Recommended Ways to Use Solar Power Generation Simulations: 8 Applications

Solar power generation simulations are not just documents to check “how much power can be generated annually.” They can be used across practical tasks: evaluating candidate installation sites, comparing vendor proposals, optimizing system capacity, estimating self-consumption, identifying generation losses, considering batteries, final checks before construction, and post-installation performance management. This article explains eight recommended ways to use simulations to improve the accuracy of installation decisions, aimed at practitioners who search for "solar power generation simulation."

Table of contents

• Solar power generation simulations as a common reference for installation decisions

• Use 1: Understand the generation potential of candidate sites

• Use 2: Compare rooftop projects and ground-mounted projects using the same criteria

• Use 3: Judge whether system capacity is excessive or insufficient

• Use 4: Estimate self-consumption and surplus electricity

• Use 5: Detect generation losses from shading, orientation, and tilt

• Use 6: Check compatibility with batteries and daytime consumption

• Use 7: Compare the validity of vendor proposals

• Use 8: Use for pre-construction checks and post-installation performance management

• Simulation assumptions to watch when using results

• Summary

Solar power generation simulations as a common reference for installation decisions

Solar power generation simulations are often the first materials checked during pre-installation consideration. By understanding annual generation, monthly generation, system capacity, self-consumption, surplus electricity, and generation losses, it becomes easier to concretely envision the effects of installing solar power. However, the value of simulations is not limited to predicting generation.

In practice, there are many occasions to compare multiple candidate sites, review multiple vendor proposals, adjust system capacity, or examine the need for batteries. If judgments are made based on intuition each time, gaps after installation are likely — for example, “it generated less than expected,” “there was too much surplus power,” or “the self-consumption rate differed from assumptions.” Using solar power generation simulations as a common reference allows you to organize the basis for decisions numerically.

For corporate facilities, factories, warehouses, stores, offices, and public facilities, not only the roof or land conditions but also the facility’s power usage patterns are important. Facilities with high daytime demand are easier to supply with self-consumption, while facilities that mainly operate at night may see increased surplus. By overlaying time-of-day generation and consumption rather than only looking at annual generation, you can better evaluate usable power.

Also, simulations are useful not only in the early stages of consideration but also before construction and after installation. Comparing the initial proposal simulation with the final layout simulation lets you confirm differences in generation due to design changes. After installation, comparing monthly generation performance with predictions makes it easier to identify factors such as shading, soiling, equipment faults, or demand changes.

Thus, solar power generation simulations can be used as a common reference connecting installation decisions, design studies, vendor comparisons, pre-construction checks, and operations management. Below are eight specific situations where practitioners can especially benefit from using them.

Use 1: Understand the generation potential of candidate sites

A basic use of solar power generation simulations is to understand the generation potential of candidate sites. Whether a roof or land is suitable for photovoltaics cannot be judged by area alone. Orientation, tilt, irradiance, shading, surrounding environment, feasible installation area, and maintainability all affect generation. Simulations allow you to check the estimated generation for each candidate site numerically.

For rooftop projects, you need to consider roof surface orientation and slope, rooftop equipment, railings, penthouses, piping, drains, and access hatches. A roof that looks large on drawings may in practice require clearance for inspection access routes and waterproofing, limiting usable installation area. In simulations, it is important to base generation estimates on the actually usable roof surfaces.

For land projects, site area, topography, slope, embankments, trees, surrounding structures, drainage, maintenance access routes, and site boundaries are relevant. Even on a large site, not all areas may be usable for panels. If row spacing is too tight, shading can occur in winter; without maintenance access routes, inspection and weeding become difficult. For land projects, you must identify areas that can both generate well and be managed easily, not just the simple area.

When assessing generation potential, check not only annual generation but also monthly generation. A site that looks sufficient annually may see large drops in winter, poor generation during the rainy season, or temperature-related losses in summer. Checking whether regional characteristics and surrounding environment are reflected in monthly generation allows more realistic decisions.

If you have multiple candidate sites, it is important to simulate them under the same assumptions. If system capacity, loss rates, treatment of irradiance, shading evaluation, and installation conditions differ, you cannot correctly compare differences between sites. Comparing under the same assumptions makes it easier to determine which site has superior generation efficiency and which has shading or maintainability issues.

Use 2: Compare rooftop projects and ground-mounted projects using the same criteria

Solar power generation simulations are helpful when comparing rooftop projects and ground-mounted projects. Installation conditions and evaluation points differ between rooftop and ground-mounted projects. Rooftop projects are more constrained by existing building conditions, while ground-mounted projects offer placement flexibility but are affected by terrain and maintenance conditions. Simulations let you compare these characteristics using the same criteria.

For rooftop projects, installing equipment on a building makes roof structure, waterproofing, load, inspection access routes, and access to existing equipment important. Roof surface orientation and tilt are harder to change, and shadowing from rooftop equipment or nearby buildings must be considered. On the other hand, generated power can often be used more easily within the same building, making rooftop installations well-suited to self-consumption.

For ground-mounted projects, you can often increase installed capacity compared to rooftops. It’s also easier to adjust racking orientation and angle. However, you must consider site boundaries, embankments, drainage, topography, trees, maintenance access routes, surrounding environment, and potential connection points. Even if generation is large, the distance to demand sites, connection conditions, and ease of operation and maintenance can change the evaluation.

When comparing rooftop and ground-mounted projects, look not only at total generation but also generation per unit capacity. Ground-mounted projects may appear favorable in total generation because capacity can be increased easily. However, when examining generation per capacity and contribution to self-consumption, rooftop projects may better match facility demand.

Also compare self-consumption and surplus electricity. Rooftop projects often have generation that aligns with building demand, whereas ground-mounted projects may be remote from demand. How generated power is used, how surplus is handled, and whether batteries or grid connection are considered will affect the evaluation.

Using simulations, you can compare rooftop and ground-mounted projects not by “which is larger” but by “which generates more usable power, is easier to manage, and better meets the installation objectives.”

Use 3: Judge whether system capacity is excessive or insufficient

Solar power generation simulations are effective for judging whether system capacity is excessive or insufficient. Increasing system capacity generally increases annual generation, but that is not always optimal. If generation exceeds daytime facility demand, surplus power will increase. Conversely, if capacity is too small, you may not fully utilize opportunities for self-consumption.

To decide on capacity, first compare generation with facility power consumption. Facilities with steady daytime demand can more easily use generated power. Facilities that operate mainly at night or have low weekend demand are more likely to see increased surplus if capacity is oversized. It is important to check not only annual consumption but also monthly and time-of-day consumption patterns.

Simulations make decision-making easier by comparing multiple capacity patterns. Smaller capacities may yield higher self-consumption rates but lower absolute self-consumption. Larger capacities increase generation but may also increase surplus electricity. Identifying at which capacity surplus rises sharply helps find the capacity that fits the facility.

The range in which capacity can be increased is also important. Increasing capacity on surfaces with little shading and good orientation can be expected to yield significant generation gains. But expanding capacity onto shaded surfaces, poorly maintainable areas, or unfavorably oriented surfaces can reduce generation per unit capacity. It is important to identify not the maximum capacity but the capacity that generates efficiently.

Also check relationships with inverter capacity and connection conditions. Even if panel capacity is increased, output may be capped by the inverter or grid connection limits. Checking the extent of peak-time clipping and whether output limits occur during time periods that affect self-consumption makes it easier to judge capacity validity.

Over- or under-sizing capacity directly affects generation, surplus, profitability, and maintainability. Simulations allow you to verify capacity suitability numerically rather than by intuition.

Use 4: Estimate self-consumption and surplus electricity

One important use of solar power generation simulations is estimating self-consumption and surplus electricity. Even if generation is large, if the power cannot be used within the facility, its contribution to electricity bill savings and profitability is limited. Separately checking self-consumption and surplus electricity lets you determine how much generated power is actually usable.

Self-consumption is the portion of generated power that is consumed within the facility. Since solar generation mainly occurs during daytime, the more daytime demand a facility has, the greater the potential self-consumption. Factories, warehouses, stores, and offices vary in how easily they can consume generated power depending on daytime operations.

Surplus electricity is the portion that cannot be used within the facility at the same time it is generated. Whether surplus is exported externally, stored in batteries, or curtailed affects installation outcomes. Large surplus may indicate oversized capacity and suggest considering batteries or load control.

Accurately estimating self-consumption requires time-of-day consumption data. Calculating based only on annual consumption does not reveal how much can be used during the day. Reflecting differences between weekdays and weekends, seasonal operation, lunchtime or holiday demand changes will produce more realistic self-consumption estimates.

Do not rely solely on the self-consumption rate. A high self-consumption rate with a small system capacity can still mean low absolute self-consumption. Conversely, a slightly lower self-consumption rate with a large absolute self-consumption can yield significant practical benefits. You need to check self-consumption rate, self-consumption amount, and surplus electricity together.

When combining batteries, compare scenarios with and without batteries. Batteries can shift surplus to other time periods, but they have charge/discharge losses and capacity limits. Simulations should show how much batteries increase self-consumption and reduce surplus.

Estimating self-consumption and surplus electricity is central to bringing solar power installation assessments closer to practical outcomes. It is important to confirm usable power, not just potential generation.

Use 5: Detect generation losses from shading, orientation, and tilt

Solar power generation simulations can be used to detect generation losses from shading, orientation, and tilt. These local conditions significantly affect generation, and if they are not adequately reflected, post-installation generation may be lower than anticipated.

Sources of shading include surrounding buildings, rooftop equipment, railings, penthouses, piping, trees, utility poles, signs, and topographic elevation differences. Shading changes by time of day and season. A site with no summer issues may experience long shadows in winter when the sun is lower. Checking monthly and time-of-day generation in simulations makes it easier to grasp shading impacts.

Orientation affects generation. South-facing surfaces tend to deliver higher annual generation, but east- or west-facing surfaces can be effective depending on facility demand timing. Facilities with high morning demand benefit from east-facing generation; those with high afternoon demand benefit from west-facing generation. It is important to look at the time-of-day generation curve as well as annual generation.

Tilt angle also affects seasonal generation. In rooftop projects you often must match the existing roof pitch and cannot freely set ideal angles. In flat-roof or ground-mounted projects you can adjust racking angle, but increasing tilt affects row-to-row shading, wind loads, spacing requirements, and maintainability. Decisions should consider not only generation but also constructability and maintainability.

In simulations, check differences between shaded and unshaded generation, generation per installation surface, monthly generation, and time-of-day generation to understand generation losses. Proposals that show more conservative generation because they account for shading are likely closer to actual operation. For proposals with very high generation, confirm how much shading and other losses they have accounted for.

Detecting generation losses from shading, orientation, and tilt makes it easier to consider improvements such as revising layout, avoiding shaded areas, narrowing installation surfaces, or adjusting system capacity.

Use 6: Check compatibility with batteries and daytime consumption

Solar power generation simulations are useful for checking compatibility with batteries and daytime consumption. Since solar generates during the day, the key to self-consumption is how much power can be used on-site during daytime. Facilities with sufficient daytime consumption can directly use generated power.

To check daytime consumption, overlay time-of-day generation and usage. When generation falls below usage, generated power can be self-consumed. When generation exceeds usage, surplus occurs. Observing when and how much surplus occurs helps judge the need for batteries or load control.

Batteries are not devices that increase generation. They store excess daytime power to use in the evening, night, or other time periods. Battery effectiveness depends on how much surplus exists, how much demand exists at discharge times, and expected charge/discharge losses.

In simulations, separate scenarios with and without batteries. Without batteries, how much can be self-consumed and how much surplus occurs? With batteries, how much does self-consumption increase and surplus decrease? Comparing these differences shows how much batteries contribute to installation benefits.

If considering emergency use, evaluate that separately from normal self-consumption. Operations that reserve battery capacity for emergencies limit capacity available during normal operation. Strategies that maximize normal self-consumption differ from strategies emphasizing emergency preparedness, and simulation results will differ accordingly.

Checking compatibility between daytime consumption and batteries reveals how effectively generated power can be used. It is important to look beyond annual generation to how generated power will be used.

Use 7: Compare the validity of vendor proposals

Solar power generation simulations are very effective materials for comparing the validity of vendor proposals. When receiving proposals from multiple vendors, annual generation, system capacity, self-consumption rate, and surplus electricity may vary even for the same building or land. To interpret these differences correctly, you must check the assumptions.

First compare system capacity and installation area. Proposals with larger capacity tend to show greater generation, so comparing only total generation is dangerous. Check generation per capacity and per installation surface to see which locations contribute to generation.

Next, check how shading and loss rates are treated. A proposal that shows high generation despite on-site shading may not have adequately accounted for shading. Also check how much temperature, wiring, conversion, soiling, snow, and degradation losses are included. Proposals with low assumed loss rates should be scrutinized for site realism.

Assumptions about self-consumption are also important. Proposals that use time-of-day consumption data are more reliable than those that estimate from annual consumption alone. Confirm whether weekday/weekend differences, seasonal variations, and daytime operating conditions are reflected. A high self-consumption rate may simply reflect a small system capacity, so also review absolute self-consumption amounts.

For proposals including batteries, separate the effects of the PV system alone from the combined effect with batteries. Looking only at the battery-inclusive result can obscure surplus and self-consumption issues present without the battery. Check charge/discharge losses and whether a reserve is kept for emergencies.

When comparing vendor proposals, do not assume the proposal with the highest generation is best. Prioritize proposals with clear assumptions that match site conditions and facility operations. Use solar power generation simulations to compare the rationale behind proposals, not just appearance.

Use 8: Use for pre-construction checks and post-installation performance management

Solar power generation simulations are useful not only for pre-installation consideration but also for pre-construction checks and post-installation performance management. The initial proposal simulation and the final design before construction do not always match. During site surveys and detailed design, layout, system capacity, wiring, and equipment locations may change.

Before construction, it is important to recheck simulations based on the final layout. For rooftop projects, inspection access routes, waterproofing clearance, shadowing from rooftop equipment, drains, railings, and structural conditions can change the installation area. For land projects, site boundaries, maintenance access, drainage, trees, topography, and potential connection points can change the layout.

Re-simulating the final layout creates a standard that is easier to compare with post-installation performance. Recording annual generation, monthly generation, generation per installation surface, self-consumption, and surplus electricity makes it easier to identify causes if discrepancies arise after installation.

For post-installation performance management, use simulations as baseline values. If monthly generation falls significantly below expectations, check weather, shading, soiling, equipment faults, and demand changes. If generation is low only during certain time periods, shading or equipment issues may be suspected. If a particular installation surface shows lower generation, check for soiling, wiring, or surrounding environmental effects.

Note that actual performance will not match simulations exactly. Weather and temperature vary year to year. The important point is not to judge by a single-month difference but to observe continuous trends and biases in certain time periods or locations. If you record the assumptions before installation, you can more easily determine whether discrepancies are due to weather or to equipment/site conditions.

Using simulations for pre- and post-construction management reduces gaps after installation and helps maintain generation performance.

Simulation assumptions to watch when using results

When using solar power generation simulations, it is important to check the assumptions. Simulations are predictions based on input conditions, and results change if assumptions change. Judging by annual generation figures alone can miss differences in site or operational conditions.

First confirm the feasible installation area. Check whether the calculation is based on the actual usable area rather than total roof or land area. Make sure rooftop equipment, inspection access routes, waterproofing clearances, land maintenance access, drainage, trees, and site boundaries are reflected.

Next check assumptions about shading and loss rates. Simulations that do not adequately account for shading will overestimate generation. Also verify how much temperature, wiring, conversion, soiling, snow, and degradation are assumed. Proposals with low assumed loss rates should be carefully evaluated for site appropriateness.

Assumptions about power usage data are also important. When estimating self-consumption, confirm whether time-of-day, monthly, and weekday/weekend differences are reflected. If facility operating realities are not reflected, projections for self-consumption and surplus electricity may be off.

Also be aware of differences between initial proposals and final designs. If layout or capacity changes after site survey, do not use initial simulations unchanged. Reconfirm with the final pre-construction layout.

Simulations are very convenient, but they become practical only when you read the assumptions as well as the results. Checking whether assumptions match site reality and facility operations is the basis of effective use.

Summary

Solar power generation simulations can be used widely: not only to check annual generation but also to evaluate candidate sites, compare rooftop and ground-mounted projects, optimize system capacity, estimate self-consumption and surplus electricity, check shading and loss assumptions, verify compatibility with batteries and daytime consumption, compare vendor proposals, and perform pre-construction checks and post-installation performance management. To improve the accuracy of installation decisions, use simulations not merely as generation forecasts but as practical documents that connect site conditions and operational conditions.

Use 1 covers understanding generation potential of candidate sites, checking not only area but orientation, tilt, shading, feasible installation area, and maintainability. Use 2 explains comparing rooftop and ground-mounted projects under the same criteria, looking at generation per capacity and contribution to self-consumption as well as total generation.

Use 3 addresses judging system capacity sizing: maximum capacity is not always optimal, and balance with daytime demand and surplus is important. Use 4 covers estimating self-consumption and surplus electricity: confirming usable power rather than just potential generation leads to better decisions.

Use 5 focuses on detecting generation losses from shading, orientation, and tilt: checking winter or morning/evening shading, differences between installation surfaces, and loss assumptions reduces post-installation gaps. Use 6 examines compatibility with batteries and daytime consumption: identifying when surplus occurs and how batteries or load control can utilize it is important.

Use 7 explains comparing vendor proposals: align system capacity, installation range, loss rates, and self-consumption assumptions to interpret why some proposals show higher generation. Use 8 covers pre-construction checks and post-installation performance management: re-simulate the final layout and compare monthly and per-surface performance after installation to support generation maintenance.

However, checking simulation assumptions is indispensable. You must verify feasible installation area, shading, loss rates, irradiance, power usage data, presence or absence of batteries, and layout differences before and after construction to judge results correctly. Read not only the generation figures but also the conditions under which they were calculated.

Accurate site information is the foundation for improving simulation accuracy. If you can precisely capture candidate installation ranges, rooftop equipment, obstacles, trees, site boundaries, inspection access routes, surrounding structures, and potential connection points, you can consistently proceed from generation forecasts and self-consumption estimates to vendor comparison, pre-construction checks, and post-installation maintenance.

If you want to increase the accuracy of solar power generation simulations by accurately recording candidate installation ranges, rooftop equipment, obstacles, site boundaries, inspection access routes, and potential connection points in the field, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. High-precision location data makes it easier to identify shading and obstacles, confirm feasible installation areas, compare vendor proposals, perform pre-construction checks, and manage post-installation maintenance. To make the most of solar power generation simulations in practice, it is important to accurately prepare both power usage data and field information.