Six easily overlooked settings for ground-mounted projects in PVSyst

Table of contents

• Why input accuracy matters for ground-mounted projects

• Setting 1: meteorological data and location conditions

• Setting 2: tilt angle, azimuth angle, and installation orientation

• Setting 3: row spacing and mutual shading

• Setting 4: temperature conditions and ground-mounted installation state

• Setting 5: loss rates and operational assumptions

• Setting 6: string configuration, voltage range, and output balance

• Summary

Why input accuracy matters for ground-mounted projects

When running simulations for ground-mounted projects in PVSyst, the number of input items can look large, but in practice you cannot always fill every item thoroughly each time. Especially in early stages, because you want a rough estimate quickly, it is common to proceed with default values or reuse data from past projects. However, compared with rooftop projects, ground-mounted projects are more sensitive to site conditions, row spacing, topography, wind flow, and shading patterns. Sloppy settings in these areas tend to translate directly into sloppy design judgments.

In reality, large differences in energy yield often come not from flashy settings but from the plain, easy-to-overlook basic settings. For example, small mismatches in location conditions, errors in how tilt or azimuth angles are entered, provisional layouts that ignore mutual shading, reliance on default temperature settings, blanket entry of loss rates, and insufficient detail in string configuration may not look like glaring mistakes, but they affect annual yield, the breakdown of losses, and even equipment balance assessments for grid connection assumptions.

To improve design accuracy in PVSyst you need more than just filling screens—you need the perspective of checking, one by one, whether each setting aligns with site reality. In ground-mounted projects it is important to be aware of any mismatch between what is visible on site and what the software is assuming. Below, I narrow down six settings that practitioners tend to overlook in ground-mounted projects, and organize why they’re easy to miss, where to pay attention, and how to verify them.

Setting 1: meteorological data and location conditions

The first thing to review is the meteorological data and location conditions. In PVSyst it’s natural to pick a location and assign meteorological conditions, but the important point here is not to be reassured simply because you chose a nearby station. For ground-mounted projects, the candidate site and the representative meteorological point don’t always match exactly—there can be differences in elevation, inland vs. coastal influence, surrounding topography, wind paths, and seasonal temperature trends. Selecting data based on distance alone can, over time, affect not only annual yield but also module temperature and loss calculations.

Also, when setting location conditions, you should not neglect elevation and how you handle horizon conditions. Especially near mountain edges, around reclaimed land, or close to valley topography, morning and evening solar access can differ from flatland. Although ground-mounted projects allow relatively free layouts, they are also more susceptible to the influence of surrounding terrain; the orientation of the site itself and elevation differences affect solar conditions. A site that looks planar on paper may in reality have local slopes or embankments that change the conditions.

This setting is easy to overlook because in the initial study you often just want capacity and a rough yield estimate, so you plug in provisional meteorological data and proceed to later stages. But if you finalize panel layouts and equipment configurations on that provisional basis, reviewing the location conditions later can destabilize the entire premise and require a full reassessment. Especially when comparing multiple options, ambiguous location conditions can make input assumptions produce errors larger than the differences between the options.

In practice, treat meteorological data not as a temporary selection but as the foundation of the assumptions you will adopt for the project. Check the candidate site’s elevation, tendencies for surrounding shading, winter temperatures, and summer high-temperature trends, and set location conditions with awareness of how closely they match the site reality. Because PVSyst’s results faithfully follow input conditions, if the initial location assumptions are weak then no matter how carefully you set subsequent parameters, it will be hard to produce a high-quality design.

Setting 2: tilt angle, azimuth angle, and installation orientation

Next, an easily overlooked area is tilt angle, azimuth angle, and installation orientation. In ground-mounted projects there is a natural tendency to input ideal tilt and azimuth values to maximize yield. But on actual sites you may not be able to install exactly at ideal values due to earthworks plans, drainage direction, racking fit, maintenance access, terrain slope, and delivery constraints. The tilt and azimuth you enter in PVSyst are not merely numeric inputs; you need to consider whether those values are actually feasible on site.

Be especially careful not to confuse site orientation, racking orientation, and the module surface azimuth. For ground-mounted systems, arranging rows to match site boundaries can look neat from a plan view but may not be optimal for solar exposure. Conversely, if you choose an azimuth solely to maximize energy yield, you may find it conflicts with grading or access plans and becomes infeasible at the drawing stage. The angles you input in PVSyst should reflect design values that balance field constraints and generation goals.

This setting tends to be postponed because, in early stages, assumptions like “roughly south-facing” and “a certain tilt” seem sufficient. However, in ground-mounted projects even a few degrees’ difference can affect row spacing and shading behavior, earthwork estimates, and projected generation. For projects that span multiple plots or are on irregularly shaped land, representing the whole site with a single azimuth and tilt can drift from reality. Treating the land as uniformly flat may lead to on-site adjustments and a widening gap with simulation results.

In practice, after entering tilt and azimuth you should confirm that those settings can be deployed across the entire site without difficulty. Be aware of the gap between ideal and feasible conditions, and where necessary choose design values that balance maintainability and constructability. PVSyst allows high freedom in setting conditions, but that freedom means you must avoid being pulled into ideal values that don’t reflect site implementation.

Setting 3: row spacing and mutual shading

A setting that particularly tends to directly affect generation in ground-mounted projects is row spacing and mutual shading. Because multiple rows of modules are lined up in ground-mounted systems, you cannot avoid the possibility of shadows from front rows falling on rear rows. In early studies, the desire to maximize the number of rows that fit on a site can lead to compressing row spacing to a minimum and advancing capacity without thoroughly evaluating shading impacts. PVSyst’s results change depending on how mutual shading is considered, so treating this area roughly weakens assessment of layout options.

What makes mutual shading dangerous is that it’s not simply a matter of a little shading in the morning and evening. The timing of shading, seasonal variation, how shading affects each row, and how circuits respond can change expected generation much more than anticipated. The temptation to tighten row spacing is stronger when the site area is limited, but even if you think you’ve increased capacity, shading losses can reduce overall efficiency. As a result, a layout that fills the site may not outperform a layout that leaves a bit more clearance.

Also, in ground-mounted projects it’s important to consider the combination of terrain and mutual shading. If the land is not perfectly flat but has gentle undulations or steps, shadows will not behave uniformly even with the same row spacing. Conditions may change between pre-development topography and the finished grading. When handling mutual shading in PVSyst, if the input layout and the actual installation image do not align, you may get pleasing-looking results on screen that are hard to reproduce on site.

The value of carefully refining this setting is not only to reduce losses. Row spacing affects site utilization, maintenance access, ease of mowing and inspection, drainage, and delivery routes during construction. In other words, it’s not just about generation—it affects whether the plant will be easy to operate. When examining row spacing and mutual shading in PVSyst, consider not only how many rows fit but whether the spacing is truly operable, and judge by balancing site utilization and generation efficiency.

Setting 4: temperature conditions and ground-mounted installation state

Among the settings often overlooked, temperature conditions are frequently underestimated in their impact on results. PVSyst allows you to set assumptions about module temperature, but many cases use default values. There is also a tendency to assume ground-mounted systems dissipate heat well, but in reality temperature conditions depend on installation height, racking type, rear clearance, reflected heat from the ground, wind paths, and surrounding obstructions. Higher temperatures reduce output, so coarse temperature settings affect annual economics.

How to view peak summer conditions is especially important. Looking only at annual generation can cause temperature losses to be averaged out and overlooked, but in practical equipment design you must consider output variation at high temperatures, voltage conditions, and operational stability. A site that is wind-exposed and open differs from one surrounded by embankments or trees that create heat pockets; the thermal environment varies. Although ground-mounted projects may superficially seem simple, subtle local differences manifest strongly in temperature conditions.

Also, temperature settings should be understood in relation to other settings. For example, meteorological air temperature, wind flow determined by row layout, ground clearance, and equipment density combine to determine actual module temperature. Thus, adjusting temperature alone later has limited meaning if the assumed installation state is unrealistic. Treating module temperature carefully in PVSyst is close to re-evaluating the installation state itself.

In practice, decide whether to adopt conservative or standard temperature assumptions based on the project characteristics. For ground-mounted systems don’t assume good ventilation automatically; set values while considering site openness, installation density, and surrounding environment. Tightening temperature settings brings generation estimates closer to reality and makes it easier to achieve a feasible equipment balance in the design stage.

Setting 5: loss rates and operational assumptions

PVSyst allows you to enter various losses in aggregate, and that convenience can itself cause oversights. In ground-mounted projects many loss factors accumulate: soiling, wiring loss, equipment downtime, mismatch, aging, and maintenance impacts. Nevertheless, if you simply reuse a template from a past project and enter a consolidated loss rate, the specific conditions of the project won’t be reflected. Items with numbers entered are easy to feel like they have been considered, but these are exactly the items that require careful review.

For example, even soiling assumptions change depending on whether the site is coastal, near farmland, has many unpaved roads, or is subject to ash or fine dust. Cleanability in practice also varies with maintenance accessibility. For wiring losses, wide layouts tend to increase distances and ground-mounted wiring plans affect results. If you enter availability or downtime rates with default assumptions without considering actual operations or inspection policies, the gap between forecast and actual performance can widen.

Loss rates are easy to overlook because each individual loss may appear small. But in practice small losses accumulate to depress annual generation. The other problem is assuming that entering a large aggregated loss is a safe approach. While a conservative view is sometimes necessary, if you inflate a number without clarifying what you are accounting for, comparisons between design options become difficult. Conversely, optimistic values produce attractive results but become hard to justify later.

Therefore, treat loss rates not as mere tuning knobs but as an exercise in quantifying project-specific characteristics. Be deliberate about which losses are likely to be significant for this project and whether the settings align with site environment and operational conditions. If PVSyst results will be used for internal review or decision-making, make sure the loss-rate rationale is explainable. Because ground-mounted projects often assume large sites and long operating periods, how you refine loss rates greatly affects design credibility.

Setting 6: string configuration, voltage range, and output balance

Finally, an often-overlooked area is string configuration, voltage range, and output balance. Ground-mounted projects tend to grow large in capacity, so the initial focus often becomes how much capacity can be installed. As a result, the number of strings, series count per string, and overall output balance can be left for later. However, even if PVSyst shows good generation, inadequate attention to voltage conditions and output ratios can create infeasibilities when moving to detailed design. You should confirm early whether the calculated generation and the electrical design are consistent.

Pay particular attention to voltage conditions that vary with seasonal temperature changes. Open-circuit voltage at low temperatures, operating voltage at high temperatures, cold-start conditions, and behavior under partial shading cannot be judged by matching rated output alone. Ground-mounted projects can show condition differences between sections, and using the same module count everywhere may not be optimal. A configuration that looks fine in PVSyst may actually leave little margin in practice.

Also, output balance shouldn’t be treated as “bigger is better.” Whether to bias the DC side or restrain the AC side depends on irradiation, temperature, loss assumptions, shading impacts, and the business plan. Ground-mounted sites often make it easy to stack DC capacity, but that can lead to more curtailment, flattened peaks in certain hours, and biased operational efficiency. When reviewing PVSyst results, judge the configuration not only by annual totals but also by when and how issues occur over time.

For practitioners, it is important not to separate chasing generation numbers from creating a realizable equipment configuration. Even if PVSyst simulation results look attractive, they are meaningless unless the configuration can operate realistically under actual conditions and endure long-term operation. String configuration, voltage range, and output balance may look mundane, but they form the backbone of the design. Careful checking here narrows the gap between simulation values and the as-built system.

Summary

For ground-mounted projects in PVSyst, the way you refine basic settings matters more for result reliability than flashy features. Meteorological data and location conditions, tilt and azimuth, row spacing and mutual shading, temperature conditions, loss rates, and string configuration and output balance are all settings that look obvious as input fields. Yet the more obvious the item, the easier it is to use defaults or reuse past values and drift away from project specifics. In ground-mounted projects that drift affects not only generation but also constructability, maintainability, and the validity of design decisions.

In practice you will usually start with provisional assumptions to grasp the overall picture, then tighten the premises. That workflow is fine, but do not proceed to comparison or decision-making while assumptions are still provisional. PVSyst returns results faithfully to the inputs, so ambiguous assumptions produce ambiguous results. Conversely, gradually aligning the easily overlooked settings with site reality turns simulation numbers into figures that are useful in design practice.

To raise the accuracy of these settings it is important not to complete the work only on the desk. For ground-mounted projects there are many on-site elements to check, such as elevation differences, installation orientation, clearances, obstacle locations, and access ways. The faster and more accurately you capture on-site information, the closer your PVSyst settings will be to reality. For example, using high-precision GNSS positioning devices attachable to an iPhone, like LRTK, makes it easier to verify candidate positions, elevation differences, and layout assumptions on site. The accuracy of a simulation is supported by the quality of the site information you input. If you want PVSyst settings to be truly usable, reviewing the accuracy of site capture will ultimately raise overall design quality.