8 Points to Review in Panel Layout to Increase Power Generation

When you want to increase the power generation of a photovoltaic system, reviewing panel layout becomes as important as cleaning and equipment inspection. Where you place panels—on which roof surfaces or land areas, which direction they face, what tilt angle they have, and how you avoid shading and maintenance access—can change the actual power output even with the same system capacity. However, simply adding panels to any available space just because you want to increase generation is not necessarily a good approach. If you force panels into heavily shaded areas, places that get dirty easily, or locations that are difficult to inspect, the actual output may not increase as much as expected. In this article, aimed at practitioners searching for "how to increase power generation," we explain eight points to check when reviewing panel layout to boost generation.

Table of Contents

• Why Power Generation Changes When You Reevaluate Panel Layout

• Point 1: Accurately Determine the Installable Area

• Point 2: Prioritize Areas with Less Shading

• Point 3: Leverage Generation Time Periods by Orientation

• Point 4: Balance Tilt Angle and Inter-row Shading

• Point 5: Design the Layout to Match Self-Consumption

• Point 6: Arrange to Minimize Accumulation of Dirt, Leaves, and Snow

• Point 7: Reevaluate Wiring Routes and Equipment Placement

• Point 8: Ensure Maintenance Access That Makes Inspection and Cleaning Easy

• Decisions to Avoid When Revising Panel Layout

• Summary

Why Revising Panel Layout Changes Power Generation

The power output of a solar power system is not determined solely by panel performance or system capacity. Even if you install the same number and capacity of panels, actual generation can vary depending on where they are placed, their orientation and tilt, surrounding shading, spacing between rows, susceptibility to dirt, and wiring conditions. In other words, to increase power generation it is important not only to add more equipment but also to review where and how existing and planned additional panels are arranged.

The most important thing when reviewing panel placement is to prioritize locations that are favorable for power generation. Just because there is available space on the roof or on the land does not mean that spot is suitable for generating electricity. Areas shaded by nearby buildings or trees, locations near rooftop equipment, around drains or inspection ports, places prone to wind or snow effects, and sites that are difficult to maintain may not produce as much electricity as expected.

Also, panel orientation affects self-consumption. Orientations closer to south tend to yield higher annual generation, while east-facing panels generate more in the morning and west-facing panels generate more in the afternoon. If a facility’s electricity use is concentrated in the morning or afternoon, generation from east- or west-facing arrays can be effective for self-consumption. It is important to consider not only total generation but also the times when generation occurs.

When reviewing panel placement, check not only the maximization of power generation but also whether that generation can be maintained over the long term. Placements without inspection walkways, placements that are difficult to clean, or placements that make it hard to access equipment can delay detection of dirt or equipment faults, prolonging reductions in power output. Rather than installing many panels in the short term, a placement that can be managed for a longer period will ultimately lead to more stable power generation.

Revising the layout to increase power generation is not simply a matter of adding more panels. It is important to combine site conditions, generation data, facility demand, and maintainability to identify where power can be generated, which time periods can be used, and what can realistically be managed.

Point 1: Accurately determine the area available for installation

The first point when revising a panel layout is to accurately determine the area available for installation. Even if the total area of a roof or land is large, you cannot use all of it for solar panels. If you plan the layout without correctly understanding the actual usable area, projected power generation may be overestimated, or major changes may be required before construction.

For rooftop projects, we account for the total roof area minus rooftop equipment, piping, penthouses, railings, drains, access hatches, waterproofing clearances, and inspection walkways. Even areas that appear open on the drawings often need to be kept clear for equipment inspection, drain cleaning, and waterproofing repairs. If panels are placed while ignoring these factors, the estimated power output may look large, but it can create problems for long-term building maintenance.

For land projects, we check site boundaries, slopes, elevation differences, trees, utility poles, drainage channels, existing structures, maintenance access routes, potential connection points, snow storage areas, and so on. Even if a site appears large, once you exclude slopes, areas with poor drainage, heavily shaded areas, and areas that should be left as maintenance access, the actually usable area is limited. Plans to place panels across the entire parcel may look like they will produce a large initial power output, but they can make inspection and weeding difficult during operation.

When checking the available installation area, it is easier to make decisions if you distinguish between the maximum layout and the realistic layout. The maximum layout serves as a reference to see how far panels can theoretically be placed. For actual installation decisions, however, you should use the realistic layout that reflects shading, inspection access, drainage, equipment placement, and maintenance space.

To increase power generation, it is important not to make the installation area appear larger but to accurately identify the areas that are conducive to generation and easy to maintain. If the usable area is correctly determined, you can prioritize locations that effectively improve power generation while avoiding impractical placements.

Point 2: Prioritize areas with minimal shading

The second point is to prioritize areas with minimal shading. If solar panels are shaded, they cannot receive sufficient sunlight and power generation decreases. Even if you add panels in areas strongly affected by shading, installed capacity will increase, but the energy produced per unit of installed capacity may be lower.

Causes of shading include nearby buildings, rooftop equipment, roof penthouses, railings, piping, air-conditioning and ventilation equipment, trees, utility poles, signs, slopes, and differences in terrain elevation. In rooftop projects, shadows from rooftop equipment and adjacent buildings tend to be problematic, while in land projects, shadows from trees, utility poles, slopes, and surrounding structures are involved.

Shadows vary with the seasons and time of day. Even if shadows are short in summer, the sun’s altitude is lower in winter, causing shadows to stretch longer. In the morning, obstacles on the east side are more likely to cast shadows, and in the evening, obstacles on the west side are more likely to do so. When reviewing a layout, it is important to consider not only shadows during sunny daytime but also those in winter and at dawn and dusk.

To prioritize areas with less shading, first check the power generation data. If generation is low only in the morning, it indicates shading on the east side; if it drops early in the evening, it indicates shading on the west side; if there is an unnatural dip around midday, check for obstructions near the panels. If you have data by installation surface or by string/system, check whether only a particular surface or row is low.

When optimizing layout, you need to decide not to force the use of heavily shaded areas. Avoiding shaded locations may reduce the number of panels, but it can improve actual energy output and energy per unit of capacity. To increase energy output, it is important not simply to install more panels, but to place them where they can generate electricity.

Also take into account tree growth and changes in the surrounding environment. Trees that cast little shade at the time of installation can create significant shade after several years. If buildings or equipment are likely to be added nearby, that should also be considered a long-term shading risk. Prioritizing placement in areas with minimal shading is effective for reducing post-installation generation shortfalls.

Point 3: Make Use of Generation Time Periods by Orientation

The third point is to make use of the generation time periods for each orientation. When arranging solar panels, it is common practice to prioritize surfaces that face south, but in real-world applications there is also potential to utilize east- and west-facing surfaces. To not only increase generation but also the amount of electricity available for use within a facility, it is important to check the generation time periods for each orientation.

South-facing surfaces tend to produce more power around midday. For facilities with high daytime electricity demand, a south-facing arrangement is more likely to contribute to self-consumption. For offices, factories, stores, and other facilities where demand is high around midday, making use of south-facing generation can be particularly valuable.

East-facing surfaces tend to generate power in the morning, while west-facing surfaces tend to generate power in the afternoon. For facilities that operate from the morning, east-facing generation can be effective. For facilities with high air-conditioning or production demand in the afternoon, west-facing generation can be useful. By looking not only at the total amount of power generation but also at when it is generated, you can assess compatibility with the facility’s demand.

When reviewing the layout, consider it alongside the facility's electricity usage patterns. Even if power generation increases, surplus may grow if the facility is not using electricity at that time. If the aim of increasing generation is to reduce purchased electricity, increasing on-site consumption can be more important than total generation.

For rooftop projects, we inspect each roof surface individually. We separate areas such as the south, east, and west faces and flat roof sections, and organize installed capacity, energy generation, generation time windows, and contribution to self-consumption. For ground-mounted projects and flat roofs, it may be possible to adjust generation time windows by changing the racking orientation.

Panel layouts that take advantage of orientation-specific generation time windows may differ from those that simply maximize annual energy production. Even if annual generation is slightly lower, if generation occurs during time periods that match facility demand, the practical benefits can be greater. When choosing panel layouts to increase energy production, it is important to consider generation and self-consumption separately.

Point 4: Consider the balance between tilt angle and inter-row shading

The fourth point is to consider the balance between the tilt angle and inter-row shading. The tilt of the panels affects how they receive solar radiation. Changing the angle can improve power generation, but increasing the angle is not always beneficial. Especially for flat rooftops and ground-mounted installations, the balance between inter-row shading and the number of panels that can be installed is important.

Increasing the tilt angle can make the panels more likely to receive solar radiation in winter when the sun is low. However, this also makes front-row panels more likely to cast shadows on rear rows. To avoid inter-row shading, the front-to-rear spacing needs to be widened. Widening the spacing can reduce the number of panels that can be installed in the same area.

On the other hand, reducing the tilt angle can make it easier to increase the number of modules that can be installed. However, a smaller angle can make dirt, leaves, and snow more likely to remain. It can also reduce exposure to winter sunlight. Reducing the angle to increase installed capacity does not necessarily lead to an improvement in annual power generation.

When reviewing the layout, check not only the per-panel energy output at each angle but also the total energy output of the entire system. If you change the angle while keeping the same area, compare how the number of panels installed, inter-row shading, and monthly energy generation change. It is important to evaluate total generation, energy yield per unit of capacity, winter generation, and maintainability together.

Inter-row shading can be pronounced in winter and during mornings and evenings. If power output is lower only in winter or dips during specific time periods, check for inter-row shading. Being able to verify power output that reflects inter-row shading not only from on-site observations but also in simulations makes it easier to judge layout improvements.

If you determine the layout without considering the balance between tilt angle and inter-row shading, you may actually reduce the effective power output even though you intended to increase generation. To increase power generation, it is necessary to take a comprehensive view of the tilt angle, the number of installed panels, shading, and maintainability.

Point 5: Consider a layout suited to self-consumption

The fifth point is to consider a layout suited to self-consumption. Even if you increase power generation, if the electricity generated cannot be used within the facility, the benefits of the installation may be limited. When reviewing panel placement, it is important to check not only total generation but also to separate and confirm on-site consumption and surplus electricity.

Self-consumption refers to the amount of electricity generated that is used within the facility. Surplus electricity refers to the amount of generated electricity that could not be consumed during the same time periods. Even if generation increases, if that increase occurs mainly during hours when the facility’s demand is low, the surplus may increase. If the purpose of increasing generation is to reduce purchased electricity, it is necessary to look at the overlap between generation hours and demand hours.

For example, at facilities where demand is high around midday, south-facing generation tends to be effective. For facilities with high demand in the morning, east-facing layouts may contribute to self-consumption; for those with high demand in the afternoon, west-facing layouts may do so. Combining east- and west-facing surfaces can disperse generation peaks and make it easier to suppress surplus.

During panel placement optimization, we also check the facility's operating days and holidays. Even if daytime demand is high on weekdays, a facility whose demand falls on holidays may see increased surplus on those days. We examine not only annual consumption but also monthly and time-of-day usage to verify that the panel placement matches demand.

When combining storage batteries, the layout and the generation curve are also relevant. If you store daytime surplus to use at other times, you need to understand during which time periods the surplus occurs. If the generation peak changes depending on the layout, the way you use storage will change as well.

Thinking about a layout that suits self-consumption is not just about increasing power generation; it’s a reassessment aimed at using the electricity generated more effectively. The layout that maximizes total generation is not necessarily the one that maximizes the benefit of the installation. It is important to check generation, self-consumption, and surplus electricity together.

Point 6: Arrange so dirt, fallen leaves, and snow are less likely to remain

The sixth point is to adopt a layout where dirt, fallen leaves, and snow are less likely to remain. Panel layout affects not only the conditions for receiving sunlight but also the maintenance of the surface condition. In layouts where dirt, leaves, or snow tend to persist, even if power generation is good immediately after installation, output can more easily decline over the long term.

Sources of soiling include sand and dust, pollen, yellow sand, bird droppings, exhaust-related contamination, and particulate matter. Surfaces located near exhaust equipment, near trees, or facing unpaved areas or roads may accumulate dirt more easily. When reviewing placement, identify the directions and areas prone to soiling and, as necessary, reflect them in the installation scope and maintenance plan.

Fallen leaves are a common issue at sites with trees nearby. When leaves accumulate on panel surfaces, power generation decreases. In rooftop projects, leaves accumulating in drains can also affect building maintenance. When placing panels near trees, it is necessary to check not only power generation but also the effects of leaves and birds.

In snowy regions, the angle and arrangement of panels affect how snow accumulates. When the slope is shallow, snow is more likely to remain. If snow that has fallen accumulates in front of panels or on walkways, it can cause shading and hinder maintenance operations. When planning the layout, check where snow will fall, snow storage space, and inspection/access routes.

Also, to manage dirt and snow, the layout must allow for inspection and cleaning. If panels are packed too tightly, cleaning and inspection become difficult. Even if capacity is increased to boost generation, if dirt and snow cannot be managed, it will be difficult to maintain long-term power output.

Designing the layout so that dirt, fallen leaves, and snow are less likely to remain is a measure to prevent insufficient power generation rather than a way to directly increase output. To increase generation over the long term, it is important to consider the layout not only for the initial output immediately after installation but also in terms of cleanability and responses to seasonal factors.

Point 7: Review wiring routes and equipment placement

The seventh point is to review wiring routes and equipment placement. Electricity generated by solar panels is routed through wiring and power conversion equipment before it can be used in the facility. Even if the panel layout is good, overly long wiring or poor equipment placement can cause losses and maintenance issues.

Wiring routes affect both power generation and maintainability. As wiring distances increase, a certain amount of loss occurs. In addition, if a wiring route is complex and difficult to inspect, identifying the cause of a fault may be delayed when a problem occurs. When reviewing panel layouts, check not only where panels can be placed but also which paths will be used to transmit power.

Equipment placement is also important. If power conversion equipment and connection points are located in places that tend to become hot, are susceptible to rain or snow, or are difficult to inspect, the risks for long-term operation increase. Check whether there is inspection space around the equipment, whether it can be accessed in the event of an abnormality, and whether wiring can be connected without strain.

Changing the panel layout can also alter wiring routes and equipment placement. Even if a layout increases power generation, operational issues can remain if wiring becomes too long or access to equipment worsens. Layouts intended to raise power generation need to be considered up to and including the electrical connection conditions.

Also confirm output capping and the handling of surplus. Even if panel capacity is increased, output may reach an upper limit due to equipment capacity or connection conditions. If output is curtailed for long periods, the improvement in energy generation from adding panels may be limited. Check installed capacity, equipment capacity, facility demand, and surplus energy together.

Revisiting wiring routes and equipment placement is often overlooked, but it directly affects improvements in power generation and long-term operation. It’s important to consider not only where to place the panels, but also how to deliver the electricity they generate to the facility.

Point 8: Ensure maintenance access that makes inspection and cleaning easy

The eighth point is to ensure maintenance access that makes inspection and cleaning easy. Even if you install many panels to increase power generation, if inspection and cleaning cannot be carried out, it will be difficult to maintain power generation over the long term. When improving power generation, it is important not only to focus on the initial output but also to arrange the layout so that power generation is preserved over time.

For roofing projects, ensure access to drains, inspection openings, rooftop equipment, the waterproofing layer, piping, and areas around handrails. If panels are placed across the entire roof, equipment inspections, drain cleaning, and waterproofing repairs can become difficult. If leaves or debris accumulate around drains and cannot be inspected, it can lead to building management issues.

In land projects, ensure maintenance access paths, weed control, drainage, and working space around equipment. If panel rows are packed too tightly, cleaning, inspections, mowing, and equipment replacement become difficult. Tall grass can cast shadows, and poor drainage can make maintenance work harder. Be aware that the more the layout is crammed to increase power output, the more maintenance accessibility may be reduced.

Having maintenance access routes makes it possible to find the cause of a drop in power output more quickly. Even if dirt, fallen leaves, bird droppings, snow accumulation, equipment malfunctions, or wiring faults occur, a layout that is easy to inspect enables faster response. Conversely, with a layout that is difficult to inspect, you may be unable to identify the cause even when power output falls, and the decline may persist longer.

When reviewing the layout, compare power generation while ensuring maintenance access routes. Ensuring maintenance access routes may slightly reduce the number of panels installed, but it is important for maintaining power generation over the long term. Prioritize the effective, manageable long-term power output over short-term maximum generation.

An arrangement that makes inspection and cleaning easy is a behind-the-scenes element for increasing power generation, but it is extremely important in practice. When designing panel layouts to increase power output, it is necessary to balance the ability to generate power with the ability to manage and maintain the panels.

Decisions to avoid when revising panel layout

One thing to avoid when revising panel layout is simply increasing the number of panels to raise generation. Increasing installed capacity may make the simulated output look higher, but adding panels in shaded areas, locations prone to dirt, or places that are difficult to maintain may not increase actual effective generation as much as expected.

Also, you should avoid deciding on the layout based solely on annual energy production. Even if annual energy production is large, if generation is concentrated during periods when the facility cannot use it, surpluses may increase. If you prioritize self-consumption, you need to compare the generation periods with the facility’s demand.

It's dangerous to underestimate shadows. If you conclude there's no problem because there are no shadows during summer daytime, you may overlook shadows in winter or at dawn and dusk. Adding panels in shaded areas will reduce generation per unit of capacity, potentially causing actual post‑installation performance to diverge from simulations.

You should also avoid decisions that put maintainability on the back burner. If you cut inspection walkways and cleaning space to cram in more equipment, it becomes difficult to deal with soiling and equipment abnormalities. If you review the layout with the aim of increasing power generation, you need to ensure maintenance access routes that will allow you to sustain power output over the long term.

Furthermore, you should avoid making decisions based solely on drawings and desk-based layouts. On site there are level differences, equipment, piping, obstacles, drainage, trees, and terrain that are difficult to discern from drawings. When revising the layout, it is important to combine on-site verification with power-generation data.

A panel layout that increases power generation is not a layout that places the maximum number of panels. It is a layout that makes generation easy, is easy to use, and is easy to maintain. Rather than trying to increase the numbers, prioritize raising the amount of power that can be reproduced on site.

Summary

When reviewing panel placement to increase power generation, it is necessary to comprehensively check available installation area, shading, orientation, tilt, inter-row shading, self-consumption, soiling and snow accumulation, wiring, equipment layout, and maintenance access. Increasing the number of panels alone is not the only way to improve generation. It is important to position panels where they can generate easily and during the time periods when the energy can be effectively used, and to create a configuration that can be managed over the long term.

In Point 1, accurately determine the area available for installation. Rather than using the total area of the roof or land, confirm the portion that can actually be used and maintained. In Point 2, prioritize areas with minimal shading. It is important not to overlook shadows in winter and in the morning and evening, or shadows cast by rooftop equipment and trees. In Point 3, make use of the power generation time windows for each orientation. Check the relationship between east- and west-facing surfaces and facility demand, not just south-facing ones.

Point 4 examines the balance between tilt angle and inter-row shading. Increasing the angle is not necessarily better; judge it in conjunction with the number of panels installed, shading, and maintainability. Point 5 considers layouts suitable for self-consumption. If generation increases but only increases surplus, the benefit of installation is limited. Point 6 considers layouts that minimize the accumulation of dirt, fallen leaves, and snow. Point 7 reviews wiring routes and equipment placement. Point 8 ensures maintenance access that facilitates inspection and cleaning.

When reviewing panel layouts, avoid simply increasing the number of panels, judging only by annual energy production, downplaying shading and maintainability, or deciding the layout based solely on drawings. To increase energy production, you need to choose a layout that, based on site conditions, balances energy generation, self-consumption, and maintainability.

To accurately review panel placement, precise on-site information is indispensable. If you can accurately identify the installation area, rooftop equipment, obstacles, trees, site boundaries, orientation, slope, inspection access routes, and potential connection points, it becomes much easier to determine where panels should be placed and which areas should be avoided.

If you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, slope, inspection/maintenance access routes, potential connection points, and efficiently proceed with reviewing panel layouts to increase power generation, using LRTK, an iPhone-mounted high-precision GNSS positioning device, is effective. By acquiring highly accurate on-site positional information, it becomes easier to identify causes of shading, determine installable areas, plan wiring routes and maintenance access routes, and to carry out, in an integrated manner, on-site verification for layout improvements, simulation comparisons, and post-installation performance management. To realize panel layouts that increase power generation, it is important not only to rely on desk-based layout proposals but to accurately grasp the site and translate that into layouts that avoid factors reducing output and can be managed over the long term.