7 Items to Strengthen Proposals with Solar Power Generation Simulations

In solar power proposals, simply listing annual generation figures and estimated benefits may not convince the operations personnel. Only when you can explain the basis for the generation figures, how site conditions were reflected, self-consumption, surplus electricity, generation losses, maintenance plans, and post-installation performance management will a proposal become persuasive. Solar power generation simulations are not just calculation results; they are materials that support the credibility of a proposal. This article explains seven items to cover to strengthen proposals, aimed at operations personnel who search for "solar power generation simulation."

Table of contents

• The approach to strengthening proposals with solar power generation simulations

• Item 1: Clarify the basis for annual generation

• Item 2: Explain seasonal variation with monthly generation

• Item 3: Show self-consumption and surplus electricity separately

• Item 4: Describe shading, orientation, and tilt conditions in detail

• Item 5: Anticipate generation losses from temperature, soiling, and snow

• Item 6: Include constructability and maintainability in the proposal

• Item 7: Leave criteria that link to post-installation performance management

• Presentation styles to avoid in proposals

• Conclusion

The approach to strengthening proposals with solar power generation simulations

To strengthen a solar power proposal, it is more important to clearly explain the basis for the numbers than to make the numbers look large. The operations personnel receiving a proposal want to know not only how much annual generation is expected, but also under what conditions that figure was calculated, how reproducible it will be after installation, and what could cause generation to fall short of expectations.

Solar power generation simulations predict generation based on equipment capacity, installable area, solar irradiance, orientation, tilt, shading, generation losses, and electricity usage. However, showing only the annual generation in a proposal does not reveal whether that number fits the site, is an overestimate, or can be compared to post-installation results. The persuasiveness of a proposal depends greatly on how much you can break down and explain the simulation results.

A strong proposal first clarifies the basis for the generation figures. Explain how much equipment will be installed in which area, what solar conditions are assumed, and how much shading and loss are accounted for. Next, show not only annual generation but also monthly generation to communicate seasonal changes. Then separate self-consumption from surplus electricity to explain how generated power will actually be used.

It is also important to reflect site conditions in the proposal. For roof projects, consider rooftop equipment, inspection walkways, drains, waterproofing, and causes of shading. For land projects, consider site boundaries, trees, slopes, height differences, drainage, maintenance paths, and candidate connection points. Proposals that reflect site conditions may show slightly lower generation, but they are closer to actual post-installation performance and therefore more reliable.

A proposal is both a pre-installation decision document and a basis for post-installation performance management. If you record monthly generation, generation by installation area, loss rates, self-consumption, and surplus electricity, it will be easier to identify causes if actual generation differs from expectations after installation. The purpose of using solar power generation simulations in a proposal is not to aggressively push installation, but to provide decision materials that remain convincing after installation.

Item 1: Clarify the basis for annual generation

The first item to strengthen a proposal is to clearly explain the basis for the annual generation figure. Annual generation is the most attention-grabbing number in a solar proposal. However, if the basis for that figure is unclear, operations personnel will find it difficult to judge.

Annual generation varies depending on equipment capacity, solar irradiance, installation location, orientation, tilt, shading, temperature, wiring, power conversion, soiling, snow, and aging. In a proposal, first show the equipment capacity and the installable area, and explain how that capacity was calculated. Indicating that the calculation is based on the actual installable area, not just the roof’s total area or total land area, increases the proposal’s credibility.

For roof projects, explain the installable area considering rooftop equipment, piping, penthouses, handrails, drains, inspection hatches, waterproof clearances, and inspection walkways. For land projects, consider site boundaries, slopes, height differences, trees, drainage channels, maintenance paths, and candidate connection points. Making such exclusion conditions explicit makes it easier to explain why the equipment capacity is what it is.

Explaining generation per unit capacity is also effective. This helps separate whether a large total generation is due to large equipment capacity or efficient placement in good conditions. If generation per unit capacity is low, it may indicate that shaded or unfavorably oriented areas are being used. Conversely, if capacity is restrained but generation per unit capacity is high, it indicates an efficient layout.

Also explain whether the annual generation is a first-year estimate or accounts for long-term changes. Solar installations are used over long periods, so first-year generation may not remain constant. When explaining long-term installation effects, separate aging and anticipated generation losses to present a more realistic proposal.

Clarifying the basis for annual generation turns a proposal from a mere presentation of numbers into a document usable for installation decisions. Being able to explain why the numbers are what they are is the primary condition of a strong proposal.

Item 2: Explain seasonal variation with monthly generation

The second item is to explain seasonal variation using monthly generation. Annual generation is an easy-to-understand metric, but to judge installation benefits in practice, you need to confirm how much generation occurs in each month. Solar generation is not uniform throughout the year; monthly generation varies with sunlight hours, solar altitude, irradiance, temperature, weather, snow, and the way shadows lengthen.

Including monthly generation in the proposal makes post-installation expectations more concrete. You can explain whether generation is concentrated in summer, how much it drops in winter, and how much influence the rainy season or cloudy weather is expected to have. Revealing generation peaks and troughs that are hidden by the annual total increases transparency.

Monthly generation is also important to explain compatibility with the facility’s electricity usage. Facilities with high air-conditioning demand in summer will see installation benefits more directly if summer generation is high. For facilities with high heating or production equipment demand in winter, how you view winter generation declines is important. Explaining whether high-generation months coincide with high-demand months makes it easier to convey the validity of self-consumption.

When explaining winter, include short daylight hours, low solar altitude, shadows from surrounding buildings, rooftop equipment, and snow effects. In snowy regions, there may be periods when panels covered by snow cannot generate. Rather than showing winter generation optimistically, present the decline factors and then the monthly generation to increase credibility.

For summer, explain not only high irradiance but also temperature losses. Even in seasons with high irradiance, panel temperature increases can reduce output. If summer generation is estimated to be high, stating that temperature-related generation losses are reflected helps operations personnel understand the basis for the numbers.

Including monthly generation in the proposal also aids post-installation performance management. Comparing monthly actuals after operation start helps check whether generation declines in specific seasons. Since a proposal serves as both a pre-installation explanation and a post-installation management baseline, presenting monthly generation is very effective.

Item 3: Show self-consumption and surplus electricity separately

The third item is to separate self-consumption and surplus electricity. Proposals sometimes present a large annual generation figure, but not all generated power is used within the facility. Separating the portion used by the facility and the portion that remains unused provides stronger practical persuasiveness.

Self-consumption is the portion of generated electricity actually consumed within the facility. It directly reduces purchased electricity and is central to explaining installation benefits. Surplus electricity is the portion generated but not consumed by the facility at the same time. Evaluation changes depending on whether surplus is exported externally, stored in batteries, or curtailed.

It is important not to confuse generation and self-consumption in a proposal. Even if annual generation is large, if self-consumption is small, the electricity usable within the facility is limited. Conversely, a somewhat modest annual generation can yield stable self-consumption if generation timing aligns well with daytime facility demand. Showing usable electricity rather than just potential generation makes the installation effect more realistic.

Explaining self-consumption requires looking at the facility’s electricity usage by time of day. Solar generates mainly during daytime, so how much daytime demand exists is crucial. Facilities that operate mainly at night may have difficulty using the generated power despite high annual consumption. Facilities with high weekday demand but low weekend demand may see increased surplus. Do not rely solely on the self-consumption rate; a high rate with small equipment capacity may still result in a small self-consumption volume. Explain self-consumption rate, self-consumption volume, and surplus electricity together so it is easy to judge whether equipment capacity matches facility demand.

If batteries are included, present scenarios with and without batteries to increase persuasiveness. Showing only the battery-included results can obscure how much surplus would occur from solar alone. If you can explain how much self-consumption increases and how much surplus decreases with batteries, the proposal’s basis becomes clearer.

Separating self-consumption and surplus electricity makes the proposal a document that explains how electricity will be used after installation, not merely a statement of large generation figures. This is critical for operations personnel.

Item 4: Describe shading, orientation, and tilt conditions in detail

The fourth item is to describe shading, orientation, and tilt conditions in detail. These factors greatly influence simulation results. If shading, orientation, and tilt explanations are vague when presenting generation figures, the credibility of the numbers declines.

Orientation indicates the direction panels face. South-facing surfaces tend to yield higher annual generation, but east- and west-facing orientations can be effective depending on facility demand timing. East-facing generation contributes to morning-heavy demand; west-facing generation contributes to afternoon-heavy demand. Explain orientation and generation by each installation surface for clarity.

Tilt angle also affects generation. On roof projects, panels are often installed to match the existing roof slope, so you cannot freely choose the ideal angle. For flat roofs and land projects, you can set racking angles, but larger angles may cause row-to-row shading, wind and load issues, spacing impacts, and maintenance challenges. In the proposal, explain why a specific tilt was chosen and how you balanced generation with constructability.

Explaining shading is particularly important. Shading can be caused by surrounding buildings, rooftop equipment, penthouses, handrails, piping, trees, utility poles, slopes, and terrain elevation differences. Shading changes with seasons and time of day. Even if shading is minimal in summer, low solar altitude in winter can lengthen shadows. Show how much shading was accounted for to clarify the basis for generation figures.

Explaining shading impact by comparing shaded and unshaded scenarios helps understanding. Showing the difference between generation without shading and generation with shading demonstrates that site conditions were reflected. If you excluded some areas to avoid shading, explain why. Even if generation is slightly reduced, you can convey that the proposal is closer to actual performance after installation.

Shading, orientation, and tilt also relate to self-consumption. If generation is skewed to morning or afternoon, compatibility with facility demand changes. If the proposal can explain the relationship between generation timing and facility demand, it will be perceived not just as an equipment proposal but as one aligned with operation.

Item 5: Anticipate generation losses from temperature, soiling, and snow

The fifth item is to anticipate generation losses from temperature, soiling, and snow. Solar equipment does not always generate at maximum under ideal conditions. In reality, generation declines due to panel temperature, soiling, snow, wiring, power conversion, equipment downtime, and aging. The proposal must explain to what extent these generation losses are assumed.

Temperature loss is output reduction caused by increased panel temperature. Pay attention to this especially for summer and rooftop installations. Even in seasons with high irradiance, high panel temperatures can prevent generation from reaching expectations. When explaining summer generation, show that temperature losses are reflected, which increases credibility.

Soiling loss is generation decline caused by dust, pollen, fallen leaves, bird droppings, exhaust-related dirt, and particulate deposition on panel surfaces. In locations near many trees, unpaved areas, dust-prone environments, or places where birds gather, a standard loss rate may be insufficient. Explain how soiling loss is considered according to site conditions.

In snowy regions, account for generation decline due to snow. Panels covered with snow create periods with no generation. Slope angles that allow snow to slide off, snow accumulation space, ease of snow removal and inspection, and snow load handling are also relevant to the proposal. When explaining winter generation, indicate how much snow and residual snow were reflected.

Wiring and power conversion losses are also part of generation losses. Power generated at the panels passes through wiring and equipment before being used in the facility, and losses occur during that process. Clarifying whether the presented generation is panel-side generation or usable after conversion makes the meaning of the numbers clear.

While generation losses are sometimes summarized as a total loss rate, it is stronger to explain major items individually where possible. Even if generation appears conservative, showing that temperature, soiling, snow, shading, wiring, conversion, and aging were realistically accounted for signals a proposal that reduces the gap after installation.

Item 6: Include constructability and maintainability in the proposal

The sixth item is to include constructability and maintainability in the proposal. Proposals based on simulations often emphasize generation and self-consumption, but actual installation requires a plan that can be constructed and maintained. A proposal that can explain constructability and maintainability gives operations personnel assurance.

For roof projects, explain considerations for structure, waterproofing, loads, rooftop equipment, drains, inspection hatches, and inspection walkways. Filling the roof entirely with panels may increase apparent generation, but if such a layout makes drain cleaning, waterproofing repairs, or rooftop equipment inspection difficult, long-term operation will face issues. Explain which areas are used for generation and which are left for maintenance.

For land projects, explain site boundaries, maintenance paths, drainage, weed control, slopes, height differences, equipment locations, and candidate connection points. Lining panels across the entire site to maximize generation can make inspection, weeding, and equipment replacement difficult. Showing that you've calculated generation while ensuring maintenance paths and workspaces increases the proposal’s realism.

Maintainability directly affects long-term generation. If you cannot check soiling, shading, equipment faults, wiring issues, or post-snow conditions, it becomes hard to identify causes of generation declines. Explain that you have considered an inspection-friendly layout, easy cleaning routes, equipment access, and abnormal condition responses.

Including constructability and maintainability may reduce generation slightly compared to a maximum layout. However, that does not weaken the proposal; rather, it increases reliability as a realistic plan for long-term operation. Operations personnel emphasize whether the plan will have fewer troubles after installation. Explaining that the equipment can be managed, not just its generation, strengthens the proposal.

Also include a commitment to re-simulate with the final layout before construction. If the layout changes after a site survey from the initial proposal, generation and self-consumption will change. Indicating that a final-layout re-calculation will occur reduces the post-installation gap.

Item 7: Leave criteria that link to post-installation performance management

The seventh item is to leave criteria that link to post-installation performance management. A proposal is a pre-installation decision document but can also serve as a basis for managing generation after installation. If simulation results are recorded in a form that can be compared with actuals, it becomes easier to find causes when generation is lower than expected.

First, record not only annual generation but also monthly generation. With monthly criteria, you can check which months deviate during winter, summer, the rainy season, or snowy periods. Low winter generation points to shading or snow; low summer generation suggests temperature losses or soiling; low spring or autumn generation could indicate pollen, fallen leaves, or dust.

Hourly generation and generation by installation surface also help performance management. If morning generation is lacking, check east-side shading; if it drops early in the evening, check west-side shading; if an unnatural midday dip occurs, inspect rooftop equipment or machinery. If only one surface shows low generation, focus on soiling, shading, wiring, and connections.

Also retain criteria for self-consumption and surplus electricity. Even if generation matches expectations, changes in facility operation can alter self-consumption. Conversely, a slight generation decline may only reduce surplus without affecting self-consumption. To verify post-installation effects, compare not only generation but also consumed and surplus energy.

A proposal that supports performance management should also record simulation assumptions. If you record equipment capacity, installation area, orientation, tilt, shading assessment, loss rates, solar conditions, electricity usage data, whether batteries are included, and maintenance conditions, it will be easier to analyze differences after installation. Without clear assumptions, it is hard to judge whether a generation decline is due to weather, equipment, or site conditions.

A proposal that considers post-installation performance management becomes a long-term operational baseline rather than just a sales document. For operations personnel, a proposal that clarifies what to check after installation is valuable. When including a solar power generation simulation in a proposal, organize it so it can be used both before and after installation.

Presentation styles to avoid in proposals

When including solar power generation simulations in a proposal, avoid emphasizing only the largeness of the annual generation. Large generation is important, but without showing the basis, operations personnel cannot judge whether it was achieved by simply increasing equipment capacity, underestimating shading and loss rates, or failing to reflect site conditions.

Next, avoid confusing self-consumption and surplus electricity. Making all generated power look like it will be used in the facility can create an exaggerated sense of benefit. In practice, it is important to separate what can be generated and what can be used. Proposals that are vague about handling surplus tend to create expectation gaps after installation.

Be careful not to represent loss rates by a single number. A single total loss rate makes it hard to see how much temperature, shading, soiling, snow, wiring, conversion, and aging each contribute. In proposals, explain major loss items separately to show they match site conditions.

Also avoid presenting pre-site-survey estimates as final numbers. Early-stage drawings and aerial photos do not reveal all conditions. Explain that installable area, shading, inspection paths, and connection conditions may change after a site survey. Showing a flow that includes re-simulation after the site survey increases trust.

Proposals that completely omit maintainability considerations are weak. Solar installations are long-lived assets. Whether inspection, cleaning, equipment checks, and performance management are possible affects post-installation satisfaction. Even if generation looks good, layouts that cannot be managed pose long-term risks.

What to avoid in proposals is showing only good numbers. A strong proposal explains both the conditions that make the generation possible and the conditions that could cause downward deviation. Rather than hiding risks, showing them with countermeasures builds trust with operations personnel.

Conclusion

To strengthen a proposal using solar power generation simulations, showing the annual generation figure alone is insufficient. Only when you can explain equipment capacity, installable area, solar irradiance, monthly generation, self-consumption, surplus electricity, shading, orientation, tilt, generation losses, constructability, maintainability, and post-installation performance management will the proposal be usable in practice.

Item 1 clarifies the basis for annual generation: where and how much equipment will be installed and under what conditions generation was calculated. Item 2 explains seasonal variation with monthly generation: how summer, winter, the rainy season, snow, and temperature losses affect generation.

Item 3 separates self-consumption and surplus electricity: potential generation and usable electricity are not the same. Explain not only the self-consumption rate but also the self-consumption volume and surplus electricity. Item 4 describes shading, orientation, and tilt conditions in detail to clarify which surfaces contribute to generation and which shading was reflected.

Item 5 anticipates generation losses from temperature, soiling, and snow. Showing loss rates suited to site conditions reduces the post-installation gap more than overstating generation. Item 6 includes constructability and maintainability: layouts considering inspection walkways, drainage, equipment access, and maintenance paths provide long-term operational assurance. Item 7 leaves criteria for post-installation performance management: recording monthly generation, hourly generation, generation by installation surface, self-consumption, and surplus electricity makes it easier to respond to post-installation declines.

Avoid emphasizing only large annual generation, confusing self-consumption and surplus electricity, being vague about loss rates, or presenting pre-survey estimates as final. A strong proposal explains both favorable conditions and downside risks clearly.

Accurate site information is the foundation that increases the persuasiveness of a proposal. If you can precisely capture candidate installation areas, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and candidate connection points, the simulation assumptions become clear and the basis for generation easier to explain.

If you want to accurately record candidate installation areas, rooftop equipment, obstacles, trees, site boundaries, orientation, tilt, inspection routes, and candidate connection points on-site and strengthen proposals using solar power generation simulations, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. High-precision site location data makes it easier to organize shading, obstacles, installable areas, wiring routes, and maintenance routes, and to create simulations and proposals based on site conditions. To strengthen proposals with solar power generation simulations, it is important not only to present desk-based generation figures but also to accurately grasp the field and clearly incorporate that information into the proposal.