How to Check the Overloading Ratio in PVSyst｜5 Design Perspectives

Table of Contents

• Understand what the oversizing ratio is from a design perspective

• Basic workflow for checking the oversizing ratio in PVSyst

• Perspective 1: Check the ratio of DC capacity to AC capacity

• Perspective 2: Examine the relationship between clipping losses and annual energy production

• Perspective 3: Check output curtailment by month and by time of day

• Perspective 4: Determine the oversizing ratio including azimuth, tilt, and shading conditions

• Perspective 5: Check considering contracted capacity, equipment conditions, and future operations

• Practical approach to comparing oversizing ratios

• Key points for summarizing PVSyst verification results in design documentation

• Summary: Assess the oversizing ratio not only by the numbers but in conjunction with site conditions

Understanding What the Overload Rate Is from a Design Perspective

The oversizing ratio generally refers to the ratio of the total capacity of the photovoltaic modules to the rated output of the power conditioner. For example, if 120 kW of photovoltaic modules are connected on the DC side and the AC-side power conditioner capacity is 100 kW, the oversizing ratio is 120%. When designing with PVSyst, the starting point is also to first understand the balance between the PV array capacity and the capacity of the conversion equipment.

At first glance, the term "overloading" may give the impression that equipment is being pushed beyond its limits. However, the rated capacity of a solar module is a value determined under standard test conditions, and in actual outdoor conditions the output is not always equal to the rated capacity due to irradiance, temperature, soiling, angle, wiring losses, conversion losses, and so on. In particular, solar output tends to decrease at high temperatures, and there are many times in the morning, evening, or on cloudy days when the DC output does not rise close to the rated value. For this reason, by designing the solar module capacity somewhat larger than the power conditioner capacity, it can in some cases increase generation under low or intermediate irradiance conditions and raise the annual energy yield.

On the other hand, if the oversizing ratio is increased too much, the DC-side available generation around midday on clear days can exceed the AC-side output limit, increasing the time during which output is curtailed. This curtailment is generally treated as clipping, or as losses due to output limitation. There is a range in which raising the oversizing ratio increases annual generation, but beyond a certain point the additional generation gained per added PV capacity becomes small. In other words, when evaluating the oversizing ratio it is important to balance the generation increase achieved by increasing DC capacity against the increase in losses due to output limitation.

In practice, the overloading ratio is not determined by a single correct value. The appropriate range varies depending on land area, racking layout, irradiance conditions, power contracts, grid connection conditions, the possibility of output curtailment, construction costs, maintainability, legal regulations and permitting requirements. PVSyst can be used as a tool to reflect these differences in design conditions in simulations and to support decision‑making by comparing multiple design options. Rather than simply looking at “what percentage the overloading ratio is,” it is important to check “which losses occur and by how much as a result of that overloading ratio, and how the annual and monthly energy generation changes.”

Also, when checking the oversizing ratio, you need to align the definitions of the facility’s DC-side capacity and AC-side capacity. DC-side capacity often refers to the sum of the nominal maximum outputs of the photovoltaic modules, while AC-side capacity generally refers to the sum of the rated outputs of the power conditioners. However, the way capacity is expressed can vary depending on design documents and internal rules. If you do not confirm that the figures checked in PVSyst match the figures used in design drawings and application documents, misunderstandings may arise during internal or customer explanations.

The oversizing ratio is an important design metric that affects the profitability of a photovoltaic (PV) system, but judging the quality of a design based solely on the oversizing ratio is risky. For example, even with the same oversizing ratio, a south-facing system with a near-optimal tilt and a system distributed east–west will exhibit different output peak profiles. Systems with significant shading or multiple orientations often have a flattened noon peak, which can reduce clipping losses even at the same oversizing ratio. Conversely, systems with good solar irradiation and panels concentrated on the same azimuth are more likely to experience increased output curtailment during peak hours.

Thus, checking the oversizing ratio is not merely a calculation of the capacity ratio, but also an exercise in reading the shape of the generation curve. When evaluating the oversizing ratio in PVSyst, you need to combine system settings, the loss diagram, monthly results, hourly data, and comparison cases to verify that it aligns with the design intent.

Basic steps to check the oversizing ratio in PVSyst

To check the oversizing ratio in PVSyst, first set the project's location, meteorological conditions, azimuth, tilt, photovoltaic modules, power conditioners, string configuration, and so on. The oversizing ratio is strongly related to the system configuration among these settings. If the number of photovoltaic modules, number of strings, number of arrays, or the number and capacity of power conversion units change, the ratio of DC-side capacity to AC-side capacity changes, and this is reflected in the simulation results.

First, what you want to check is the total capacity of the PV array displayed on the system settings screen and the total capacity on the inverter side. In PVSyst, when you set the module type and number of modules, the nominal DC-side capacity is calculated. Also, when you set the power conditioner model and number of units, you can confirm the AC-side capacity. Here, check how much larger the DC-side capacity is relative to the AC-side capacity. The calculation of the oversizing ratio itself is simple, but in design you must also look at module count, string voltage, input current, and the usable input range at the same time.

Next, run the simulation and check the loss diagram on the results screen. The effects of oversizing are represented as losses when the output limit is reached. In the loss diagram, the flow from solar irradiance to PV output, DC losses, conversion losses, and AC output is displayed step by step, so you can see where and how much loss is occurring. Raising the oversizing ratio increases the potential generation on the PV side, but may increase losses that are curtailed by the converter-side limit. Verify whether these losses are within an acceptable range relative to the annual energy production.

Also check monthly generation and monthly losses. Output limiting due to oversizing does not occur evenly throughout the year. Because solar altitude, temperature, and irradiance change with the seasons, there are months when clipping is likely to occur and months when it hardly occurs. For example, in seasons with low temperatures and strong irradiance, PV output tends to be higher and the time spent at the output limit may increase. Conversely, in summer, even if irradiance is high, module output can be reduced by high temperatures, resulting in less clipping than expected. By looking at PVSyst’s monthly results, you can identify which seasons the effects of oversizing are concentrated in.

In practice, it is important to prepare and compare several design options with different overloading ratios. For example, you can create cases with overloading ratios of 110%, 120%, and 130% and compare each one's annual energy yield, specific yield, losses, output limits, and installed capacity. At this point, rather than simply choosing the option with the largest annual energy yield, you should check how much the energy yield increased relative to the additional module capacity. Even if annual energy yield increases as the overloading ratio is raised, if the magnitude of that increase diminishes, a careful judgment is required that takes cost and constructability into account.

The basic procedure for checking the oversizing ratio in PVSyst is to check the capacity ratio, run the simulation, verify output limitation in the loss diagram, look at monthly and hourly trends, and compare multiple cases. By standardizing this workflow each time, you can reduce variability in decisions among personnel and produce design documentation that is easier to explain in internal reviews.

Perspective 1: Verify the ratio of DC capacitance to AC capacitance

The first perspective in design is to correctly verify the ratio of DC capacity to AC capacity. Because the oversizing ratio is calculated by dividing the PV capacity on the DC side by the power conditioner capacity on the AC side, it is very important which capacities are used in the calculation. In PVSyst, the DC-side total capacity is calculated from the modules' nominal output, the number of modules, and the string configuration. For the conversion equipment side, the total capacity is determined based on the rated capacity and number of units of the configured equipment.

One thing to watch here is the units and terminology used to indicate DC capacity and AC capacity. On the photovoltaic module side it is often expressed as the sum of the nominal maximum outputs, while on the AC side it is expressed as the rated output. In design documents, several similar terms may be used, such as PV capacity, plant capacity, output capacity, and grid interconnection capacity. Confusing these can lead to inaccurate explanations of the oversizing ratio. It is important to reconcile the capacity values confirmed in PVSyst with the expressions used in internal design tables, single-line diagrams, site layouts, and application documents.

When calculating the oversizing ratio, you need to check not only the total capacity but also the load balance for each power conversion device. Even if the oversizing ratio looks appropriate for the overall installation, the input-side balance can be upset if one converter has many strings connected while another has few. When configuring the system layout in PVSyst, check not only the simple total capacity but also whether the allocations for each input, each array, and each orientation are appropriate.

Also, when increasing DC capacity, checking the voltage range and current range is indispensable. When considering the oversizing ratio, attention tends to focus on increasing the number of modules, but changing the number of modules in series within a string affects the open-circuit voltage at low temperatures and the operating voltage at high temperatures. It is necessary to confirm that the configuration does not exceed the input range of the power conversion equipment and that there is margin relative to the maximum input current. PVSyst may indicate electrical mismatches or out-of-range conditions as warnings, so it is important not to ignore those warnings and to review the design conditions.

When checking the oversizing ratio, you should not judge based solely on the aggregate figures for the entire installation; you need to be able to explain why that ratio is what it is. For example, the same oversizing ratio can reflect different design intentions depending on whether the DC capacity was increased because there is ample land and the goal is to boost generation during low-irradiance periods, whether the AC-side capacity was limited due to a cap on contracted capacity, or whether orientations were diversified to smooth the peak. When sharing PVSyst results internally, explaining not only the oversizing ratio but also the DC capacity, AC capacity, number of modules, number of power conversion units, and orientation configuration makes the basis for the judgment easier to understand.

Perspective 2: Examining the relationship between clipping losses and annual energy yield

One of the most important perspectives when evaluating the overloading ratio is the relationship between clipping loss and annual energy production. Increasing the overloading ratio raises the capacity of the solar PV modules, which can increase generation during cloudy conditions, in the morning and evening, and during low-irradiance periods. On the other hand, if the peak output on sunny days exceeds the AC-side limit, the excess cannot be delivered even though it could be generated. This discarded portion is the clipping loss.

In PVSyst simulation results, by examining the loss diagram you can understand the extent of losses caused by the output limit of the conversion equipment. In cases with a low oversizing ratio, the PV-side output reaches the AC-side limit for less time, so clipping losses are small. However, if DC capacity is insufficient, the time during which the power conditioner cannot be fully utilized increases, which can make annual energy production harder to increase. Conversely, in cases with a high oversizing ratio, you can expect an uplift during low-output periods, but clipping at peak times increases.

The important point is not to immediately judge the presence of clipping loss as bad. In oversized system design, it is common to accept a certain amount of clipping loss while increasing annual energy production and equipment utilization. For example, even if a small amount of clipping loss occurs, the design can be reasonable if the increase in generation during low-irradiance periods over the course of the year outweighs it. In PVSyst, you can create multiple cases with different oversizing ratios to compare increases in clipping loss with increases in annual energy production.

The key point to look at in this comparison is the increase in generated energy relative to the added DC capacity. Although annual energy production can increase as the oversizing ratio is raised, the magnitude of the increase tends to diminish gradually. This is because even if the additional modules generate more during peak hours, that amount is truncated on the AC side. Therefore, when considering an oversizing ratio, you should examine not only the absolute value of annual generation but also the amount of increase from raising the oversizing ratio, the increase in clipping losses, and the change in the loss rate.

Also, even if annual energy generation increases, the evaluation may change depending on feed-in conditions and self-consumption conditions. In self-consumption systems, if demand is low at generation peaks, surplus energy is likely to occur and the additional generation from oversizing may not be used effectively. On the other hand, for facilities where increasing generation in the morning, evening, or on cloudy days has value, raising the generation curve through oversizing can be effective. PVSyst results should be interpreted together with the system’s intended use.

When examining clipping losses, pay attention not only to the loss rate but also to the scale of the energy being generated. In small-scale systems the same loss rate may have limited impact in monetary terms or on operations, but in large-scale systems even a slight difference in loss rate can lead to a large difference in annual energy production. Also, the larger the system capacity, the greater the impact of design changes on equipment costs, construction costs, and maintenance costs. Therefore, when checking clipping losses in PVSyst, it is practical to evaluate them together with annual energy production, system size, and operational objectives.

Perspective 3: Check output restrictions by month and time of day

When evaluating the oversizing ratio, relying only on annual totals can lead to incorrect conclusions. Annual energy production and the annual loss rate are useful indicators, but unless you check in which months and at which times of day output curtailment occurs, design risks and opportunities for improvement can be difficult to see. In PVSyst, by reviewing monthly energy production and losses and, when necessary, hourly output data, you can understand the effects of oversizing more concretely.

Looking at the monthly results reveals whether output constraints are concentrated in specific seasons. Because the output of solar cells is influenced not only by irradiance but also by temperature, module output tends to be higher during periods when ambient temperatures are low and solar irradiance is sufficient. As a result, the AC-side output limit is more likely to be reached and clipping losses can increase. Conversely, in summer, although irradiance is higher, module temperatures rise and output falls, so clipping may be smaller than expected.

By examining the data by time of day, you can determine whether output curtailment is concentrated around midday or occurs broadly from the morning into the afternoon. In systems that are nearly a single south-facing orientation, generation peaks tend to concentrate around midday, and increasing the oversizing ratio makes clipping more likely during that period. In contrast, in layouts divided east–west or in systems that utilize roofs with multiple orientations, generation peaks are dispersed, so output curtailment may be relatively reduced even with the same oversizing ratio.

This time-of-day check is particularly important for self-consumption systems. If a facility’s power demand is higher in the morning or evening, an increase in generation only at noon may not be effectively utilized. Conversely, for facilities with stable demand throughout the daytime, oversizing can meaningfully increase generation in the morning and evening. By checking hourly output in PVSyst, you can understand how oversizing alters the generation curve and more easily assess its compatibility with the demand curve.

Even when output clipping occurs frequently, the assessment changes depending on whether it is only short peaks or if it continues for long periods. If it only remains pegged at the rated output for short periods, the annual loss may be limited. However, if it is pegged at the maximum output for long periods on many sunny days, the oversizing ratio may be too high. Even if PVSyst’s results make the annual losses appear within an acceptable range, examining hourly data may reveal that the design intent is not being met.

Checking by month and by time of day is also useful for design explanations. To customers and internal approvers, rather than simply saying “what is the overloading ratio (%)?”, it is better to explain “output curtailment mainly occurs around noon in months with strong solar irradiation, but the impact on annual energy production is limited to this extent,” as that more effectively conveys the validity of the design. Based on PVSyst results, being able to explain the numerical overloading ratio, clipping losses, monthly trends, and time-of-day trends together will increase your persuasiveness during reviews.

Perspective 4: Assess the overloading rate including orientation, tilt, and shading conditions

When assessing the oversizing ratio, you must check not only DC capacity and AC capacity but also orientation, tilt, and shading conditions together. Even with the same PV module capacity and the same power conditioner capacity, if installation conditions change, the shape of the generation curve changes and the occurrence of clipping losses also changes. Because PVSyst can simulate orientation and tilt conditions and nearby shading settings, it is important to enter these conditions correctly when evaluating the oversizing ratio.

When the orientation is close to south and the tilt angle is near conditions that favor power generation, the output peak on sunny days tends to be higher. If the oversizing ratio is increased for such systems, output limiting tends to occur around midday. On the other hand, when installed split east–west or distributed across multiple roof surfaces, generation peaks can be divided into morning and afternoon, which can suppress the noon peak. As a result, clipping losses can be smaller even with the same oversizing ratio.

The tilt angle is also important. The seasonal distribution of generation changes depending on whether the tilt is large or small. With a low tilt, generation tends to increase in summer, while a larger tilt can lead to relatively higher generation in winter. The season in which output limitations due to oversizing occur also depends on the tilt angle. Comparing cases with different tilt angles in PVSyst shows that not only the annual energy yield but also the seasonal distribution of clipping losses changes.

Shadow conditions also affect the assessment of the oversizing ratio. When shading occurs due to surrounding buildings, trees, gaps between rows of mounting racks, equipment structures, and so on, the output of the solar modules is reduced. In systems with shading, even if the oversizing ratio appears high when looking only at simple capacity ratios, the actual output peak may be suppressed and clipping losses may not become that large. However, it is dangerous to simply assume that a higher oversizing ratio is acceptable just because there is shading. Because shading causes mismatch losses and output reductions at the string level, the overall energy generation efficiency may deteriorate.

When setting near shading and orientation dispersion in PVSyst, it is important to enter inputs that closely reflect the actual site conditions. Underestimating shading conditions can lead to an overestimation of energy production, and clipping losses may also differ from reality. Conversely, overestimating shading conditions can make the effects of oversizing appear too small. Approximate inputs are acceptable in the early stages of design, but as you approach the final design, more accurate inputs that reflect on-site surveys, layout plans, surrounding obstacles, and terrain conditions are required.

When evaluating the oversizing ratio, it is important to look at the shape of the power generation curve including azimuth, tilt, and shading conditions. For systems where the output peak rises sharply, even a small increase in the oversizing ratio can increase clipping. For systems where the output peak is spread out, increasing the oversizing ratio may keep output curtailment relatively low. Confirming this difference in PVSyst makes it easier to determine an oversizing ratio appropriate to the system conditions.

Viewpoint 5: Confirm contracted capacity, equipment conditions, and future operations

The overloading ratio should not be determined solely by the simulated energy yield. In actual design, decisions must take into account the contracted capacity, grid connection conditions, equipment certification, protective devices, wiring capacity, constructability, maintainability, and future operational policies. PVSyst is very effective for evaluating energy production and losses, but for final design decisions it is essential to reconcile the simulation results with the equipment and system conditions.

First, you should check whether the AC-side output capacity complies with the contract terms and interconnection conditions. Even if you install many PV modules, the AC-side output limit may be constrained by the contracted capacity or grid-connection conditions. In this case, increasing the oversizing ratio can raise generation during low-irradiance periods, but it will make it easier to reach the output limit at peak times. Even if PVSyst shows an increase in annual energy production, if it does not align with actual output control or operational rules, you may not obtain the expected benefits.

Next, verify the allowable conditions for wiring and equipment. Increasing the overloading ratio means that the DC-side module capacity and the number of strings will increase. This affects the design of junction boxes, DC cables, protective devices, and input circuits. Even if the energy yield looks good in PVSyst, it cannot be adopted if the actual equipment specifications or installation conditions are infeasible. In particular, voltage rise at low temperatures and input current under high irradiance are related to safety and therefore must be separately verified in the electrical design.

Maintainability is also a perspective that must not be overlooked. Increasing the number of modules to raise the oversizing ratio increases the installation area and can constrain inspection access routes and maintenance space. For rooftop installations, the relationship with walkways and emergency escape routes, load conditions, and waterproofing measures is also important. For ground-mounted systems, row spacing, mowing, drainage, snowfall, and ground conditions have an impact. Even if PVSyst simulations allow an increase in capacity, if the site cannot be safely constructed and maintained, it cannot be considered a practical design.

Future degradation over time must also be taken into account. Photovoltaic modules gradually lose output during long-term operation. Even if clipping due to oversizing is somewhat large immediately after commissioning, module output decreases as years pass and clipping losses may be reduced. On the other hand, a design that imposes too large an output restriction in the first year will affect investment decisions and generation planning. When examining long-term degradation conditions in PVSyst, it is advisable to consider not only the first year but also the energy production and losses over the entire operational period.

Additionally, confirm the potential for future equipment expansion and operational changes. In self-consumption systems, the assessment of an oversized design can change due to future load increases, the addition of storage equipment, changes in operating hours, and so on. Even systems that currently tend to produce surpluses at peak times may be able to utilize generated power more effectively if demand increases in the future. Conversely, if future electricity consumption is expected to decline, oversizing may increase surplus and curtailment. Comparing multiple demand scenarios and design conditions in PVSyst makes it easier to understand the sensitivity to future operational changes.

Practical steps for comparing overload rates

When comparing oversizing ratios in PVSyst, it is practical to create several cases step by step rather than fixing on a single value from the outset. First make a baseline design, then create variants by changing the number of solar PV modules and the number of strings. In doing so, keep azimuth, tilt, shading conditions, meteorological conditions, and loss conditions as identical as possible so that only the differences in oversizing ratio are reflected in the results. If you change multiple conditions at the same time, it becomes difficult to determine whether differences in energy yield are due to the oversizing ratio or to other factors.

In the comparison, we examine annual energy production, specific yield, clipping losses, conversion losses, monthly energy production, and trends in the occurrence of output limiting. By comparing how much annual energy production increases with how much clipping losses increase when the oversizing ratio is raised, the appropriate range of oversizing becomes apparent. Up to a certain point, increases in energy production are large, but if the oversizing ratio is increased further there may be a point at which only losses increase. Identifying this boundary is the purpose of the comparative evaluation.

When creating comparison cases, it is also important not to include proposals that are not viable from a design perspective. For example, proposals in which the string voltage exceeds the input range or the input current exceeds the specifications are inappropriate as subjects for comparison in simulations. If PVSyst issues a warning, check its content and modify the configuration so that it is electrically valid. Any proposal included in the comparison table must at least meet the basic equipment requirements.

Also, when comparing oversizing ratios, evaluate not only power generation but also how easy the design is to understand. Extremely complex string configurations or arrangements in which orientation-by-orientation allocation is hard to follow can lead to mistakes during construction or maintenance. Even if PVSyst shows good results, a design that is difficult to reproduce in the field carries a high practical risk. When comparing design proposals, it is important to evaluate power generation performance, constructability, maintainability, and the ease of documentation together.

For internal reviews, prepare to explain the results for each overloading ratio in prose. For example, being able to say "Increasing the overloading ratio increases annual energy production, but beyond a certain point the increase in clipping losses becomes large," "In this proposal, output curtailment is mainly concentrated around noon in spring and autumn," and "Because azimuths are diversified, peaks are suppressed even at similar overloading ratios" will clarify the rationale for design decisions.

Points for Summarizing PVSyst-Verified Results in Design Documents

After checking the oversizing ratio in PVSyst, you need to summarize the results clearly in design documents and internal briefing materials. In practice, it is not sufficient for only the person who ran the simulation to understand them. Sales personnel, design engineers, construction staff, customers, reviewers, and other stakeholders may view the results. Therefore, it is important to organize and communicate the oversizing ratio figures, design conditions, the impact on power generation, and the details of losses.

First, what should be recorded are the DC-side capacity, the AC-side capacity, and the oversizing ratio. These are the basic information for oversizing design. However, because numbers alone can be hard to interpret, it is also advisable to indicate the number of photovoltaic modules, the string configuration, the number of power conversion devices, the orientation, and the tilt. In particular, for facilities with multiple orientations or multiple arrays, organizing not only the overall oversizing ratio but also which array is connected to which power conversion device will make downstream checks easier.

Next, present the annual energy production and the main losses as simulation results. For losses related to the oversizing ratio, explicitly indicate how much clipping due to the output limit occurs. When doing so, it is easier to understand if you supplement the loss rates with a written explanation of their impact on annual energy production. If losses occur but are more than offset by increased generation during low-irradiance periods, explain that design intent.

Monthly results are also useful. If the impacts of oversizing are concentrated in specific months, checking monthly generation and losses makes it easier to convey the seasonal operational profile. For self-consumption systems, explaining the facility’s demand patterns together with monthly and time-of-day generation trends makes it easier to assess the appropriateness of oversizing. In particular, if surplus at peak times or output control becomes an issue, it is advisable to reflect the time-of-day verification results in the documentation.

In design documentation, it is useful to record not only the adopted proposal but also summaries of the alternatives that were compared. To explain why a particular oversizing ratio was chosen, results comparing it with other oversizing ratios are necessary. For example, if you can explain that a proposal with an even higher oversizing ratio was not adopted because the increase in annual energy production would be small while clipping losses would be large, that adds credibility to the design decision. Conversely, you can also explain that a proposal with a lower oversizing ratio was not adopted because, although clipping losses would be smaller, power generation during low-irradiance periods would be insufficient.

Finally, ensure the documentation makes clear that PVSyst results are simulations based on the input conditions. Actual operational results may vary due to meteorological data, shading, topography, soiling, maintenance status, output control, actual equipment behavior, and other factors. Rather than treating the simulation results as definitive, present them as predictions based on the design conditions and evaluate them together with site conditions and operational conditions.

Summary: Assess the overload rate not only by the numerical value but also in light of on-site conditions

The basic method for checking the oversizing ratio in PVSyst is to understand the ratio of DC capacity to AC capacity and to check clipping losses, annual energy production, and output limitations by month and time of day from the simulation results. However, consideration of the oversizing ratio does not end with simply checking the capacity ratio. It is necessary to make a comprehensive assessment that includes azimuth, tilt, shading, weather conditions, contracted capacity, equipment conditions, maintainability, and future operation.

Increasing the oversizing ratio can potentially increase generation during low-irradiance periods and in the morning and evening. On the other hand, on sunny days the peak output may reach the AC-side limit, increasing clipping losses. What is important in design is not whether losses exist, but whether tolerating those losses still results in higher annual generation or greater operational value. In PVSyst, you can check this balance by comparing multiple cases with different oversizing ratios.

In practice, it is important not only to convey the oversizing ratio to internal staff or customers, but also to be able to explain why that value was chosen. Organize the DC capacity, AC capacity, generation, clipping losses, monthly trends, and time-of-day trends, and explain them together with the design intent to make it easier for stakeholders to understand. In particular, for self-consumption systems and multi-orientation installations, the shape of the generation curve becomes important, so you should check not only the annual totals but also the hourly breakdown.

Also, the accuracy of results obtained with PVSyst is heavily dependent on the accuracy of the site conditions entered. If information on azimuth, tilt, shading, topography, layout, and surrounding obstacles remains ambiguous, the assessment of the oversizing ratio will also be uncertain. While rough estimates may be acceptable in the early stages of design, as you approach the final decision it becomes necessary to accurately reflect on-site information. In photovoltaic system design, linking desk-based simulations with measured on-site data is indispensable for improving the reliability of energy yield predictions.

If you need to accurately determine site azimuth, tilt, racking positions, surrounding obstructions, and ground elevation, high-precision positioning using a smartphone can also be effective. LRTK is a GNSS high-precision positioning device that attaches to an iPhone, enabling easy acquisition of site location information and helping with verification of photovoltaic system layouts and assessment of existing conditions. When evaluating overloading ratio and energy yield in PVSyst, having accurate location and elevation information obtained on site makes it easier to improve the input accuracy for azimuth, tilt, and shading conditions. To bring simulation-based design decisions closer to actual site conditions, it is important to proceed with attention to acquiring and organizing on-site data alongside checking the overloading ratio.