Understand the process of checking annual energy production in PVSyst in 5 minutes

Even if you want to check annual energy production in PVSyst, the many input items and result screens can make it hard to know where to look. Especially for first-time users, after running a calculation the meanings of the numbers that appear are often unclear, and they frequently get stuck deciding which value to treat as the annual energy production.

However, the overall flow is not that complicated. Decide the location, choose the irradiation conditions, enter the equipment conditions, sort out losses and shading, and check the annual total on the result screen. If you remember only this sequence, reading the annual energy production can be understood in a short time. What matters is not simply looking at the annual total number, but confirming together which assumptions that number is based on.

This article organizes the procedure for checking annual energy production in PVSyst in a way that even beginners can follow. It explains not only the steps to check annual energy production, but also which screens to look at, the prerequisites to prepare before checking, commonly misread caveats, and how to use the results in practice. First grasp the flow, then move on to the finer verification points to make the annual energy production figures more usable in practice.

Table of contents

• Overall flow for viewing annual energy production in PVSyst

• Prerequisites to decide before checking annual energy production

• Basic steps to check annual energy production

\- Screens you must check and how to read the numbers

\- Points to watch when viewing annual energy production

\- How to think when using annual energy production in practice

\- Why the accuracy of on-site conditions affects the results

\- Summary

Overall flow for viewing annual energy production in PVSyst

The task of checking annual energy production in PVSyst is not as difficult as it looks. First, understand that annual energy production is not a single independent number but a result determined by multiple stacked conditions. Location irradiation conditions, module orientation and tilt, plant capacity, equipment configuration, temperature conditions, losses from wiring and equipment, and the effects of surrounding shading all combine and finally appear as the annual total energy.

Therefore, it is easier to understand the flow for checking annual energy production by thinking backward from the result screen. What you ultimately want to see is the annual total energy, but just before that are the monthly production values, and before that is the breakdown of losses. Before the loss breakdown are the input conditions such as irradiation, azimuth/tilt, and equipment configuration. In other words, viewing annual energy production means not only reading the results but sequentially confirming the assumptions that led to the results.

In practice, it is particularly important to be aware of which point’s annual energy production you are looking at. In photovoltaics there are multiple perspectives: the energy incident on the module surface, the energy obtained as DC from the solar cells, the energy on the AC side after converters, and the energy actually sent to the grid. PVSyst also organizes intermediate-stage energy amounts and the final output-side energy as separate values. For business planning and internal explanations, the annual energy production usually refers to the AC-side or grid-supplied annual total, so it is important not to be vague about which value you adopt.

If you want to understand the flow quickly, keep the main sequence in your head: decide the location, set equipment conditions, set loss conditions, run the calculation, and view the annual total on the result screen. If the numbers seem odd, go back to monthly results or the loss breakdown to find the cause. Once you can go back and forth like that, checking annual energy production becomes not just an operation but a validation of the result’s plausibility.

Prerequisites to decide before checking annual energy production

The most important thing before checking annual energy production is to prepare the prerequisites first. If you run calculations with these unclear, you may see an annual total number but be unable to judge whether it is reliable. PVSyst calculates faithfully according to the input conditions, so if the prerequisites are sloppy, the annual energy production you get will be difficult to use in practice.

First organize the conditions related to the plant location. Which region is the project in, which meteorological conditions will you use, and what is the terrain and surrounding environment like? If this part is inconsistent, the annual irradiation will change, and consequently the generation will change significantly. Even with the same-capacity plant, annual energy production changes if the meteorological settings differ. Therefore, first confirm that you have chosen irradiation conditions appropriate for the location.

Next, the module orientation and tilt are important. Whether the array is near south-facing or an east-west layout, and what the tilt angle is, will change the distribution of received irradiation. Annual energy production is an annual total, but its content is an accumulation by month. Thus, changes in azimuth or tilt not only raise or lower the annual total but also change monthly biases. If you do not enter these correctly, the annual total alone may not reflect reality.

Equipment conditions are obviously important as well. What is the DC capacity, what conversion equipment configuration is used, what is the DC/AC capacity ratio, and are the series and parallel counts reasonable? If this setup is unnatural, converter saturation or mismatched operating ranges are more likely to occur, affecting annual energy production. In early stages people tend to input capacity first and feel reassured, but it is important to also check the DC/AC balance and operational consistency.

Furthermore, loss conditions are indispensable as assumptions. Temperature-related degradation, wiring losses, internal equipment losses, soiling and aging assumptions, mismatch, and shading losses all reduce generation. In practice it is common to use initial or typical values while fine details are undetermined and then treat the result as definitive. Using general conditions at the estimate stage is fine, but in that case you must state that it is a rough estimate and plan to revise them at the detailed design stage.

To correctly read annual energy production, quickly check whether the four foundations—location, orientation, equipment, and losses—are in place. If these four are organized, when you look at the annual total on the result screen it will be easier to judge how usable that number is in practice.

Basic steps to check annual energy production

The basic steps to check annual energy production in PVSyst can be understood by following the sequence from project setup to reading results. At the entry point, determine what kind of project you are dealing with. For a typical grid-connected PV assumption, create the project with that premise and input the conditions necessary for checking generation.

First confirm the location and meteorological conditions. Decide which regional meteorological data to use for the project. Annual energy production is strongly tied to annual irradiation, so this setting is a major branching point. If you use meteorological conditions from a point far away or ignore differences in actual terrain or elevation, the foundational part will be off no matter how carefully you enter equipment settings later.

Next set the module orientation and tilt. Fix whether it is fixed, east-west, or what the tilt angle is. Even if you want to hurry and check only the annual production, if you put these in by feel the results are likely to look unnatural later. Enter orientation and tilt close to the actual plan so that monthly production trends and the annual total are consistent.

Then configure the equipment. Organize module capacity, converter capacity, circuit arrangement, etc., and check whether the setup makes sense as a plant. Here you must confirm not just the capacities but also whether the DC/AC relationship and the combinations during operation are reasonable. Annual energy production is affected by the equipment capability and operating conditions, so avoid unrealistic configurations at this stage.

After equipment configuration, organize the loss conditions. Set temperature, wiring, soiling, mismatch, equipment losses, and add shading conditions if necessary. The important point here is not to estimate losses as near zero. When people want to make annual energy production look large, they tend to set losses optimistically, but in practice such numbers are soon questioned. Rather, it is more important that you can explain the basis for the loss assumptions you entered.

Then run the simulation. When the calculation finishes the result screen appears and you can check the numbers related to annual energy production. The first thing to look at here is the energy indicated as the annual total. However, do not stop there—also check the monthly results, the loss flow, and the equipment utilization state. Checking annual energy production can take a few seconds if you only read one number on the screen, but to verify whether that number is usable in practice you need to check the surrounding screens as well.

If you remember this sequence, checking annual energy production in PVSyst becomes well organized. If you want to understand it in the first five minutes, remember: location, orientation, equipment, losses, results.

\## Screens you must check and how to read the numbers

Knowing which screens to look at can greatly speed up understanding when checking annual energy production. In PVSyst input screens and result screens are separated, so looking only at results may not reveal the causes of anomalies. Therefore, it is important to connect and review at least the minimum set of screens.

First check the meteorological conditions screen. Here you identify which regional conditions the calculation is using. If the annual energy production seems too high or too low, review this screen before the equipment capacity. If the irradiation conditions differ, the output will change no matter how detailed the equipment conditions are. Use this screen as the foundation for judging the plausibility of annual energy production.

Next look at the azimuth and tilt settings screen. This organizes which direction the module surface faces and how much it tilts. While attention tends to go to the annual total, in practice you may need to justify whether these conditions are appropriate. For example, if you input ideal orientation and tilt despite site constraints, the apparent annual production may look good but the plan will not be feasible. You need to check not only the number but whether it matches site conditions.

The next important screen is the equipment configuration screen. Here confirm the DC-side capacity, the relationship with converters, and circuit configuration. You might wonder why you need to look at the equipment screen just to see annual production, but if you read only the results without this you won’t know whether the converters are bottlenecking the output or whether the plant capacity itself differs. When comparing projects in particular, checking this screen is indispensable to separate whether differences in annual totals stem from capacity differences or from differing condition settings.

On the result screen first check the annual total energy. This number is the annual energy production most commonly used in practice. However, it helps to also look at annual production per unit capacity to make comparisons easier. The absolute annual total alone favors larger-capacity projects, so to compare project quality you need a per-capacity metric as well. Make it a habit to look at both the annual total and generation per unit capacity to avoid misinterpreting the numbers.

Also be sure to view the monthly results screen. Looking only at the annual total makes it hard to notice seasonal biases or anomalies. For example, if production drops sharply in a particular season, shading effects or input errors may be suspected. Viewing results arranged by month reveals patterns behind the annual total. In practice, when explaining annual energy production, showing monthly output trends as well as the annual total increases credibility.

Furthermore, the screen showing the loss flow is important. This lets you see at which stages the incident irradiation is reduced and how it leads to the final annual energy. If annual production is lower than expected, this helps identify whether the cause is temperature, wiring, shading, or conversion losses. Conversely, if the number is too high, it helps to check whether the loss assumptions were too optimistic.

To read annual energy production correctly, view the four sets together: the annual total on the result screen, monthly results, the loss flow, and the input conditions. Just by following this flow, PVSyst’s screens become not just operation panels but materials for judgment.

\## Points to watch when viewing annual energy production

The most common mistake when checking annual energy production in PVSyst is taking the displayed annual total as the answer. While the simulation output is one result, whether it can be used as-is is another matter. Annual energy production must be read together with its assumptions.

First, do not equate annual energy production with actual generation. PVSyst results are annual estimates under the set conditions and are not guaranteed to match actual operating performance one-to-one. On-site weather variability, construction errors, operational constraints, soiling accumulation, downtime, and many other factors additionally affect real-world performance. Treat annual energy production as a conditional forecast.

Next, pay attention to which point’s energy you are looking at. Energy seen on the DC side is not the same as the extracted AC energy. The number also differs depending on whether you use the energy delivered to the grid or the output inside the plant. If the definition is vague in internal materials or explanations to the client, numbers may not match later. When reading result screens, be conscious of which stage the value represents.

Comparing projects with different capacities using only the annual total is also dangerous. Larger-capacity projects tend to show larger absolute annual energy, so you cannot compare conditions this way. When comparing, look at annual energy per unit capacity, loss behavior, and monthly trends together. This prevents being misled by capacity differences and makes it easier to understand condition differences.

Shading treatment is another easily overlooked point. If surrounding buildings, terrain, or row-to-row shading are not sufficiently reflected, annual energy is likely to be optimistic. Especially at morning and evening extremes, in winter when sun altitude is low, or in tight row spacing layouts, shading effects gradually impact the annual total. Simplification is acceptable for rough initial studies, but do not treat those numbers as final.

Also be careful with default initial loss settings. Wiring, soiling, temperature, mismatch, and equipment losses each affect the annual total slightly but meaningfully. In practice, general conditions are often used because inputs are undecided, but in that case explicitly note that those conditions are provisional. If the annual energy number circulates independently and conditions are refined later, large corrections may follow and cause discrepancies in stakeholders’ understanding.

When viewing annual energy production, prioritize consistency with the assumptions over the magnitude of the number. In practice, being able to explain why a number arose is more valuable than whether the result looks favorable.

\## How to think when using annual energy production in practice

Annual energy production checked in PVSyst is used in many practical situations: initial proposal estimates, project comparisons, design validation, internal approvals, explanations to clients, and comparisons with operational performance. However, required precision and presentation differ by use, so the same annual energy number should be handled differently depending on purpose.

In the initial proposal stage, annual energy production is used as a rough estimate to judge project direction. At this stage site conditions and detailed equipment may not be finalized, so aligning how assumptions are set is more important than numerical precision. When comparing multiple options, use consistent meteorological and loss conditions for a fair comparison. Always note differences in assumptions, not just the relative sizes of annual totals.

As design progresses, annual energy production becomes more concrete for decision-making. At this point bring azimuth/tilt, equipment configuration, shading conditions, and loss assumptions closer to the actual plan to strengthen the explanatory power of the results. For example, be prepared to explain why a particular azimuth was chosen, why a given capacity ratio was selected, and what level of losses you assumed. Being able to justify these points increases confidence in the annual energy numbers.

When explaining to clients or stakeholders, it is more effective to present monthly trends and the loss rationale along with the annual total. The annual total alone leaves the audience focusing only on that number’s magnitude. Explaining seasonal output trends and what causes losses deepens understanding. Because annual energy production often becomes central to presentation materials, supplement the background assumptions clearly in words.

After operations begin, you will compare PVSyst’s annual energy with actual results. Do not evaluate simply on whether the prediction hit. If actual production is lower, separate factors like weather differences, downtime, soiling, shading, or optimistic settings. If actual production is higher, determine whether it was a favorable weather occurrence or conservative assumptions. Such comparisons refine simulation assumptions for future runs.

In practice, treat annual energy production not as a single definitive value but as a conditional decision-making input. Whether at the estimate, design, presentation, or post-operation comparison stage, the meaning and weight of the number change. Being aware of those differences and using the results accordingly is key to leveraging PVSyst in practice.

\## Why the accuracy of on-site conditions affects the results

To correctly check annual energy production, it is crucial not only to operate the software but also to accurately capture on-site conditions. PVSyst is an excellent calculation tool, but if the input conditions are detached from the site, the simulated annual energy will also be detached from reality. Information such as azimuth, tilt, installation position, elevation differences, obstacle positions, and row spacing are areas where desk assumptions and actual site conditions easily diverge.

For example, even a slight difference in module azimuth changes how annual irradiation is received. If row spacing is underestimated, shading in winter or at morning/evening can be underpredicted. If you cannot accurately grasp the positions and heights of surrounding obstacles, shading modeling becomes coarse. These small discrepancies may seem trivial individually, but when accumulated they become non-negligible differences in annual energy production.

Therefore, in practice the accuracy of site reconnaissance directly affects simulation accuracy. While rough assumptions may be acceptable in early design, at the detailed design and presentation stages update the inputs to reflect the site as much as possible. To make annual energy numbers truly usable, the input assumptions need to be substantiated.

A helpful means to efficiently obtain site position, elevation, and layout information is LRTK, an iPhone-mounted GNSS high-precision positioning device that pairs well with situations where on-site high-precision location data are desired. If you can capture candidate installation positions, obstacle relationships, post-grading ground status, and surrounding checkpoints on site, it becomes easier to raise the accuracy of assumptions entered into PVSyst.

Checking annual energy production is not a task that can be completed only within the software. Rather, how plausibly you can organize site conditions greatly influences the reliability of the results. If you want simulation numbers to be more practice-ready, consider building the evidence for input assumptions as part of the process.

\## Summary

The flow to check annual energy production in PVSyst can be understood in the order of deciding the location, setting azimuth and tilt, entering equipment configuration and loss conditions, running the simulation, and reading the annual total. At first the number of screens may be overwhelming, but organizing the points to check makes the task much clearer.

Most importantly, do not chase only the annual total number. Confirm which meteorological conditions were used, whether the equipment conditions are appropriate, how losses and shading were set, and whether monthly trends show anything unusual. Only by checking these backgrounds together does the annual energy production become a number usable in practice. Viewing the annual total on the result screen, the monthly results, the loss flow, and the input conditions together is the quickest way to avoid misreading.

Also, in practice annual energy production is used for rough estimates, project comparisons, internal and client presentations, and comparisons with operational performance. Therefore, handle it as a conditional decision-making input rather than a standalone number. In practice, being able to explain why a number resulted is more important than whether the number looks good.

Finally, if you want to improve the accuracy of annual energy production, pay attention not only to PVSyst operations but also to the accuracy of on-site condition capture. The more site information—layout, azimuth, elevation differences, obstacle positions—is organized, the closer the simulation assumptions will be to reality. When you want to acquire high-precision site position data and strengthen the basis for design and analysis, using means such as LRTK (an iPhone-mounted GNSS high-precision positioning device) helps increase the reliability of assumptions entered into PVSyst. If you want the annual energy numbers to be more convincing, it is important to connect simulation and site reconnaissance.