PVSystの使い方を5分で把握するための基礎知識7選

目次

• PVSystの使い方を5分で整理する前に

• 基礎知識1 プロジェクトとバリアントで考える

• 基礎知識2 地点と気象データの前提を先に固める

• 基礎知識3 方位角と傾斜角は発電量の土台

• 基礎知識4 最初の1回目は最小構成で回す

• 基礎知識5 影は遠方影と近接影で分けて扱う

• 基礎知識6 損失設定は既定値のままにしない

• 基礎知識7 レポートは損失図から読む

• 実務担当者が迷わない進め方

• まとめ

PVSystの使い方を5分で整理する前に

What practitioners who want to grasp PVSyst quickly must first understand is that this software is not merely an automatic energy-production calculator. It is a detailed simulation tool for comparing design options by sequentially building up site conditions, meteorological conditions, surface orientation, system configuration, shading, and various losses. The official documentation likewise frames project design as based on detailed time-step simulations, using geographic location and time-resolved meteorological data as the foundation and enabling comparison of multiple simulation scenarios. In other words, learning how to use PVSyst is not about memorizing every button name, but about understanding the order in which to fix assumptions so as to minimize judgment errors.

In fact, the official tutorial recommends defining a project first, running an initial simulation with minimal settings, and then progressively adding conditions such as shading and losses for comparison. From this it follows that rather than trying to build a perfect final model from the start, it is better to create a baseline case and then add conditions one by one to observe differences—this approach aligns with the software’s design philosophy. If you want to get an overview quickly, don’t try to read every screen from edge to edge; first internalize the flow of design evaluation as a single line.

Furthermore, the official overview distinguishes a simple preliminary study mode from a detailed project design mode; in the latter, time-step simulation is used to analyze orientation, system configuration, wiring, temperature, quality differences, shading, and so on in detail. Many readers searching for “how to use PVSyst” are likely less interested in rough estimates and more in how to improve accuracy for real projects. For that reason, this article organizes seven foundational ideas that serve as a practical basis to avoid getting lost in actual work, rather than offering a superficial quick-reference.

基礎知識1 プロジェクトとバリアントで考える

A common initial stumbling block in learning PVSyst is treating a single project as a single calculation result. However, the official documentation explains that project design is carried out within a “project” framework, where the project primarily holds the geographic location and time-resolved meteorological data, and multiple simulation runs can be compared as variants. This is very important in practice: simply adopting the mindset of separating the case itself from the comparative options within the case greatly clarifies how to operate the software.

The official tutorial shows the flow of first saving an initial variant with the minimum configuration, then creating subsequent variants that incrementally add distant shading, near shading, and individual loss conditions. Following this approach makes it easier to explain which changes affected the results and by how much. For example, keeping separate variants for a basic-case-only scenario, a scenario with shading, a scenario with more realistic site losses, and a scenario with altered orientation allows you to trace why the final results changed. Conversely, continuously adding conditions by overwriting a single case makes it difficult to isolate causes of energy differences.

The official procedure also uses warning colors that change according to input status: red indicates an issue that prevents simulation, orange indicates a tolerable but cautionary condition, and green indicates a reasonable setting. This is more than cosmetic; it’s an important hint for judging what is undefined and what is comparable. When using PVSyst for the first time, focusing on eliminating red warnings and establishing a baseline variant rather than creating a perfect model speeds up understanding.

With this mindset, PVSyst appears less like a difficult piece of software and more like a tool for comparative design. In practice—whether explaining to clients or reviewing internally—the value lies not only in the final number but in how results change when conditions are varied. Adopting the habit of thinking in terms of projects and variants improves both operational efficiency and explanatory power. If you want to learn PVSyst quickly, make this your foundation.

基礎知識2 地点と気象データの前提を先に固める

In PVSyst, the location and meteorological data are the entry point for all calculations. The official overview places geographic location and time-resolved meteorological data at the core of project design, and results are built on that foundation. The meteorological data viewer not only lets you inspect the time-step meteorological file contents but also provides tools to evaluate data quality. In other words, selecting a location does not finish the job; understanding which meteorological dataset you are using and how to verify its quality is essential to properly using PVSyst.

A particularly important point is not to confuse the project site with the measurement or interpolated point of the meteorological data. The official meteorological data screen explains that meteorological files include the location information where the data were measured or interpolated, and you can also check the data source and whether any items were supplemented from other sources. In practice, it is tempting to assume that “closer to the site is better,” but unless you actually check the dataset’s contents, provenance, and whether it was supplemented, you may misjudge the reliability of the numbers. If you proceed with ambiguous meteorological assumptions, no matter how much you refine shading or losses later, the underlying uncertainty remains.

When importing meteorological data from external sources, you must pay attention to the definition of timestamps. Official documentation states that PVSyst’s convention is that time labels refer to the start of the recording interval, whereas external data may use the end of the interval, the midpoint, UTC, or be affected by daylight saving time—definitions can vary. To correct these mismatches, PVSyst uses the concept of time shift, which is an important correction applied across the simulation. Especially when conversions use solar position, timestamp mismatches strongly affect morning/evening calculations and the conversion to tilted surfaces, so do not neglect the input data’s time definition.

The official documentation warns that if the time shift is inappropriate, solar position calculations will not work correctly and conversion errors can be large; appropriate correction is crucial for good results. In short, what really matters in using PVSyst is not just loading meteorological data, but understanding what time definition the data use, their quality, and which location they represent. Firmly grasping this changes how you interpret later results.

基礎知識3 方位角と傾斜角は発電量の土台

Azimuth and tilt are often treated lightly as just another input item in PVSyst. However, the official orientation setup procedure clearly states that the most basic orientation of a fixed surface is defined by these two parameters. The orientation screen also includes a simple optimization function that gives a rough idea of how much energy production might be affected compared to the optimal values. In other words, orientation is not an auxiliary item for later fine-tuning but the foundation that determines the broad scale of energy production.

Practitioners should be aware that orientation affects not only the incident irradiance but also morning/evening contributions, seasonal variation, and shading patterns. When energy production does not match expectations, it’s easy to jump straight to loss rates or equipment configuration, but often the surface orientation was simply inappropriate. In PVSyst, it is easier to start by considering a simple fixed surface and then, if necessary, progress to multi-orientation arrangements or specialized layouts; this makes it easier to understand the meaning of results. If orientation is left ambiguous while only refining details, overall consistency is hard to achieve.

The official documentation also explains that when a rectangular base defined in the 3D scene has a slope, the actual surface orientation may differ from the values seen in the field settings. That’s a reminder not to be reassured by numbers alone. Even if the angles on the screen seem correct, including 3D base conditions and placement conditions can change the actual receiving surface posture. As you become more familiar with PVSyst, you’ll understand azimuth and tilt not as mere form inputs but as core assumptions describing the physical posture of the surface.

基礎知識4 最初の1回目は最小構成で回す

The official tutorial strongly recommends that the initial variant be defined with the minimum necessary parameters, leaving others to reasonable defaults, and that you run a simulation once before adding further conditions such as distant shading, near shading, and individual loss conditions step by step. This is not a simplification for beginners but the standard approach to increase reproducibility in practice. If you build an all-inclusive model from the start, you may get numbers but won’t know which conditions dominate the results.

The official documentation notes that array losses and system losses have reasonable default values initially, and that after the first system study you should carefully define each loss parameter according to the specific project. Under this philosophy, the first run is merely the baseline case. In practice, having that baseline allows you to compare how much production drops when shading is added, how things change when loss rates are adjusted, and how seasonal contributions shift when orientation is changed. If you jump into details without a baseline, you’re likely to end up with numbers that are difficult to explain later.

The overview also states that time-step simulation results include many variables by month, day, and hour. The point of running the first simulation quickly is not merely to hurry the work but to have a starting point for comparisons as early as possible. If you want to learn PVSyst efficiently, it’s generally faster to run the first model and get used to checking differences than to spend too much time perfecting the initial model.

基礎知識5 影は遠方影と近接影で分けて扱う

Many practitioners struggle with handling shading in PVSyst. The official near-shading tutorial explicitly states that near shading is one of the more difficult parts of PVSyst. The simulation workflow shows that distant horizon shading and near shading are processed at different stages: distant shading is mainly corrected at the irradiance incidence stage, while near shading is applied to the beam component using predefined shading coefficients, resulting in a linear evaluation of shading losses. Therefore, it is essential in PVSyst to treat distant shading and near shading as distinct things rather than lumping all shading together.

What makes it more complicated is that near shading involves not only geometric shading but also electrical non-uniformity losses. The official module layout function explains that after defining each module’s position and string connections, PVSyst can calculate electrical mismatch losses from partial shading in detail. Using this function requires the 3D scene and system definition to be sufficiently finalized, which is why module layout is usually handled in the latter stages of project study. This is a very important point: shading should be considered early, but it is not necessary to perform the most detailed electrical shading evaluation from the very start.

Another official page explains that shading coefficients are calculated as the fraction of shadowed area according to solar position, and that precomputed lookup tables can be used to speed up calculations. For regular row layouts, quicker approximate models exist to estimate electrical shading losses without the detailed module layout, and these approximations are particularly effective for regular row arrangements. Therefore, in practice it is efficient to deepen the analysis in this order: no shading, then distant shading, then near shading, and if necessary a detailed electrical shading evaluation.

The official approximations also point out that even a single cell-level shadow can cause large mismatch losses for an entire string. Knowing this changes the way you examine site photos and layout plans: rather than thinking “only a little shade,” you begin to ask “which array, at which orientation, at what time, and affecting which electrical configuration does that shade impact?” Using PVSyst is not just deciding whether to include shading; it’s designing at what level of granularity to model shading.

基礎知識6 損失設定は既定値のままにしない

The official documentation states that array and system loss parameters are initially set to reasonable defaults, and that after the first simulation you should carefully define each loss factor according to project conditions. Losses to consider include incidence angle, soiling, low-irradiance behavior, temperature, initial degradation, quality differences, mismatch, wiring, auxiliaries, downtime, and so on. Practitioners need to understand that defaults are a convenient starting point, not a conclusion. Even if you get numbers using defaults, that does not mean the outputs appropriately reflect site reality.

The simulation flow shows that from meteorological data the irradiance on the plane is computed, followed by shading correction, incidence angle correction, soiling correction, and then the effective incident energy on the cell surface is calculated; thereafter, low-irradiance characteristics and temperature-related losses are evaluated. In other words, loss settings are not an afterthought but central to the flow that leads to energy production. Handling this carelessly makes it unclear whether production is too high or too low. In practice, you need to translate site-specific conditions—ventilation, surroundings, cleaning frequency, wiring length, downtime risk, etc.—into loss parameters one by one.

The documentation also shows that soiling losses strongly depend on rainfall and can be defined monthly, and that the impact of each loss can be visualized on an hourly, daily, and monthly basis. This indicates that loss configuration is not a single fixed-rate exercise but a task of reflecting site characteristics and seasonal variation in the model. For example, sites with different soiling tendencies in dry and rainy seasons or large seasonal temperature differences cannot be accurately represented by a single uniform setting. The difference in how practitioners use PVSyst often comes down to how they refine losses.

Equally important is not to try to finalize all loss settings at once. After running the baseline case, decide the order in which you will shift each loss toward site-realistic values so that you can trace the reasons for result changes. That way you can see in which months temperature changes have the greatest effect, how changing soiling assumptions affects seasonal as well as annual totals, and whether wiring adjustments have the expected impact. Graduating from default values to site-specific settings is what turns PVSyst from an estimation tool into a decision-making design tool.

基礎知識7 レポートは損失図から読む

When reviewing PVSyst results, stopping at annual energy alone is a missed opportunity. The official documentation describes the loss diagram as a quick insight into PV system design quality and a help for identifying the main loss sources. The loss diagram is always included in the annual report and can also be checked monthly, enabling you to read seasonal impacts and how different losses take effect. Experienced PVSyst users typically look at the loss diagram first to identify where energy is being eroded before delving into details.

The documentation also explicitly states that each loss percentage is relative to the immediately preceding energy quantity and that simple addition of losses is not valid. This often-overlooked point is crucial to avoiding misinterpretation. If you sum apparent loss numbers to intuitively judge total loss, the reality of the energy flow will be misrepresented. The loss diagram does not simply show “how much was lost”; it shows the order in which energy is reduced. That is why you can understand whether the issue is orientation, shading, or temperature/soiling not by raw numbers alone but by the structure they form.

Additionally, the overview notes that many simulation variables can be checked monthly, daily, and hourly, and that technical reports including conditions and key results can be output for each simulation. For practitioners, the real value is not just producing numbers but being able to explain them. Whether presenting internally or to a client, “This option is good” is insufficient. You should be able to say, “Given these location assumptions, this orientation, and this loss structure, this stage is the weakness,” and only then can you be said to be proficient in PVSyst.

実務担当者が迷わない進め方

Based on the foundational knowledge above, the workflow for using PVSyst can be well organized. First, create a project for each case and fix the assumptions for location and meteorological data. Next, run a minimal baseline variant using only orientation and an approximate configuration. Then add variants separately for shading, losses, orientation differences, and configuration differences and compare deltas. Finally, review not only annual figures but also loss diagrams and monthly variations to determine which conditions are influencing design decisions. This flow aligns with the official tutorial and is also practical for explaining results in a real-world context.

Following this order makes the process robust against changing assumptions. For example, if on-site verification reveals additional obstacles, add a shading variant; if maintenance conditions change, create a variant with revised losses; if more orientation candidates appear, focus on comparing those. The key to applying PVSyst in practice is not attempting an all-in-one one-shot model but accumulating studies in a comparable format. For more complex projects, following this order often makes the difference in final quality.

Even if you carefully refine simulation conditions at your desk, if on-site position confirmation and sharing of target points take time, the design intent may not smoothly translate to operations. Therefore, it is highly compatible to use PVSyst to organize assumptions during design and to use smartphone-mounted high-precision GNSS devices such as LRTK on site to speed initial position confirmation, sharing of target locations, and as-built verification. Linking desk-based assumptions with field positioning helps balance the accuracy of deliberation with operational speed.

まとめ

To grasp the use of PVSyst in five minutes, what you should first remember is not rote memorization of procedures but understanding the flow of design evaluation. The seven essentials are: manage cases with projects and variants; fix location and meteorological assumptions first; treat azimuth and tilt as the foundation of energy production; run the first simulation with a minimal configuration; separate distant and near shading; do not leave loss settings at defaults; and read results from the loss diagram. Mastering these seven points will make PVSyst appear not as an overly complex tool but as a practical instrument for structuring design decisions.

Moreover, considering how to leverage desk-based simulation results in the field further raises the quality of practice. Use PVSyst to sort condition differences in design, and employ high-precision positioning like LRTK on site for fast confirmation work so you can detect misalignments between planning and the field at an early stage. If you want to turn generation simulation into usable on-site judgment rather than a mere desk exercise, the natural and effective next step for practitioners is to combine understanding of PVSyst with the use of high-precision positioning such as LRTK.