10 Causes and Improvement Measures for Low Solar Power Generation

When operating solar power systems, you may feel, "the output is lower than expected," "the output has declined compared to last year," or "I don't know how to increase output." The causes of low output are not necessarily singular; shading, soiling, seasonal variations, temperature rise, snowfall, equipment degradation, wiring or device malfunctions, and misjudged simulation conditions may overlap. What matters is not to immediately consider equipment replacement or expansion, but to check in order where the output is being lost. This article explains, in 10 items for practitioners searching for "how to increase output," the causes of low solar power generation and improvement measures.

Table of Contents

• What to check first if you feel your power generation is low

• Cause 1: Treating weather or seasonal fluctuations as abnormal

• Cause 2: Generation is reduced due to the effects of shading

• Cause 3: Dirt on the panel surface is reducing the amount of sunlight received

• Cause 4: Temperature-related losses caused by high temperatures

• Cause 5: Panels are covered by snow or fallen leaves

• Cause 6: Orientation or tilt angle does not match the conditions for power generation

• Cause 7: There are losses or faults in wiring or power conversion equipment

• Cause 8: Not accounting for equipment degradation or aging-related changes

• Cause 9: Confusing generated power with self-consumption

• Cause 10: Not accurately understanding on-site conditions

• Prioritize improvement measures to increase power generation

• Summary

What to check first if you feel the power generation is low

When you feel the solar power generation is low, the first thing to do is not to assume something is wrong by looking only at the generation numbers. First, you need to confirm which conditions those numbers are being compared against. Whether the output is lower than the previous month, lower than the same month last year, lower than the simulated value, or lower than the typical generation for the same system capacity will determine what you should check.

Solar power generation is affected by weather, seasons, temperature, solar irradiance, shading, dirt, snow, and other factors. Therefore, judging output as "low" based only on a single month's generation can lead to mistaking natural seasonal variations for equipment abnormalities. For example, in winter, shorter hours of sunshine and a lower solar altitude make generation more likely to decrease. In summer, although solar irradiance is higher, panel temperatures rise and generation efficiency can decline. During the rainy season and periods of prolonged rain, fewer sunny days make it difficult for generation to increase.

To correctly assess power generation, it is useful to check by month, by time of day, and by installation surface. Viewing by month reveals seasonal trends. Viewing by time of day shows whether output is low only in the morning, drops at midday, or falls early in the evening. Viewing by installation surface lets you determine whether only a specific roof surface or panel group has low output or whether the entire system is underperforming.

Also, when power generation is low, we check not only the generation itself but also on-site consumption and surplus electricity. Even if generation is lower than expected, if the decrease occurs during a period that already has a large surplus, the practical impact may be limited. On the other hand, if generation falls during periods of high facility demand, it directly impacts the effectiveness of reducing the amount of electricity purchased.

To consider how to increase power generation, it is important to first isolate the causes. By checking in order whether it is the weather, shading, dirt, equipment, or site conditions, the priority of improvement measures will become clear. Before hastily adding or replacing equipment, confirming from both data and on-site inspection the reasons why generation appears low is the first step to an improvement that will not fail.

Cause 1: Mistaking Weather and Seasonal Variations for Abnormalities

The most basic thing to check when solar power output is low is the weather and seasonal variations. Because solar power generation relies on sunlight, output decreases in months with many cloudy or rainy days, months with shorter hours of sunshine, and months with snowfall. This is not an equipment malfunction but a fluctuation due to natural conditions.

What beginners particularly tend to overlook is making simple month-to-month comparisons. For example, it is natural for power generation to decrease from summer to autumn and from autumn to winter. In winter, daylight hours are shorter and the sun’s altitude is lower, so even under the same clear-sky conditions you may not generate as much as in summer. Also, because of the lower solar altitude, shadows cast by surrounding buildings, trees, and rooftop equipment extend farther, which can further reduce power generation in winter.

Conversely, in spring and autumn the balance between solar irradiance and ambient temperature is often favorable, so systems can generate electricity relatively easily. Although summer tends to produce higher generation because of increased solar irradiance, output can fall when panel temperatures rise. Therefore, even if you feel "it's not generating as much as expected for summer," you should check for temperature-related losses and weather conditions.

As a corrective measure, first compare the power generation to the same month in the previous year and to the same season. Further, cross-check against simulated monthly generation values and past trends. Do not deem it an anomaly simply because it is lower than the previous month; verify whether the generation is reasonable for the season and whether it is low even when accounting for the weather.

When weather or seasonal variations are the cause, there is often no major problem with the equipment. However, if power generation is lower than can be explained by seasonal variation alone, you should check for other causes such as shading, soiling, or equipment malfunctions. To increase power generation, it is important to distinguish between declines due to natural conditions and declines that can be corrected.

Cause 2: Power generation is reduced due to the effects of shading

Shading is a common cause of reduced solar power generation. When panels are shaded, they cannot receive sufficient sunlight, and power output decreases. The impact of shading may appear only during certain times of day or may change significantly with the seasons. Therefore, when you feel that power generation is low, you should always check for the presence of shading.

Sources of shadows include surrounding buildings, rooftop equipment, rooftop penthouses, handrails, piping, air-conditioning equipment, utility poles, signboards, trees, slopes, differences in terrain elevation, etc. Even if there were no problems at the time of installation, shadows can appear later as trees grow, structures are added nearby, or rooftop equipment is installed.

Shadows change with the seasons. In summer, the sun's angle is higher, so shadows are shorter and may seem less problematic. However, in winter the sun's angle is lower, and shadows stretch longer. Even locations that had no shading during on-site checks in summer may cast shadows on panels in winter. If only winter power generation is significantly lower, it is important to check for winter shadows.

By looking at power generation by time of day, it becomes easier to infer the cause of shading. If generation is low in the morning, suspect shading on the east side; if generation falls early in the evening, suspect shading on the west side; if there is an abnormal dip around midday, consider shadows from rooftop equipment, penthouse structures, or piping near the panels. If only a particular surface is producing less power, check whether that surface is being shaded.

As mitigation measures, you can avoid installing in areas with heavy shading, review the placement, consider pruning trees, and focus inspections on the surroundings of obstacles that cause shade. Even if systems are already installed, identifying the sources of shade and recording the times and extent of shading will make it easier to explain the causes of reduced power generation.

In shade mitigation, the important thing is not to eliminate all shadows, but to identify the shadows that significantly affect power generation and prioritize measures against them. Once you understand the impact of shading, it becomes clear which areas to review to increase power output.

Cause 3: Dirt on the panel surface makes it harder to receive solar radiation

Dirt on the panel surface is also a major cause of reduced power generation. Because solar panels generate electricity by receiving sunlight on their surface, when dirt adheres it becomes harder for light to reach the cells, lowering generation efficiency. Dirt can appear suddenly, but in many cases it accumulates gradually, so it can be difficult to notice as the cause of reduced output.

Causes of soiling include sand and dust, pollen, fallen leaves, bird droppings, exhaust-related deposits, particulate matter, and residual deposits after snowfall. In locations with many trees nearby, surfaces are more susceptible to accumulation from fallen leaves and birds. If there are unpaved areas, farmland, material storage yards, land under construction, or roads with heavy traffic nearby, soil dust and particulates are more likely to adhere. On rooftops, dirt can easily accumulate near exhaust outlets and ventilation equipment.

The impact of dirt also depends on the tilt angle of the panels. If the tilt is sufficient, light dirt may be washed away by rain. However, if the tilt is small or if bird droppings, fallen leaves, or dust have adhered, rain alone may not be enough to remove them. In particular, if dirt remains on the lower edge of a panel or in certain areas, it can affect power generation.

As a countermeasure, first check the condition of dirt within the range that can be inspected safely. If power generation is gradually declining, only certain panels are producing less power, or generation does not recover after rain, suspect soiling. If cleaning is necessary, choose methods that will not damage the panels and ensure safety. Roof work is hazardous, so avoid attempting tasks beyond safe limits.

Measures to prevent soiling are not something you do just once. In spring there is pollen and airborne dust, in autumn fallen leaves, and in winter residues left after snowfall—the types of soiling change with the seasons. By setting inspection timing according to local conditions and identifying locations prone to soiling, you can more easily prevent reductions in power generation.

To increase power generation, keeping the condition of the panel surfaces good is fundamental. Before considering expanding or replacing equipment, first check whether dirt is causing a loss of the panels' expected power output.

Cause 4: Temperature losses due to high temperatures

Temperature losses from high temperatures should not be overlooked as a cause of low solar power generation. Although solar power generation tends to increase with greater solar irradiance, output can fall when panel temperatures rise. Therefore, in summer, despite the high solar irradiance, power generation may not increase as much as expected.

Temperature loss can occur, particularly in rooftop installations. When the roof surface becomes very hot or ventilation behind the panels is poor, panel temperatures are likely to rise. On flat roofs using low mounting structures, or where there is a lot of equipment nearby that restricts airflow, heat can also become trapped.

Ground-level installations can often be relatively easy to keep well-ventilated, but if grass grows and obstructs airflow or nearby structures make it hard for wind to pass through, the temperature environment can be affected. In other words, temperature loss is influenced not only by the regional air temperature but also by the heat-dissipation conditions at the installation site.

Countermeasures include arranging panels so as not to obstruct ventilation behind the panels, keeping equipment and mounting structures from trapping heat, and ensuring vegetation or other obstacles do not impede airflow. However, changing mounting height or tilt angle to prioritize heat dissipation can affect wind loads, constructability, inter-row shading, and installed capacity. Therefore, decisions should not be made based solely on temperature measures; power generation, constructability, maintainability, and safety must be considered together.

When analyzing power generation data, focus on summer output. If output is not increasing in months that should have high solar irradiance, temperature-related losses may be involved. Spring or autumn may show more stable generation. To increase output, do not evaluate summer generation solely by irradiance; it is important to account for temperature-induced output reductions.

Thermal losses are a cause that is not immediately apparent, but they affect annual power output. For facilities that prioritize on-site consumption during the summer, it is important to realistically assess power output under high-temperature conditions and to ensure installation and maintenance environments that facilitate heat dissipation.

Cause 5: Panels Covered by Snow or Fallen Leaves

Accumulation of snow or fallen leaves covering the panels can also cause low power generation. Because solar panels generate electricity by receiving sunlight, when the surface is covered by snow or leaves the area able to generate power is reduced and the amount of power generated drops significantly. Even partial coverage can affect generation, and this often appears as a pronounced seasonal decrease in output.

In snowy regions, decreases in winter power generation should be carefully considered. Not only the hours during which snow is falling, but also the time snow remains on the panels after a snowfall affect generation. If the panels have a shallow tilt angle or cold days persist, snow may not slide off easily and the period of generation stoppage can become long. Even after snow has slid off, snow accumulated at the lower edge or in front of the panels can cast shadows.

The impact of fallen leaves should not be overlooked. In locations with many trees nearby, leaves can accumulate on and around panels in autumn, causing reduced power generation and poor drainage. Fallen leaves not only cast shadows, but can also stick to the panel surface when wet or collect in drainage outlets. In rooftop projects, leaves accumulating around drainage outlets can also affect building maintenance.

As a countermeasure, it is important to identify locations prone to snowfall or falling leaves and to carry out inspections appropriate to the season. In snowy regions, check panel tilt, snow fall zones, snow accumulation space, and inspection access routes. In areas with many fallen leaves, manage surrounding trees, check drainage outlets, and inspect panel surfaces.

However, clearing snow or removing leaves from roofs carries safety risks. Avoid attempting work beyond your limits and choose methods that will not damage the equipment or the roof. Measures to increase power generation are meaningless if they compromise safety or the protection of the equipment.

Snow accumulation and fallen leaves are seasonal factors, but they can recur every year. If power generation drops during a particular season, don't simply attribute it to seasonal variation; check whether the panels are being covered.

Cause 6: Orientation or tilt angle do not match the conditions for power generation

If the orientation or tilt angle does not match the conditions for power generation, it can also cause lower solar power output. The amount of power a solar panel generates changes depending on the angle at which it receives sunlight. Because of constraints such as installation location and roof shape, it is not always possible to install panels at the ideal orientation or tilt, but it is important to understand the conditions.

Orientation affects annual power generation and the times of day when generation occurs. Surfaces that face closer to south tend to achieve higher annual generation, but east- and west-facing surfaces are not necessarily worse. East-facing surfaces tend to generate more in the morning, and west-facing surfaces in the afternoon. If a facility's electricity demand is skewed toward the morning or afternoon, generation from east- and west-facing surfaces can help with self-consumption.

The tilt angle affects seasonal power generation. Depending on the angle, the layout may be optimized for stronger summer output, for easier winter generation, or for a configuration that achieves a more balanced annual output. Increasing the angle can make it easier to receive winter solar radiation, but it affects inter-row shading, wind, snow accumulation, and constructability. Decreasing the angle can make it easier to increase installed capacity, but it may also make soiling and snow retention more likely.

On rooftop projects, because installations are often matched to the existing roof’s orientation and slope, it can be difficult to make major changes after installation. In such cases, it is important to check the power generation for each surface and prioritize using the surfaces with better generation conditions. When adding capacity or revising the layout, it can be more effective to utilize surfaces with better conditions or areas with less shading than to force additional panels onto surfaces with low generation.

For ground-mounted projects and flat roofs, you can compare mounting angles and layout orientations. Simulate multiple patterns and evaluate them together based on annual generation, monthly generation, self-consumption, surplus electricity, inter-row shading, and maintainability. It is important to choose conditions that not only provide the theoretical maximum generation but can also be constructed on-site and managed over the long term.

If energy output is low because of orientation or tilt angle, it may not be possible to improve it immediately. However, if you understand the causes, you can move to a better design when expanding capacity, changing the layout, during the next renovation, or when replacing equipment. To increase energy output, it is important to correctly understand site conditions and choose a layout that is likely to receive sunlight.

Cause 7: Losses or faults in wiring and power conversion equipment

Even if the panels themselves have no problems, losses or faults in the wiring or power conversion equipment can reduce the amount of electricity actually available for use. Solar power systems work by sending the electricity generated by the panels to the facility through wiring and equipment. Therefore, you need to check not only the panels but also the condition of the components that carry and convert the power.

Wiring losses occur during the process of delivering power from the panel to the equipment and from the equipment to the facility-side equipment. When wiring distances are long, wiring routes are complex, or connection points are difficult to inspect, it becomes hard to verify losses or faults. If wiring routes or equipment locations have been changed from the initial design, the expected losses may differ from the actual losses.

Malfunctions of power conversion equipment can also cause reductions in power generation. Even if the panels themselves are capable of producing electricity, if the equipment is not operating, the amount of electricity available to the facility will decrease. If only some systems are showing low generation, it is necessary to check the equipment, connection points, and wiring for abnormalities. When generation drops suddenly, suspect equipment shutdown or poor connections rather than dirt or seasonal variation.

We also check the balance between equipment capacity and panel capacity. Even if panel capacity is increased, output can become capped due to the equipment-side capacity or connection conditions. The presence of a capped output is not necessarily bad in itself, but it is necessary to check during which time periods and to what extent generation is being curtailed. If the generation peak coincides with facility demand, also check the impact on self-consumption.

As a countermeasure, it is effective to check power generation data by system and by equipment to see whether only specific areas are showing reduced output. Whether the output is low overall or only in part will change which locations need to be inspected. It is also important to ensure equipment is arranged for easy access, that there is space for inspections, and that anomalies can be checked when they occur.

To increase power output, check not only the panel surface and any shading but also the path the electricity takes to reach the facility. By reviewing the condition of wiring and equipment, you may be able to restore the power output that should have been achieved.

Cause 8: Failing to account for equipment degradation and aging

Solar power generation systems are intended for long-term use, and their performance immediately after installation does not remain unchanged. If equipment degradation and aging are not taken into account, this can be a reason why the power output feels low after several years. In particular, when comparing against the simulation values at the time of installation or the first-year generation, it is necessary to consider aging effects.

Aging-related changes include degradation of panel performance, deterioration of power conversion equipment, changes in the condition of wiring and connections, deterioration of mounting structures and fasteners, accumulation of dirt, and changes in the surrounding environment. These do not necessarily occur all at once and may gradually affect power generation.

The aging of panels is an unavoidable factor in long-term operation. However, it is not appropriate to immediately assume panel degradation just because power generation is low. First check the weather, shading, dirt, equipment, and wiring, and only if the decline cannot be explained after those checks should you suspect equipment deterioration.

Power conversion equipment and peripheral devices also require inspection during long-term operation. If equipment condition deteriorates, the power generated by the panels may not be fully utilized. Faults in wiring or connections can also cause reduced output or shutdown. Regular inspections and record-keeping are important.

Changes in the surrounding environment should also be considered part of the aging process. Changes such as trees growing and increasing shade, rooftop equipment being added, buildings being constructed nearby, or increased dust from unpaved areas affect power generation. Even if the equipment itself has not deteriorated, if the site conditions differ from those at installation, power generation will decrease.

As a remedial measure, compare the simulation conditions at the time of installation with the current on-site conditions. Check the installation area, shading, obstructions, susceptibility to soiling, equipment condition, and maintenance records, and clarify the causes of the decline in power generation. In the long term, record monthly generation and generation by installation surface to determine whether output is gradually decreasing or whether it dropped suddenly during a specific period.

Equipment deterioration and aging-related changes cannot be completely avoided, but if noticed and addressed early, declines in power generation can be mitigated. Increasing power generation requires inspections and performance management that are premised on long-term operation.

Cause 9: Confusing power generation with self-consumption

Among the reasons you may feel generation is low, in some cases it is not the amount of power generated itself but differences in understanding of self-consumption and the benefits of installation. The electricity generated by solar power is not all used on-site. It is important to consider power generation, self-consumption, and surplus electricity separately.

Generation refers to the amount of electrical energy produced by a solar power generation system. Self-consumption refers to the portion of that electricity that was used within the facility. Surplus electricity refers to the portion of generated electricity that could not be consumed within the facility during the same time period. Even if generation is sufficient, if the facility’s demand and the time of day do not align, self-consumption tends not to increase.

For example, if generation occurs during the day but the facility’s electricity use is concentrated at night, the amount that can be self‑consumed will be limited. Even if self‑consumption is possible on weekdays, surpluses will increase if demand is low on holidays. Even when annual generation is as expected, changes in how the facility uses electricity can make self‑consumption and electricity bill savings seem lower than anticipated.

Before aiming to increase power generation, determine whether the issue is low generation or low self-consumption. If the generation itself is low, check for shading, soiling, equipment problems, temperature, and snow accumulation. If generation is sufficient but the installation’s effectiveness is low, examine the facility’s demand patterns, the amount of surplus electricity, and the potential for batteries or load adjustment.

As a countermeasure, overlay monthly and time-of-day power generation and electricity consumption. Check whether there is demand during periods of high generation and in which time periods surpluses occur. If surpluses are large, consider whether the installed capacity is too large relative to demand, whether loads can be shifted toward daytime, and whether they can be utilized with battery storage.

Increasing generation output and improving the effectiveness of an installation are not necessarily the same. In practice, it is important not only to increase the amount that can be generated but also to increase the amount that can be used. By checking generation output, self-consumption, and surplus electricity separately, you can avoid misidentifying the areas that need improvement.

Cause 10: Inability to accurately assess on-site conditions

Not being able to accurately assess on-site conditions is also a major cause of low solar power generation. If the condition of roofs or land, obstacles, orientation, tilt, shading, and inspection/maintenance access routes are not accurately captured during the simulation and design stages, the actual performance after installation is likely to differ from the predictions.

For roof projects, it is necessary to accurately verify rooftop equipment, piping, roof penthouses, guardrails, drains, inspection openings, waterproofing condition, roof slope, and the positional relationship with surrounding buildings. Areas that appear to be free on drawings may in fact be unusable because they are required for equipment inspection or drain cleaning. If the height and position of rooftop equipment are not accurately understood, the impact of shadows may be underestimated.

In land projects, we check site boundaries, trees, utility poles, slopes, elevation differences, drainage channels, existing structures, maintenance access routes, and candidate connection points. Even if land appears large, the area available for installation may actually be limited by slopes, poor drainage, tree shading, or boundary constraints. If elevation differences are not properly understood, issues with shading, drainage, and constructability can arise later.

If site conditions are not adequately understood, it becomes difficult to verify later the causes of reduced power output. If there is no record of which area was used at the time of installation, which obstacles were taken into account, and which shadows were anticipated, it becomes hard to analyze the causes when actual performance is low.

As a countermeasure, during the site survey accurately record the installation area, obstacles, causes of shading, inspection routes, and equipment locations. After installation, regularly check for tree growth, additions to rooftop equipment, and changes in the surrounding environment. Keeping the site information updated will make it easier to identify the causes of reduced power generation.

Measures to increase power generation are effective only after the on-site conditions are accurately understood. Rather than deciding on improvements based solely on desk calculations, it is important to inspect the site and specifically identify the causes that are reducing power generation.

Prioritize measures to increase power generation

There are multiple causes for low solar power generation, so there is no single corrective measure. What’s important is to address issues in order, starting with the causes that have the greatest impact on output. Instead of immediately considering equipment replacement or expansion, begin with low-cost checks—inspections, cleaning, shadow checks, and data analysis—to reduce unnecessary actions.

First, check the generation data and identify the pattern of the decline in power output. Determine whether it is lower by month, by time of day, or only on a particular surface. Next, perform an on-site inspection and check for shading, dirt, fallen leaves, snow accumulation, equipment condition, wiring, and inspection access routes. By looking at both the data and the site, it becomes easier to isolate the cause.

The priority of improvement measures is determined by the magnitude of the cause and the ease of addressing it. If soiling is evident and can be cleaned, improvement through cleaning can be expected. If the cause of shading is trees and they are within a manageable range, pruning can be considered. If equipment shutdown can be confirmed, inspection and repair should be prioritized. Issues with orientation or tilt may not be immediately changeable on existing installations, but they can be applied to design improvements when expanding or upgrading.

When increasing power generation, it is also important to compare data from before and after improvements. After implementing measures, check how much monthly generation and generation by time of day have changed. If the effectiveness of the improvements is visible, it becomes easier to decide which measure to take next. If no effect is seen, re-examine other possible causes.

Also, consider increasing power generation and increasing self-consumption separately. If increased generation only leads to more surplus, the improvement in the effectiveness of the installation is limited. It's important to confirm whether generation increases during the facility's demand hours or whether self-consumption increases.

Improving power generation is not something that can be completed in a single effort. Local environmental conditions, equipment condition, the seasons, and how the facility is used all change. By regularly checking data and performing necessary inspections, cleaning, and reassessments of equipment placement, it becomes easier to maintain power generation over the long term.

Summary

The causes of low solar power generation are varied, including weather and seasonal variations, shading, soiling, temperature-related losses, snow cover, orientation and tilt, wiring and equipment malfunctions, system degradation, mismatches with self-consumption, and insufficient understanding of local site conditions. To increase generation, it is important to isolate each cause one by one and prioritize measures that have the greatest effect.

For Cause 1, check whether weather or seasonal variations are being mistaken for abnormalities. For Cause 2, check the impact of shading. Shadows in winter or at dawn and dusk, and shadows from trees or rooftop equipment are major causes of reduced power output. For Cause 3, check the cleanliness of the panel surface. Sand and dust, pollen, fallen leaves, bird droppings, and particulate matter reduce generation efficiency. For Cause 4, check for temperature losses due to high heat. In summer and for rooftop installations, rising panel temperature affects power output.

For Cause 5, check whether the panels are covered by snow or fallen leaves. For Cause 6, verify that the orientation and tilt angle match the conditions for power generation. For Cause 7, check for losses or faults in the wiring and power conversion equipment. For Cause 8, account for equipment deterioration and aging-related changes. For Cause 9, verify that generated power and self-consumption are not being confused. For Cause 10, confirm that the on-site conditions are being accurately understood.

Improvement measures are carried out by combining data analysis and on-site verification. By examining monthly generation, generation by time of day, and generation by installation surface, it becomes easier to identify where generation is being lost. On site, check for shading, dirt, obstacles, equipment, wiring, and inspection routes. After improvements, compare how much generation and self-consumption have changed, and use that to inform the next measures.

Accurate on-site information is the foundation for increasing power generation. 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 address issues such as shading, soiling, wiring, and maintainability.

If you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, tilt, inspection and maintenance routes, etc., and identify the causes of low solar power generation to develop improvements, using LRTK, an iPhone-mounted high-precision GNSS positioning device, is effective. By obtaining highly accurate on-site positional information, it becomes easier to sort out causes of shading, areas prone to soiling, feasible installation areas, cable routing, and maintenance access routes, and to carry out on-site verification for generation improvement, simulation comparisons, and post-installation performance management in a consistent manner. To correctly identify the causes of low solar power generation and increase output, it is important not to rely solely on desk-based assumptions but to accurately understand the site and appropriately address the factors that are reducing generation.