ratio relative to the inverter's rated AC output. In general, in solar PV systems the DC capacity is sometimes designed to be larger than the AC capacity, but if it is excessively large, peak-time output limitation—so-called clipping—may increase. Conversely, if the DC capacity is too small, the inverter may not be fully utilized. In PVSyst, you can check this kind of capacity balance in terms of energy production and losses.

When deciding on series and parallel string counts, it is important not simply to allocate the total number of modules, but also to ensure that the strings connected to the same MPPT have similar conditions. Grouping strings with different azimuths or tilt angles, strings that experience very different shading, or strings with differing numbers of modules under the same MPPT can increase mismatch losses and prevent the expected energy production. You need to consider how to arrange the array on an MPPT-by-MPPT basis while consulting the PVSyst manual.

Also, for rooftop installations and projects with complex terrain, it may not be possible to configure all strings with the same number of modules. In such cases, it is necessary to consider how far to treat conditions as identical, how much difference to tolerate, and what design compromises to accept. PVSyst is a tool that helps with this assessment, but ultimately decisions must be made by taking equipment specifications, electrical design, constructability, and maintainability into account.

Setting the number of series and parallel strings is one of the areas in array design where "calculation" and "practice" particularly intersect. By using the PVSyst manual to understand the relationships between voltage, current, capacity, MPPT, and temperature conditions, you will find it easier to interpret the meaning of warnings and errors. As a result, you can move toward a design that is not only higher in energy yield but also more feasible.

Basic Item 5: Do not judge inverter matching solely by the overloading ratio

In array design, it is necessary to appropriately combine the module-side and inverter-side conditions. When learning from the PVSyst manual, be careful not to judge inverter selection solely by the oversizing ratio. The oversizing ratio is an important metric, but if you evaluate a design only by that, you may overlook factors such as voltage range, input current, MPPT configuration, orientation differences, shading, and output limitations.

The first thing to check when pairing with an inverter is the input voltage range. The string voltage is determined by the number of modules connected in series, and that voltage needs to fall within the inverter’s MPPT operating range. Open-circuit voltage rises at low temperatures, and operating voltage falls at high temperatures. In other words, you cannot judge based only on the voltage under standard test conditions. Consider the installation site’s ambient temperature conditions and verify that the voltage will remain within the appropriate range throughout the year.

The next important factor is the input current. Some recent high-output modules have very large currents. If these do not match the inverter’s maximum input current or short-circuit current limit, you may be unable to increase the number of parallel strings, or you may need to revise the allocation of input terminals. If PVSyst issues a warning, don’t simply change the numbers to make it disappear; instead, confirm which constraint is being violated.

MPPT configuration should not be overlooked. If an inverter has multiple MPPTs, connecting arrays with different orientations, tilts, or shading conditions to separate MPPTs can sometimes improve generation efficiency. For example, rather than putting east- and west-facing strings on the same MPPT, separating them onto different MPPTs makes it easier to control each according to its own generation characteristics. Conversely, if the number of MPPTs is insufficient, design priorities must be determined.

The oversizing ratio is often used as the ratio of DC-side capacity to AC-side capacity. Increasing the oversizing ratio makes it easier to effectively use the inverter during times or seasons of low solar irradiance, but it also makes output clipping more likely at peak times. In PVSyst, you can check losses corresponding to inverter losses and clipping, so rather than simply looking at the oversizing ratio value, you need to confirm how much loss is occurring as a result.

Also, the combination with the inverter affects constructability and maintainability. Designs with too many strings, overly complex input assignments, difficulty managing by roof surface, or that are hard to trace during future inspections may be valid in simulation but difficult to handle in practice. While using the PVSyst manual to verify electrical compatibility, it is important to also confirm that the drawings, panel configurations, cable routes, and maintenance/inspection aspects are practical.

In inverter selection, a configuration that maximizes energy yield is not always optimal. Equipment cost, installation space, maintainability, grid interconnection conditions, output control, and potential for future expansion must also be considered. PVSyst is an effective tool for quantitatively comparing energy yield and losses among these factors. By evaluating not only the oversizing ratio but also voltage, current, MPPT, losses, and operating conditions, you can achieve an array design that is closer to real-world practice.

Basic Item 6: Verify design quality including shading, losses, and margin conditions

To improve the completeness of array design, you need to check not only combinations of modules and inverters but also shading, losses, and design margins. When learning array design from the PVSyst manual, you should focus especially on the verification items that come after the basic inputs are completed. This is because, in real photovoltaic power generation, output is not produced only under ideal solar irradiance conditions; various loss factors accumulate to determine the actual energy output.

The impact of shading is one of the most evident loss factors in array design. For ground-mounted systems, shading from front-row arrays onto rear-row arrays, and shading from nearby buildings, trees, and terrain are problematic. For rooftop installations, parapets, level changes, adjacent buildings, equipment, lightning rods, and piping can create shading. Shading not only blocks solar radiation but can also cause electrical mismatch when some modules within a string are shaded.

In PVSyst, you can evaluate the impact of shading using concepts such as near shading, far shading, and 3D scenes. However, shading analysis depends on the accuracy of the input model. If the height or position of obstacles, array spacing, or module layout differ from reality, the shading loss results will also change. Therefore, when setting shading while referring to the PVSyst manual, you need to verify not only the on‑screen operations but also the accuracy of the underlying drawings and site conditions.

Loss conditions are also important. In PVSyst, various losses—such as temperature losses, wiring losses, mismatch losses, soiling losses, angle-of-incidence losses, and inverter losses—are reflected in the results. These losses are closely related to array design. For example, with low tilt angles, soiling and drainage effects can become a concern. In layouts with long cables, wiring losses may increase. In hot regions, temperature losses tend to be larger, and ventilation conditions and racking details should also be considered.

Margin conditions refer to the safety-margin considerations in design. For example: whether there is headroom in the inverter’s upper limit relative to the maximum voltage at low temperatures, whether there is sufficient headroom in the input current, whether the system remains valid if the number of modules or the module type is changed, and whether alternative equipment can be used during future replacements. A configuration that only just works in PVSyst may be vulnerable to changes in actual practice. During the design phase, it is important not only to pursue energy yield but also to consider configurations that include a certain margin.

Also, shading and loss settings also affect how you explain results in the report. If the energy production is lower than expected, you will not be able to identify design improvements unless you can explain which losses are large. Conversely, even if the energy production appears high, lax loss settings may mean it is overestimated. It is important to make a habit of interpreting PVSyst’s loss diagram to check at which stages and to what extent losses occur.

By checking shadows, losses, and margin conditions, an array design is transformed from a mere layout proposal into a design that can explain energy production and viability. When using the PVSyst manual, you should not be satisfied simply after completing the basic inputs; it is necessary to carefully verify, while reviewing the results screen and loss displays, that the design conditions are reasonable.

Practical workflow for advancing array design using the PVSyst manual

When carrying out array design in PVSyst, rather than indiscriminately entering data into the screens, it is more efficient to organize the conditions according to the project workflow. The first thing to do is confirm the project's assumptions. Organize the installation location, meteorological conditions, installation method, roof or land constraints, expected system capacity, modules planned for use, inverters planned for use, grid interconnection conditions, and the purpose of the energy production assessment. If you input data into PVSyst while these assumptions remain vague at this stage, large corrections will be necessary later.

Next, determine the conditions of the installation surfaces. Organize the azimuth, tilt angle, number of installation surfaces, array spacing, and constraints for each roof surface. For ground-mounted installations, consider the site shape, racking pitch, aisles, maintenance space, and terrain slope. For roof installations, roof orientation, pitch, obstacles, load constraints, evacuation routes, and inspection space are also relevant. In PVSyst, decide how much of these conditions to reproduce in detail based on the project’s objectives.

Next, configure the modules and inverters. Here, verify the equipment specifications based on the datasheets and cross-check them with the PVSyst database information. If the selected equipment has not been finalized, representative equipment may be used, but in that case it should be assumed that the specifications will be rechecked against the actual equipment later. Once the modules and inverters are chosen, consider the number of series strings, number of parallel strings, and MPPT assignments, and verify the compatibility of voltage, current, and capacity.

Next, set shadows and losses. For initial assessments, you can compare under simplified conditions, and for detailed assessments you can reflect 3D scenes and specific obstacle conditions. The important thing is to distinguish which losses are treated as standard values and which are set as project-specific conditions. It is not necessary to input everything in detail; practically, you should prioritize improving accuracy for the factors that have the greatest impact on the results.

After running the simulation, check not only the annual energy production but also the monthly energy production, Performance Ratio, loss diagram, inverter losses, shading losses, temperature losses, wiring losses, and so on. In particular, when comparing design proposals, it is important not just to look at simple differences in energy production but to be able to explain why those differences occurred. By interpreting whether the difference is due to azimuth angle, tilt angle, oversizing ratio, or shading losses, you obtain results that can be used for design decisions.

Finally, record the input conditions and the results. PVSyst reports are convenient, but in practice, organizing separately which assumptions were used for the simulation makes internal review and customer explanations easier. By clarifying the module model, inverter model, installation angle, capacity, loss conditions, shading conditions, and differences between comparison scenarios, it becomes easier to recalculate if conditions change later.

The PVSyst manual can be used not only to confirm how to operate the software but also as a reference to support such practical workflows. By understanding the meaning of the screens and linking design conditions to input fields, PVSyst becomes more than just calculation software—it becomes a tool that enhances the quality of design studies.

Common Mistakes and Checkpoints in Array Design

When designing arrays with PVSyst, there are points that are easy to overlook for both beginners and experienced users. One common mistake is focusing only on matching the number of modules to the inverter capacity, while insufficiently checking voltages and currents. Even if the capacity ratio alone appears acceptable, the maximum voltage at low temperatures can be too high, or the input current may be too close to the inverter’s specifications. You need to check the warnings and numerical values in PVSyst and understand which condition is acting as the constraint.

Another common issue is oversimplifying arrays with multiple orientations. On rooftop installations, modules may be placed on several planes facing east, west, south, and north, but combining these into a single representative angle can lead to discrepancies with the actual generation profile. This is especially significant for east–west faces, where the timing of generation peaks differs, creating an important difference when evaluating self-consumption systems. It is important to check the PVSyst manual and consider how multiple faces should be handled.

Failing to account for shading conditions is a common mistake. Obstacles that appear small on site can cast long shadows when the sun is low in winter. Shadows from rooftop equipment and parapets can affect not only annual energy production but also cause drops in generation during specific times. Underestimating shading can lead simulations to overestimate production compared to actual performance.

Care should be taken about continuing to use the loss settings at their default values. Standard values are acceptable for initial assessments, but in detailed studies there are items that should be reviewed according to the project. For projects with long wiring distances, wiring losses are important; in environments where dust or bird fouling is expected, soiling losses matter; and for rooftop installations that tend to become hot, temperature losses are critical. PVSyst's loss settings are an important factor for realistically estimating energy production.

Also, there are cases where a design proposal that yields higher energy production is taken as the optimal solution as-is. In practice, decisions are made not only on energy production but also on constructability, maintainability, cost, equipment procurement, grid constraints, available installation space, and safety. For example, even if energy production is slightly higher, it may be better to avoid a design with a complex string configuration that is difficult to maintain or a layout that is vulnerable to shading. PVSyst results are material for decision-making, not the design decision itself.

As check points, first verify that the input conditions match the drawings and equipment specifications. Next, check that the voltage, current, capacity, and MPPT allocation are reasonable. After that, confirm that the azimuth and tilt angles, shading, and loss conditions reflect the actual conditions of the project. Finally, review the breakdown of losses in the simulation results and check for any losses that are unnaturally large or too small.

The biggest advantage of using the PVSyst manual is that it allows you to carry out these checks systematically. The more familiar you become with the operation, the more you’ll want to finish the inputs quickly, but in array design the quality of the checks determines the reliability of the results. Especially for simulations submitted externally, it is important to be able to explain the assumptions and the rationale for the settings.

Summary

The basics of array design taught in the PVSyst manual are not simply the task of placing modules and producing energy. Array design is the foundation of energy production simulations and involves comprehensively organizing equipment specifications, installation angles, string configurations, inverter matching, shading, losses, and margin conditions. Because each input value affects the results, it is essential not only to operate the interface but also to understand the meaning of the design parameters.

In Basic Item 1, we confirmed that array design serves as the premise for the entire power generation simulation. In Basic Item 2, we outlined the importance of aligning module conditions with actual equipment specifications and design intent. In Basic Item 3, we observed that azimuth and tilt angles affect annual energy generation and seasonal characteristics. In Basic Item 4, we explained that the number of series and parallel strings must be considered in terms of voltage, current, and capacity alignment. In Basic Item 5, we explained that when combining with inverters you should not judge solely by the oversizing ratio but also check MPPT and input constraints. In Basic Item 6, we summarized the importance of verifying design quality, including shading, losses, and margin conditions.

When mastering PVSyst, it is important not to focus solely on the energy production numbers. By interpreting why a result occurred, which input conditions are having an effect, which losses are large, and which design options have room for improvement, the simulation becomes a document useful in practice. Conversely, presenting only the energy production figures while the rationale for the input conditions remains unclear makes it difficult to use for design decisions or for explaining things to clients.

In array design, it is important not only to pursue ideal energy output but also to create a configuration that can actually be constructed, operated, and explained. By referring to the PVSyst manual, understanding the meaning of each setting, and cross-checking with equipment specifications and on-site conditions, you can produce more reliable simulations. In solar power system design studies, mastering the fundamentals of array design is the first step to improving the accuracy of energy yield assessments and the quality of proposals.