5 Steps Beginners Should Follow When Reviewing Solar Power Generation Simulations

When you first look at a solar power generation simulation, you’ll see many figures such as annual generation, monthly generation, system capacity, self-consumption, surplus electricity, loss rate, and payback period, making it hard to know where to start. However, if you decide on an order to review the data, you can organize the key points needed for an installation decision without being swayed only by total generation. This article explains five steps that allow practitioners searching for “solar power generation simulation” to check simulations without hesitation, even if they are beginners.

Table of Contents

• The importance of the order in which you review solar power generation simulations

• Step 1: First check system capacity and installation conditions

• Step 2: Check annual generation and monthly generation

• Step 3: Check orientation, tilt, shading, and loss rate

• Step 4: Separate self-consumption and surplus electricity

• Step 5: Check installation effects and post-installation management

• Common points beginners tend to overlook

• Conclusion

The importance of the order in which you review solar power generation simulations

A solar power generation simulation is a document to understand expected generation and installation effects before implementation. It lets you check how much power a system is expected to generate annually, how much is generated each month, how much can be used within the facility, and how much surplus will occur. However, if a beginner looks only at the annual generation first, they tend to judge based only on the size of the number.

What matters in a solar power generation simulation is not just the generation result, but understanding which conditions produced that result. The same annual generation can come from a large system capacity, or from favorable installation conditions that allow efficient generation. Conversely, the generation may look high because shading or loss rates were not sufficiently considered.

When beginners review a simulation, rather than immediately evaluating the generation numbers, it’s easier to understand if they first check the assumptions, then the breakdown of generation, and afterwards review generation losses, self-consumption, surplus, and post-installation management. If you check in the wrong order, you may overlook issues such as high annual generation that cannot actually be self-consumed, oversized system capacity, shading not reflected in the model, or poor maintainability.

For practitioners, what’s particularly important is whether the generation aligns with the installation purpose, not just whether it’s large. If the goal is to reduce electricity costs, self-consumption matters. If you plan to utilize surplus power, you need to check when and how much surplus is produced. When using roof or land, constructability and maintainability cannot be ignored.

By reading the simulation numbers in order, the overall picture for an installation decision becomes clear. First check system capacity and installation conditions, then annual and monthly generation. Next, verify orientation, tilt, shading, and loss rate, and separate self-consumption and surplus electricity when making judgments. Finally, if you check installation effects and post-installation management, beginners will find it easier to translate the simulation into practical terms.

Step 1: First check system capacity and installation conditions

The first things to check are system capacity and installation conditions, not the annual generation. The generation predicted by a solar power generation simulation varies greatly depending on the assumed system capacity. A larger system capacity tends to yield higher annual generation, but that alone does not mean the plan is good. First confirm where and how much equipment is assumed to be installed.

For rooftop projects, the usable area rather than the total roof area is important. Roofs have air-conditioning equipment, piping, drain outlets, inspection hatches, roof structures, handrails, waterproofing clearances, and inspection walkways. If the initial simulation assumes panels cover the entire roof without considering these, the apparent generation may be large but you may need to reduce the number of panels before construction.

The same applies to land projects. Even if the total land area is large, considering site boundaries, slopes, elevation differences, trees, drainage channels, maintenance paths, existing structures, and potential connection points limits the usable area. A plan that fills the entire site with panels may look like it generates a lot, but inspection, weed control, drainage, equipment replacement, and emergency response can become difficult.

When checking system capacity, pay attention not only to total generation but also to generation per unit capacity. Even if a proposal shows a large total generation, if it’s only because the system capacity is large, it doesn’t mean the efficiency is high. Low generation per unit capacity may indicate inclusion of shaded areas or unfavorably oriented faces. Conversely, a plan that keeps total capacity modest but uses favorable faces may have more reliable actual generation.

Beginners should first confirm over what area and how much equipment the generation numbers are based. Check whether the calculation uses the area that can actually be installed and maintained, not just the roof or land area on a drawing. If system capacity and installation conditions are unrealistic, the annual generation and financial figures you review later will deviate from reality.

In the initial simulation review, avoid jumping at the generation number; grasp the assumed system capacity, installation area, panel layout, and equipment locations. Understanding these makes it easier to evaluate the size of the generation objectively.

Step 2: Check annual generation and monthly generation

After confirming system capacity and installation conditions, next check annual generation and monthly generation. Annual generation is the basic figure showing how much the system is expected to generate over a year. It’s important for grasping the broad impact of installation, but judging by annual generation alone is risky. Always check it together with monthly generation.

Solar power generation does not produce the same output throughout the year. Monthly generation varies with daylight hours, solar altitude, insolation, temperature, weather, snowfall, and the way shading changes. Generation may increase from spring to summer, but during the rainy season, typhoons, or overcast periods it may drop. In summer, although insolation is high, panel temperature rises and temperature-related losses can occur.

Winter generation is also important. In winter, shorter daylight and lower solar altitude tend to reduce generation. Shadows from nearby buildings, roof equipment, handrails, and roof structures can lengthen. In snowy regions, panels covered with snow can lead to periods with no generation. Even if annual generation looks sufficient, reduced winter generation may affect the benefit for facilities with high winter demand.

Monthly generation shows which months have high or low output. Overlaying this with facility power usage reveals months when the installation effect is likely to be strong or weak. Facilities with high air-conditioning demand in summer benefit more from summer generation. Facilities with high heating or production demand in winter need to pay attention to winter generation expectations.

Beginners should always check “how generation is distributed monthly” after looking at annual generation. Even if annual generation is large, if generation concentrates in months with low demand, surplus may increase. Conversely, a modest annual generation that aligns with months of high demand can yield significant practical benefits.

Monthly generation is also useful for post-installation performance management. Comparing actual performance after operation starts with monthly estimates reveals in which months generation is below expectations. Low summer generation may indicate temperature or soiling issues; low winter generation may suggest shading or snow; seasonal drops may point to environmental changes. Viewing annual and monthly generation together is fundamental to understanding simulations.

Step 3: Check orientation, tilt, shading, and loss rate

Once you’ve checked overall generation, next confirm factors that reduce generation. Beginners often overlook orientation, tilt, shading, and loss rate. These greatly influence predicted generation. Even simulations showing high annual generation can deviate from actual performance if these factors are not sufficiently reflected.

Orientation indicates which direction the panels face. South-facing surfaces tend to yield higher annual generation. However, east- or west-facing surfaces can be useful depending on facility usage times. Facilities with large morning demand benefit from east-facing panels; those with afternoon demand benefit from west-facing panels. Orientation affects not only annual generation but also the time-of-day when generation occurs.

Tilt angle is the angle at which panels are installed. On rooftops, panels often follow the existing roof pitch and you cannot freely choose an ideal angle. On flat roofs or land projects, you can set the racking angle, but increasing the angle affects inter-row shading, wind loads, snow, constructability, and maintainability. Even if a steeper angle slightly improves generation, it may be impractical if it complicates construction or maintenance.

Shading is a representative factor that reduces generation. Surrounding buildings, rooftop equipment, roof structures, handrails, piping, trees, utility poles, slopes, and terrain elevation differences create shading. Shading changes with season and time of day. Something that’s not a problem in summer can cast long shadows in winter due to lower solar altitude. Check whether shading is reflected in the simulation.

Loss rate is also important. Solar power generation estimates subtract various losses from ideal generation to produce an effective generation estimate. Typical loss factors include temperature, wiring, power conversion, soiling, snow, aging, and equipment downtime. If the loss rate is too low, the generation will look large but may fall short after installation.

After seeing the generation results, beginners should confirm “which losses were assumed for this generation.” There is a big difference between numbers that do not reflect shading and those that present effective generation after shading is considered. If temperature losses, soiling, or snow are not included, actual generation may be lower than the simulation.

Checking orientation, tilt, shading, and loss rate makes it easier to judge the reliability of generation estimates. Beginners should focus less on the size of the generation and more on how comprehensively the factors that reduce generation have been considered.

Step 4: Separate self-consumption and surplus electricity

Next, check self-consumption and surplus electricity separately. Simulations often show a large annual generation, but not all generated electricity can necessarily be used within the facility. To consider generation as an installation benefit, you need to separate self-consumption and surplus electricity.

Self-consumption refers to the portion of generated electricity used within the facility. This directly contributes to electricity cost savings and reduced purchased electricity. Surplus electricity is the portion generated but not used by the facility at the same time. Whether surplus is exported externally, stored in batteries, or curtailed changes the installation benefit.

A common beginner misunderstanding is assuming that more generation always means greater benefit. In reality, if a large portion of generation cannot be used on-site, the benefit may be limited. Facilities that operate mainly at night or have low demand on weekends may not be able to consume daytime generation, increasing surplus.

When checking self-consumption, verify facility electricity usage by time of day. Even with large annual usage, if daytime demand is low, self-consumption won’t increase. Conversely, facilities with a stable daytime base load can make effective use of generation. Check differences between weekdays and weekends, summer and winter, and operating hours.

Do not judge by self-consumption rate alone. A high self-consumption rate may look good, but it could be because system capacity is small and absolute self-consumed energy is low. Conversely, even with a slightly lower self-consumption rate, if the absolute self-consumed energy is large, the installation benefit can be high. Check self-consumption rate, self-consumed energy, and surplus electricity together.

If combining batteries, review results with and without batteries separately. Batteries do not increase generation; they shift surplus to other time periods. Looking only at results with batteries can obscure how much surplus the photovoltaic system alone would produce. Consider charge/discharge losses and capacity constraints when judging.

After generation, checking self-consumption and surplus electricity lets you connect the simulation to installation benefits. For beginners, this step is vital: focus on usable energy rather than just generated energy for practical decision-making.

Step 5: Check installation effects and post-installation management

The final step is to check installation effects and post-installation management. A solar power generation simulation is a pre-installation decision document, but it also relates to post-installation operation. After confirming generation and self-consumption numbers, verify what those figures mean for installation effects and how you will manage the system after installation.

When assessing installation effects, don’t rely solely on annual cash flow or payback period. Annual cash flow is convenient for grasping the overall picture, but it can hide monthly fluctuations, surplus occurrence, and the impact of generation losses. After checking monthly generation, self-consumption, and surplus, judge whether the results match the installation objectives.

Also check risks that could reduce installation benefits: abnormal weather, shading, temperature losses, soiling, snow, equipment downtime, equipment degradation, and changes in facility demand. Good first-year generation does not guarantee the same effects long-term. When evaluating long-term returns, consider aging, maintenance, and potential equipment replacement.

Constructability and maintainability are also important. For rooftop projects, confirm access to drain outlets and inspection hatches, and whether waterproofing repairs or equipment inspections will be obstructed. For land projects, confirm maintenance paths, drainage, weed control, equipment locations, and potential connection points. A layout that maximizes generation but prevents inspection or cleaning makes it hard to identify causes of generation decline after installation.

Use the simulation as a baseline for post-installation performance management. Comparing monthly generation with actual performance shows which months fall below expectations. Time-of-day generation data helps identify morning or evening shading or midday equipment problems. Generation by installation face helps find soiling, shading, or wiring issues on specific faces.

Beginners tend to treat simulations as documents only for pre-installation, but they are also valuable as operational baselines after installation. Deciding in advance what to check and which figures to use as references makes troubleshooting easier.

Finally, confirm whether the simulation is usable as documentation for post-installation management. If the simulation organizes not only annual generation but also monthly, time-of-day, face-by-face generation, self-consumption, surplus electricity, and assumed loss rates, it can be used for post-installation operation.

Common points beginners tend to overlook

What beginners often overlook when reviewing solar power generation simulations are the assumptions behind the generation figures. Large annual generation can be reassuring, but unless you check which system capacity, which area, and which loss rate were used in the calculation, you cannot judge whether the simulation is truly reliable.

Pay particular attention to differences in system capacity. When comparing multiple proposals, the one with higher annual generation may look attractive. However, if it’s only because the system capacity is larger, it does not indicate higher efficiency. Without checking generation per unit capacity, it’s hard to tell whether the proposal is based on favorable conditions.

Overlooking usable installation area is another common issue. Assuming that the entire roof or land area is usable can lead to overestimation of generation. Confirm whether rooftop equipment, inspection paths, drain outlets, waterproofing, site boundaries, slopes, and maintenance paths are reflected.

Failing to reflect shading can also create gaps post-installation. Without an on-site survey, winter and morning/evening shading may not be fully captured. A realistic generation estimate that reflects shading is often closer to actual performance than a higher estimate that ignores shading.

Beginners also frequently confuse self-consumption and surplus electricity. Large generation becomes surplus if the facility cannot use it. If your goal is to reduce electricity costs or improve the installation’s effectiveness, focus on self-consumed energy rather than total generation.

Finally, overlooking maintainability is risky. If panels cannot be inspected, cleaned, or accessed for equipment servicing after installation, it becomes difficult to address declines in generation. When reviewing simulations, check whether the plan is manageable long-term as well as whether it maximizes generation.

Beginners should follow the review order: system capacity, generation, generation losses, self-consumption, and post-installation management. This prevents being swayed by the numbers.

Conclusion

When beginners review solar power generation simulations, it’s important not to judge based solely on annual generation but to confirm items in a set order. Generation figures are based on assumptions including system capacity, usable installation area, insolation, orientation, tilt, shading, loss rate, self-consumption, surplus, and maintenance conditions. If you review results without checking assumptions, actual performance after installation may differ.

Step 1 is to check system capacity and installation conditions: which roof faces or land areas and whether calculations use a realistically installable area. Step 2 is to check annual and monthly generation: understand variations in summer, winter, rainy seasons, and snowy periods as well as annual totals.

Step 3 is to check orientation, tilt, shading, and loss rate to see how thoroughly generation-reducing factors are reflected and thereby judge simulation reliability. Step 4 is to separate self-consumption and surplus electricity, focusing on usable energy rather than just generated energy for judging installation benefits.

Step 5 is to check installation effects and post-installation management: whether generation and self-consumption match the installation purpose, whether long-term maintenance is feasible, and whether there are baselines for comparing actual performance.

Beginners commonly overlook differences in system capacity, constraints on usable installation area, reflection of shading, distinctions between self-consumption and surplus electricity, and maintainability. Confirming these in order helps avoid being misled by generation figures and enables realistic installation decisions.

Accurate on-site information is indispensable for beginners to correctly read simulations. If you can accurately grasp candidate installation ranges, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and potential connection points, the simulation assumptions become clear and the meaning of generation figures is easier to understand.

If you want to accurately record on-site candidate installation ranges, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and potential connection points and prepare on-site information that makes solar power generation simulations easier for beginners to interpret, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. High-precision on-site positioning makes it easier to organize shading and obstacles, usable installation areas, wiring routes, and maintenance routes, facilitating consistent comparison of vendor proposals, pre-construction verification, and post-installation performance management. To correctly review solar power generation simulations, it’s important not to rely solely on desk-based numbers but to accurately grasp the site and confirm assumptions in order.