【How to Determine Array Configuration in PVSyst｜6 Steps for Beginners】

Table of Contents

• What to understand before deciding the array configuration in PVSyst

• Step 1: Organize site conditions and design objectives

• Step 2: Check the basic specifications of modules and inverters

• Step 3: Determine the number of modules in series from voltage conditions

• Step 4: Adjust the number of parallel strings and the capacity ratio

• Step 5: Split the array according to azimuth, tilt, and shading conditions

• Step 6: Finalize the configuration after reviewing simulation results

• Common points where beginners tend to get stuck with array configuration

• Survey data required to correctly reflect site conditions

• Summary: PVSyst array configurations are affected by the accuracy of site information

What to understand before deciding the array configuration in PVSyst

In PVSyst, the array configuration refers to the settings that determine how photovoltaic modules are combined to form a power generation system. Specifically, it relates to the module type, number of modules in series, number of parallel strings, the inverter to which they are connected, azimuth, tilt angle, and how sub-arrays are divided, among other factors. Beginners often think of the array configuration as "the place to input the number of modules," but in professional practice that alone is insufficient.

In solar power generation, connecting modules in series raises the voltage, while connecting them in parallel increases the current and capacity. Converters have allowable input voltage and current ranges, and configurations that do not fall within those ranges are not practical designs. PVSyst calculates energy production and losses while checking such electrical compatibility. Therefore, even if no errors appear on the screen, it is necessary to verify that the design matches the intended real-world configuration.

Also, array configuration affects not only energy production but also how losses occur. Even with the same total capacity, forcibly treating surfaces with different orientations as a single array can result in calculations that are more simplified than reality. If you aggregate areas with different shading patterns too much, the assessment of shading losses becomes coarse. Conversely, dividing them too finely makes management more complex and can lead to input errors. In PVSyst, it is important to configure arrays at an appropriate level of granularity, considering both the actual electrical design and ease of handling in the simulation.

What beginners should first be aware of is not to try to decide the array configuration perfectly on the first attempt. If you proceed by clarifying the design objectives, checking equipment specifications, tentatively setting the number of modules in series and in parallel, and then adjusting while reviewing simulation results, the rationale for your decisions becomes clear. Because PVSyst lets you compare design proposals while checking the results, it is important not to be overly fixated on the initial input values and to consider multiple options.

Step 1: Organize site conditions and design objectives

The first step in deciding the array configuration is to organize the site conditions and design objectives. Before selecting modules or inverters in PVSyst, you need to be clear about what kind of power plant you are envisioning in the first place. Whether it is rooftop, ground-mounted, on a slope, whether you want to maximize capacity on a limited site, or prioritize stable power output while minimizing the impact of shading, the approach to array configuration will change.

For example, in projects with limited area, there is a tendency to try to install as many modules as possible. However, if you pack them too tightly, inter-row shading increases and the annual energy generation growth can slow. Installed capacity may increase, yet the energy generation per unit capacity can decrease. Conversely, arranging modules with more spacing makes it easier to reduce shading losses, but you may not be able to fully utilize the site. Decisions like these should be organized as assumptions for the array configuration.

The design purpose is also important. At the preliminary estimation stage, a somewhat simplified array configuration can still convey the overall picture. However, when the simulation is to be used for internal approvals, business feasibility studies, pre-construction checks, or verification of procurement specifications, a configuration that more closely reflects reality is required. If modules have multiple orientations or mounting surfaces, you must decide how finely to subdivide them. If you want to obtain high-accuracy results in PVSyst, it is essential to decide before entering data “what this simulation is intended to determine.”

When organizing site conditions, also check buildings, trees, slopes, equipment, fences, and other items that block solar radiation. Especially for ground-mounted installations, the terrain’s undulations and land development plans affect array layout. A layout based on flat land and a layout reflecting actual elevation differences change how shadows form and how to consider row spacing. Before deciding the array configuration in PVSyst, understanding the on-site conditions as well as the drawings can reduce modifications in later stages.

At this stage you do not need to decide the exact number of modules in series right away. First, organize the approximate number of modules that can be installed, the number of installation surfaces, candidate azimuths and tilt angles, areas where shading is a concern, and the space where inverters can be grouped together. If you prepare this much before entering PVSyst, you will be able to assemble the array configuration as a design decision rather than simply performing data-entry work.

Step 2: Confirm the basic conditions of modules and converters

Next, confirm the basic specifications of the solar PV modules and inverters to be used. In PVSyst you can select registered equipment data to build an array configuration, but beginners should be careful not to assume everything is correct just because they selected a device. Verify the actual model numbers to be used and the voltage, current, power output, temperature coefficients, maximum input ratings, and other items listed on the datasheets, and check that they match the simulation settings.

Important module-side parameters include output at standard test conditions, open-circuit voltage, maximum power operating voltage, short-circuit current, maximum power operating current, and temperature coefficients. In particular, when determining the number of modules in series, you need to account for the increase in open-circuit voltage at low temperatures. In colder regions, the maximum voltage can be higher even with the same number of modules in series and may approach the inverter's input limit.

On the converter side, check the maximum input voltage, operating voltage range, maximum input current, number of input circuits, rated output, and the approach to allowable overloading. If PVSyst shows warnings, possible causes include too many modules in series, too few modules in series, too many parallel strings, or an extreme capacity ratio. Rather than simply clearing the warnings, it is important to understand why the warning has appeared.

What beginners often find confusing is the relationship between the total module capacity and the inverter capacity. Designs that make the PV array's DC capacity larger than the inverter's AC capacity are commonly used, but making it too large can increase losses due to output curtailment and inverter-side limitations. Conversely, if the capacity ratio is made too small, the inverter may not be utilized fully. The optimal capacity ratio depends on irradiance conditions, temperature conditions, installation tilt, orientation, shading, and project objectives, so it is practical to decide by comparing scenarios in PVSyst.

What is important in this step is to treat the equipment specifications as constraints on the array configuration. Instead of deciding the number of modules first and then forcing them to match the inverter, check the range of voltages and currents the inverter can safely accept, and assemble the number of modules in series and parallel within that range. PVSyst can help verify the consistency of the input values, but the final decision must be made by the designer.

Step 3: Determine the number of cells in series from the voltage conditions

Among array configuration parameters, the number of modules in series is particularly important. The number of modules in series indicates how many modules are connected in a single string. Because connecting modules in series increases the voltage, the greater the number of modules in series, the higher the string voltage becomes. When deciding the array configuration in PVSyst, first check whether this number of modules in series falls within the inverter's input range.

When deciding the number of modules in series, you need to consider both the maximum voltage at low temperatures and the operating voltage at high temperatures. At low temperatures a module's open-circuit voltage rises. Therefore, you must ensure that the string voltage on cold mornings does not exceed the inverter's maximum input voltage. Conversely, at high temperatures the operating voltage falls. If the number of modules in series is too low, the inverter's operating voltage range may not be met during hot periods, which can reduce power generation efficiency.

In PVSyst, when you enter the number of modules in series, warnings or cautions regarding the voltage range may be displayed. Beginners tend to focus only on red notices or warnings, but it’s important to check the margin even if no warning appears. A configuration that is too close to the maximum voltage can become risky with only slight changes in conditions. Likewise, a configuration that is too close to the lower limit of the operating voltage range can become unstable during summer or in high-temperature regions.

In practice, the number of modules in series affects not only equipment specifications but also constructability. If all strings can be arranged with the same number of modules in series, design drawings and construction management become easier to understand. Even when the number of modules differs by installation surface, adjusting the layout so that the series module count is as uniform as possible will make later verification easier. However, if roof shape or obstructions make it impossible to use the same count, measures such as dividing the system into sub-arrays are required.

When deciding the number of modules in series in PVSyst, first enter a candidate number of modules, check the displayed voltage range, and adjust as needed by increasing or decreasing one module at a time. If you try to force a larger capacity by raising the series module count too much, you may hit the voltage upper limit at low temperatures. Conversely, if you reduce the series module count too much out of an overly conservative approach, you may lack sufficient operating voltage. Because the series module count affects both energy yield and safety, it should be one of the first items carefully decided in the array configuration.

Step 4: Adjust the number of parallels and the capacity ratio

Once you have decided the number of modules in series, next adjust the number of strings in parallel. The parallel count refers to how many strings, each connected in series in the same way, are placed side by side. Increasing the number of parallel strings increases the total number of modules and the DC capacity. In PVSyst, the overall capacity of the sub-array is determined by the combination of the series count and the parallel count.

When considering the number of parallel strings, the important factors are the inverter's input current and capacity ratio. Increasing the number of strings increases generation capacity, but it also increases the input current. Configurations that exceed the inverter's allowable range are not practical. If PVSyst issues a warning about input current, it is necessary to respond by reducing the number of parallel strings, splitting the inputs, or reviewing the inverter configuration.

Capacity ratio is an indicator that looks at the relationship between the DC capacity on the solar side and the AC capacity on the inverter side. If the capacity ratio is low, the module capacity is small relative to the inverter’s capability, and the system may not be able to fully utilize the equipment. If the capacity ratio is high, during periods of strong sunlight the inverter can hit its output limit, increasing the amount of curtailed generation. However, a high capacity ratio is not necessarily bad: DC capacity is sometimes designed somewhat larger to boost generation in the morning, evening, and on cloudy days with the aim of increasing annual output.

Beginners should be careful not to judge a system solely by the capacity ratio. What matters is to look at the balance between annual energy production, losses, losses due to inverter limitations, and equipment utilization. In PVSyst, various losses are shown in the simulation results, so by comparing cases with different parallel string counts you can check how much benefit increasing capacity provides. Even if you add modules, if shading losses or output limitations become too large, the expected increase in energy production may not materialize.

When adjusting the number of modules in parallel, it is also important to ensure consistency with the number that can actually be placed on the installation surface. Even if the string count looks neat on paper, the site's shape, walkways, maintenance clearances, and surrounding equipment can prevent that arrangement. The number of modules entered into PVSyst is meaningless unless it corresponds to the actual layout. Especially on roofs or complex sites, how to deal with leftover modules becomes an issue. Rather than forcing in fractional or leftover modules, splitting arrays or revising the layout will often result in a configuration that is more natural both electrically and operationally.

When adjusting the number of parallel strings in PVSyst, change the parallel count while keeping the number of modules in series fixed, and observe the total capacity, the capacity ratio with the inverter, warning messages, and changes in losses. This task is not completed in a single pass. It is important to create multiple candidates and, by comparing differences in energy yield and losses, narrow them down to configurations that are easy to explain in practice.

Step 5: Divide the array according to azimuth, tilt, and shading conditions

In array configuration, it is necessary to consider not only the electrical number of series and parallel connections but also the installation surface conditions. Treating groups of modules with different azimuth or tilt angles as the same array can fail to adequately represent actual power generation behavior. In PVSyst, by separating areas with different installation conditions into sub-arrays, you can achieve simulations that are closer to reality.

For example, when placing modules on a building roof on south-facing and east-facing surfaces, each surface receives sunlight differently. Some faces receive stronger irradiance in the morning, some at midday, and some in the afternoon, and the timing of the generation peak also changes. Combining these into a single set of conditions results in averaged conditions, which can deviate from the actual generation characteristics. Even for ground-mounted installations, it is more natural to treat subarrays separately when the slope orientation changes partway or when the tilt differs due to site grading.

Shadow conditions are also an important criterion when deciding array groupings. Even within the same power plant, there are areas that are shaded only in the morning, areas where shadows extend in the afternoon, and areas that are affected by shadows only in winter. Treating groups of modules that clearly experience different shading patterns the same makes the assessment of shading losses less accurate. When performing shading analysis in PVSyst, separating areas that receive shading from those that are less likely to be shaded makes interpreting the results easier.

However, dividing subarrays too finely makes data entry and management complicated. If a beginner tries to treat every small difference as a separate array, the configuration becomes hard to understand and it becomes difficult to verify the numbers later. In practice, it is important to prioritize splitting based on differences that significantly affect power generation. Cases such as substantially different azimuths, different tilt angles, clearly different shading conditions, or different inverters to be connected are candidates for separation into subarrays.

When dividing arrays in PVSyst, also confirm consistency with the actual electrical system. Even if they are separated in the simulation, if the real connections are unified you need to consider whether that treatment is appropriate. Conversely, if they are managed as separate inputs or separate circuits in reality, combining them in the simulation will make it difficult to explain the results. A sub-array is a setting that links the on-site layout, shading, orientation, and electrical system. Divide them with attention not only to the visible layout but also to how they are actually connected.

Step 6: Review the simulation results and finalize the configuration

After setting the number of modules in series, the number in parallel, the capacity ratio, and the sub-array division, run the simulation and review the results. In PVSyst, the array configuration you entered will display the annual energy production, various losses, performance indicators, and monthly energy production. The task of defining the array configuration does not end with entering it; it also includes examining the results and judging their validity.

First, what you should check is whether there are any warnings or errors. If messages about voltage range, current range, capacity ratio, converter limitations, or the like are displayed, read their contents and determine whether they are acceptable from a design standpoint. Beginners tend to focus solely on clearing warnings, but it is important to understand what the warnings mean. For example, even if a notice appears that the capacity ratio is high, it can remain a candidate if, after looking at annual power generation and output-limitation losses, it meets the business objectives.

Next, check the breakdown of losses. Examine losses due to module temperature, wiring, conversion, shading, and those related to output limits, and confirm that there are no items that are excessively large. If only a particular loss is large, there may be an issue with the array configuration or installation conditions. For example, if increasing capacity raises energy production but also increases losses from output limits, it may be worth reviewing the capacity ratio. If shading losses are larger than expected, reconsider the layout, row spacing, and sub-array division.

Checking monthly power generation is also important. Even if the annual generation looks fine, there may be significant losses in particular seasons. Trends such as larger inter-row shading during winter periods when the sun’s altitude is low, stricter voltage conditions during high summer temperatures, or shadows from specific directions affecting mornings and evenings are easier to identify by looking at monthly and time-of-day results. Before finalizing the array configuration, check not only the annual totals but also seasonal behavior.

When comparing multiple proposals, we look at the number of modules, the number in series, the number in parallel, the capacity ratio, annual energy production, main losses, and shading conditions from the same perspective. The option with the highest energy production is not always the best. A configuration that is easier to install, easier to maintain, easier to explain, or that provides extra safety margin may be chosen. PVSyst results are material for decision-making, and it is important to make judgments by considering the overall balance of the design.

When you finalize the array configuration, be prepared to explain why you chose that number of modules in series, why you chose that number in parallel, and why you divided the subarrays. For internal reviews and client briefings, simply saying "these are the results calculated by PVSyst" is not sufficient. Organizing the design conditions, input parameters, comparison criteria, and the reasons for selection will increase the reliability of the simulation results.

Common pitfalls beginners encounter in array configurations

What beginners often struggle with in PVSyst’s array configuration is that the input fields span both electrical design and layout planning. Unlike items such as site settings or meteorological conditions, which can be completed by entering them in sequence, the array configuration must be decided by moving back and forth among multiple conditions. For that reason, it can be hard to know where to start at first.

One common stumbling block is trying to match only the total capacity. For example, even if you adjust the number of modules to approach the target capacity, it won’t be a practical configuration if the series count doesn’t fall within the converter’s voltage range. Total capacity is important, but it only matters once the series count, parallel count, voltage, current, and capacity ratio are all aligned. If you first satisfy the electrical feasibility conditions and then work toward the target capacity, you’ll have less confusion.

A common stumbling block is how to divide subarrays. You may wrestle with decisions such as whether it’s acceptable to group surfaces with different azimuth angles, whether to separate areas with only slightly different tilts, or what to do when shadows fall on only part of a surface. As a rule, it’s easier to interpret results if you separate ranges whose power-generation behavior is clearly different. However, if the differences are small and the practical impact is limited, it can be acceptable to treat them together. The important thing is to be able to explain the rationale for whether or not you split them.

Handling warning messages is another area where beginners tend to get confused. In PVSyst, notices and warnings may appear for input values. If you become worried by these and change numbers arbitrarily to clear the warnings, you may unintentionally undermine the design intent. When a warning appears, it is important to determine which condition is causing it and to isolate whether you should review the number of series strings, the number of parallel strings, inverter selection, the capacity ratio, or the temperature conditions.

Also, the on-site layout and the settings in PVSyst often do not match. Even if it appears neatly arranged on the drawings, there are in reality constraints such as access ways, maintenance spaces, equipment storage areas, fences, slopes, and drainage facilities. If you determine the array configuration without adequately reflecting site conditions, you may have to change the number of modules or strings later. It is important not to rely solely on PVSyst inputs; always verify them against on-site conditions and the layout drawings.

Furthermore, it is important to be careful about judging simulation results solely by energy production. Even proposals with high energy production can have problems such as large losses, extreme capacity ratios, poor constructability, or high susceptibility to shading. In practice, energy production, losses, safety, constructability, maintainability, and ease of explanation are evaluated comprehensively. PVSyst is not a tool that automatically determines the optimal option; it should be used as a tool to organize the information designers need to make judgments.

Survey data required to accurately reflect on-site conditions

Properly determining array configuration in PVSyst requires a thorough understanding of on-site conditions. Especially for ground-mounted systems and projects with complex roof geometries, elevation differences, orientation, the location of obstructions, and the heights of surrounding features influence the array configuration. Entering data based solely on drawings may fail to adequately capture the actual shading and slopes.

For ground-mounted installations, the land is not always perfectly flat. Even slight undulations can affect considerations such as inter-row shading and racking height. On sloping terrain, even if you intend to arrange modules at the same tilt angle, conditions change depending on whether you install along the natural topography or grade and level the site. When performing shading analysis and array layout in PVSyst, the more accurate the terrain information, the closer the assessment will be to actual conditions.

Even for rooftop installations, on-site verification is important. Roof slope, orientation, changes in elevation, equipment and fixtures, guard rails, and adjacent buildings all affect power generation. Objects that cast shadows in particular can be difficult to understand in terms of height and positional relationships from plan views alone. If on-site positioning data or point cloud data are available, you can more accurately identify the structures causing shadows and more easily organize the input conditions for PVSyst.

The on-site information required when deciding the array layout is not limited to just the site outline. The areas where modules can be placed, areas to avoid, sources of shading, locations for inverters and junction boxes, cable routes, and maintenance access routes are also relevant. If this information remains ambiguous, a configuration that is valid in PVSyst may not match the actual construction plan.

Also, when explaining PVSyst results to internal stakeholders or clients, the presence or absence of on-site data affects credibility. If the array configuration has been developed based on knowledge of the site's coordinates, elevation, and the positions of obstacles, it becomes easier to explain why that layout was chosen and why the subarrays were divided as they were. Conversely, if site conditions remain unclear, it becomes difficult to substantiate the accuracy of the results when asked.

Learning how to use PVSyst is important, but the accuracy of the on-site information that forms the basis of the input values is just as important. Simulations produce results based on the conditions entered. In other words, if the site conditions are not accurate, no matter how carefully you operate PVSyst, there are limits to the reliability of the results. To make the array configuration suitable for practical use, it is essential to consider software operations and on-site surveying together.

Summary: PVSyst Array Configuration Is Affected by the Accuracy of On-site Information

When deciding the array configuration in PVSyst, the basic workflow is to organize the site conditions, confirm the specifications of the modules and inverters, determine the number of series-connected modules from the voltage conditions, adjust the number of parallel strings and the capacity ratio, split into sub-arrays according to azimuth, tilt, and shading conditions, and finally check the validity by reviewing the simulation results. By following these six steps, even beginners can proceed with the design while understanding the meaning of the input values.

Array configuration is not just a task to increase power generation. It also requires keeping voltages within a safe range, confirming compatibility with inverters, properly assessing shading losses, and aligning with the actual layout and constructability. Even if numbers are entered on PVSyst's screen, if they do not match site conditions and equipment specifications, the simulation will not be usable in practice.

It is especially important to accurately ascertain the site’s geometry, obstacles, orientation, tilt, and elevation differences. The accuracy of the array configuration is influenced not only by the software settings but also to a large extent by the quality of the on-site information collected before input. By carefully performing site positioning, verifying equipment locations, and identifying structures that cause shading, the results from PVSyst will more closely reflect reality.

If you want to efficiently obtain high‑precision location information usable on site, leveraging an iPhone‑mounted GNSS high‑precision positioning device such as LRTK makes it easier to check candidate sites for solar power plants and assess current site conditions. By organizing the installation area, obstacles, survey points, and terrain conditions based on coordinates and surrounding conditions obtained on site, you can also improve the accuracy of the assumptions entered into PVSyst. Rather than leaving array configuration to desk‑based study alone, tying it to on‑site positional information and reflecting that in the design is a quick way to enhance the reliability of power generation simulations.