7 Steps to Understand How to Read PVSyst Without Diagrams

In the practical work of designing solar power generation systems and forecasting generation, the quality of judgment depends on how you read simulation results. Even if you carefully prepare the input conditions, if you cannot correctly understand what the output results mean, neither the quality of the design, the validity of comparative evaluations, nor the accuracy of explanations to internal and external stakeholders will improve. Especially for practitioners searching for information on "how to read PVSyst," there are many items displayed on screens and in reports, and it is often difficult to know where to start to grasp the overall picture.

On the other hand, in practical work situations, you can't always have drawings or screens at hand to interpret. Sometimes you need to explain things verbally in a meeting, and other times—while traveling for an on-site check or in the middle of preparing materials—you want to organize the structure in your head. What helps in those situations is an approach to reading that can be understood from text and sequence alone, without relying on diagrams. If you organize which items to look at, in what order, and what each one means, you'll have a basis for judgment even without a results screen.

The results from PVSyst are not just a collection of numbers. There are solar irradiance conditions, incident radiation conditions, losses, DC output and AC output, and a flow that leads to the final annual energy production. When you can mentally trace this flow in sequence, it becomes easier to grasp the framework of the results even without diagrams. Conversely, if you only follow the numbers point by point, you may end up looking solely at the annual production or judging things only by PR, which can lead to precarious decisions in practice.

This article organizes and explains PVSyst reading in 7 steps for practitioners who want to understand it without diagrams. Each step is structured so you can mentally follow the sequence even without a screen. To make it useful for design, comparative assessment, explanations, and on-site checks, we provide careful explanations not just of the items but also of why to view them in that order. If you want to turn your ability to read results into practical decision-making rather than screen dependence, start by mastering these 7 steps as your foundation.

Table of Contents

• Why reading PVSyst becomes easier to understand without diagrams

• Step 1｜First, understand the positioning of annual energy generation

• Step 2｜Read the assumptions about solar irradiation

• Step 3｜Read the relationship between incident light conditions and installation conditions

• Step 4｜Follow the order of losses in the text

• Step 5｜Do not confuse PR and specific yield

• Step 6｜Grasp seasonal characteristics from monthly results

• Step 7｜Check the flow from DC to AC

• Practical perspectives that are indispensable when reading without diagrams

• The accuracy of on-site verification deepens understanding of the simulation

• Summary

Why Reading PVSyst Is Easier to Understand Without Diagrams

When reading PVSyst results, many people are first drawn to the appearance of the screen or report. Because attention goes to the placement of numbers, graphs, loss diagrams, and the order of tables, the more information there is, the harder it is to feel like you understand it. However, what is truly necessary in practice is not memorizing display formats but understanding the flow of the results. Trying to understand without diagrams naturally shifts your focus to the skeleton of “what comes first and what comes later” and “what is input and what is a result.” This can actually deepen your understanding.

There is a discrepancy between the visual clarity of solar power generation simulation results and an understanding that is useful in practice. Even if many items appear in parallel on the screen, they are not actually parallel. First comes solar irradiance; the way it is received is determined, losses occur there, the DC-side output is then set, and that output is converted to AC to become the final generated power. By understanding this flow step by step, you will be less likely to be swayed by individual figures.

Also, being able to understand things without diagrams makes it easier to explain them in meetings and discussions, because the other person may not necessarily be looking at the detailed screen. If you can explain in the order of showing the annual power generation, discussing the solar irradiance conditions that form its basis, explaining the incident-light conditions and losses, and finally describing the flow of output, it increases confidence in the results. In other words, practicing understanding without diagrams directly leads to improved explanatory skills.

Furthermore, the ability to read without diagrams is also useful for comparative evaluation. When comparing multiple proposals, you can first follow the same structure in the same order, without being swayed by the appearance of the results screen. By reviewing, in the sequence of what the solar irradiation conditions are, what the conditions of incident light are, where losses are occurring, and how the downstream conversion proceeds, it becomes easier to organize the differences between projects. There are cases where diagrams make things easier to understand, but being able to explain things in an ordered way without diagrams is a very powerful tool for practitioners.

Step 1 | First, understand the role of annual electricity generation

What’s easiest to check first is the annual power generation. Because this represents a solar power project as a single number, it is the most visible metric and the easiest item to explain to stakeholders. In practice, when comparing projects or conducting initial rough estimates, people often start with this figure. However, the first thing to grasp when understanding it without diagrams is that annual power generation is a starting point, not the answer itself.

Annual energy production is the final result after all assumptions and losses have been applied. In other words, while it is an easy-to-read figure, its breakdown is completely hidden. For this reason, it is dangerous to immediately conclude that a design is superior simply because its annual energy production is high. It may merely reflect originally favorable solar irradiation conditions, and conversely, in projects that are making clever adjustments under harsh conditions, the appearance of annual energy production alone may not be sufficient for evaluation.

When reading without figures, the moment you look at the annual power generation you should be aware that this is the end result. And check it on the premise that you will later trace back the path that led to that number. For example, if it is lower than expected, you will need to go back and see where it decreased, and if it is higher than expected, you need to verify which conditions are having an effect. Annual power generation is convenient, but precisely because it is convenient, it is important not to stop reading there.

Also, annual generation alone cannot account for differences in system scale. The same number can mean different things if the installed capacity differs. Therefore, in practice you also need to be mindful of the concept of specific yield. Even when organizing information without diagrams, it helps to think of annual generation as the figure that conveys scale, and specific yield as the figure that conveys efficiency or performance. However, the same applies here: a good specific yield does not necessarily mean the design is good. In the initial stage, the objective is to grasp the project's size and its rough positioning.

The key point at this step is to treat the annual power generation as an entry point rather than a conclusion. While getting a first impression of the result, adopt the premise that you will then look at, in sequence, the underlying solar irradiance conditions, losses, and output structure—this is the first step toward understanding without diagrams.

Step 2｜Read the assumptions for solar radiation

After checking the annual power generation, the next thing to look at is the assumed solar irradiance. Since solar power generation starts with sunlight, if you don’t understand this, it becomes difficult to interpret the subsequent figures. When reading without diagrams, it’s important to first hold in your mind what level of solar irradiance is being assumed. The purpose here is to understand the starting point for the generation results.

In practice, it's common to assume that locations with higher solar irradiance are more advantageous, but that alone is not sufficient. What is important in simulation results is not merely the irradiance at a location, but how that irradiance is utilized under the installation conditions. However, unless you first grasp what level of irradiance was assumed as the original input, you cannot see whether the subsequent losses and outputs are reasonable. Even without figures, first aim to be able to explain in words what baseline level of solar irradiance this project is based on.

When reading the assumptions about solar irradiation, it is also useful in practice for comparing projects. When there is a difference in annual power generation between two projects, you need to distinguish whether the difference is due to the underlying irradiation assumptions or to the quality of the design. If the irradiation itself is different, that difference should to some extent be accepted as part of the assumptions. Conversely, if the irradiation conditions are similar but the generation difference is large, you should focus on the conditions affecting received irradiance and the structure of losses.

Also, when trying to understand it without diagrams, you don't need to remember the solar irradiance as a single number. What matters is whether the solar resource that underpins power generation for this project is relatively strong, standard, or relatively weak. With that context, when you read the subsequent received irradiance conditions and losses, you can tell whether that solar condition is being adequately utilized. Solar irradiance itself is a premise that is difficult to change, and it's important to have the sense that design measures are built on top of that premise.

If you skip this step, you’re likely to overreact to the loss and PR figures that appear later. That’s because you’ll be judging the results solely by whether they look good or bad without knowing how solid the foundation is. If you want to understand PVSyst without diagrams, you must first set the foundation of solar irradiance conditions in your mind and make a habit of reading the design results by building them up on that foundation.

Step 3｜Understand the relationship between illumination conditions and installation conditions

Once you've established the assumptions about solar irradiance, the next thing to examine is the receiving conditions. Here you read how the given solar irradiance is actually received under the real installation conditions. To understand this without diagrams, it helps to think of this as "the transformation of solar irradiance until it reaches the equipment." In other words, the site irradiance is not used directly for power generation; it is transformed into the irradiance used for generation through factors such as azimuth, tilt, and the conditions of the mounting surface.

In practice, what matters is to regard the incident-light conditions as part of the results. You need to read from the results how those conditions were reflected in power generation, not merely note the fact that installation conditions were entered. For example, even if the baseline solar irradiance is not bad, if the conditions of the receiving surface are insufficient, subsequent power output will not increase. Conversely, even if the solar baseline is not outstanding, if the receiving conditions are straightforward, it can lead to stable results.

When thinking without diagrams, it becomes easier to understand if you think of solar radiation as the material and the installation conditions as the vessel that receives it. The shape of this vessel is influenced by orientation, tilt, layout, and the surrounding environment. What is important here is that the light-receiving conditions are closely related to downstream losses. Installations that do not receive sunlight well at the upstream stage may not see significant improvement no matter how much you reduce subsequent losses.

Also, the light-receiving conditions are elements closely tied to the actual site. Whether the orientation and tilt set on the drawings match the on-site situation, and whether the effects of surrounding obstacles have been properly accounted for — the accuracy of site understanding matters here. In that sense, the light-receiving conditions are both desk-based input items and a reflection of on-site understanding. When reading without drawings, being conscious of this connection to the site deepens comprehension.

The aim of this step is to be able to visualize in your mind how the assumed solar irradiance is transformed into the incident light conditions through the installation conditions. Once this is organized, the meaning of the losses that follow becomes easier to understand. This is because it becomes easier to distinguish which losses are an extension of the incident light conditions and which occur at different stages.

Step 4｜Trace the sequence of losses in prose

The most important aspect of reading PVSyst is understanding the losses in sequence. A diagram makes the loss chart easier to view, but you can fully grasp it without one. If anything, when trying to understand it without a diagram, the core is to follow in text where, what, and in what order things are reduced. What practitioners truly need is not the appearance of the losses but their meaning and order.

First, be aware that losses do not occur all at once. Solar irradiance must first be processed by the receiving conditions before it becomes usable; it then undergoes various losses—those that affect it at that stage, losses due to temperature and module characteristics, and additional losses related to wiring and conversion. In other words, losses accumulate in stages, and their significance depends on which stage they occur in. If you do not understand this sequence, it is easy to misjudge things by looking only at the magnitude of the numbers.

Losses that occur in earlier stages reduce the foundation for all subsequent stages. Losses in later stages act on the amount remaining up to that point. Therefore, even losses that appear to be of similar proportion carry different practical weight depending on whether they occur early or late. For example, in cases where losses near the light-receiving stage are large, slightly improving the conversion efficiency in later stages has only a limited effect on the overall outcome. Conversely, when the early stages are solid, fine-tuning later stages is more likely to be meaningful.

When reading without a figure, it is easier to organize losses by dividing them into three broad areas. The first is losses related to light reception and layout, the second is losses related to modules and temperature, and the third is losses related to electrical wiring and conversion. By dividing them into these three layers and considering where the largest losses occur, the directions for improvement become clearer. This is an organizational method that can be done effectively even without a diagram.

Also, when interpreting losses, you need to consider not only the magnitude of the numbers but also the potential for improvement. Some losses are close to natural conditions and cannot be completely avoided, while others can be reduced through design or equipment configuration. If you focus only on items with large losses without taking this distinction into account, discussions tend to become inefficient in practice. Understanding without diagrams also means interpreting by organizing the meaning rather than relying on visual impressions.

By mastering this step, you'll be less likely to be thrown off when you look at the results screen. That's because you'll be able to explain in words which loss belongs to which stage. A way of reading that is usable in practice doesn't mean understanding only when you can see the figure; it means being able to describe the sequence even without the figure. What underpins that is the sense of following these losses in order.

Step 5｜Don't confuse PR and specific yield

When looking at PVSyst results in practice, both PR and specific yield are commonly referenced indicators. However, if you want to understand them without figures, it is very important not to confuse the two. They may both look like numbers representing performance, but they do not mean the same thing. Leaving this unclear when explaining or comparing them can easily lead to inconsistent judgments.

Specific yield is a way of looking at how much electricity is generated per unit of installed capacity. It helps gauge a project's sense of efficiency and is useful when comparing projects of different sizes by normalizing them to some extent. The PR, on the other hand, is a summary metric for assessing how well the system is performing under the given conditions. Both are useful, but their roles differ. It is easier to understand if you think of specific yield as the perspective that standardizes the presentation of generation amounts, and PR as the perspective for grasping how the system is performing as a whole.

In practice, when the two are viewed side by side, evaluations are sometimes decided based on only one of them. For example, one might judge a project to be excellent because its specific yield is high, or feel reassured because its PR is high. However, since the underlying assumptions differ in reality, it is dangerous to determine superiority or inferiority by the numbers alone. If solar irradiance conditions differ, the way specific yield appears will change, and if site conditions are challenging, the PR may not be as high as it appears.

To understand this without diagrams, it's important to treat these two indicators not as numbers to be used for a final evaluation but as auxiliary guides that summarize the results. First grasp the annual power generation, insolation conditions, incident light conditions, and the flow of losses; then, when you look at PR and specific yield, the meaning of the numbers becomes concrete. Conversely, if you look only at these two indicators without seeing the overall framework, you won't see the background of the results and the discussion becomes abstract.

Also, this distinction is important when explaining things. When explaining to colleagues or clients, if you talk about specific yield and PR in the same way, you can easily cause misunderstanding. Precisely because both are useful figures, you need to organize what each represents and use them accordingly. If you make a habit of explaining them in order without diagrams, it becomes easier to convey the difference in their roles naturally.

What to develop at this step is the habit of not immediately passing judgment when you look at PR and specific yield, but of thinking about what assumptions those figures are based on. Simply having this habit will make your reading of PVSyst much more practical.

Step 6｜Identify seasonal patterns from monthly results

If you only look at annual values such as annual generation or PR, you will overlook seasonal biases and behavioral quirks. In practice, it is essential to check monthly results to see what characteristics appear in each season. To understand this without figures, it is important to start from the premise that "even if there is a single annual number, its components fluctuate seasonally."

When looking at monthly results, the point is not simply to list which months have more or fewer values. What matters is considering whether those variations are natural or unnatural, and what is behind them. For example, if there is a sharp drop only in winter, the influence of sun angle or surrounding obstructions may be strong. If summer growth is muted, the impact of temperature-related losses may be large. In other words, monthly results are material that show the loss structure from a different angle.

When organizing without charts, it's easier to understand if you treat the monthly results as a cross-check of the annual results. A project that doesn't look bad on an annual basis may show weaknesses concentrated in specific seasons when viewed month by month. Conversely, a project with mediocre annual figures may actually have good seasonal balance and be more stable. In practice, this difference affects how you approach operations and how easy it is to explain the results.

Also, monthly results can provide clues that call the validity of the input conditions into question. Even if the annual values look plausible, you may see unnatural dips or biases when viewed by month. In that case, it may be necessary to recheck shading conditions, installation conditions, and how solar radiation data are handled. Even when reading without figures, keeping a sense of whether seasonal variations look natural will make it easier to inspect the reliability of the results.

For operational staff, monthly results are important because they are easy to use when explaining things to stakeholders. They allow you to describe site characteristics that are not visible from annual totals in seasonal terms. Explanations such as "there are issues to watch in winter," "temperature effects tend to show up in summer," or "it is stable throughout the year" only become possible after looking at monthly results. If you practice understanding results without figures, it is important to be able to describe seasonal patterns in words.

Step 7｜Confirm the flow from DC to AC

Finally, what I want to confirm is the flow from the DC side to the AC side. Solar cells generate DC, but in practice what you ultimately want to evaluate is the output and generation on the AC side. Between them there are processes such as wiring and conversion, and losses occur during that process. To understand this without a diagram, it is easier to think of this part as "the power produced in the earlier stage being converted into the final output in the later stage."

Many people tend to focus on upstream solar irradiation and light-receiving conditions but underestimate the importance of downstream conversion. However, what matters in practice is how much usable power is ultimately produced. Even if the DC-side results are good, if the connection to the AC side is strained, the overall evaluation changes. Therefore, it is necessary to look at the difference between DC and AC and be aware of how much is being lost in the downstream stages.

In this step, it is important not only to look at the magnitude of the difference but also to consider the nature of that difference. You should examine how much of it is attributable not to preceding natural conditions or layout conditions, but to equipment configuration or electrical conditions. Because this area is relatively amenable to refinement in design, it has practical significance when seeking opportunities for improvement.

Also, this perspective is useful when comparing multiple proposals. Even if two proposals have similar final power output, one may be strong in the early stages and then drop off in the later stages, while the other may be ordinary early on but better at consolidating the later stages. Understanding this difference makes it easier to see which proposal is more straightforward and easier to explain, and which one depends on specific conditions.

To understand this without diagrams, it's ideal to be able to summarize the flow covered so far in a single statement. There are solar irradiance conditions, light-receiving conditions, losses, DC output, and after subsequent conversion it becomes AC output. If you can describe this sequence of steps in words, you will have a solid grasp of PVSyst's framework. Ultimately, what you need is not to memorize the look of the screens, but to be able to mentally replay this flow.

Essential practical considerations when reading without diagrams

If you grasp the seven steps covered so far, reading PVSyst becomes much more organized. However, in practical work there are still perspectives you need to be mindful of. One of them is not to evaluate numbers in isolation. Rather than looking only at annual energy production, PR, or losses, it is important to always interpret them within their context. The advantage of understanding things without diagrams is precisely that it makes it easier to focus on these contextual relationships.

Another important point is not to separate the assumptions from the results. Results are, after all, a reflection of the input conditions. If understanding of site conditions and installation conditions is insufficient, however neatly the numbers may appear, there are limits to their interpretation. In practice, people may be reassured by the neat appearance of numbers, but what should actually be examined is the assumptions on which those numbers are based.

Furthermore, in comparative evaluations, it is important to read in the same order. When comparing multiple projects or multiple proposals, judgments will diverge if you look at different aspects for each project. First check the annual power generation, then standardize the sequence to examine solar irradiation conditions, incident-light conditions, losses, PR and specific yield, monthly fluctuations, and the differences between DC and AC. Understanding without figures is also useful when creating this comparison framework.

Also, when creating presentation materials, it's a good idea to check whether you can explain the content in your head using words alone before adding a figure. If you cannot explain it using only words, adding a figure often does not fundamentally clarify the matter. Conversely, results that you can present logically without a figure tend to be easier to convey when turned into materials. Practicing figure-free understanding is also effective training for improving the quality of explanations both inside and outside the organization.

Accuracy of on-site verification deepens understanding of simulations

No matter how well you organize the way you read PVSyst, if your grasp of the site conditions is unclear, there are limits to the accuracy of your interpretation. In particular, incident irradiance conditions, shading, azimuth, surrounding obstacles, and the spatial relationships of installation positions directly affect the preceding results. In other words, if you want to understand a simulation without diagrams, you need to consider not only the numerical outputs but also how accurately you have captured the on-site positional relationships.

In practice, even if something appears to be valid on drawings, slight positional shifts or differences in elevation on site can affect shading conditions. Those differences influence how you read light-receiving conditions, how you interpret losses, and how you understand month-by-month variations. The resulting figures can be confirmed at a desk, but the positional relationships that underlie them are often difficult to verify except on site. For that reason, interpreting simulations and on-site verification are inherently inseparable.

If you can accurately grasp the on-site positional relationships, the precision of input conditions improves and you can be more confident in interpreting the results. For example, if separations from surrounding objects, repeatability of the planned installation position, understanding of orientation, and ease of sharing information on-site are improved, it becomes easier to clarify the assumptions regarding irradiance and shading conditions. As a result, reading PVSyst shifts from merely checking numbers to making judgments grounded in the actual site.

In that sense, in practical work where you want to grasp the positional relationships on site with high accuracy, interest in LRTK for iPhone-mounted GNSS high-precision positioning devices naturally increases. By making it easier to confirm installation locations and surrounding conditions with high accuracy, you can better organize the assumptions entered into simulations and increase the certainty of interpreting the results. Understanding how to read PVSyst without diagrams not only deepens desk-based understanding but also makes one aware of the need to improve the accuracy of on-site assessments.

Summary

To understand how to read PVSyst without diagrams, it's important to first take annual energy production as the starting point; establish the assumptions about solar irradiance; interpret the relationship between irradiance conditions and installation conditions; understand the losses in order; avoid confusing PR with specific yield; grasp seasonal patterns from the monthly results; and finally confirm the flow from DC to AC. If you can mentally follow these seven steps in sequence, you'll find it easier to understand the framework of the results even without the screen.

In practical work, what matters is not memorizing individual numbers but being able to explain which numbers are the results of what and what precedes them as causes. If you can read results without diagrams, you are less likely to be swayed by how the results look, and your comparisons and explanations will be less likely to shift their focus. This not only improves the accuracy of design decisions but also has significant implications for smoothing communication both inside and outside the company.

To make these interpretations more practical for actual work, an accurate understanding of on-site conditions is indispensable. If you want to set high-precision assumptions for shadows, orientation, and installation positions, considering LRTK, an iPhone-mounted GNSS high-precision positioning device, can also be effective. By combining the ability to understand PVSyst results without figures with the ability to accurately grasp positional relationships in the field, you can more easily arrive at more convincing power generation forecasts and design decisions.