7 Ways to Read PVSyst Result Sheets | Don't Get Lost in Practice

The Result Sheet in PVSyst is the key page to read first when reviewing power generation simulation results for a solar power plant. Although PVSyst provides many outputs—Detailed Losses, Loss Diagram, Monthly Results, Graphs, etc.—the Result Sheet consolidates the information needed for practical decision-making, including the project's basic parameters, energy production, PR, solar irradiation, an overview of losses, and installed capacity.

However, the Result Sheet contains many items and can be difficult for a first-time reader to know where to start. In particular, for power generation assessments submitted to banks, design confirmations with the EPC, performance comparisons in O&M, and checks of assumptions for project cash flows, it is necessary not just to look at the annual generation but to interpret the connection between the assumptions and the results.

In this article, we break down into seven points the key things to know to read PVSyst's Result Sheet confidently in practical work. When reviewing PVSyst results, we clarify which items to check and in what order, what to watch out for, and how to evaluate the energy production and PR.

Table of Contents

• What is the PVSyst Result Sheet?

• First, check the project conditions

• Second, check the system capacity and equipment configuration

• Third, read the solar irradiation and weather conditions

• Fourth, check the annual energy production and Specific Production

• Fifth, do not evaluate the PR alone

• Sixth, check the overview of losses

• Seventh, read by cross-referencing with other pages

• Points to note when using the Result Sheet in practice

• Confirming PVSyst results and the importance of on-site information

• Summary

What is the Result Sheet in PVSyst?

The PVSyst Result Sheet is a summary document that organizes the simulation results of a photovoltaic power generation system on one or several pages. It compiles the annual energy production and monthly energy production calculated by PVSyst, the Performance Ratio, installed capacity, tilt angle, azimuth, meteorological data, and major losses.

The Result Sheet is not a page that displays all detailed calculation steps. Rather, it is a summary page for quickly checking the simulation assumptions and results. Therefore, in practice you should not draw conclusions based solely on the Result Sheet; if anything seems questionable, you need to return to pages such as the Loss Diagram, Detailed Losses, or Monthly Results to identify the cause.

When reading a Result Sheet, what matters is not just looking at the results, but examining the conditions from which those results were produced. Whether the annual energy generation is high or low, or whether the PR is good or bad, depends on conditions such as module capacity, PCS capacity, solar irradiation, temperature, tilt angle, azimuth, wiring losses, soiling, shading, and output curtailment.

In other words, the Result Sheet is not merely a results report but an entry point for verifying the consistency between the design conditions and the power output.

First, confirm the project conditions

The first items to check on the Result Sheet are the project name, site name, country, region, coordinates, elevation, and meteorological data. If any of these are incorrect, no matter how detailed the calculations are, the overall reliability of the results will be diminished.

Particularly important is the consistency between the site location and the meteorological data. In solar power generation simulations, solar irradiance and ambient temperature have a large impact on power output. If meteorological data from a location different from the actual plant site are used, the annual energy production and monthly trends may deviate from reality.

For example, even within the same prefecture, solar irradiance and temperature differ between mountainous areas, coastal areas, basins, and snowy regions. In areas where snow has a large impact, such as Hokkaido and Tohoku, the way winter solar irradiance, snow cover, albedo, and soiling losses are considered also affects the results. In regions with severe high-temperature conditions, such as Kyushu and Shikoku, output reductions caused by module temperature in summer are also important.

Also, the Result Sheet may state the simulation version and the creation date. When comparing multiple scenarios, it is important to confirm that they are being compared using the same PVSyst version, the same meteorological data, and the same assumptions. When comparing an older report with a newer one, results may change due to updates to the equipment database or the meteorological data.

In practice, we first check the top of the Result Sheet to confirm that this report is for the relevant project, that the target site is correct, and that the meteorological data used are appropriate. We look at the power generation and PR only afterwards.

The second is to check system capacity and equipment configuration

Next, what you should check is the system capacity and equipment configuration. The Result Sheet lists the model of the solar modules, the number of modules, DC capacity, the model of the PCS or inverter, the number of units, AC capacity, and so on.

What's important here is the relationship between DC capacity and AC capacity. In solar power plants, it is common for the DC capacity, which is the total capacity of the modules, and the AC capacity, which is the output capacity of the PCS, to differ. When the DC capacity is larger than the AC capacity, clipping can occur on the PCS side during periods of high irradiance.

This DC-to-AC ratio is closely related to power generation and losses. The larger the DC capacity, the easier it is to increase generation during mornings, evenings, and cloudy conditions, but during sunny periods output may be limited by the PCS capacity. When reviewing generation in the Result Sheet, check whether the DC/AC ratio is reasonable rather than simply whether the capacity is large or small.

Also, it is important to confirm that the module model numbers and PCS model numbers are correct. If the model numbers differ, output, temperature coefficients, efficiency, voltage range, overload characteristics, and other parameters will change. In particular, for power generation evaluations and documents for financial institutions, it is necessary to confirm that the specifications of the equipment used match the contract documents and the design drawings.

String configuration is another aspect that's easy to overlook. If the number of modules in series, the number in parallel, or the allocation to MPPTs is inappropriate, losses and constraints related to voltage range and current limits can arise. The Result Sheet alone may not reveal all the details, but at a minimum you can confirm whether the overview of the equipment configuration matches the design documentation.

The purpose of checking the system capacity on the Result Sheet is to verify that the denominator for comparison is correct before looking at the power generation itself. Even if the power generation looks large, if it is simply due to a large capacity, that does not necessarily mean the performance is good. Conversely, even if the annual power generation looks small, it may simply be because the capacity is small.

The third is to read solar irradiance and meteorological conditions

In PVSyst's Result Sheet, indicators related to solar irradiation and meteorological conditions are also important. In particular, items such as GlobHor, GlobInc, DiffHor, and Tamb are indispensable for understanding the assumptions behind the energy yield.

GlobHor is a field representing global horizontal irradiance. It is the annual or monthly solar radiation incident on a horizontal surface. It is a fundamental value in meteorological data and is used to assess a region's solar potential.

GlobInc is an item that represents irradiance on an inclined surface. It is the irradiance that takes into account the tilt angle and azimuth angle at which the solar module will actually be installed. In photovoltaic power generation, how much solar radiation strikes the module surface has a more direct effect on power output than irradiance on a horizontal plane. Therefore, when viewing the Result Sheet, check GlobInc as well as GlobHor.

Tamb is the ambient temperature. Because the output of solar photovoltaic modules decreases as temperature rises, ambient temperature has a large impact on power generation. In regions with high solar irradiance but also high temperatures, temperature losses can be large and PR can decrease. Conversely, in cold regions, even if solar irradiance is not that high, temperature conditions can be advantageous.

When examining meteorological conditions, it is important to pay attention to monthly trends as well as annual values. If the Result Sheet includes a monthly table, check whether solar irradiance is high in summer, drops in winter, or whether the effects of the rainy season or snowfall are visible. If the plant’s regional characteristics do not align with the monthly generation trends, you need to review the meteorological data and loss settings.

Also, if the assumptions about solar irradiation differ from those in other companies' reports, this can be a major cause of differences in power generation. When comparing PVSyst results, it is necessary to check not only the loss settings but also the source of the meteorological data and differences in the annual average solar irradiation.

Fourth, look at annual power generation and Specific Production

On the Result Sheet, the annual energy production is the first thing many people look at. In PVSyst, the annual energy sent to the grid is displayed under entries such as E_Grid or Energy injected into grid. This is an important figure that serves as the basis for project finances and electricity sales revenue.

However, judging performance solely by annual power generation is risky. Because generation increases in proportion to installed capacity, projects with different capacities cannot be compared directly. That’s where Specific Production becomes important.

Specific Production is an indicator that shows the annual power generation per 1 kWp. It is commonly expressed in units such as kWh/kWp/year. By looking at this, you can, to some extent, normalize differences in system size and compare them.

For example, even if one power plant has an annual generation of 1,000,000kWh and another has 2,000,000kWh, the latter is not necessarily better performing. If the latter's DC capacity is more than twice as large, the generation per unit of capacity may actually be lower. By looking at Specific Production, you can understand the generation efficiency relative to capacity.

In practice, annual energy production, DC capacity, and Specific Production are evaluated together. In addition, regional solar irradiance conditions, tilt angle, azimuth, shading, snowfall, and PCS capacity are also checked. When Specific Production is high, it may indicate good solar irradiance, favorable temperature conditions, low losses, and appropriate design. When it is low, it may indicate low solar irradiance, significant shading or soiling, large PCS clipping, or high wiring and temperature losses.

The important point is that Specific Production is a useful comparative indicator, but it is not a universal metric. If you simply line up projects from different regions and with different design conditions and judge them as higher or lower, you may draw incorrect conclusions. On the Result Sheet, when reading generation figures you should always review them together with the underlying assumptions.

Fifth: Do not judge PRs alone

On PVSyst's Result Sheet, the indicator that is particularly noteworthy is PR. PR stands for Performance Ratio and is a representative metric that indicates the performance of a photovoltaic power generation system. In general, it shows how the actual amount of electricity produced compares to the theoretical energy that could be obtained.

PR is useful for comparing the performance of power plants, but it is risky to judge quality based on PR alone. PR is affected by many factors such as solar irradiance, temperature, PCS clipping, wiring losses, mismatch, soiling, shading, auxiliary power consumption, transformer losses, etc.

For example, in regions with high solar irradiance, power generation tends to be higher, but module temperatures also tend to rise, which can lead to greater temperature-related losses. As a result, there can be cases where the power generation is good but the PR is not particularly high.

Also, when the DC/AC ratio is designed to be high, PCS clipping may increase, causing the PR to decrease. However, that design can also improve annual power generation and project viability. In other words, a low PR does not necessarily mean a poor design.

Conversely, caution is needed even when PR appears high. If loss settings are lax, soiling losses are set too low, the effects of shading are not reflected, wiring losses are underestimated, or auxiliary consumption is not included, PR may appear higher than reality.

In practice, when reviewing PR we always check generation, irradiance, loss settings, and the DC/AC ratio together. PR is a convenient indicator that shows at a glance whether the results are good or bad, but it does not tell you the cause. After confirming PR on the Result Sheet, it is important to check the Loss Diagram and Detailed Losses next to identify which losses are affecting the PR.

6th: Review the overview of losses

The Result Sheet may include an overview of losses. PVSyst includes many different losses, such as losses due to the angle of incidence of solar radiation, shading losses, soiling losses, temperature losses, mismatch losses, wiring losses, inverter losses, transformer losses, and auxiliary losses.

In the Result Sheet, these losses may not all be displayed in detail, but you can grasp the trends of the main losses. What is important here is not only the magnitude of the loss rates themselves, but whether they are natural values for that particular case.

For example, if temperature losses are large, this can be acceptable in high-temperature regions, low-wind conditions, rooftop installations, or on racking with poor ventilation. Conversely, if temperature losses are extremely large in cold regions or in well-ventilated ground-mounted installations, you may want to check the heat loss coefficient settings.

Wiring losses are also important. Check whether the loss settings for DC wiring, AC wiring, MV wiring, etc. match the actual cable lengths and cross-sectional areas. Wiring losses may look like small numbers at first glance, but they cannot be ignored in long-term project economics. In particular for large-scale power plants, the distance from the junction box to the PCS, the distance from the PCS to the transformer, and the transmission distance after stepping up affect the results.

Soiling losses and snow impacts are items that are easily overlooked. The Result Sheet alone may not make the detailed rationale for the settings clear, so check whether the annual and monthly values are reasonable. If winter losses are not included at all in snowy regions, or if soiling losses are extremely small in areas with heavy dust, the assumptions need to be reviewed.

The purpose of reviewing the loss overview is to investigate the reasons for high or low power generation. If annual power generation is low, you need to consider separately whether it is due to low solar irradiance, large temperature losses, significant shading, or limitations imposed by the PCS. The Result Sheet serves as the entry point for that.

Read the seventh by cross-referencing with other pages

The Result Sheet is a helpful summary, but it should not be used alone to make detailed judgments. In practice, items that raise concerns on the Result Sheet are confirmed by cross-checking with other pages.

The Result Sheet is useful for viewing an overall picture of energy production and PR. The Loss Diagram is effective for checking the flow of losses. Check Detailed Losses to view the detailed loss settings. To check monthly trends, see Monthly Results. To verify system configuration and equipment settings, you need to view pages such as System Definition, Orientation, and Near Shadings.

For example, if you feel the PR is low on the Result Sheet, first look at the Loss Diagram to see at which stage it is dropping significantly. If temperature loss is large, check ambient temperature, wind speed, heat loss coefficient, and mounting conditions. If inverter loss or clipping is large, check the DC/AC ratio and PCS output limit. If shading loss is large, check the Near Shadings and Horizon settings.

Also, when comparing with other companies' reports, the Result Sheet alone is insufficient. If PR or annual generation differs, it is necessary to distinguish and verify whether the difference is due to the solar irradiance data, loss settings, installed capacity, or the definition of the energy being calculated.

Be especially careful about which point’s energy is being compared — for example, E_Grid, EArray, EOutInv. Even when referring to generated energy, the meaning differs between array output, inverter output, and energy injected into the grid. If the comparison targets are misaligned, you cannot perform a correct differential analysis.

Use the Result Sheet to get an overall picture, and carry out detailed checks on separate pages. Keeping this division of roles in mind makes it less likely that you'll get confused when reading PVSyst.

Points to note when using Result Sheets in practice

When using the Result Sheet in practice, it is important to first verify the consistency of the numerical values. Check that the project name, capacity, meteorological data, equipment model, tilt angle, azimuth, power generation, and PR match the design documents and contract terms.

Next, it is important to align the assumptions for the comparison. When comparing multiple proposals, check that the meteorological data, loss settings, equipment data, output limits, auxiliary losses, transformer losses, albedo, soiling losses, and so on are based on the same assumptions. If you compare only the energy production while the assumptions differ, you will be comparing differences in the condition settings rather than the merits of the design proposals.

Also, the figures in the Result Sheet are simulation results and not measured values. Actual power generation can vary due to year-to-year weather variability, equipment downtime, output curtailment, malfunctions, soiling, snow accumulation, changes in the surrounding environment, maintenance condition, and other factors. Therefore, the Result Sheet should not be regarded as a guarantee of future power generation but should be treated as a forecast based on certain assumptions.

When submitting to banks or using it for investment decisions, check whether the assumptions are conservative and whether there are any excessively optimistic settings. For example, verify that soiling losses are not too small, that wiring losses are realistic, that auxiliary consumption is included, and that shading and snow are appropriately reflected.

In meetings with EPCs and design companies, it is effective to use the Result Sheet to share the overall picture and to confirm detailed issues with the Loss Diagram and Detailed Losses. Relying only on the Result Sheet during discussions tends to make identification of causes vague. By checking the background behind the numbers as you proceed, the accuracy of design reviews improves.

Verification of PVSyst Results and the Importance of On-site Information

To correctly read the PVSyst Result Sheet, cross-checking with on-site information is also important. The simulation calculates the power generation based on the input conditions. Therefore, if the actual site conditions—terrain, surrounding structures, utility poles, trees, slopes, snow accumulation, drainage, access roads, mounting structure layout, cable routes, etc.—are not reflected in the input conditions, the results may deviate from reality.

In particular, the effects of shading and the as-built condition after construction can be difficult to assess from drawings alone. Even if the design phase assumes little shading, in reality shadows can occur in the mornings and evenings due to surrounding trees and undulations in the terrain. Also, if the installation angle or position of the mounting structure deviates from the design, the actual solar radiation conditions may differ from those assumed.

Such verification is aided by on-site positioning and comparison with drawings. Using a system like LRTK that leverages an iPhone and GNSS to acquire position information on site and overlay it with drawings and construction information makes it easier to find discrepancies between the assumptions in PVSyst and actual site conditions. In solar power plant design reviews, it is important to verify not only simulation results but also the site location, topography, and equipment layout.

PVSyst is a highly effective tool for estimating power generation, but by verifying the validity of input conditions on site you can make judgments that are closer to real-world practice. When reading the Result Sheet, it is important not merely to look at the figures on the screen but to be aware of whether those figures reflect the actual conditions at the site.

Summary

PVSyst's Result Sheet is an important document for quickly grasping the simulation results of a photovoltaic (PV) power generation system. Because it consolidates annual energy production, PR, Specific Production, solar irradiance, system capacity, and major losses, it can be used as an entry point for design reviews, generation output assessments, feasibility checks, and comparisons with other companies' reports.

However, it is risky to draw conclusions based on the Result Sheet alone. First check the project conditions and meteorological data, then look at the system capacity and equipment configuration. After that, sequentially review the solar irradiance, annual energy production, Specific Production, PR, and an overview of losses. If any figures are concerning, it is important to go back to pages such as the Loss Diagram, Detailed Losses, and Monthly Results to identify the causes.

To avoid confusion in practical work, it is important to read the Result Sheet not as a report card but as a document for verifying the consistency between assumptions and outcomes. Rather than simply looking at whether energy production is high or low, or whether the PR is good or bad, you can make more accurate use of PVSyst reports by interpreting which conditions produced those results.