6 Steps to Find the Optimal Orientation with a Solar Power Generation Simulation

When checking generation using a solar power generation simulation, orientation is as important as system capacity or the number of panels. The direction the solar panels face affects annual generation, monthly generation, hourly generation curves, self-consumption, and surplus energy. However, the optimal orientation is not determined simply by pointing south. You need to judge including roof shape, site conditions, tilt angle, shading, daytime facility demand, and whether battery storage is present. This article explains six practical steps to find the optimal orientation for practitioners who search for "solar power generation simulation."

Table of Contents

• The importance of looking at orientation in a solar power generation simulation

• Step 1: Organize candidate installation surfaces by orientation

• Step 2: Compare annual generation by orientation

• Step 3: Overlay monthly generation and seasonal demand

• Step 4: Check the hourly generation curve

• Step 5: Re-compare reflecting shading, tilt, and loss rates

• Step 6: Decide the optimal orientation by self-consumption and surplus energy

• Pitfalls to watch when deciding the optimal orientation

• How to review orientation conditions in vendor proposals

• Summary

The importance of looking at orientation in a solar power generation simulation

The reason to look at orientation in a solar power generation simulation is that the direction the solar panels face changes how they receive sunlight and when they generate power. Generally, surfaces closer to south-facing tend to produce more annual generation. However, in practice it is important not simply to choose the orientation that maximizes annual generation. You must judge how much of the generated power can be used within the facility, how much surplus will be produced, and whether construction and maintenance are manageable.

In rooftop projects, the orientation is often almost determined by the existing roof shape. A large south-facing roof surface may look advantageous, but in reality the installable area may be limited by rooftop equipment, shading from surrounding buildings, waterproofing constraints, and inspection walkways. East- or west-facing roof surfaces may look modest compared to south-facing surfaces in terms of annual generation, but if their generation matches the facility’s power usage times they can be useful for self-consumption.

For land projects or flat roofs, orientation can be designed to some extent. Even in those cases, do not mechanically choose only south-facing orientation; consider row-to-row shading, installed capacity, racking tilt, wind impact, access walkways, and the location of connection equipment together. Changing orientation shifts the time of generation peaks, so it is important to view orientation in combination with facility demand.

When looking at orientation in a solar power generation simulation, check annual generation, monthly generation, hourly generation, self-consumption, and surplus energy in that order. Although surfaces closer to south-facing may be advantageous for annual generation alone, for facilities with large morning demand east-facing surfaces may be effective in practice, and for facilities with large afternoon demand west-facing surfaces may be effective. The optimal orientation is not the one that maximizes generation, but the one that is most effective given on-site conditions and facility operation.

Step 1: Organize candidate installation surfaces by orientation

The first step to finding the optimal orientation is to organize the candidate installation surfaces by orientation. In a solar power generation simulation, the generation varies depending on which surface the panels are installed on. Instead of viewing the roof or land as a single whole, separate and organize areas with different conditions such as south-facing, east-facing, west-facing, north-leaning surfaces, flat-roof sections, and ground-mounted sections.

In rooftop projects, a building’s roof may be divided into multiple surfaces. A gable roof mainly has two surfaces, a hip roof has multiple surfaces, and a single-slope roof has one large unidirectional surface. For flat roofs, orientation may be set by the direction of the mounting frames. In early stages you can identify orientations from drawings or aerial photos, but after a site survey you need to revise them to reflect the actual roof surface directions and obstacle locations.

When organizing orientations, also check the installable area. Even if there is a south-facing surface, if the area is small or usable range is limited by rooftop equipment or inspection walkways, you may not be able to place sufficient system capacity. East- or west-facing surfaces that are wide, have little shading, and are easy to construct on can be strong practical candidates.

For land projects, organize orientations while looking at the overall site shape and surrounding conditions. If the site is narrow and long, ideal south-facing row layouts may not be possible. Constraints on possible orientations can arise from access walkways, drainage, neighboring boundaries, the location of connection equipment, and existing structures. If the terrain has elevation differences, not only orientation but also slope aspect will affect insolation conditions.

After organizing candidate installation surfaces by orientation, provisionally list for each surface the installable area, estimated system capacity, presence of shading, tilt angle, and maintainability. The important point at this stage is not to narrow candidates to south-facing only. By comparing multiple orientations in the simulation, you can determine which surfaces contribute to annual generation and which contribute to self-consumption.

If orientation organization is vague when running simulations, you will not be able to read the generation results correctly. You will lose track of which surface’s generation is being shown, which orientation is contributing, and which area is increasing surplus. To find the optimal orientation, start by separating candidate installation surfaces and organizing conditions by orientation.

Step 2: Compare annual generation by orientation

The next step is to compare annual generation by orientation. After organizing the candidate installation surfaces, simulate how much each orientation can generate. Comparing annual generation shows which orientation is advantageous in terms of generation volume.

Surfaces closer to south-facing generally tend to gain more annual generation. In practice, however, south-facing surfaces alone may not secure sufficient system capacity. Also, if the south-facing surface is shaded or has a small installable area, including east and west surfaces may increase overall generation and operational effectiveness.

East- and west-facing surfaces may look inferior to south-facing ones when looking only at annual generation. However, east-facing surfaces tend to generate more in the morning and west-facing surfaces in the afternoon. This can avoid generation concentrating too much around midday and can broaden generation time windows. Depending on the facility’s power usage pattern, east-west generation can be effective for self-consumption.

When comparing annual generation, it is important to look not only at total generation but also at generation per installed capacity. A large total generation for an orientation may simply be because installed capacity is large. Looking at generation per capacity helps determine which orientation is more efficient for the same capacity.

Also, compare orientation-specific annual generation reflecting shading and loss rates. Under ideal conditions without shading, south-facing can look advantageous, but in reality generation may decrease from shading by surrounding buildings or rooftop equipment. If east- or west-facing surfaces have less shading, they may be advantageous in effective generation.

For orientation comparison, run simulations under the same assumptions. If solar irradiance, loss rates, tilt angles, system capacity, and shading treatment differ, you cannot correctly compare orientation differences. Compare under the same conditions and then reflect site-specific shading and installation constraints.

Comparing annual generation is an important step in finding the optimal orientation, but it is too early to draw conclusions here. Annual generation is merely the total. Next, check monthly generation and hourly generation to see compatibility with facility demand and make a more practical orientation judgment.

Step 3: Overlay monthly generation and seasonal demand

The third step is to overlay monthly generation and seasonal demand. Comparing annual generation by orientation tells you which orientation generates more over the year. However, actual installation benefits depend on when generation is high during the year and when facility power demand is large.

Solar generation fluctuates seasonally. Generation tends to increase from spring to summer, but there are periods when generation drops due to the rainy season, typhoons, shorter daylight in winter, snow cover, and longer shadows. Orientation also changes how monthly generation behaves.

South-facing surfaces may generate relatively evenly throughout the year, but monthly generation varies with region, tilt, and shading conditions. East- and west-facing surfaces differ in monthly generation and hourly generation curves because they receive sunlight at different times. In the simulation, check monthly generation for each orientation and identify seasonal strengths and weaknesses.

Facility seasonal demand is also important. For facilities with large air conditioning demand in summer, summer generation directly contributes to self-consumption. For facilities with heavy heating or production equipment loads in winter, winter generation affects installation benefits. Even if annual generation is high, if generation is low during months with high demand, practical effectiveness may be reduced.

Overlaying monthly generation and seasonal demand can change orientation evaluation. Even if south-facing is advantageous in annual generation, if the facility has large afternoon demand and strong summer demand, west-facing generation may be practically useful. For facilities with morning equipment startups or large morning HVAC loads, east-facing surfaces can be effective.

Also pay attention to winter shading. In winter the sun angle is low and shadows from surrounding buildings, rooftop equipment, and trees lengthen. When checking monthly generation by orientation, confirm whether any surfaces are affected by winter shading. Ignoring shading in monthly generation risks overestimating winter installation benefits.

To find the optimal orientation, look not only at annual maximum generation but also at whether it aligns with facility seasonal demand. Overlaying monthly generation and demand makes it easier to connect generation to real operational benefits.

Step 4: Check the hourly generation curve

The fourth step is to check the hourly generation curve. Orientation differences are most clearly reflected in hourly generation. Solar generates during daytime, but the hours when generation increases vary by orientation. To judge the optimal orientation, you need to check hourly generation curves in addition to annual and monthly totals.

Surfaces closer to south-facing tend to have larger generation around midday. East-facing surfaces tend to produce more in the morning, and west-facing surfaces more in the afternoon. Combining east and west surfaces can prevent over-concentration of generation around midday and widen generation hours.

These hourly differences are strongly related to self-consumption. If facility demand is large around midday, it will likely overlap with the south-facing generation peak. East-facing generation can be effective for facilities with large morning startup or HVAC demand. West-facing generation can contribute to self-consumption for facilities with large afternoon-to-evening demand.

Examining generation curves also reveals when surplus power occurs. If generation is high around midday and exceeds facility demand, surplus results. Combining east and west surfaces can smooth generation peaks and reduce surplus in some cases. However, you must also check the balance with total generation and installed capacity.

Hourly generation is also linked to inverter capacity and output capping. A south-facing-centric layout may concentrate peaks and reach output limits during high-generation hours. Combining east and west surfaces disperses peaks and, depending on system configuration, may suppress output capping. In simulations, also check the relationship between orientation-specific generation curves and output constraints.

Shading effects appear in hourly generation curves as well. Poor morning generation growth may indicate shading on the east side; early evening drop-offs may indicate west-side shading; an unnatural midday dip may indicate shading from rooftop equipment or surrounding structures. When comparing orientations, it is important to view generation curves that consider shading.

The optimal orientation is not the one with the highest generation but the one that produces when the facility uses power. Checking hourly generation curves allows you to evaluate generation as usable power.

Step 5: Re-compare reflecting shading, tilt, and loss rates

The fifth step is to re-compare orientations reflecting shading, tilt, and loss rates. Initial simulations may compare theoretical generation per orientation. However, actual sites see generation affected by shading, roof pitch, racking tilt, temperature, wiring, dirt, and snow. Deciding the optimal orientation requires an effective comparison that reflects these factors.

Shading can greatly change orientation evaluation. Even if a south-facing surface looks advantageous, generation will drop if there are tall buildings, rooftop equipment, or trees on the south side. East- or west-facing surfaces can also have significant morning or evening shading. Comparisons that ignore shading can make generation look higher than real conditions. After a site survey, re-simulate reflecting shading sources.

Tilt angle also affects orientation comparison. Even for the same orientation, roof pitch and racking tilt change how sunlight is received. Rooftop projects often follow existing pitches, so ideal tilt angles used in comparisons may not be adoptable in practice. For flat roofs and land projects, changing tilt alters row-to-row shading and installable capacity. Compare orientation together with tilt angles.

Reflecting loss rates is also important. How much you anticipate losses from temperature, wiring, power conversion, dirt, snow, and aging changes the perceived generation. For example, surfaces prone to high rooftop temperatures may suffer greater temperature losses. Surfaces near trees may see more soiling and leaf debris effects. In snowy regions, orientation and tilt impact winter generation.

In the re-comparison, check not only total generation but also generation per capacity. After reflecting shading and losses, generation for some orientations may decrease. Even if a surface with large installed capacity has large total generation, if generation per capacity is low it may be inefficient. Conversely, a surface with moderate total generation but little shading and stable generation can be highly valuable in practice.

Orientation comparison is not a one-time task. By progressively reflecting site conditions through initial comparison, post-site-survey comparison, and pre-construction final comparison, you can reduce post-installation gaps. Decide the optimal orientation based on effective values that reflect shading and losses, not theoretical values.

Step 6: Decide the optimal orientation by self-consumption and surplus energy

The final step is to decide the optimal orientation by self-consumption and surplus energy. Simulations comparing orientations show which orientation has the largest annual generation. However, when the purpose is self-consumption, the orientation with the highest generation is not always optimal. What matters is how much of the generated power can be used within the facility.

Self-consumption is the amount of generated energy that is used within the facility. Since solar generates mainly during daytime, the more the facility’s power usage hours overlap with generation hours, the higher the self-consumption. Because orientation changes generation hours, choose an orientation that matches the facility’s demand pattern.

For example, for facilities with large demand around midday, orientations closer to south-facing may be effective. For facilities with large morning startup or HVAC loads, east-facing surfaces can help. For facilities with large afternoon demand, west-facing surfaces may contribute to self-consumption. Combining east and west surfaces can widen generation hours and reduce surplus.

Surplus energy is also important. Even with large annual generation, if generation concentrates during hours when facility demand is low, surplus increases. The evaluation depends on whether surplus can be exported, stored in batteries, or curtailed. For self-consumption-focused planning, prioritize orientations with less surplus and more usable energy.

Do not judge solely by self-consumption ratio. Orientations with small installed capacity tend to show high self-consumption ratios but may have small absolute self-consumption. Orientations with large installed capacity may show lower self-consumption ratios yet increase absolute self-consumption. To decide the optimal orientation, look at self-consumption ratio, absolute self-consumption, and surplus energy together.

When combining battery storage, check the relationship between the timing of surplus by orientation and the battery charge/discharge patterns. For facilities with daytime surplus and evening or nighttime demand, batteries may increase self-consumption. Note, however, batteries have charge/discharge losses and capacity limits. Compare orientations with and without batteries to make a clearer decision.

The optimal orientation is determined by the balance of generation, usable energy, surplus, constructability, and maintainability. In solar power generation simulations, focus on the usability of the power for the facility’s operational objectives rather than on maximum generation.

Pitfalls to watch when deciding the optimal orientation

A pitfall to avoid when deciding the optimal orientation is assuming south-facing is always the correct answer. Indeed, south-facing surfaces tend to produce more annual generation. But depending on site conditions and facility demand, east-facing, west-facing, or multi-orientation combinations may be effective. Judging based only on annual generation can overlook the usable power perspective.

Another pitfall is underestimating shading. Even south-facing surfaces can have reduced generation from shading by surrounding buildings, rooftop equipment, or trees. East- or west-facing surfaces with less shading may be advantageous in effective generation and self-consumption. When comparing orientations, judge using generation that considers shading.

Differences in installed capacity are also a caveat. Large generation for an orientation may simply reflect larger installed capacity, not a better orientation. You must check generation per capacity as well as total generation to assess generation efficiency.

Be careful in interpreting self-consumption ratio. A high self-consumption ratio does not automatically make an orientation optimal. It may be high because installed capacity is small and generated energy is easily consumed, making absolute self-consumption small. The important thing is to check self-consumption ratio together with absolute self-consumption and surplus energy.

Also do not overlook constructability and maintainability. Even if an orientation yields high generation, if construction is difficult, it interferes with rooftop inspections, complicates waterproofing renewals, or makes access paths hard to secure on land, it may be unsuitable for long-term operation. Decide optimal orientation including whether the system can be safely managed after construction, not just generation.

When searching for the optimal orientation, separate and check theoretical generation, site conditions, facility demand, constructability, and maintainability, and then make an overall judgment. In practice, an orientation that produces stable, usable power and is easy to manage can be more suitable than one with slightly higher theoretical generation.

How to review orientation conditions in vendor proposals

When comparing orientation conditions in vendor proposals, check not only generation figures but also how much capacity is allocated to each orientation. Even for the same building or site, vendors may prioritize different design policies—favor south-facing surfaces, utilize east-west surfaces, maximize capacity, or focus on low-shade surfaces.

First confirm the installed capacity per surface. Check how much capacity is allocated for south-facing, east-facing, west-facing, flat-roof, and land sections. Total generation alone does not tell you which orientation contributes to generation. By checking capacity and generation per surface you can better judge which surfaces are efficient and which are low-performing.

Next compare annual generation by orientation and generation per capacity. Surfaces with high generation per capacity likely have good conditions. However, confirm whether shading and loss rates are adequately accounted for. If generation per capacity is extremely high, check whether assumptions about insolation or losses are overly optimistic.

Also review hourly generation curves. South-facing-centric proposals tend to have strong midday generation, while proposals using east-west surfaces can broaden generation hours. Compare which aligns with the facility’s power usage pattern. If the purpose is self-consumption, prioritize whether generation occurs during demand hours rather than overall annual generation.

How shading is handled is another comparison point. Some proposals may include shaded south-facing surfaces to increase total generation, while others may concentrate on low-shade east-west surfaces. Total generation alone cannot decide. Compare effective generation considering shading, self-consumption, and surplus energy.

In vendor proposals, confirm whether orientation-specific generation, self-consumption, and surplus energy are clearly presented. If explanations are vague, ask why a particular orientation was chosen, which surfaces were prioritized, and how shading and losses were factored. Proposals that can explain their orientation choices provide better material for judgments closer to real post-installation conditions.

Summary

To find the optimal orientation with a solar power generation simulation, proceed through these steps: organize candidate installation surfaces, compare annual generation by orientation, overlay monthly generation and seasonal demand, check hourly generation curves, re-compare reflecting shading/tilt/loss rates, and make a comprehensive judgment using self-consumption and surplus energy. The optimal orientation is not simply the one that maximizes annual generation, but the one that best fits site conditions and facility operations.

In Step 1, organize candidate surfaces such as south-facing, east-facing, west-facing, flat-roof, and land sections. In Step 2, compare annual generation and generation per capacity by orientation. In Step 3, overlay monthly generation with facility seasonal demand to see when generation contributes to installation benefits.

In Step 4, check hourly generation curves: south-facing peaks around midday, east-facing in the morning, west-facing in the afternoon. Determine which orientation matches the facility’s usage hours. In Step 5, re-compare reflecting shading, tilt, and loss rates—judge by effective values that reflect site shading and generation losses rather than theoretical values.

In Step 6, decide the optimal orientation by self-consumption and surplus energy. Even with high generation, if surplus increases during low-demand hours, practical benefits are limited. Check not only self-consumption ratio but also absolute self-consumption, surplus energy, and whether batteries are used.

Do not assume south-facing is always best. Low-shade east-west surfaces or surfaces with generation hours matching facility demand can be effective. When comparing vendor proposals, check installed capacity, generation, shading assessment, self-consumption, and surplus energy under the same assumptions.

Accurate on-site information is the foundation for improving orientation judgment accuracy. If you can precisely capture candidate installation ranges, rooftop equipment, obstacles, trees, site boundaries, orientations, tilt, inspection routes, and surrounding structures, the assumptions for the solar power generation simulation become clear and the decision on optimal orientation becomes more realistic.

If you want to increase the accuracy of on-site recording—candidate installation ranges, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, etc.—using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. If you can obtain high-precision on-site location information, you can more easily organize orientation-specific installation candidate ranges, shading causes, wiring routes, and maintenance routes, making it easier to compare vendor proposals, verify before construction, and manage maintenance after installation. To find the optimal orientation correctly in a solar power generation simulation, establish a system to accurately grasp the site rather than relying solely on desktop orientation comparisons.