【How to Read PVSyst Loss Diagram in 5 Minutes | For Beginners】

Table of Contents

• What the PVSyst loss diagram is intended to show

• Basic process to understand before reading the loss diagram

• Changes in solar irradiance to look at first in the loss diagram

• Points to note when examining losses due to shading

• How to read temperature losses and module efficiency

• How to interpret wiring losses and electrical losses

• Key points for checking PCS capacity and conversion losses

• Common mistakes beginners make when reading the loss diagram

• Order to check the loss diagram in practice

• Approach to using the loss diagram for design improvements

• Summary

What does the PVSyst loss diagram show?

The PVSyst loss diagram is a chart that shows, step by step, how the solar irradiance energy entering a photovoltaic system is converted into the final amount of generated electrical energy. In English it may be referred to as a loss diagram or losses diagram, and in reports it is one of the particularly important items to verify among the simulation results.

In simulations of solar power generation, solar irradiance first reaches the panel surface, is converted into DC power by the photovoltaic module, passes through wiring and equipment, and is finally output as AC energy. However, the input energy does not directly become generated power. Various factors—installation angle effects, shading, efficiency degradation due to temperature rise, module variability, wiring resistance, equipment conversion efficiency, output limitations, and so on—cause incremental losses.

A loss diagram is arranged so you can trace these losses from top to bottom. It may seem difficult for beginners because it looks like there are many numbers, but the basic way to read it isn’t that complicated. The important thing is not to look at each item in isolation, but to understand, as a flow, at which stages and by how much the energy is being reduced.

In practice, by looking at a loss diagram you can determine whether the simulation results are reasonable. For example, if the annual energy production is lower than expected, simply looking at the generation number alone won't reveal the cause. You need to check whether the solar irradiance conditions are low, the shading settings are too strict, temperature losses are large, wiring losses are excessive, or there is a problem with the equipment capacity settings. In that case, the loss diagram serves as a map for finding the cause.

Loss diagrams are useful not only for designers but also for clients and construction personnel. If you can explain under what assumptions the power generation was calculated and which losses were incorporated, the credibility of the simulation results will increase. In particular, in the design and proposal of photovoltaic power systems, being able to explain the basis for the power generation figures is more important than the figures themselves.

When learning how to use PVSyst, the loss diagram is an unavoidable item. You don’t need to try to understand every number in detail from the start. First, it’s important to grasp the overall flow: solar irradiation enters, is converted by the modules, passes through DC-side losses, and becomes AC-side output. From there, if you check in order which items account for the largest losses, even beginners can grasp the meaning of the results in a short time.

The basic flow you should understand before reading a loss diagram

Before reading a loss diagram, it is necessary to understand the flow of energy in a photovoltaic system. In a solar power system, there is first the solar irradiance incident on a horizontal plane. From there, the irradiance incident on the panel surface is determined by the tilt and azimuth of the actually installed PV modules. In other words, even if the solar irradiance in the same region is the same, the amount of irradiance the panels receive will change if the installation angle or orientation changes.

Next, that solar irradiance reaches the photovoltaic module. Here, the amount of irradiance actually available for power generation is reduced by factors such as reflection and incidence-angle effects, shading, and soiling. The module then converts the irradiance into direct-current power, but conversion efficiency decreases when the module temperature is high. Although solar cells generate more easily with stronger irradiance, their efficiency falls as temperature rises, so losses can be greater in summer.

After DC power is generated, losses arise from electrical mismatches between modules, wiring resistance, connection conditions, differences in operating points, and other factors. In addition, the DC power is converted to AC power by a power conversion device, and losses corresponding to the conversion efficiency occur in this process. Finally, where necessary, losses related to voltage transformation and grid connection are added, and the final amount of electricity generated is calculated.

The loss diagram displays this flow in stages. It helps to think of items related to solar radiation at the top, module and DC-side items in the middle, and AC-side and final output items at the bottom. Reading from top to bottom, you can see at which stages energy is lost.

When beginners look at a loss diagram, the important thing is not to memorize the technical terms for each item perfectly from the start. First, it is important to view it in the major categories: irradiance-side losses, module-side losses, DC-side losses, and AC-side losses. By keeping these categories in mind, you can organize and read loss diagrams that initially appear complicated.

Also, the percentages shown in a loss diagram are not necessarily all relative to the same reference. Some may be displayed as losses relative to the input value at a given stage, while others are better understood as the difference between the amounts of energy before and after. Therefore, rather than looking only at the magnitudes of the numbers, it is necessary to check where in the flow of the diagram each loss is located.

In practice, learning how to read loss diagrams makes it easier to notice mistakes in simulation settings. For example, if shading losses are extremely large, it prompts a review of nearby obstacles, terrain, and array spacing settings. If wiring losses are large, you can check whether there are errors in cable length, cross-sectional area, or input conditions. If output limits are large, you need to reconfirm the ratio of module capacity to inverter capacity.

As such, loss diagrams are not merely a display of results but a practical tool for inspecting design details. To learn how to use PVSyst, it is essential to develop the habit of not only using the input screens but also reviewing the output loss diagrams to determine whether the settings are appropriate.

Changes in Solar Irradiance to Look at First on a Loss Diagram

When looking at a loss diagram, the first thing you should check is changes in solar irradiance. Photovoltaic power output is ultimately influenced not only by installed capacity and equipment efficiency but also—and often significantly—by how much solar irradiance it receives. Therefore, the irradiance-related items shown at the top of a loss diagram are a crucial part that forms the foundation of the whole.

In general, at the initial stage, values corresponding to horizontal irradiance and global irradiance are shown. These are baseline solar radiation values based on the meteorological data at the location. Next, the irradiance incident on the tilted surface is calculated according to the tilt and azimuth of the module to be installed. It is natural for increases or decreases to occur here. For example, if installed at an appropriate tilt angle, the irradiance received on the tilted surface may be greater than the irradiance received on the horizontal plane. Conversely, under unfavorable azimuth or tilt conditions, the tilted-surface irradiance may not reach the expected level.

What beginners should be careful about is not to regard changes in solar irradiance solely as losses. When converting to a tilted surface, some components may increase depending on the conditions. This is because the installation angle can allow sunlight to be received more efficiently. Because of the name "loss diagram," one tends to assume that all items act in a decreasing direction, but in reality some are shown as increases during the solar conversion stage.

The next thing to check is losses due to the angle of incidence. When sunlight strikes the module surface at an oblique angle, effects such as reflection reduce the solar irradiance actually absorbed. This impact tends to be greater during periods of low solar elevation, such as mornings and evenings or in winter. Normally this loss occurs to some extent, but if it is abnormally large you should check the installation tilt and azimuth settings and the input for reflection characteristics.

Also, if losses due to soiling are being set, their effect can be considered as losses on the solar irradiance side. Sand and dust, pollen, bird droppings, and contamination from the surrounding environment reduce the solar irradiance reaching the module surface. Even if they appear as a small percentage on a loss diagram, when converted to annual energy yield they can amount to a non-negligible difference. In particular, in locations with low cleaning frequency or high levels of airborne dust, it is important to check that the soiling loss setting is not underestimated.

When reading the stages of solar irradiance, you must also be aware of the validity of the meteorological data. If the site settings are misaligned, the elevation or surrounding environment do not match reality, or the period or representativeness of the meteorological data used is insufficient, the initial values in the loss chart can diverge greatly from actual conditions. No matter how finely you check losses in the lower part of the loss chart, if the initial solar conditions are inappropriate, the reliability of the final results will be low.

When an operations staff member reviews a loss diagram, they should first examine the pattern of solar irradiance and verify that the selected site, tilt, azimuth, and meteorological data fall within a reasonable range. If there is no major discrepancy there, they should then proceed to check shading, temperature, and electrical losses. Conversely, if any of the solar-related items at the top look suspicious, it is important not to jump straight to the lower power-generation figures but to go back and verify the site and meteorological data settings.

Precautions When Assessing Losses Due to Shading

Among the items in the loss diagram, losses caused by shading are particularly important not to overlook in practice. Shading has a major impact on the energy production of photovoltaic installations. Causes of shading vary by site and include surrounding buildings, trees, mountains, utility poles, fences, adjacent rows of mounting structures, and terrain undulations. PVSyst allows shading effects to be reflected in the settings, but it is important to verify how those results are represented in the loss diagram.

When checking shading losses, first verify that the values are not excessively large. If shading losses are shown as large despite the site being an open area with almost no shading, there may be errors in the heights or positions of nearby obstacles, the terrain data, or the array layout settings. Conversely, if the site is near buildings or in a valley but shading losses are shown as negligible, the shading settings may not be sufficiently reflected.

It is also important not to judge shading losses solely by their annual percentage. Even if the annual loss appears small, shading may be concentrated in specific times of day or seasons. For example, if shading occurs on winter mornings and evenings, the impact on annual energy generation may seem limited. However, when checking plans for selling electricity, self‑consumption plans, or expected generation for specific time periods, shading during those times can be important.

Shadows have both geometric and electrical effects. A geometric shadow can be understood as the area-based impact in which solar irradiance no longer reaches the module surface. On the other hand, an electrical shadow is an effect whereby, depending on the connection configuration of modules and strings, shading of even a part can cause a wider reduction in output. Beginners tend to assess losses based only on the shaded area, but the actual impact on power generation is also governed by the electrical configuration.

In power plants with rows of mounting racks, mutual shading between arrays is also important. Especially during periods of low solar altitude, modules in the front rows can cast shadows on the rear rows. The narrower the spacing between arrays, the higher the land-use efficiency, but shading losses may increase. If shading losses are large on the loss chart, rather than simply seeing it as a drop in power output, consider whether it can be improved by reviewing the array spacing and tilt angle.

Shading losses are highly dependent on how faithfully on-site conditions are reproduced. If obstacles are oversimplified in simulations, the actual impact of shading can be underestimated. Conversely, overly conservative settings can lead to unduly low estimates of power generation. Both are problematic in practice. While it may be acceptable to take a conservative approach at the proposal stage, design decisions require settings that are well justified.

When checking shadow losses on a loss diagram, it is useful to cross-check it against on-site photos, survey results, layout drawings, surrounding topography, and obstacle height information. By verifying not only the numerical values on the diagram but also what is located in which directions at the actual site and during which seasons or times of day shadows are likely to occur, you can interpret the loss diagram more accurately.

How to Read Temperature Loss and Module Efficiency

In solar power generation, stronger solar irradiance increases power output, while higher module temperature reduces power generation efficiency. This efficiency reduction due to temperature is shown as temperature loss in loss diagrams. It may seem a bit counterintuitive to beginners, but it is a very important loss term in practical work.

The output listed in solar module catalogs is specified under fixed standard conditions. However, in actual outdoor environments it is common for module temperatures to be higher than those standard conditions. In particular, during daytime in summer the module surface temperature rises significantly not only because of ambient air temperature but also due to strong solar irradiance. As a result, voltage decreases and power generation efficiency drops. Because this effect accumulates over the course of a year, losses due to temperature cannot be ignored.

When looking at temperature losses on a loss diagram, be aware of the relationship with the installation method. If installed flush to the roof, rear ventilation tends to be insufficient and module temperatures are more likely to rise. On the other hand, when installed on the ground with sufficient airflow behind, temperature increases may be suppressed. In other words, even in the same region and with the same module capacity, temperature losses vary depending on the installation method.

If temperature loss is larger than expected, first check the weather conditions and the installation method. In regions with high outside air temperatures, weak wind conditions, or installations with poor rear ventilation, larger temperature losses are to be expected. However, it may also be that the ventilation conditions set in the model are worse than the actual conditions, or that there are errors in the input of temperature characteristics. Conversely, if temperature loss is too small, you need to check whether the calculation was performed under excessively favorable conditions.

Items related to module efficiency are also points that should be checked on a loss diagram. After solar radiation reaches the module, not all of the energy is converted into electricity. Depending on the module's conversion efficiency, DC power is generated. The loss diagram shows, at this stage, the flow from the theoretical solar energy to the actual DC output.

What often confuses beginners is treating temperature loss and module efficiency as the same thing. Module efficiency is, at its core, the fundamental performance metric that indicates how much incident solar energy can be converted into electrical power. Temperature loss, by contrast, is the additional reduction that occurs when the actual operating temperature is higher than the standard performance. Understanding these two separately makes the meaning of a loss diagram much clearer.

Also, characteristics under low irradiance and changes in incident conditions also affect the module's output. Under cloudy skies or during periods with weak solar irradiance, such as morning and evening, the module's operating characteristics differ from standard conditions. These effects may appear small individually, but they accumulate and are reflected in the results of annual simulations.

In practice, we look at temperature loss and assess whether there is room for design improvement. For example, one might consider changing the installation method, reviewing the mounting-structure height, ensuring ventilation, or avoiding layouts where heat becomes excessively trapped. However, because temperature loss strongly depends on climatic conditions, it cannot be completely eliminated. The important thing is to verify that the temperature loss is reasonable for the site conditions.

How to Interpret Wiring Losses and Electrical Losses

In the middle to lower sections of the loss diagram, DC-side wiring losses and electrical losses are displayed. These items may seem inconspicuous compared with solar irradiance and temperature, but in practice they are checkpoints that must not be overlooked. If wiring losses are excessive, there is a possibility they can be improved by reviewing the design. Conversely, if wiring losses are unnaturally small, the input conditions may be more favorable than reality.

Wiring losses are losses that occur due to resistance when current flows through a cable. Losses increase as the cable length increases, the cross-sectional area decreases, or the current increases. In photovoltaic systems there are multiple wiring sections, such as DC wiring from the modules to the combiner box and inverter, and AC wiring from the inverter to the point of interconnection. In PVSyst, these losses are reflected in the calculations according to the settings.

What beginners should check is whether the wiring loss value is within a reasonable range. If it is excessively large, check the cable length, cross-sectional area, string configuration, voltage conditions, and so on. For example, if you have entered a cable length longer than the actual one, set the cross-sectional area too small, or have voltage conditions that differ from what was assumed, the wiring loss may be displayed as large.

On the other hand, caution is required when wiring losses appear to be almost nonexistent. In real installations, losses due to wiring always occur. If the losses are extremely small, it may be because wiring lengths were not entered sufficiently, the loss rate was set excessively low, or part of the design was omitted. When presenting power generation figures in proposal materials, overly favorable wiring loss settings can create a risk when explaining the proposal later.

Electrical losses also include mismatch losses caused by variations among modules. In practice, not all modules have exactly the same characteristics. Manufacturing variations, aging, temperature distribution, uneven soiling, and other factors cause differences in output even within the same string. As a result, the overall output is reduced compared to the ideal value. This is treated as mismatch loss.

Losses associated with maximum power point tracking can also be considered electrical losses. In photovoltaic power generation, the operating point that produces power most efficiently changes with irradiance and temperature. Equipment tracks this operating point, but in practice it may not always do so perfectly. In particular, when there is shading or complex string configuration, deviations of the operating point can affect the amount of power generated.

When viewing these items on a loss diagram, it is important to distinguish between losses that can be improved through design and those that are unavoidable to some extent. Wiring losses may be improved through cable design and equipment layout. Mismatch losses cannot be completely avoided, but they can sometimes be reduced by adjusting string configuration and mitigating shading effects. Losses related to equipment operating points also have room for improvement by revising the configuration.

In practice, when wiring losses or electrical losses stand out on a loss diagram, it is important not merely to interpret this as a reduction in power generation, but to cross-check with the design drawings, single-line wiring diagrams, equipment layout, and cable routes. Rather than completing the process solely on the PVSyst screen, verifying against on-site constructability and design conditions will yield a simulation that is closer to reality.

Key Points to Check for PCS Capacity and Conversion Loss

In the lower part of the loss diagram, we check the losses that occur at the stage where DC power is converted into AC power. Key factors here are PCS capacity, conversion efficiency, and output limitations. In a photovoltaic power generation system, the DC power generated by the modules is not used directly but is converted into AC power through power conversion equipment. A certain amount of loss occurs during this conversion process.

Conversion losses occur according to the efficiency of the equipment. In general, efficiency changes depending on the magnitude of the input power. It may be higher near the rated load, while it can decrease under light-load conditions. The loss diagram shows conversion losses that reflect annual operating conditions. Beginners do not need to consider the mere presence of conversion losses as abnormal. What matters is whether they are within a reasonable range for the specified equipment and capacity.

What deserves particular attention regarding PCS capacity is its relationship with module capacity. In solar power generation, it is common to design the modules' DC capacity larger than the PCS's AC capacity. This is because, due to irradiance and temperature conditions, modules do not always generate at their rated maximum. However, if the PCS capacity is too small relative to the DC capacity, the portion that exceeds the converter's limit can be lost as output curtailment on sunny days and similar conditions.

If the item corresponding to output limiting is large in the loss diagram, check the capacity ratio settings. The occurrence of output limiting to some extent may be acceptable depending on the design policy. However, if it is larger than expected, it may indicate that the PCS capacity is too small, the string configuration is inappropriate, the input conditions do not match reality, or that the oversizing design policy is not consistent with the expected power generation and profitability.

On the other hand, having no output limits at all is not always desirable. Increasing PCS capacity will reduce output limits, but it can also lead to oversized equipment capacity and excessive system configuration. In practice, it is necessary to make a comprehensive judgment based on power generation, equipment capacity, installation conditions, and operational policies. A loss diagram shows whether output limits exist and how large they are, and can be used as material for that judgment.

AC-side losses also need to be checked. After conversion, power may incur losses associated with AC wiring and voltage transformation before it reaches the point of receipt or the grid interconnection point. In large-scale installations, the effects of AC-side wiring distance and equipment configuration cannot be ignored. Even in small-scale installations, if settings are omitted excessively, the estimated power generation can appear higher than the actual.

The lower part of the loss diagram is directly linked to the final amount of generated electricity. The final output shown here will be used as the annual energy production for proposals and evaluations. Therefore, you should avoid adopting only the final generation figure without verifying whether conversion losses and output limitations are reasonable. In particular, when comparing multiple options, it is important to compare how differences in PCS capacity and oversizing ratio are reflected in the loss diagram.

Common Mistakes Beginners Make When Reading Loss Plots

PVSyst's loss diagram is convenient, but there are points that beginners are prone to misunderstand. One common issue is that people tend to view all the numbers shown in the loss diagram as inherently bad. The word “loss” can make the presence of numbers feel like an indication of a design problem. However, in photovoltaic systems, temperature loss, wiring loss, conversion loss, and the like inevitably occur. What matters is not that losses are nonzero, but whether their magnitude is reasonable given the site conditions and design parameters.

Another common mistake is looking only at the largest loss item and assuming the cause. For example, just because temperature loss appears large, it is premature to immediately conclude a design flaw. In high-temperature regions or installation configurations with poor ventilation, large temperature losses are to be expected. Likewise, if shading losses are large, that may be a reasonable result if there are many obstructions on site. The magnitude of the values should always be evaluated against the input conditions and the site conditions.

Also, judging solely by annual values is a mistake that beginners often make. Loss diagrams are useful for grasping the overall annual picture, but they may not show at a glance the seasonal or time-of-day impacts. For example, shading losses may appear small on an annual basis, yet be concentrated on winter mornings. For systems intended for self-consumption, the times when generation occurs are important, so in addition to annual values you should check monthly and time-of-day results as needed.

Furthermore, you may sometimes mistake errors in the input settings for characteristics of the results. Because the loss diagram is calculated based on the input conditions, if the input is incorrect, the results will also be incorrect. If there are errors in settings such as location, meteorological data, azimuth, tilt, capacity, wiring, shading, or equipment specifications, the loss diagram will reflect those errors. When viewing the loss diagram, it is important not only to interpret the results but also to return and check the input conditions.

Be careful not to evaluate loss items in isolation. For example, widening array spacing may reduce mutual shading losses, but it could reduce the capacity that can be installed on the site. Increasing PCS capacity may reduce output curtailment, but it changes the balance of the overall system. Changing cable design to reduce wiring losses also involves trade-offs with constructability and system configuration. Loss diagrams indicate where improvements can be made, but they do not mean you should simply minimize every loss.

Beginners will find it easier to understand loss plots if they view them not as answer keys but as diagnostic results for checking a design. It is important to look at the diagnostic results and consider which items stand out, whether there are any contradictions with the input conditions, and whether there is room for improvement. With this mindset, loss plots become a practical resource for verifying the validity of a design rather than a difficult specialist screen.

Order for Checking Loss Plots in Practice

When reviewing a loss diagram in practice, the basic procedure is to check from the top down. First, confirm the solar radiation based on the site and meteorological data. If there is a significant inconsistency here, it becomes less meaningful to examine the subsequent losses in detail. Verify whether the assumed regional solar radiation conditions are reasonable and whether the tilted-surface irradiance yields natural values for the installation’s tilt angle and azimuth.

Next, check the effects of shading and the angle of incidence. If there are obstacles on-site, check to what extent shading losses are being reflected. If shading losses are large on an open site, there may be a configuration error. Conversely, if there are many nearby obstacles but shading losses are small, the shading conditions may not have been entered adequately. Also confirm that losses due to the angle of incidence are reasonable in relation to azimuth and tilt.

Next, we examine module-side losses. These include temperature losses, module quality, low-irradiance characteristics, and mismatch losses. Here we check whether the results are reasonable for the mounting method and the local climate. If a roof-mounted installation has poor ventilation, temperature losses can be significant; if a ground-mounted installation has good ventilation, they can be relatively reduced.

Next, check the DC-side wiring losses and electrical losses. If wiring losses are large, review the cable length, conductor cross-sectional area, string configuration, and equipment layout. If losses related to mismatch or operating point are noticeable, consider the effects of shading, string separation, and module placement. This is an important area for practitioners to verify because there is room for improvement through design.

Finally, check PCS conversion losses, output limitations, and AC-side losses. Verify that the PCS capacity is appropriate, that output limitations due to oversizing are within the expected range, and that losses related to AC-side wiring and transformers are not omitted. The final annual energy generation is the result of passing through this stage. Rather than looking only at the final figure, confirming the process that led to it leads to a reliable simulation.

Checking in this order lets you read loss diagrams efficiently. By fixing the sequence to solar irradiance, shading, temperature, the DC side, and the AC side, you can inspect the results using the same procedure each time. For practitioners handling multiple projects, standardizing this verification procedure is important. If the order in which you review them changes from project to project, missed checks and inconsistencies in judgment are more likely to occur.

Also, when checking the loss diagram, it is important to make a habit of returning to the input conditions to verify any items that concern you. The loss diagram is a results screen, but in many cases the cause of a problem lies somewhere in the input conditions. By moving back and forth between the results and the inputs while checking, your understanding of how to use PVSyst will also deepen.

Approach to Using Loss Maps for Design Improvement

A loss diagram is not merely a document for explaining simulation results; it is also a tool for gaining insights into design improvements. By identifying which losses are largest, you can determine where there is room to improve energy production. However, it is not sufficient to simply reduce every loss. In practice, decisions must be made while balancing energy production, site conditions, constructability, operation and maintenance, and system configuration.

For example, if shading losses are large, reconsidering the layout can be an option. Methods include increasing array spacing, adjusting tilt angles, increasing distance from obstacles, or changing string configurations. However, increasing array spacing may reduce installed capacity. If installed capacity decreases, reducing shading losses does not necessarily mean total power generation will increase. Therefore, decisions should be made not only based on loss rates but also in conjunction with the expected annual energy production and the project's objectives.

If temperature losses are large, consider redesigning or changing the installation method to ensure ventilation. For roof-mounted installations, racking height and rear clearance affect this; for ground-mounted installations, airflow and row spacing have an impact. However, depending on the installation environment, it may be difficult to substantially reduce temperature losses. In that case, it is important to accept the temperature loss as a site condition and avoid producing overly optimistic power generation estimates.

If wiring losses are significant, there may be room to revisit cable routing and equipment placement. Methods include moving the power conversion equipment closer to the module array, re-evaluating cable cross-sectional area, and shortening wiring distances. However, it is also necessary to balance these measures with constructability, maintainability, and safety. The loss diagram shows wiring losses as numerical values, but actual improvement requires coordination with on-site construction planning.

If output curtailment is significant, review the relationship between module capacity and PCS capacity. Options include adjusting the degree of oversizing, changing PCS capacity, and revising the string configuration. However, eliminating output curtailment entirely is not always optimal. Determine how much output curtailment to tolerate based on annual energy production, equipment utilization rate, peak output, and the installation’s purpose.

What is important when using loss diagrams to inform design improvements is comparing the before-and-after state. Looking at only a single condition makes it difficult to judge whether it is optimal. By simulating multiple scenarios—such as changing the tilt angle, changing the array spacing, changing the PCS capacity, or changing the wiring conditions—and comparing the loss diagrams and the annual energy generation, it becomes easier to make design decisions.

Also, when using a loss diagram as explanatory material for internal or external audiences, rather than simply listing technical terms, it's helpful to include brief explanations of what each loss means. For example, explain that temperature loss is the effect of reduced efficiency when a module becomes hot, wiring loss is the loss that occurs when electricity passes through cables, and shading loss is the effect of incident sunlight being blocked by obstacles or inter-row shading; explaining them this way makes it easier for non-specialist stakeholders to understand.

To acquire practical-level proficiency with PVSyst, it is important not just to enter inputs and produce results, but to repeatedly review the loss diagram, return to the design conditions, and consider improvement proposals. This repetition makes it clear which settings have the greatest impact on energy yield and also strengthens your ability to explain the simulation results.

Summary

The loss diagram in PVSyst is an important chart for step-by-step verification of how the solar radiation entering a photovoltaic system becomes the final electrical energy output. It may look complex to beginners because there are many items, but if you view it in the sequence of solar irradiation, shading, temperature, DC-side losses, and AC-side losses, you can grasp the overall picture even in a short time.

The first thing to check is the flow of solar irradiance. If the site, meteorological data, tilt, and azimuth are not appropriate, the subsequent estimated power generation will be difficult to trust. Next, check the impact of shading. By verifying whether surrounding obstructions, array spacing, and terrain conditions are reflected, you can confirm the consistency between on-site conditions and the simulation results.

In addition, we examine temperature losses and module-side losses. Because solar cells lose efficiency as temperature rises, temperature loss is an important item in many projects. Taking into account the installation method, ventilation conditions, and the local climate, we assess whether the values are reasonable. Furthermore, by sequentially checking wiring losses, mismatch losses, electrical losses, PCS conversion losses, and output limitations, we can explain the rationale that leads to the final annual energy production.

When looking at a loss diagram, it is important not to overstate the mere presence of losses. In solar power generation, temperature losses, conversion losses, and wiring losses inevitably occur. What matters is whether each loss is reasonable given the site conditions and design parameters. If there are losses that are extremely large or unnaturally small, you need to go back and check the input conditions.

In addition, loss diagrams can also be used to improve designs. If shading losses are large, they can prompt a review of layout and array spacing; if temperature losses are large, ventilation conditions should be examined; if wiring losses are large, cable routing and equipment placement should be reconsidered; and if output limitations are significant, it can lead to a reassessment of the relationship between PCS capacity and module capacity. Reading the loss diagram is not only a way to verify the results of power generation, but also a task aimed at bringing the design closer to reality.

In practice, not only the simulation settings in PVSyst but also the site's location information, terrain, obstacles, panel layout, and the accuracy of survey data greatly affect the results. In particular, for shadow assessment, layout planning, and understanding terrain conditions, it is important to acquire the site's coordinates and elevations accurately. As an iPhone-mounted high-precision GNSS positioning device, LRTK can be used on-site to obtain location information and to support confirmation of potential solar power installation sites, layout planning, and assessment of current conditions. By correctly interpreting loss diagrams in PVSyst and combining them with precise on-site location information, you can reduce discrepancies between simulations and actual site conditions and arrive at more convincing estimates of power generation.