PVSyst Loss Settings Overview｜Explaining 10 Items That Cause Differences in Power Generation

Table of Contents

• Why PVSyst Loss Settings Have a Major Impact on Energy Production

• Key Concepts to Understand Before Reviewing Loss Settings

• Loss Setting 1: Differences Due to Solar Irradiance Data and Meteorological Conditions

• Loss Setting 2: Incidence Angle Loss Settings

• Loss Setting 3: Losses from Near and Distant Shading

• Loss Setting 4: Temperature Losses and Thermal Characteristics

• Loss Setting 5: Module Quality Loss Settings

• Loss Setting 6: Module Mismatch Loss Settings

• Loss Setting 7: DC-side Losses from Wiring

• Loss Setting 8: Power Conditioner Conversion Losses

• Loss Setting 9: Losses Related to AC-side Wiring and Grid Connection

• Loss Setting 10: Losses from Soiling, Degradation, and Downtime

• Practical Check Procedures for Verifying Loss Settings

• Steps Needed to Align Simulation Values with On-site Conditions

• Summary

Why do loss settings in PVSyst have such a large impact on energy production?

When simulating the power output of a solar power plant in PVSyst, the factors that tend to draw attention first are panel capacity, tilt angle, azimuth, solar irradiation data, and inverter capacity. Of course, these are important conditions that determine generation. However, in practice, large differences in simulation results are not caused by these basic conditions alone. Rather, when results differ despite using the same installed capacity, the same location, and the same tilt angle, the cause is often differences in the loss settings.

The loss settings in PVSyst are parameters intended to reflect that a power plant is operated in the field rather than under ideal conditions.

The solar irradiance reaching photovoltaic panels is gradually lost before being converted into electrical generation due to various factors such as angle, shading, soiling, temperature, wind, mounting conditions, wiring resistance, equipment conversion efficiency, module-to-module variability, and aging.

Each individual loss may appear to be less than a few percent, but when multiple losses accumulate they significantly affect annual energy production, electricity sold, investment decisions, internal explanations, documentation for financial institutions, and post-construction performance evaluations.

Particularly for practitioners searching for "how to use PVSyst", it is important to understand which loss items they should configure themselves and to what extent, which items are risky to leave at their default values, and which items to compare to reveal differences between design proposals. By treating loss settings not as mere input fields but as a checklist to ensure the simulation reflects the realities of the power plant, PVSyst’s results become more practical and easier to use in real-world work.

In this article, we explain 10 loss settings in PVSyst that are likely to cause differences in energy yield. The exact names on the user interface may vary depending on your environment and version, but the basic concepts are common. So that this can be used from early design and feasibility assessment through detailed design and post-construction verification, we organize, from a practical viewpoint, how each loss affects energy yield and what points should be checked.

Fundamental concepts to grasp before looking at loss settings

When understanding PVSyst's loss settings, the first point to grasp is that losses are not determined all at once but occur progressively along the power generation chain. In a photovoltaic system, sunlight first reaches the installation surface. That light is incident on the panel surface, converted into DC power by the cells, passes through the DC wiring, is converted to AC by the power conditioner, and is then sent to the grid via AC wiring and substation/transformer equipment. At each stage of this sequence, small losses occur.

For example, shading losses occur before and after light reaches the panels. Temperature losses appear as a reduction in efficiency when the panels generate power. Wiring losses occur when the generated power is transmitted to equipment. Conversion losses occur at the stage of converting DC to AC. Losses such as downtime or output curtailment reflect periods when, even though conditions would allow generation, that potential cannot be accounted for as generated output.

Being aware of where losses occur in this way makes it less likely that you will misunderstand the meaning of the settings. For example, treating soiling losses and shading losses the same way makes explanations of site conditions ambiguous. Confusing wiring losses with conversion losses makes it unclear what should be reviewed when improving the design. If temperature losses are treated too conservatively, power generation will be underestimated; conversely, if treated too leniently, the discrepancy with actual performance will be large.

Also, regarding loss settings, the idea that “entering standard values will be correct” is dangerous. Standard values are convenient in the early stages of study, but in an actual power plant conditions vary depending on the region, mounting structure type, cable length, equipment used, maintenance frequency, surrounding terrain, snowfall and dust, construction accuracy, and the occurrence of shading. PVSyst is an advanced simulation software, but if the input conditions are out of sync with the site, the output results will also diverge from the actual site.

In practice, it is more important to be able to explain loss settings with justification than merely to make them more detailed. When sharing internally or explaining to a client, you will be asked, "Why was this loss rate chosen?", "Which losses would improve if the design were changed?", and "Which items can be verified after construction?". For this reason, PVSyst loss settings should be treated not only as inputs for calculating energy yield but also as items for organizing the rationale behind design decisions.

Loss Setting 1: Differences Due to Solar Irradiance Data and Weather Conditions

The loss factor to check first is the difference caused by irradiance data and weather conditions. Strictly speaking, irradiance data itself is more of an input condition than a loss setting, but it is one of the factors that most strongly affects differences in energy production in PVSyst. If irradiance changes, no matter how carefully you adjust the loss settings, the baseline of annual energy production will change.

In solar power generation simulations, the irradiance incident on the installation surface is calculated from meteorological data such as horizontal plane irradiance, diffuse irradiance, direct irradiance, air temperature, and wind speed. If site selection is coarse or observation points located far from the site are used, actual irradiance conditions can differ in mountainous areas, coastal zones, basins, and regions with snowfall. In particular, in areas affected by local terrain, projected power generation can vary even within the same municipality.

In PVSyst, when importing meteorological data and configuring sites, it is important to decide which data to use, which period to take as representative, and how to handle missing data or interpolation. When comparing design proposals by annual energy production, you must compare them using the same meteorological conditions. If one proposal uses different data, you cannot determine whether the difference is due to the design or to the meteorological data.

In practical work, simply assuming “it’s fine because it’s close to the power plant” when checking meteorological conditions is not sufficient. Elevation, surrounding mountains, sea breezes, snowfall, fog, the tendency for local cloud formation, and temperature highs and lows all affect power output. In particular, temperature-related losses are influenced by air temperature and wind speed, so you should verify the validity of temperature data as well as solar irradiance.

If the solar irradiance data is overestimated, the energy production will be overestimated even if the losses are set correctly. Conversely, if the solar irradiance data is underestimated, the generation will appear low even if the design is good. When checking the loss settings in PVSyst, the basic workflow is to first verify whether the meteorological conditions are reasonable as assumptions for the plant, and then review the individual loss items.

Loss Setting 2: Incident Angle Loss Configuration

Incidence angle loss is the loss that occurs when sunlight strikes the panel surface at an oblique angle, increasing reflection and reducing the light that actually reaches the cells. Solar panels capture sunlight more efficiently when sunlight arrives at angles close to perpendicular to the surface. The impact of oblique incidence is greater in the morning and evening, during winter, for installations with azimuth misalignment, and for installations with a low tilt angle.

In PVSyst, this loss is calculated through settings related to the panel surface’s optical properties and the incident-angle correction. What practitioners often overlook is that incident-angle loss is not set in isolation but varies with tilt angle, azimuth, racking type, reflection conditions, and module characteristics. Even with the same installed capacity, a layout close to due south versus one rotated east–west will differ not only in the generation curve but also in how the incident-angle loss manifests.

Also, for low‑slope roof installations and ground‑mounted systems, even if they may at first glance appear to have little shading and seem efficient, the angle of incidence and the tendency for dirt to remain can affect energy production. In particular, for designs that prioritize morning and evening generation or that use east‑west layouts to make efficient use of land, it is necessary to evaluate incidence‑angle losses over the year, not just peak generation.

When checking incidence angle losses, look at how large the losses appear on PVSyst’s result screens and loss diagrams. When comparing design options, checking how incidence angle losses change when you vary the tilt angle and azimuth angle reveals design characteristics that are not apparent from annual energy production alone.

However, incidence-angle losses are parameters that are difficult to measure directly on site and hard to explain. Therefore, in practice, rather than making excessively fine adjustments, it is important to check that the settings are not unreasonable given the module specifications and installation conditions. In particular, if you make large changes from the standard values, recording the reasons in the design documentation will make it easier to explain the results later.

Loss Setting 3: Losses from Near-Field and Far-Field Shadows

Shading losses are a typical factor that greatly influences the difference in energy production in PVSyst. Shading can be divided into near shading—caused by surrounding buildings, trees, utility poles, fences, equipment, terrain, the same row or adjacent rows—and far shading—caused by distant mountains or horizon obstructions. Both reduce the amount of sunlight reaching the panels and thus affect annual energy production.

For near-field shading, it is important to create a 3D scene that reflects the spacing between arrays, racking height, tilt angle, and the position and height of surrounding obstacles. For ground-mounted systems, narrow row spacing makes shadows from the front rows more likely to fall on the rear rows during winter mornings and evenings. For rooftop systems, ridges, parapets, HVAC units, guardrails, and adjacent buildings can produce localized shading. Even when such shading affects only some modules, the impact on energy production can spread depending on the string arrangement and circuit configuration.

For distant shading, we check the effect of mountains, hills, and surrounding terrain obscuring the sun when it is low. Distant shading may be visible only briefly, but it affects energy production in winter and during mornings and evenings. In particular, in mountainous or valley terrain, simply treating the horizon as zero can lead to an overestimate of actual energy output.

When setting shading losses, be careful that modeling the shape of shadows too coarsely can easily lead to discrepancies with actual on-site conditions. If the height, distance, or position of obstacles are inaccurate, the timing and extent of shadow occurrence will change. Rough estimates are acceptable in the early design stage, but when using them for detailed design or client presentations, you need to improve reproducibility as much as possible based on on-site surveys, drawings, point clouds, photographs, and so on.

Also, while shading losses are a factor that reduce power generation, being overly conservative can make the project’s viability look worse than it actually is. What matters is not whether there is shading or not, but when, where, and to what extent it occurs, and how much it affects the annual energy yield. In PVSyst results, check whether shading loss appears large compared to other losses and how much it improves when the design proposal is changed.

Loss Setting 4: Temperature Losses and Thermal Property Settings

Temperature loss is the loss in power generation efficiency that occurs when the temperature of a solar panel rises. Generally, when a solar panel is exposed to sunlight, its surface temperature increases, and the higher the cell temperature, the lower the output. One of the reasons why power generation does not increase as much as expected on hot summer days with strong sunlight is this temperature loss.

In PVSyst, temperature losses are calculated based on ambient temperature, wind speed, racking conditions, ventilation characteristics, the module temperature coefficient, and other factors. For installations that are flush-mounted to a roof, ground-mounted installations with good airflow, and agrivoltaic installations with a gap to the ground surface, the heat dissipation conditions on the rear side of the panels differ. Therefore, even when using the same module, temperature losses vary depending on the racking type.

In practice, be careful not to judge temperature-related losses solely by ambient air temperature. Panel temperature is not the same as ambient air temperature. Under conditions of strong solar radiation, weak wind, and poor rear ventilation, cell temperature can be considerably higher than ambient air temperature. Conversely, in well-ventilated locations heat can escape more easily and the temperature rise can be limited.

When setting temperature losses in PVSyst, it is important to match the mounting arrangement and ventilation conditions to the actual on‑site design. Check whether the array is roof‑mounted or ground‑mounted, whether there is space behind the panels, and whether the structure tends to trap heat around the panels. In particular, for roof installations or installations close to walls, treating them the same as a standard open rack can lead to underestimating the actual temperature losses.

Temperature losses affect not only annual energy production but also how monthly generation is interpreted. Even in regions with high solar irradiance during summer, high temperatures reduce efficiency. When checking monthly generation, the month with the most irradiance may not be the month of maximum actual generation. When explaining PVSyst results, examining how temperature losses influence seasonal generation makes it easier to consider discrepancies with actual performance.

Loss Setting 5: Module Quality Loss Setting

Module quality loss is the loss that reflects the deviation of a solar panel's actual output from its nominal value. The output listed in catalogs is the value under specific test conditions, but actual modules have manufacturing variations and output tolerances. Not all modules will produce exactly the nominal output.

In PVSyst, quality losses are set taking into account module quality and output tolerances. If the module specifications include only a positive tolerance, or if measured values from pre-shipment inspections are available, the approach to setting these values changes. Conversely, when detailed information is not available, conservative values may be used.

The important point in this item is not to confuse quality loss with other losses. Module quality loss refers to variability in the output of the panel itself. It is a different concept from soiling, shading, temperature, wiring, or aging. If you have already applied a similar safety margin in another item, assigning a large value to quality loss as well may result in counting the loss twice.

Also, the way module quality loss is handled can differ between the initial design stage and after project completion. In the initial design stage it is set based on the nominal values in the specifications, but if actual module measurement data or shipment data are available after completion, a more realistic assessment becomes possible. When it concerns energy yield guarantees or performance evaluations, it is important to clarify which point in time the information used for the settings refers to.

Quality losses may not look large numerically, but for large-scale power plants their impact on annual energy production cannot be ignored. When reviewing PVSyst's list of losses, check whether the quality loss is unnaturally large, or, conversely, unjustifiably close to zero.

Loss Setting 6: Module Mismatch Loss Settings

Module mismatch loss refers to the loss that occurs when the characteristics of modules within the same string or the same circuit are not perfectly matched. Solar panels, even of the same model, have slight differences in current and voltage characteristics. In series-connected strings, modules with lower output or modules in poorer conditions affect the overall current, causing mismatch losses.

Mismatch losses are related not only to inherent differences between modules, but also to shading, soiling, differences in installation angle, differences in azimuth, temperature differences, and variations in degradation over time. For example, an arrangement where only some modules are shaded, or a design that mixes modules with different orientations within the same string, can result in larger mismatch losses.

When setting mismatch losses in PVSyst, you should not simply enter a standard percentage; you need to check them together with the string design and the installation layout conditions. The concept of mismatch loss is especially important for complex roofs, multiple orientations, racks with level differences, and sites where partial shading is unavoidable. Even for ground-mounted installations, row-by-row conditions can vary depending on terrain slope and grading accuracy.

A common practical mistake is to feel reassured by looking only at shading losses. Even if shadows appear small, depending on the circuit configuration a portion of the shading can affect an entire string and propagate as mismatch-related power loss. Conversely, the impact of shading can be overestimated by double-counting, yielding an excessively large forecast when both shading loss and mismatch loss are counted.

To properly handle mismatch losses, it is important to organize panel layout, string grouping, power conditioner inputs, and the presence of mixed azimuths and tilts. By checking not only the PVSyst results but also cross-referencing them with the design drawings, it becomes easier to explain why losses occur.

Loss Setting 7: DC-side losses due to wiring

DC-side wiring losses are the losses caused by cable resistance that occur while the DC power generated by solar panels is being transmitted to the junction box or the power conditioner. When current flows through a cable, resistance causes a voltage drop, and part of the energy is lost as heat. Losses increase as the wiring length becomes longer, the current becomes larger, and the cable cross-sectional area becomes smaller.

In PVSyst, the effects of DC wiring are reflected in energy production by setting the DC wiring resistance and loss rate. In early design stages you may use approximate values, but in detailed design you need to verify and set the wiring distances from the strings to the combiner boxes and from the combiner boxes to the power conditioner, the cable sizes, and the number of circuits.

DC-side wiring losses are strongly related to the layout of the power plant. If the panel area is large, if the power conditioners are placed far away, or if the collection routes are complex, wiring lengths tend to increase. Equipment placement may also be constrained by land shape and site development conditions, which can increase wiring losses. Conversely, by optimizing equipment placement, wiring lengths can be shortened and losses reduced.

What you should be careful about in this item is not to treat wiring losses as mere electrical design figures. Even if they appear as a small percentage in PVSyst, they have a continuous effect on annual energy production. Also, if you try to reduce wiring losses by using thicker cables, you will need to consider constructability, material costs, and the routing for installation. It is important to make decisions by looking at the balance of the overall design, not just energy output.

The practical workflow for using PVSyst is to first perform a rough estimate with standard loss rates, and then update it to match the actual wiring plan once detailed design has progressed. When comparing design proposals, looking at how DC-side wiring losses change with different power conditioner placements and array segmentation lets you evaluate not only the energy yield but also the feasibility of the construction plan.

Loss Setting 8: Power Conditioner Conversion Loss

Power conditioner conversion loss refers to the loss that occurs when converting the direct current power generated by solar panels into alternating current power. No matter how high the efficiency of the equipment, the conversion efficiency will never reach 100 percent. Additionally, the conversion efficiency is not constant; it varies depending on input voltage, input power, operating load ratio, temperature conditions, and other factors.

In PVSyst, conversion losses are calculated based on the characteristic data of the power conditioner. What practitioners should check are the relationship between the capacity of the selected equipment and the solar panel capacity, the input voltage range, the maximum input current, the overloading ratio, and the occurrence of clipping. In particular, designs that increase the DC/AC ratio can raise annual energy production, but may cause output limiting during periods of strong insolation.

Conversion loss and clipping loss are often confused. Conversion loss refers to losses related to the efficiency of converting DC to AC. By contrast, clipping is the phenomenon in which, during periods when generation could exceed the power conditioner’s output limit, the portion above the limit is not output. Both occur around the power conditioner, but they have different meanings.

When selecting a power conditioner, it is important not only to match the rated capacity but also to consider at which load factors it will operate for the majority of the year. In power plant design, not only peak periods but also operating points during cloudy conditions, mornings and evenings, and seasonal variations are taken into account. The longer it can operate within a range of high conversion efficiency, the more favorable the annual energy output becomes.

When reviewing PVSyst results, verify that conversion losses are not larger than expected, that clipping is not occurring excessively, and that there are no warnings about the power conditioner's input conditions. When comparing design proposals, you need to look at differences in energy production not only in terms of equipment capacity but also including string configuration and input splitting.

Loss Setting 9: Losses Around AC-side Wiring and Grid Connection

AC-side wiring losses are the losses that occur as the power converted to AC by the power conditioner is transmitted to the collection board, transformer equipment, the receiving point, and the grid interconnection point. Like on the DC side, losses vary depending on cable resistance, current, wiring length, and equipment configuration. In large-scale power plants, the AC-side collection route can become long, making it a non-negligible factor.

In PVSyst, by setting AC-side wiring losses and transformer losses, the final amount of generated electricity sent to the grid is evaluated. What is important here is to be aware of which point’s energy the generation value in PVSyst represents. The comparison target changes depending on whether the value is at the panel output, the power conditioner output, the point of interconnection, or the export meter.

In practice, when comparing simulated and actual values, differences in the measurement point can become an issue. If PVSyst includes losses up to a certain point while the actual data were measured at a different point, a simple comparison will show discrepancies. When guaranteeing energy production or performing performance evaluations, it is necessary to make clear which losses are included in the reported values.

Also, on the AC side, losses in transformer equipment are taken into account. Transformers have load losses and no-load losses, and these can affect not only periods with high generation but the entire duration that the equipment is connected. Even losses that seem small occur throughout the year and therefore impact the final amount of power transmitted.

When checking AC-side losses, it is important not to simply use standard values but to verify the equipment configuration, wiring distances, voltage class, transformer equipment specifications, and the metering point.

In particular, for internal documents and submission materials, clearly stating which point’s generation output is being shown will make misunderstandings less likely later.

Loss Setting 10: Losses from Soiling, Degradation, and Downtime

Losses due to soiling, degradation, and outages are items that tend to appear as differences between projections and actual performance during the operation phase of a power plant. Even if irradiance and equipment conditions are set very accurately in PVSyst during design, in the field factors such as panel surface soiling, vegetation, bird damage, dust, pollen, snowfall, salt corrosion, shutdowns for inspection, equipment failures, and grid-related outages affect power generation.

Soiling losses are losses in which the transmission of solar irradiance is impeded by dust and mud, pollen, bird droppings, salt from coastal areas, and dust around agricultural land that adhere to the panel surface. In some regions these are naturally washed away by rain, but soiling losses can be significant in low-tilt installations or in environments where dirt tends to accumulate. On low-slope roof installations, rainwater does not run off easily and dirt can remain at the lower edge of the panels.

Degradation losses reflect the decline in the performance of modules and equipment over time. Because solar power plants are intended for long-term operation, it is necessary to evaluate not only first-year energy production but also the output several years and ten or more years later. The degradation rate significantly affects project viability, so it should be handled carefully when assessing long-term financial performance.

Downtime losses are losses that occur when equipment is not operating despite solar irradiation conditions sufficient for power generation. These include scheduled inspections, equipment replacement, communication failures, activation of protective devices, grid-side constraints, and output curtailment. They are easily overlooked at the design stage but are extremely important when considering actual power generation.

When setting these losses in PVSyst, it is important to match them to the local area and the operation plan. In dry regions, areas near farmland, sites close to construction, coastal locations, and snowy regions, the effects of soiling and deposition differ. The losses to be assumed also change between plants with frequent maintenance and those with long inspection intervals. Rather than simply entering uniform values, considering cleaning schedules, weed control plans, inspection regimes, and whether remote monitoring is in place will result in settings that are closer to real-world practice.

Practical Checklist for Verifying Loss Settings

When checking PVSyst loss settings in practice, it is easier to organize them by following the power generation flow in sequence rather than adjusting individual detailed items from the start. First confirm the site and meteorological data, then check the irradiance conditions on the installation surface, shading, temperature, module characteristics, the DC side, conversion, the AC side, and operational losses, in that order. Viewing them in this order makes it easier to trace where the power output is being reduced.

In the initial check, verify that the input conditions match the design drawings and site conditions. Confirm that the location, elevation, tilt angle, azimuth, array capacity, string configuration, and power conditioner capacity are correct. If there are errors here, no matter how much you adjust the loss settings you will not obtain a valid comparison.

Next, check the items with large losses on the loss diagram and results screen. By looking at the loss diagram, you can understand at which stage and by how much the power generation is reduced in the flow from solar irradiation to the final output. What is important here is not to minimize all losses, but to look for any unnatural losses. For example, if shading losses are large at a site that should have little shading, you need to check the 3D scene and obstacle settings. If wiring losses are large despite a design with short wiring distances, review the cable conditions and loss rate settings.

Also, when comparing design proposals, it is important that the same assumptions are used for each proposal. If solar irradiance data, soiling losses, degradation rates, or downtime rates differ between proposals, you cannot compare the pure design differences. When examining differences between design proposals, fix as many factors as possible other than the items you want to change so that you can trace the causes of differences in power generation.

In submitted documents and internal communications, it is also important to record the rationale for loss settings. Organizing which losses used standard values, which were based on drawings or on-site measurements, and which were based on maintenance plans will make later explanations easier. Rather than showing only the PVSyst results, managing the input conditions and loss settings together is a key point for improving practical quality.

What Is Necessary to Align Simulation Values with On-Site Conditions

The purpose of correctly handling loss settings in PVSyst is not simply to make the predicted energy yield look larger, nor to make it look conservatively lower. It is to create an explainable simulation that closely reflects site conditions. For that reason, it is important not only what you enter into the software but also how accurately you can obtain information from the field.

Shadows, terrain, racking height, surrounding obstacles, installation area, equipment layout, and wiring routes in particular can be difficult to grasp from drawings alone. If there are discrepancies between the initial design drawings and the actual site, the PVSyst model can also become misaligned with the field. Changes in post-development ground elevation, the positions of surrounding structures, tree heights, or the placement of fences and equipment will also affect shading and wiring plans.

Also, when evaluating a power plant’s performance after construction, it is necessary to reconcile the simulation conditions used at the design stage with the actual measured on-site conditions. Verifying where the panels were installed, whether the mounting angles match the design, whether there are any obstacles that cast shadows, and whether the wiring or equipment layout has been changed makes it easier to sort out the causes of differences in power output.

In such on-site checks, the accuracy of location information and site records is important. Traditionally, surveying instruments, drawing verifications, and photographic records have often been managed separately, which can make it time-consuming to later reconcile them with PVSyst input conditions. If site coordinates, photos, point clouds, and as-built information can be managed together, it becomes easier to check shadows, grasp the installation area, organize terrain conditions, and compare with design values.

PVSyst is a powerful tool for performing simulations, but the accuracy of the site information you enter determines the reliability of the results. The more thoroughly you understand the loss settings, the more you realize how important measured on-site data is. Connecting desk-based settings with actual site conditions is essential for improving the accuracy of energy yield forecasts.

Summary

The loss settings in PVSyst are important input items for bringing a solar power plant’s predicted generation closer to reality. The main items that cause differences in generation include irradiance data and meteorological conditions, incidence angle losses, near-field and far-field shading, temperature losses, module quality losses, module mismatch losses, DC-side wiring losses, power conditioner conversion losses, AC-side wiring and grid-connection-related losses, soiling and degradation, and losses due to downtime.

These losses may seem independent, but in reality they are connected to design conditions and site conditions. Tilt angle and azimuth affect incidence-angle losses, and racking conditions affect temperature losses. Nearby obstructions and row spacing affect shading losses, and string configuration affects mismatch losses. Equipment layout and cable routing relate to losses on the DC and AC sides. Maintenance planning and cleaning frequency relate to soiling and expected downtime.

When using PVSyst in practice, it is important not just to look at the final energy production figure but to check the breakdown of losses and be able to explain which conditions are affecting the results. Even when using standard values, confirm that those values match site conditions, and as you move toward detailed design and post-construction verification you should incorporate drawings, site surveys, photographs, point clouds, and equipment information.

In particular, understanding shading, terrain, mounting positions, site elevation differences, and surrounding structures directly affects simulation results. If these aspects remain ambiguous and you only adjust the loss settings, it becomes difficult to explain the discrepancy with actual energy production. To improve the accuracy of energy production forecasts, information management that links the settings in PVSyst to the actual on-site conditions is indispensable.

If you want to streamline on-site position verification and record-keeping, leveraging LRTK, a GNSS high-precision positioning device that can be attached to an iPhone, makes it easier to link installation areas, structures, site photos, and point clouds with highly accurate positional information for management. By combining the work of refining loss settings in PVSyst with the task of obtaining accurate positional information on-site, you can bring desktop simulations and the actual condition of the power plant closer together. Not only learning how to use PVSyst, but also establishing a process to correctly capture and reflect on-site conditions, is a practical and important step to improve generation forecasts and design quality.