8 Reviews to Increase Solar Panel Power Generation

When you want to increase the power generation of solar panels, the first things that may come to mind are adding panels or replacing equipment. However, in reality, the causes of low power generation are not limited to the number of panels; they include shading, dirt, orientation, tilt, temperature rise, wiring, equipment condition, snowfall, lack of maintenance, and more. To truly increase power generation, it is important to understand where current generation is being lost and to review measures in order, starting with the areas that will have the greatest improvement effect. This article explains eight reviews to check to increase solar panel power generation for practitioners searching for "how to increase power generation".

Table of Contents

• What to check before increasing solar panel output

• Review 1: Organize power generation data by month and time of day

• Review 2: Check shading sources and seasonal variations

• Review 3: Examine panel surface soiling and cleaning conditions

• Review 4: Check for inefficiencies in orientation, tilt, and layout

• Review 5: Reassess temperature rise and ventilation conditions

• Review 6: Check wiring, equipment, and output limits

• Review 7: Manage seasonal factors such as snow, fallen leaves, and bird damage

• Review 8: Continue maintenance planning and performance tracking

• Decisions to avoid when increasing power generation

• Summary

What to check before increasing the power output of solar panels

To increase the power output of solar panels, you first need to confirm whether the current output is actually low. Power output varies with solar irradiance, weather, season, temperature, panel condition, and the surrounding environment. If you judge it abnormal solely because it is lower than last month or last week, you may mistake natural seasonal variations for equipment trouble.

Especially in solar power generation, the amount of electricity produced is not constant throughout the year. In spring and autumn, the balance between ambient temperature and solar irradiance is favorable, so generation can be relatively easier. In summer, although solar irradiance is high, panel temperatures rise, which can reduce output. In winter, daylight hours are shorter and the solar elevation is lower, so shadows from surrounding buildings, trees, and rooftop equipment tend to be longer. In snowy regions, snow can cover the panels, causing periods when generation is not possible.

Therefore, before taking measures to increase power generation, check the comparison with the same month of the previous year, monthly trends, power generation by time of day on sunny days, and power generation per unit of installed capacity. It is important to determine whether generation is low overall, low only in specific months, low only in the morning or evening, or low only on particular roof surfaces or specific systems.

Also, it is important not to confuse power generation with self-consumption. Even if the solar panels are generating enough power, it will become surplus if the facility cannot use it up during that period. What you need to review will differ depending on whether you want to increase the amount generated or increase the amount of electricity that can be used within the facility. If the generation itself is low, check for shading, soiling, temperature, equipment, and wiring. If there is generation but the installation’s effect is small, check the timing of self-consumption and the amount of surplus electricity.

The objective of increasing power generation is not simply to inflate the numbers in a simulation. It is about finding the generation opportunities that are actually being lost on site and choosing improvement measures that are reproducible. The starting point for successful power-generation improvement is to first understand the current situation with data and then confirm the on-site conditions.

Review 1: Organize power generation data by month and time of day

The first review to increase power generation is to organize generation data by month and by time of day. Looking only at the total annual generation does not reveal where generation is being lost. Viewing data by month reveals seasonal causes of declines, and viewing it by time of day can provide clues to shading and equipment malfunctions.

When analyzing monthly power generation, first identify which months have high generation and which have low. If it drops significantly only in winter, check for shorter sunshine hours, winter shading, and snow cover. If it does not increase in summer as expected, check for temperature-related losses, soiling, high equipment temperatures, and output limitations. If decreases are observed in spring or autumn, soiling factors such as pollen, dust, fallen leaves, and bird droppings may be involved.

When you examine power generation by time of day, you can identify more specific causes. If generation is weak in the morning, shading on the east side is suspected; if generation drops early in the evening, shading on the west side is suspected. If there is an unusual dip around midday, check for shading from rooftop equipment, penthouses, piping, or surrounding structures, or for effects from equipment or output restrictions. If generation falls at similar times every day even on sunny days, it is more likely related to site conditions rather than the weather.

If there are data by installation surface or by system, examine them in more detail. Whether the whole is low or only part of it is low changes what you should check. If only a specific roof surface is low, check that surface’s orientation, tilt, shading, and soiling. If only a specific system is low, check the wiring, connection points, power conversion equipment, and output limitations.

When organizing power generation data, it's important not to rely solely on month-over-month comparisons. Because solar power generation varies by season, comparing with the same month in the previous year, sunny days in the same season, and simulation values makes it easier to understand the actual situation. Even when you feel the power output is low, distinguish whether the decrease is reasonable given the weather and season, or whether it is an abnormality that should be corrected.

Measures to increase power generation should be started by reviewing the data. If you can identify the months, times of day, and installation surfaces where generation is declining, it becomes clear what to check on-site next. Organizing the data is the foundation for improving power generation.

Review 2: Confirm shading sources and seasonal changes

Checking for shading is extremely important when trying to increase the power output of solar panels. If panels are shaded, they cannot receive sufficient sunlight and their power output decreases. Shading may seem easy to identify because the source is visible, but in reality it changes with the seasons and time of day, making it an easily overlooked factor.

Sources of shadows include surrounding buildings, rooftop equipment, penthouses, railings, piping, air conditioning equipment, ventilation equipment, utility poles, signs, trees, slopes, and changes in terrain elevation. On roofs, even small pieces of equipment located near panels can cast long shadows in winter and at dawn and dusk. In land projects, trees on adjacent properties, utility poles, and nearby structures can cast shadows.

What you should check especially is shadows in winter. Because the sun’s altitude is lower in winter, shadows that didn’t reach the panels in summer can extend to them. Even if an on-site check during a summer daytime shows no shadows, shadows can occur in winter. If winter power generation is lower than expected, you need to check the effect of shadows as well as the shorter hours of sunlight.

Shadows in the morning and evening are also important. If generation doesn't rise in the morning, obstacles on the east side may be casting shadows; if generation drops off quickly in the evening, obstacles on the west side may be creating shadows. If the facility's power demand is high in the morning or evening, shadows at those times will also affect self-consumption. If you want to increase not only generation but the amount of usable energy, check whether shadows overlap with your demand periods.

Measures to mitigate shading include avoiding additional installations in heavily shaded areas, considering pruning and management of trees, prioritizing less-shaded surfaces when changing the layout, and incorporating shadows into power generation simulations. Even for systems already installed, check whether conditions have changed since installation due to tree growth or the addition of rooftop equipment.

Forcibly adding more panels in shaded areas may increase total capacity, but it can reduce energy output per unit of capacity. To increase generation, accurately identify the causes of shading and prioritize areas that are more suitable for power generation.

Review 3: Reassess panel surface soiling and cleaning conditions

The third review concerns soiling of the panel surface and the cleaning conditions. Because solar panels generate electricity by receiving sunlight on their surface, when dirt adheres the light has difficulty reaching the cells and power generation decreases. Dirt often accumulates gradually, so it is an item that is easily overlooked as a cause of reduced power output.

Causes of soiling include sand and dust, pollen, fallen leaves, bird droppings, exhaust-related dirt, particulate matter, and residue remaining after snowfall. Areas with many trees nearby are more susceptible to fallen leaves and bird-related effects. If there are unpaved grounds, farmland, material storage yards, land under construction, or busy roads nearby, soil dust and particulates are more likely to adhere. On rooftops, panels located near exhaust equipment or vents can become dirty more easily.

The effect of soiling also depends on the panel's tilt. If the tilt is sufficient, light dirt may be washed away by rain. However, when the tilt is small, or when soiling consists of bird droppings, fallen leaves, or adhered dust, rain alone may not be enough to remove it. If dirt remains on the lower edge of the panel or in certain areas, it can affect power generation.

If power generation is gradually declining, if output does not recover after rain, or if only certain panels are producing less, check for dirt. When determining whether cleaning is necessary, safety is the top priority. Work on roofs is hazardous, so avoid attempting tasks beyond safe limits. Also avoid any methods that could scratch the panel surface or otherwise adversely affect the equipment.

Cleaning conditions should also be reviewed. Check whether there are inspection walkways, whether panels can be approached safely, and whether access to drains and rooftop equipment is being obstructed. In layouts that are difficult to clean, response will be delayed even if soiling leads to reduced power generation. When installing new systems or expanding existing ones, it is important to decide the layout with consideration not only for power output but also for ease of cleaning.

Measures to prevent soiling are not completed with a single cleaning. Because the types of soiling change with the seasons, it is important to decide inspection timing according to the local environment—such as periods of heavy pollen or dust, leaf-fall season, or after snowfall. Keeping the panel surface in good condition is fundamental to increasing power generation.

Review 4: Check for orientation, tilt, and layout inefficiencies

The fourth review concerns inefficiencies in orientation, tilt, and layout. Even with the same system capacity, energy output varies depending on which direction the panels face, the angle at which they are installed, and the area over which they are arranged. To increase energy output, you need to confirm that the panels are positioned under conditions that allow them to receive ample sunlight.

Orientation affects both the amount of electricity generated and the time of day it is produced. Surfaces that face closer to south tend to yield higher annual generation, but east- and west-facing surfaces can also be effective depending on a facility’s demand hours. For facilities with high demand in the morning, east-facing generation can help with self-consumption, while for facilities with high demand in the afternoon, west-facing generation can be useful for self-consumption. When increasing generation, check not only the annual output but also when the generation occurs.

The tilt angle affects how solar radiation is received across the seasons. Increasing the angle can make it easier to receive solar radiation in winter, but it also affects inter-row shading, wind, snow accumulation, and installation spacing. Decreasing the angle can make it easier to fit more panels, but it can also make dirt and snow more likely to remain. The tilt angle should be decided based not only on power generation but also on constructability and maintainability.

When checking for layout inefficiencies, check whether you're forcing the use of areas with poor conditions. Adding panels to surfaces that are heavily shaded, unfavorably oriented, difficult to inspect around equipment, or located near drains may not increase power generation as much as expected. It's important not only to increase capacity but also to verify the power generation per unit of capacity.

For roof projects, we check the power generation for each roof surface. By separating areas such as south-, east-, and west-facing surfaces and flat-roof sections, you can see which surfaces contribute to power generation. For land projects, we review the layout considering row spacing, maintenance access aisles, drainage, topography, and shading. Packing panel rows closer together increases capacity, but it can worsen row-to-row shading and maintainability.

When reviewing the layout, compare simulations from before and after the change. Check not only total generation but also generation per unit capacity, self-consumption, surplus electricity, and monthly generation. Even if total generation increases, if only the surplus increases, the improvement in the effectiveness of the installation is limited.

Reviewing orientation, tilt, and layout is a design measure to increase power output. It is important to select a layout tailored to site conditions that facilitates power generation and simplifies maintenance.

Review 5: Reassess temperature rise and ventilation conditions

The fifth item to review is temperature rise and ventilation conditions. Solar power systems generally generate more electricity with higher solar irradiance, but their output can decrease when panel temperatures rise. Especially in summer and for rooftop installations, even with strong sunlight, generation may not increase as expected due to temperature-related losses.

Temperature rise varies depending on the installation environment. If the roofing material tends to retain heat, the roof surface temperature can affect the temperature around the panels. When the space behind the panels is small or when there are many rooftop installations nearby that limit airflow, heat is more likely to become trapped. Using low mounts on a flat roof can also make the system more susceptible to heat from the roof surface.

For ground-mounted installations, it can be easier to secure ventilation than on roofs, but tall grass can impede airflow and nearby structures can cause air to stagnate. Ventilation conditions affect power generation in summer, so it is important to check whether the environment facilitates heat dissipation.

With generation data, focus on monthly generation during the summer. If solar irradiance should be high but generation does not increase, temperature-related losses may be involved. You may also observe more stable generation in spring and autumn. If you want to improve summer generation, check the heat dissipation conditions around the panels.

As countermeasures, ensure that airflow behind the panels is not obstructed, that vegetation or other obstacles do not block air movement, and that heat does not accumulate around equipment. However, changing rack height or tilt angle to improve ventilation can affect wind loads, constructability, inter-row shading, and maintainability. Therefore, temperature countermeasures should not be considered in isolation but must be assessed comprehensively.

Reviewing temperature rise and ventilation conditions is important, especially if you want to increase power generation in summer. Although these generation losses are not easily visible, they affect annual generation and self-consumption, so verify them in both simulations and actual performance.

Review 6: Check wiring, equipment, and output limits

The sixth item to review is wiring, equipment, and output limitations. The electricity generated by solar panels is used within the facility after passing through wiring and power conversion equipment. Even if the panels are receiving sunlight, if there are problems with the paths that deliver power or with the conversion equipment, the amount of electricity actually available for use will be reduced.

Wiring losses vary depending on wiring distance and the condition of connections. If the wiring is long, the route is complex, or connection points are difficult to inspect, detection of losses or faults may be delayed. When installing new systems or adding capacity, it is important to check not only panel layout but also wiring routes and equipment installation locations.

The condition of power conversion equipment also affects power generation. If equipment is stopped or some systems are not operating normally, even if the panels are generating power, the amount of electricity available for use at the facility will be reduced. If generation suddenly drops, if only certain systems are low, or if there is an unnatural plateau in output around midday, check the equipment and connections.

You also need to check output limits. Even if you increase panel capacity, output may reach an upper limit depending on equipment capacity and connection conditions. The fact that output is capped is not necessarily a bad thing in itself, but you need to confirm at what times and to what extent generation is being curtailed. If the generation peak coincides with facility demand, also look at the impact on self-consumption.

We also check the equipment’s installation environment. If equipment is located in places prone to high temperatures, exposed to rain or snow, or difficult to inspect, risks for long-term operation increase. Ensuring that equipment is easily accessible and that there is space to carry out inspections and replacements is important for maintaining power generation.

To increase power generation, you should check not only the panels themselves but also the path the generated electricity takes until it can be used by the facility. By reviewing the wiring, equipment, and output conditions, you may be able to recover electrical energy that is being lost.

Review 7: Manage seasonal factors such as snow accumulation, fallen leaves, and bird damage

The seventh review concerns seasonal factors such as snow accumulation, fallen leaves, and bird damage. These do not always occur, but they can significantly reduce power generation during certain times. To increase annual power generation, it is important to identify seasonal causes of decline and manage them as recurring issues.

In snowy regions, snow accumulating on panels causes periods during which they cannot generate electricity. Not only the time when it is snowing, but also the time after snowfall when snow remains affects power generation. If the panel tilt is low, snow may be less likely to slide off. When snow slides off, it can accumulate at the lower part of the panels and around them, creating shading. If winter power generation is low, check the effects of snowfall and remaining snow.

Fallen leaves are a factor that commonly occurs at sites with trees nearby. When leaves settle on panel surfaces they block sunlight and reduce power generation. Leaves that get wet in the rain and stick tend to remain, and when they accumulate around drains they can also affect roof maintenance. Caution is needed not only in autumn but also on windy days and after pruning.

Bird damage is also a cause of reduced power generation. When bird droppings adhere to the panel surface, they can locally block solar radiation. If structures or trees that attract birds are nearby, soiling can repeatedly occur in the same place. Bird damage is not only a soiling issue but also a maintenance planning issue.

As a countermeasure, it is effective to decide inspection timings for each season. After snowfall, during periods with many fallen leaves, when the effects of birds are noticeable, and when pollen or dust is abundant, check power generation data and on-site conditions. If cleaning or removal is necessary, ensure safety and choose methods that will not damage the panels or the roof.

Seasonal factors are not something you address once and then forget. Because they can recur every year, it is important to incorporate them into operational plans. Rather than trying to increase power generation, you need to focus on suppressing seasonal declines in output to stabilize annual power generation.

Review 8: Continue maintenance planning and performance management

The eighth review is maintenance planning and performance management. To increase solar panel power generation, you need not only one-off measures but a system to sustain generation over the long term. Shade, dirt, equipment malfunctions, snow accumulation, and wiring faults are issues that should be checked repeatedly during post-installation operations.

A maintenance plan specifies what to check, when, and how to check it. Record monthly generation, generation by time of day, generation for each installation surface, self-consumption, and surplus electricity, and compare them with expected values and the same month of the previous year. If generation is low, investigate the causes in this order: weather, shading, dirt, snow accumulation, equipment, wiring, and changes in demand.

For rooftop projects, ensure access to inspection walkways, drainage outlets, rooftop equipment, and machinery. Even if you increase the number of panels to raise power output, a layout that prevents inspection or cleaning will make it difficult to sustain power generation in the long term. For land projects, secure maintenance access paths, vegetation control, drainage, and working space around equipment.

In performance management, comparing data before and after countermeasures is important. Confirm whether power generation improved after cleaning, whether generation during specific time periods increased after shade mitigation, and whether output recovered after equipment inspection. Recording the effects of improvements makes future maintenance decisions easier.

Also, keep a record of the simulation conditions from the time of installation. If equipment capacity, installation extent, azimuth, tilt, shading, loss rates, and solar irradiance conditions are known, it becomes easier to analyze discrepancies with actual performance. Without knowing the assumptions, it is difficult to determine whether low power generation is due to site conditions or the equipment condition.

Maintenance planning and performance management may seem like low-profile measures to increase power generation. However, in the long term they are among the most important areas to review. To raise power generation, it is necessary not only to implement measures but also to verify their effectiveness and establish a system for continuous management.

Decisions to avoid when trying to increase power generation

What should be avoided when trying to increase the power generation of solar panels is considering adding panels or replacing equipment without first identifying the cause. If the low output is due to shade, dirt, or equipment shutdown, on-site inspection and maintenance may be more effective than adding panels. It is important to first confirm what is causing the reduced power generation.

Avoid judging the effectiveness of improvements solely by annual power generation. Even if annual generation increases, if the increase only becomes surplus, improvements in self-consumption and the benefits of installation will be limited. When increasing generation, check self-consumption, excess electricity, and the time periods in which generation occurs.

Be careful not to force adding panels in shaded areas or in locations that are difficult to maintain. Increasing system capacity will generally raise total power generation, but in places with significant shading the generation per unit of capacity may be lower. Arrangements that prevent inspection or cleaning make it difficult to maintain generation over the long term.

Underestimating loss rates is also problematic. If improvement effects are calculated without adequately accounting for temperature, soiling, snow accumulation, wiring, power conversion, and aging, the expected and actual results may diverge after installation. To increase power generation, comparisons should be made using realistic simulations tailored to local conditions.

It is a decision to avoid postponing on-site surveys. Drawings and aerial photographs alone may not make it possible to accurately grasp rooftop equipment, trees, piping, drainage, inspection routes, slopes, elevation differences, and other factors. Measures to improve power generation should be decided after accurately assessing the on-site conditions.

The purpose of increasing power generation is not to enlarge the apparent installed capacity. It is to recover the power that is currently being lost and to establish conditions that allow for stable, long-term generation. It is important to choose improvement measures based on data and on-site verification.

Summary

To increase the power generation of solar panels, it is important to identify the causes reducing output before increasing the number of panels. Points to review are wide-ranging, including generation data, shading, soiling, orientation, tilt, temperature, wiring, equipment, snowfall, fallen leaves, bird damage, and maintenance planning. Measures to increase output are not singular; priorities must be set according to site conditions.

In Review 1, organize the power generation data by month and by time of day. Check which months, which time periods, and which installation surfaces are showing reduced generation. In Review 2, check the sources of shading and seasonal changes. Shadows in winter and during mornings and evenings are major causes of reduced generation. In Review 3, review the cleanliness of the panel surfaces and the cleaning conditions. When dirt accumulates, generation will decrease even with the same equipment.

Review 4 checks for wasted orientation, tilt, and layout. Prioritize surfaces that are easier to generate power on, and avoid forcing expansions into shaded or otherwise unfavorable areas. Review 5 checks temperature rise and ventilation conditions. In summer and for rooftop installations, temperature-related losses can make it difficult for generation to increase. Review 6 checks wiring, equipment, and output limits. The route that brings the power generated by the panels into a usable state for the facility is also important. Review 7 manages seasonal factors such as snow accumulation, fallen leaves, and bird damage. Review 8 continues maintenance planning and performance management. To sustain generation over the long term, it is necessary to continue verifying the effects of measures with data.

When trying to increase power generation, what you should avoid are adding equipment without confirming the cause, judging solely by annual generation, and increasing panels at the expense of maintainability. Improving power generation is not about increasing apparent installed capacity, but about accurately addressing the on-site causes that are reducing generation.

Accurate on-site information forms the foundation for increasing power generation. If you can accurately assess the installation area, rooftop equipment, obstacles, trees, site boundaries, orientation, slope, inspection access routes, and potential connection points, it becomes easier to organize issues related to shading, soiling, temperature, wiring, and maintainability.

If you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, tilt, inspection routes, and so on, and clarify improvement points to increase solar panel power generation, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. By acquiring high-precision on-site location information, it becomes easier to sort out causes of shading, places prone to soiling, installable areas, wiring routes, and maintenance routes, and to proceed consistently from on-site verification for power generation improvement and simulation comparisons to post-installation performance management. To truly increase solar panel power generation, it is important not only to pursue desk-based improvements but also to accurately grasp the site and respond appropriately to the causes that are reducing generation.