What is PVSyst? An introductory guide to using it to improve design accuracy

Table of Contents

• What PVSyst is used for

• Fundamental concepts to understand before improving design accuracy

• Input conditions that affect the accuracy of power generation forecasts

• How to handle meteorological data and solar irradiance

• Correctly reflect layout planning and the effects of shading

• Carefully configure equipment parameters and electrical design

• Approach to making loss conditions closer to reality

• Key points to check in result screens and reports

• Workflow for using PVSyst to improve accuracy

• On-site verification and positioning accuracy underpin design quality

• Summary

What is PVSyst used for?

PVSyst is a specialized analysis tool for simulating the power generation of photovoltaic systems in advance and for evaluating a plant’s performance while organizing design conditions and loss conditions. It is used not merely to produce an annual generation figure but to combine solar irradiation, temperature, tilt angle, orientation, shading, equipment configuration, wiring, conversion efficiency, and various losses to numerically confirm the expected generation performance at the design stage.

Many practitioners who search "What is PVSyst" want to know how reliable the figures it produces can be in situations such as photovoltaic system design, feasibility studies, energy yield forecasting, report preparation, internal explanations, and explanations for clients. PVSyst is a useful calculation tool, but if the input conditions are not correct, the output results will also deviate from reality. Therefore, to improve design accuracy, it is important not only to know how to operate the software, but also to understand what to base the inputs on, how to interpret which results, and where uncertainties remain.

In the design of photovoltaic systems, even installations with the same capacity can yield different actual energy output depending on location, tilt, orientation, weather conditions, surrounding obstructions, module layout, grid conditions, construction quality, and maintenance practices. PVSyst is characterized by its ability to structure these conditions as thoroughly as possible and to evaluate, in sequence, the factors that influence energy production. In other words, it is easier to understand PVSyst if you think of it not as a tool that automatically gives you the “answer,” but as a tool that visualizes design conditions and verifies the validity of energy production forecasts.

In practical work, the important thing is not to take simulation results at face value. You must distinguish which input values are supported by strong evidence and which are merely assumptions, and prioritize checking the conditions that have a large impact on the results. Mastering PVSyst does not mean filling in the fields on the screen; it means gathering the information necessary for power generation forecasts, reconciling design intent with site conditions, and compiling an explainable report.

Fundamental Concepts to Understand Before Improving Design Accuracy

To improve design accuracy in PVSyst, you first need to clarify what "accuracy" means. Here, accuracy does not simply mean producing numbers with many decimal places. It refers to a state in which site conditions, design assumptions, equipment characteristics, and the way losses are accounted for are close to reality and can be explained to stakeholders. Even if the output shows detailed numbers, if the input conditions are ambiguous, the reliability of the results will not be high.

In solar power generation simulations, there are many factors that influence the amount of electricity produced. Some depend on natural conditions, such as irradiance and ambient temperature, while others can be adjusted through design, such as module orientation and tilt angle, electrical wiring, equipment selection, and shading. Furthermore, there are losses that affect output after generation, such as soiling, degradation over time, mismatch, conversion losses, cable losses, and downtime. Because PVSyst evaluates these cumulatively, step by step, it is important to enter inputs while understanding the meaning of each stage.

What should be avoided when improving design accuracy is continuing to use initial or conventional values without careful consideration. Of course, detailed information may be unavailable in the early stages. Even in that case, it is necessary to make clear that inputs are provisional and to ensure they can be updated later based on site surveys and finalized designs. The required level of accuracy differs between preliminary studies, basic design, detailed design, and pre-construction checks. Even if the purpose of a preliminary study is only rough comparison, detailed design requires bringing elements such as shadow extent, wiring lengths, installation angles, and equipment specifications closer to reality.

Also, PVSyst results alone do not prove that a design is correct. They only become meaningful when combined with on-site surveys, drawings, meteorological data, equipment specifications, construction conditions, and maintenance conditions. If the basis for the input values is inconsistent, the explanation of the simulation results will also be unstable. Conversely, if you organize the rationale for input conditions, keep a record of changes, and can explain the main loss factors, you will be more persuasive in internal reviews and when explaining the project to the client.

The basic idea of leveraging PVSyst to improve design accuracy is not just to predict energy generation. It is also valuable to understand how much the results change when conditions are altered, and to identify design risks and opportunities for improvement. For example, by comparing multiple cases — such as changing the tilt angle, changing the azimuth, excluding the effects of shading, or applying more conservative loss assumptions — you can establish a basis for design decisions.

Input conditions that affect the accuracy of power generation forecasts

PVSyst's power generation forecasts are highly dependent on the quality of the input conditions. Particularly important are the installation site, meteorological data, the module surface tilt and azimuth, surrounding shading, equipment configuration, and various loss conditions. If even one of these deviates significantly from reality, not only the annual energy production but also the monthly generation trends and behavior at peak times will change.

The installation site provides the basic information that defines latitude and longitude, elevation, and the region's meteorological characteristics. If the location information is inaccurate, it will affect calculations of solar radiation and solar altitude and the selection of meteorological data. In particular, in mountainous areas, coastal zones, snowy regions, and confined urban sites, nearby locations can exhibit different tendencies in solar radiation and temperature. Do not make the representative point of the planned site vague; it is important to set coordinates that reflect the actual site as closely as possible.

Tilt and azimuth angles are also conditions that directly affect power generation. Whether the array is closer to south-facing or tilted toward the east or west, whether it follows the roof pitch or the angle is adjusted with a mounting system, will change the annual generation and the generation patterns by time of day. You should check not only the simple annual generation figure but also electricity demand, grid interconnection constraints, and approaches to peak shaving. For example, with an east-west distributed layout, it is important to evaluate not only the annual maximum but how much generation contributes in the morning and evening.

In equipment configuration, it is necessary to reconcile the PV module capacity, the number of modules in series and in parallel, the capacity of the conversion equipment, the input voltage range, output limits, and so on. Even if the numbers appear to allow a connection, temperature conditions can cause voltages to fall outside the input range, and depending on the approach to oversizing, output limitations may increase during certain times of day. Rather than assuming there is no problem simply because PVSyst shows no errors, it is important to confirm that the design conditions are on the safe side and that the power generation forecast is reasonable.

Loss assumptions also have a significant impact on design accuracy. Soiling, shading, temperature, wiring, mismatch, conversion, downtime, degradation, and other factors may each appear to make only a small difference individually, but when they accumulate they can greatly affect annual energy production. In particular, setting optimistic loss values without solid justification tends to make simulated energy production higher than actual performance. Conversely, applying overly conservative assumptions can lead to underestimating a project's viability. To improve accuracy, reasonable settings that reflect site and operational conditions are necessary.

When handling input conditions, it is also important to manage which values are confirmed information, which are assumptions, and which will be updated in subsequent stages. A simulation is not something you create once and then finish; it should be updated as the plan progresses. In the initial study, adopt relatively broad assumptions; in the detailed design, correct them based on drawings and on-site verification; and before construction, check them against the final conditions to improve the reliability of the power generation forecast.

How to handle meteorological data and solar radiation

One of the most fundamental inputs in PVSyst is the meteorological data and solar irradiance. Because photovoltaic power generation is a system that converts solar energy into electricity, if the assumed solar irradiance is off, the entire power generation forecast will be off. No matter how carefully equipment settings and loss parameters are configured, if the assumed solar irradiance does not match the actual site conditions, there are limits to the design accuracy.

When looking at meteorological data, it's important not to judge based solely on annual solar irradiation. Monthly variability, seasonal trends, temperature, wind effects, and regional characteristics such as snowfall or the rainy season also affect power generation. Even in regions with similar annual solar irradiation, generation patterns differ depending on whether they are strong in summer or weak in winter, or whether clouds tend to form in the mornings and evenings. For project feasibility assessments and grid connection studies, checking monthly and time-of-day trends as well as the annual total makes design decisions easier.

Also, there is the concept of a representative year for weather data. Using the measured values from a single year as they are versus using data that reflect long-term average trends leads to different interpretations of the results. For long-term forecasts in power generation projects, it is common to use average weather conditions so the forecast is not overly influenced by a single year's weather. On the other hand, when comparing with the actual performance of existing facilities, you must use data that are close to the actual weather conditions of the period in question; otherwise, the assumptions underlying the comparison will not align.

When setting solar irradiance, it is also important to understand the process of converting irradiance on a horizontal plane to irradiance on a tilted plane. Photovoltaic modules are often installed at a fixed angle rather than horizontally. Therefore, it is necessary to convert the irradiance received on the horizontal plane to the irradiance received on the module surface. This conversion involves direct irradiance, diffuse irradiance, reflected components, solar altitude, installation angle, and other factors. PVSyst incorporates these into its calculations, but if the entered tilt or azimuth is incorrect, the tilted-plane irradiance calculation will also deviate from reality.

Air temperature is also important. Photovoltaic modules have the property that their power generation efficiency decreases as temperature rises. In hot regions, even if solar irradiance is high, temperature losses can become large. Conversely, in cold climates, while there are challenges with solar irradiance conditions and snowfall, the temperature aspect can sometimes be advantageous. When handling meteorological data, you need to consider the impact on power generation not only from solar irradiance but also from temperature conditions.

To improve design accuracy, it is important to verify the source and representativeness of meteorological data and to select data that are appropriate for the local conditions. When using data from locations distant from the planned site, check whether terrain, elevation, sea breezes, fog, snowfall, or localized cloud formation could affect the results. Especially in mountainous areas and complex terrain, nearby representative data alone may not fully reflect local conditions. Meteorological data are the foundation of simulations, and treating them carefully is the first step toward improving design accuracy.

Accurately reflect the layout plan and the effects of shadows

In the design of solar power generation systems, layout planning and the effects of shading have a major impact on energy yield. PVSyst can perform simulations that take into account surrounding obstacles and inter-row shading, but to accurately reflect shading conditions it is necessary to identify the site’s terrain, buildings, trees, structures, and racking layout as precisely as possible.

Shadows can be broadly divided into those caused by surrounding objects and those that occur within the installation. Shadows from surrounding objects are produced by neighboring buildings, utility poles, trees, slopes, mountains, fences, and equipment. Shadows within the installation occur when spacing between module rows is insufficient, when the tilt angle is large, or when mounting racks and ancillary structures cast shadows. Especially in seasons and times of day with a low solar elevation, even small obstructions can cast long shadows, so it is important not to underestimate shadows in winter and during the morning and evening.

When reflecting a layout plan in PVSyst, simply entering the capacity is not sufficient. By taking into account module arrangement, row spacing, tilt, orientation, terrain slope, and the height and positional relationships of surrounding obstacles, you can evaluate shading losses that are closer to reality. For roof installations, the orientation and pitch of each roof surface, changes in elevation, protrusions, and shadows from adjacent buildings are important. For ground-mounted installations, you need to check site shape, earthwork slopes, row spacing, north-south clearances, maintenance aisles, and shadows from nearby trees and structures.

Shading affects not only annual energy output but also power generation at different times of day. For example, an arrangement that is shaded only in the morning and one that is shaded around midday can have different impacts on energy production even if the total shading duration is the same. In solar power generation, losses are greater when shading occurs during periods of strong solar irradiance. Therefore, it is necessary to check not only whether shading occurs but also when it occurs, over what area, and to what extent.

Also, the impact of shading is related to the electrical connections. If some modules are shaded, that shading can propagate to the outputs within the same circuit. If the areas prone to shading are not aligned with the circuit configuration, losses larger than expected may occur. When evaluating shading in PVSyst, being aware not only of layout-related shading losses but also of their relationship to the circuit configuration makes it easier to improve the design.

To improve design accuracy, it is important to reflect information obtained from on-site inspections in the layout plan and not to underestimate shadow conditions. In particular, even if drawings appear problem-free, tree growth, neighboring structures, microtopography, and existing equipment on site can create shadows. During the planning stage, it is essential to combine site photographs, survey data, simplified models, and as-built/existing-condition drawings to ensure shadow-generating factors are not overlooked.

Carefully set equipment conditions and electrical design

To improve the design accuracy of PVSyst, it is necessary to carefully configure the equipment conditions and electrical design settings. A photovoltaic power generation system is made up of a combination of solar modules, conversion equipment, wiring, protection devices, junction boxes, and power receiving and transformer equipment. In simulations you mainly input the components related to power generation, but if those settings do not match the actual design, the reliability of the power production forecast will decrease.

First, what I want to check is the specifications of the solar modules. Nominal output, temperature characteristics, voltage, current, efficiency, output tolerance, and so on affect the amount of power generated and the electrical feasibility. In particular, voltage variations due to temperature are relevant when determining the number of modules in series. Because voltage increases at low temperatures and decreases at high temperatures, it is necessary to verify whether it will fall within the input range of the power conversion equipment. Even if there is no problem under normal conditions, if there is a possibility of falling outside the range under extreme temperature conditions, that becomes a design risk.

Next, check the capacity of the conversion equipment and the input conditions. How large the conversion equipment capacity should be relative to the photovoltaic capacity affects generated output, equipment utilization, output limits, and economics. When oversizing is applied, output can be curtailed by the capacity limit of the conversion equipment during periods of strong solar irradiance. This limitation is not necessarily a bad thing, but it is important to verify to what extent it appears as a loss in simulations and to be able to explain it as an intentional part of the design.

Settings for the series and parallel counts are also important. If the series count is too low, the voltage may not rise sufficiently, which can affect conversion efficiency and the operating range. If the series count is too high, there is a risk that the maximum voltage at low temperatures will exceed the limit. The parallel count is related to current conditions, the number of inputs, and the circuit configuration. PVSyst allows you to input the connection configuration, but it is essential to verify that it matches the actual construction drawings and electrical design.

Wiring conditions are also an item that is easily overlooked. Cable length, cross-sectional area, circuit configuration, voltage drop, and resistive losses affect power generation. In initial studies, approximate values are often used, but in the detailed design stage they need to be updated based on actual layouts and equipment locations. This is especially true for large-scale installations, where wiring distances tend to be long and losses accumulate. Setting wiring lengths shorter than they actually are can lead to overestimating power generation.

When setting equipment parameters, it's important not only to enter the specification values as-is, but also to verify that they are consistent across the entire design. Checking that the module layout, circuit configuration, converter inputs, wiring, and shading extents are properly connected helps make the simulation closer to the actual power plant. PVSyst offers detailed configuration options, but precisely because of that it is a tool where input mistakes or omissions readily affect the results. For that reason, each equipment parameter needs to be set individually with a clear rationale.

Approaches to Making Loss Conditions More Realistic

When improving design accuracy in PVSyst, setting the loss conditions is extremely important. In photovoltaic power generation, the energy received as solar irradiation does not directly become electrical power. Various losses occur during the process of reaching the module surface, the process of conversion in the module, the process of being transported as electricity, the process through conversion equipment, and the process of being sent to the grid. In PVSyst, these losses can be evaluated separately by item.

Typical losses include temperature loss, shading loss, soiling loss, mismatch loss, wiring loss, conversion loss, output limitation, downtime loss, and degradation over time. These are not all of the same nature. Some depend strongly on meteorological conditions, some can be improved by design, some are influenced by construction quality, and some vary with operation and maintenance. Therefore, instead of assigning a uniform loss value, it is important to consider them according to site conditions and equipment specifications.

Temperature loss is the loss in power generation efficiency that occurs when module temperature rises. In regions with high ambient temperatures, installations close to the roof with poor ventilation, or environments prone to reflected heat, temperature losses can be larger. Even at the same ambient temperature, module temperature rises differently for ground-mounted installations with good ventilation compared to installations close to the roof. Considering the thermal conditions according to the installation method produces results that are closer to reality.

Soiling losses are caused by sand and dust, pollen, bird droppings, fallen leaves, ashfall, salt, and dirt after snowfall. The extent of soiling varies depending on the region, surrounding environment, cleaning frequency, and the tilt angle of the panels. In some environments rain will naturally wash them away, while in low-tilt installations dirt tends to remain. If there is unpaved land, farmland, factories, coastal areas, or trees nearby, you should not underestimate soiling losses.

Mismatch losses occur when differences in performance between modules or variations in irradiance conditions cause the circuit’s overall output to be unbalanced. They are caused by module variability, partial shading, differences in degradation, uneven soiling, and similar factors. Even if modules of the same specification are used at installation, variability can increase during long-term operation. Although it is difficult to predict them with excessive precision at the design stage, care is needed for layouts that are prone to shading or uneven soiling.

Do not forget downtime losses and operational losses. Inspections, failures, grid constraints, communication failures, protective actions, planned outages, and the like can cause situations in which generation cannot take place during times when it should be possible. Although it is difficult at the design stage to predict precisely when and how often such events will occur, when evaluating a power generation project you must take into account that equipment will not always operate under ideal conditions.

The key to bringing loss assumptions closer to reality is to understand both optimistic and conservative values. Before deciding on the final adopted values, compare cases with different loss conditions and grasp how much the energy production varies; this makes it easier to explain design risk. The loss diagram in PVSyst is an important document for checking where and how much energy is being lost. Rather than simply looking at the final energy yield, read the breakdown of losses and separate losses that can be improved from those that are difficult to avoid—doing so leads to improved design accuracy.

Points to Check on the Results Screen and in the Report

When checking PVSyst results, many people first look at the annual energy production and the capacity factor. Of course the final energy production is important, but to improve design accuracy you need to verify the process that leads to those numbers. The results screen and reports contain a lot of information, including solar irradiance, plane-of-array irradiance, various losses, monthly energy production, performance indicators, and equipment-specific behavior.

The first thing to check is whether the input conditions and the results are consistent. Verify that the installation location, orientation, tilt, capacity, equipment configuration, and meteorological conditions are as intended. If you do not confirm that the assumptions are correctly reflected before judging whether the power generation is high or low, you will misinterpret the results. In particular, files created by reusing past projects may still retain the previous project's location, equipment, loss conditions, report name, and so on.

Next, review the monthly generation. Looking only at the annual total can cause you to miss seasonal trends or unnatural biases. For example, if winter generation is extremely low, check the effects of solar irradiance conditions, snow cover, shading, tilt, and orientation. If summer generation is lower than expected, temperature losses and output limitations may be significant. Examining monthly trends makes it easier to detect errors in input conditions or design issues.

Loss diagrams are also important. A loss diagram lets you see how much each item reduces the solar energy during the process until it becomes the final output. If a particular loss is extremely large, verify whether you can explain the reason. If shading losses are large, check the layout and surrounding obstacles; if temperature losses are large, check the installation method and meteorological conditions; if wiring losses are large, check the wiring length and cross-sectional area; if conversion losses are large, there may be room to review the equipment capacity and operating range.

Checking performance indicators is also important. Because installations with high electricity generation often have large capacities, it can be difficult to compare the quality of designs based on raw generation alone. By checking indicators such as energy produced per unit of capacity and the efficiency of power generation relative to solar irradiance, it becomes easier to compare installations of different scales and under different conditions. However, indicators are not infallible. If regional solar irradiance conditions or installation constraints differ, you may not be able to compare them directly using the same indicators.

When using a report in practice, it is important to make it readable and understandable to all stakeholders. A document that only the simulation engineer can understand is difficult to use for design decisions and approvals. Ensuring that the main assumptions, the loss values adopted, notable uncertainties, and the differences from comparison cases can be explained will make internal reviews and explanations to the client run smoothly. A PVSyst report is not only a table of generation results but also documentation explaining the design conditions.

Workflow for improving accuracy

To leverage PVSyst to improve design accuracy, it is effective to establish the workflow in advance. If you start entering items as they occur to you, omissions in settings and a mix of assumptions are likely to happen. In practice, progressing through the sequence of clarifying objectives, collecting information, creating an initial model, confirming conditions, comparing cases, incorporating details, and reviewing the report makes it easier to improve accuracy step by step.

The first thing to do is to clarify the purpose of the simulation. Whether it is an initial candidate-site comparison, a validation of the basic design, a power-generation forecast for detailed design, or the preparation of materials for explaining to the client, the required level of accuracy and the input information will differ. If you begin work with an unclear purpose, you may spend time on unnecessarily detailed settings or, conversely, omit important assumptions.

Next, organize the input information. Gather the installation location, site plan, roof plan, survey information, meteorological conditions, equipment specifications, layout proposals, grid conditions, surrounding obstacles, construction conditions, operating conditions, etc. If information is lacking at this stage, clearly identify the items that will be treated as assumed values. Using assumed values itself is not a problem, but confusing them with confirmed values can lead to incorrect judgments later.

Once you have created the initial model, first check whether the major conditions are correct. Verify that capacity, orientation, tilt, meteorological data, equipment configuration, and major losses match the intended settings. At this stage, it is more important to confirm the overall direction than to focus on detailed numbers. Review the monthly generation and loss diagrams to check for any extreme values.

After that, create comparative cases for the design. For example, compare scenarios such as changing the tilt angle, changing the azimuth, widening row spacing, avoiding shading, changing equipment capacity, or adopting conservative loss assumptions. By comparing cases, you can determine which conditions have the greatest impact on power generation. This is very useful for prioritizing design improvements.

In the detailed design phase, the model is adjusted to reflect on-site verification and updated drawings. Wiring lengths, actual equipment locations, obstacles, installation angles, circuit configurations, and so on are incorporated, and the differences from the initial model are checked. What is important here is not simply aligning with the latest drawings, but understanding how the changes have affected power generation and losses. If you can explain the impact of design changes, it becomes easier to build consensus among stakeholders.

Finally, review the report and verify the consistency between the input conditions and the results. Emphasize explainability as well as the presentation of the numbers. Clarify why this meteorological data was used, why these loss values were adopted, which site conditions the shading assessment is based on, and which items remain uncertain. By performing this verification, PVSyst’s results can be used not merely as simulation outputs but as a basis for design decisions.

On-site verification and positioning accuracy underpin design quality

No matter how carefully you set the conditions in PVSyst, if the on-site information is inaccurate there are limits to the design accuracy. In solar PV design, much information depends on the site, such as location, elevation, site shape, roof shape, obstructions, orientation, tilt, and the surrounding environment. If these are not correctly understood, even if the simulation yields tidy results, discrepancies may occur in actual construction and power generation performance.

What is particularly important is understanding the positional relationship between the site and the roof and identifying surrounding obstructions. If drawings are outdated, on-site structures, trees, or equipment layouts may not be reflected. Post-development topography, changes to adjacent properties, newly added equipment, and obstacles that have not been removed can also affect shading and construction planning. Because the shading and layout conditions entered into PVSyst depend on the accuracy of on-site information, it is important not to rely solely on desk-based materials.

Awareness of orientation and slope also affects power generation forecasting. For rooftop installations, the orientation and tilt of each roof surface may differ from the assumptions. For ground-mounted installations, the overall gradient of the site and microtopography can affect inter-row shading and racking layout. A difference of a few degrees may not make a large difference, but when multiple factors combine, they can affect annual energy yield and seasonal generation patterns.

During on-site inspections, it is important not only to take photos but also to record location and height information together. If you make sure you can later confirm where obstacles are, which direction they cast shadows, and what area they affect, modeling in PVSyst becomes easier. If the information obtained on site is ambiguous, you will need to re-check later, which can cause design rework.

Using LRTK (an iPhone-mounted GNSS high-precision positioning device) is an effective means of improving the accuracy of such on-site verifications. In the design of solar power generation facilities, the ability to record site boundaries, obstructions, equipment installation locations, survey points, and on-site verification points with high precision leads to improved reliability of the assumptions entered into PVSyst. If location information acquired on site can be more easily reflected in design documents and layout studies, it will also make it easier to confirm shading conditions and layout constraints.

PVSyst is a powerful tool for energy yield prediction and design studies, but what underpins its accuracy is on-site information. Rather than limiting work to simulations alone, obtaining precise positions on site, cross-checking them against drawings and models, and establishing a workflow to feed necessary information back into the design will improve the reliability of energy yield forecasts. By combining this with on-site positioning systems like LRTK, it becomes easier for design teams and field personnel to share information, reducing discrepancies between desk-based studies and actual site conditions.

Summary

PVSyst is a specialized simulation tool for predicting the energy production of photovoltaic power systems and for evaluating plant performance while organizing design parameters and loss conditions. To improve design accuracy, simply learning how to operate the software is not enough; you must correctly understand the installation site, meteorological data, tilt, azimuth, shading, equipment configuration, wiring, loss conditions, and other factors, and input them so they are consistent with actual site conditions.

In power generation forecasting, it is important to verify not only the final annual energy production but also monthly trends, loss diagrams, performance indicators, and the consistency of input conditions. Rather than judging results solely by whether the numbers are large or small, being able to explain which assumptions produced those numbers leads to simulations that are usable in practice.

Also, the accuracy of PVSyst depends greatly on the accuracy of site information. If the site layout, roof geometry, surrounding obstacles, orientation, tilt, equipment locations, and so on remain ambiguous, no matter how carefully you configure settings on-screen you cannot completely avoid discrepancies with reality. To improve design accuracy, it is important not to separate simulation from on-site verification and to reflect information obtained in the field in the design.

In designing solar power systems, both the ability to predict energy yield and the ability to accurately grasp site conditions are required. By carefully examining energy production and losses in PVSyst and acquiring high-precision site positioning with an LRTK (iPhone-mounted GNSS high-precision positioning device), it becomes easier to connect desk-based designs with the actual field. Practitioners who want to improve design accuracy using PVSyst should, while reviewing simulation conditions, also pay attention to the accuracy of on-site positioning and site assessment so they can advance solar power designs that are easier to explain and closer to reality.