Five Materials to Get Internal Approval Using Solar Power Generation Simulations

When putting forward the introduction of solar power generation for internal approval, showing only the size of the generated electricity does not always lead to approval. What approval reviewers need are materials to judge why that generation is expected, how much of it can be used internally, what risks exist, and how it will be managed after installation. A solar power generation simulation is not only a document that predicts generation, but also a document to organize the evidence needed for internal explanations. This article explains five materials to prepare to get internal approval, aimed at practical staff who search for "solar power generation simulation."

Table of contents

• Thinking about using solar power generation simulations for internal approvals

• Material 1: Evidence for annual generation and monthly generation

• Material 2: Relationship between self-consumption and electricity usage

• Material 3: Risks that reduce introduction benefits and countermeasures

• Material 4: Explanation of constructability, maintainability, and long-term operation

• Material 5: Management criteria to verify performance after introduction

• Explanation styles to avoid in approval documents

• Conclusion

Thinking about using solar power generation simulations for internal approvals

When submitting the introduction of solar power generation for internal approval, the easiest material for the person in charge to prepare first is a simulation result showing annual generation and the assumed introduction benefits. However, those who review approvals do not approve based on generation figures alone. They check the reason for introduction, the basis for the figures, the appropriateness as an investment decision, risks, impacts on internal operations, and how it will be managed after introduction.

Therefore, a solar power generation simulation should be used not as a document to exaggerate generation but as a document to organize the evidence you can explain internally. It is important not only to state how much annual generation there will be, but also to be able to explain which roof or land, which system capacity, which irradiance conditions, and which loss rates those generation figures assume.

In approvals, whether the introduction effect can be stably expected is emphasized. Solar generation varies with insolation and is affected by season, weather, shading, soiling, temperature, and snow. Even if the first-year annual generation looks good, generation may drop in winter or cloudy periods. Over long-term use, generation decline due to soiling, equipment degradation, or changes in the surrounding environment must also be considered.

It is also important how much of the generated power can be used internally. Even with large generation, if daytime facility demand is small, surplus power increases. If the amount that can be self-consumed is small, the introduction effect may be smaller than expected. In approvals, you must explain not only total generation but also self-consumption, surplus power, and the relationship with the electricity usage pattern.

Furthermore, internal approvals require clarification of management responsibilities after installation. If generation falls, who will check it, which data indicate an anomaly, whether inspections and cleaning are feasible, and whether construction will not impede building or land management after installation—all these must be explained or approvers will be uneasy.

In short, to use a solar power generation simulation for internal approval, it is important to explain generation, usable electricity, risks, and operational management in one flow. Below we organize the five materials to include in approval documents.

Material 1: Evidence for annual generation and monthly generation

The first material required for internal approval is the evidence for annual generation and monthly generation. Annual generation is the most easily understood number to explain the benefits of introducing solar power. However, simply showing annual generation is weak as approval material if you cannot explain why that generation is expected.

As evidence for annual generation, first explain the system capacity. Be clear about which roof surface or land area and what capacity are assumed to be installed. For rooftop projects, it is important to base assumptions on the actually usable area rather than the roof's total area. Explain how much can be installed after excluding rooftop equipment, piping, drains, inspection hatches, waterproofing setbacks, and inspection walkways. For land projects, show the installable area considering site boundaries, slopes, elevation differences, trees, drainage channels, maintenance paths, and candidate connection points.

Next, explain the irradiance conditions. Generation depends on regional insolation. Explaining which regional conditions the irradiance is based on and whether monthly seasonal variations are reflected increases the reliability of the generation estimate. Annual generation alone does not show differences between summer and winter or sunny and cloudy seasons. Showing monthly generation allows you to explain in which seasons generation increases and decreases.

Monthly generation is particularly effective in approval documents. Internal approvers may want to know not just whether there is an annual effect but whether generation coincides with periods of high demand. For facilities with high air-conditioning demand in summer, explain how much generation can be expected in summer. For facilities with high winter demand, explain how much generation reduction due to winter daylight hours, shading, and snow is anticipated.

Orientation and tilt are also indispensable as evidence for generation. South-facing surfaces tend to yield higher annual generation, but east- or west-facing surfaces can be effective depending on how they match facility demand. Explain whether tilt angles reflect the existing roof pitch or racking conditions. It is important to show that the simulation is based on conditions that can actually be constructed, not ideal conditions.

Also explain how much generation loss you have assumed. Organize whether temperature, wiring, power conversion, shading, soiling, snow, and aging are included in the total loss rate. Documents that incorporate downside factors are more trusted in approvals than those that only show high generation.

By carefully showing the basis for annual and monthly generation, approval documents become decision materials based on site conditions rather than mere estimates.

Material 2: Relationship between self-consumption and electricity usage

The second material required for internal approval is the relationship between self-consumption and electricity usage. Annual generation tends to attract attention in solar power generation simulations, but to explain introduction benefits in internal approvals, you need to show how much of the generated power can be used by your company.

Self-consumption is the amount of generated power that is actually used within the facility. Even with large generation, if there is no coincident demand, the rest becomes surplus. In self-consumption-oriented installations, self-consumed energy can be more important than total generation.

In approval documents, overlay the facility's electricity usage with generation. Annual usage alone is insufficient. Because solar generation primarily occurs during the day, how much power is used during daytime is important. Facilities that mainly operate at night may have large annual usage but find it difficult to self-consume. Facilities with weekday daytime demand but lower demand on weekends may see increased surplus.

Monthly electricity usage is also important. Facilities with large air-conditioning demand in summer are more likely to have demand coincide with summer generation. For facilities with large heating or production equipment demand in winter, confirm whether winter generation is sufficient. For facilities with busy and off seasons, if months of high generation coincide with months of low demand, surplus power may increase.

In approvals, do not explain using only the self-consumption rate. A high self-consumption rate may make a proposal look good, but it could simply mean the system capacity is small and the absolute self-consumed energy is low. Conversely, even with a slightly lower self-consumption rate, if the self-consumed energy is large, the introduction effect may be high. Explaining self-consumption rate, self-consumed energy, and surplus energy together makes it easier for approvers to understand the actual situation.

Be sure to explain how surplus energy will be handled. Whether surplus is exported externally, stored in batteries, or curtailed changes the thinking about introduction benefits. Leaving surplus handling ambiguous is a risk for approvals. Especially when increasing system capacity, explain how much surplus is expected to increase.

If including battery storage in the proposal, explain cases with and without batteries separately. Show how much self-consumption increases, how much surplus decreases, and whether charge/discharge losses are assumed. Showing only results with batteries can make it difficult to understand the effect of solar generation alone.

By explaining the relationship between self-consumption and electricity usage, a solar power generation simulation becomes a document that shows not only how much is generated but how much can be used internally. This is crucial for getting internal approval.

Material 3: Risks that reduce introduction benefits and countermeasures

The third material is the risks that reduce introduction benefits and the corresponding countermeasures. In internal approvals, it is important not only to show optimistic prospects but also to demonstrate how downside scenarios are considered. When explaining introduction benefits with a solar power generation simulation, organizing the factors that reduce generation and showing how they will be addressed increases the credibility of the approval documents.

Typical causes of decreased generation include shading, temperature losses, soiling, snow, wiring losses, power conversion losses, equipment downtime, and aging. Shading can be caused by surrounding buildings, rooftop equipment, railings, penthouses, piping, trees, utility poles, slopes, and terrain elevation differences. Shading varies by season and time of day, and may be strong in winter or during morning and evening.

For shading risks, compare generation with and without shading, avoid large shaded areas, adjust layouts, and reflect shading impacts in monthly generation—explain these countermeasures. Even if shading cannot be completely eliminated, showing that you have judged based on generation that incorporates shading-related reductions reduces concerns in approvals.

Temperature loss is generation decrease due to elevated panel temperature. This requires particular attention in summer and for rooftop installations. For facilities where summer generation strongly affects introduction benefits, explain how much high-temperature output drop is assumed. Also check rooftop ventilation and installation conditions.

Soiling losses arise from sand, pollen, fallen leaves, bird droppings, exhaust-derived soiling, and dust. If there are trees, unpaved areas, or dust sources nearby, explain the soiling propensity and your approach to cleaning and inspection. In snowy regions, explain winter generation, snow shedding, snow accumulation space, and the ease of snow removal and inspection.

Aging and equipment downtime are long-term risks. First-year generation does not necessarily continue for the long term. When explaining long-term profitability and introduction benefits, include assumptions about aging, maintenance, and potential equipment replacement.

In approval documents, do not hide risks; instead, show that the introduction decision was made with risks accounted for. Approvers worry about unforeseen problems after introduction. Explaining downside factors and countermeasures in advance increases the credibility of the materials and makes internal consensus easier.

Material 4: Explanation of constructability, maintainability, and long-term operation

The fourth material is the explanation of constructability, maintainability, and long-term operation. Internal approvals check not only generation and introduction benefits but also whether the system can be constructed safely, managed after introduction, and used long-term. Especially when facility management, general affairs, or equipment departments are involved, you need to show that building or land management will not be adversely affected.

For rooftop projects, explain considerations for structure, waterproofing, load, rooftop equipment, drains, inspection hatches, and inspection walkways. Filling the roof with panels may increase generation, but can make drain cleaning, waterproofing repairs, air-conditioning equipment inspections, and piping repairs difficult. In approval documents, indicate which areas will be used for installation and which will be left for maintenance and building management.

For land projects, explain site boundaries, slopes, elevation differences, drainage, maintenance paths, mowing, equipment locations, and candidate connection points. Simply placing the maximum number of panels on the land can make inspection, mowing, cleaning, and equipment replacement difficult. Showing that generation estimates were calculated while securing maintenance paths and work space conveys the realism of long-term operation.

Maintainability is directly linked to maintaining generation. If there is no access route to check for soiling, shading, equipment abnormalities, or wiring faults, cause identification is delayed. Systems that are difficult to inspect after introduction are harder to respond to when generation falls. In approval documents, explain inspection routes, equipment access, ease of cleaning, and response procedures for anomalies.

Long-term operation requires consideration of aging. Solar power equipment is long-lived and panels, power conversion equipment, wiring, connections, and racking may need inspection or replacement. Presenting a management policy to maintain generation over the long term, not just first-year generation, strengthens the persuasiveness of approval documents.

Also explain the internal operational structure after introduction. Clarifying who will check generation results, which department will respond if generation falls, and the contact point with maintenance vendors makes responsibilities clear after introduction.

Approval documents that can explain constructability, maintainability, and long-term operation are proposals that look beyond mere equipment installation to internal operation. Reducing approvers’ concerns about post-introduction issues is a major factor in decision making.

Material 5: Management criteria to verify performance after introduction

The fifth material is management criteria that allow verification of performance after introduction. In internal approvals, it is important not only to show expected benefits before introduction but also to demonstrate that those benefits can be verified after introduction. If you keep the simulation as a baseline, you can compare it to actual performance after operation starts and detect generation declines or operational issues early.

First, keep monthly generation as a management baseline. Annual generation alone does not show which months deviate from expectations. If winter generation is low, you can check for shading or snow; if summer generation is low, check temperature loss or soiling; if spring or autumn generation is low, check pollen, fallen leaves, or dust. Monthly baselines make post-introduction checks concrete.

Hourly generation and generation by installation surface are also effective. If morning generation is weak, suspect east-side shading; if generation drops early in the evening, suspect west-side shading; if there is an unusual midday drop, suspect rooftop equipment shading or equipment issues. If you can see generation by surface, it is easier to check whether a particular surface has soiling, shading, or wiring faults.

Baselines for self-consumed energy and surplus energy are also important. Even if generation is as expected, self-consumption changes with facility operating conditions. Conversely, if generation drops slightly but only surplus decreases, the impact on self-consumption may be small. In approval documents, state that you will check not only generation but also self-consumed energy and surplus energy after introduction to clarify how you will verify effects.

Organizing procedures to investigate when generation falls below expectations is also effective. Show the flow to determine whether the cause is weather, shading, soiling, snow, equipment downtime, or changes in facility demand. This helps approvers understand that there is a system to respond if problems occur after introduction.

Management criteria should also retain the simulation assumptions. Recording system capacity, installation range, orientation, tilt, shading assessment, loss rate, irradiance conditions, electricity usage data, presence of batteries, and maintenance conditions makes it easier to analyze differences from actual performance. Without recorded assumptions, post-introduction performance evaluation becomes ambiguous.

Including management criteria in approval documents expands the value of a solar power generation simulation from a pre-introduction estimate to a post-introduction operation management document. In internal approvals, the perspective that the system can be managed is an important approval factor.

Explanation styles to avoid in approval documents

When seeking internal approval, be careful about how you explain things. Avoid emphasizing only the magnitude of annual generation. Large generation is attractive, but without an explanation of the basis, it becomes a source of concern for approvers. If you cannot explain whether you simply increased system capacity, whether you adequately considered shading and loss rates, or whether site conditions are reflected, the approval materials are weak.

Next, avoid overly linking generation to reduction benefits. Not all generated power is used within the facility. If you explain without separating self-consumed energy and surplus energy, the introduction benefits may be perceived as exaggerated. It is important to separate the amount that can be generated, the amount that can be used, and the amount that will be surplus.

Also avoid documents that do not explain risks. Materials that do not show downside factors such as shading, temperature, soiling, snow, equipment degradation, downtime, and demand changes may seem easy to understand but will invite questions during the approval process. Rather than hiding risks, explain which risks are assumed to what extent and how they will be managed—this is more trustworthy.

Be careful not to treat pre-site-survey estimates as final values. Initial simulations based on drawings or aerial photos may leave conditions unknown. Explain that you will re-calculate after a site survey to reflect equipment locations, shading, inspection paths, drains, boundaries, and elevation differences; doing so increases transparency.

Also avoid omitting maintenance and operational explanations. If it is unclear who will check generation after introduction, how to respond if generation falls, or the approach to inspection and cleaning, approvers will worry about long-term operation. In approvals, you must show not only the effect at introduction but also that it can be managed afterward.

Good approval documents do not only show favorable numbers. They balance good conditions, possible downsides, and management methods. When using solar power generation simulations, explaining generation bases and risk management together is important for getting approval.

Conclusion

To get internal approval with a solar power generation simulation, annual generation numbers alone are insufficient. What approvals require are the basis for generation, self-consumption, surplus energy, risks, constructability, maintainability, and post-introduction management criteria. Organizing these makes it easier for approvers to decide whether to proceed.

Material 1 shows the basis for annual and monthly generation: system capacity, installable area, irradiance conditions, orientation, tilt, and loss rate—clarifying why that generation is expected. Material 2 explains the relationship between self-consumption and electricity usage: how much of the generated power can be used internally and how much will be surplus.

Material 3 explains the risks and countermeasures that lower introduction benefits: shading, temperature losses, soiling, snow, aging, and equipment downtime. Material 4 explains constructability, maintainability, and long-term operation: showing that the plan is not only installable but also inspectable, cleanable, and manageable over the long term. Material 5 records management criteria to verify performance after introduction: monthly generation, self-consumed energy, surplus energy, and loss-rate assumptions so that actual performance can be compared after introduction.

Avoid emphasizing only the size of annual generation, conflating generation with introduction benefits, not explaining risks, or treating pre-site-survey estimates as final. Internal approvals evaluate not only good numbers but the clarity of the basis and whether the plan can be managed.

A foundation that increases the persuasiveness of approval documents is accurate site information. If you can accurately capture installable ranges, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and candidate connection points, the assumptions of the solar power generation simulation become clear and it becomes easier to organize the evidence needed for internal explanations.

If you want to accurately record installable ranges, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and candidate connection points on site and strengthen the persuasiveness of approval documents that use solar power generation simulations, utilizing an iPhone-mounted high-precision GNSS positioning device called LRTK is effective. High-precision site location data makes it easier to organize shading and obstacles, installable ranges, wiring routes, and maintenance routes, and to explain the basis for generation within the company. To get internal approval with solar power generation simulations, it is important not to rely only on desk-based generation figures but to accurately understand the site and produce documents that can explain through to after introduction.