8 Reasons Power Generation Isn't Increasing | How to Improve It and Review Procedures

Table of Contents

• When power output isn't increasing, don't assume there's only one cause

• Cause 1: Reviewing generation data too roughly and overlooking anomalies

• Cause 2: Confusing reductions due to weather or solar irradiation conditions with equipment faults

• Cause 3: Dirt or deposits on panel surfaces are reducing the amount of light received

• Cause 4: Some generation is being obstructed by shadows from weeds or trees

• Cause 5: Not noticing differences in generation at the string level

• Cause 6: Faulty connections or cables are preventing electricity from being collected

• Cause 7: Power generation is capped by shutdowns of power conversion equipment or output curtailment

• Cause 8: Power generation losses are recurring due to poor drainage or changes in terrain

• Review procedure for implementing power generation improvements in practice

• Summary

When power generation isn't increasing, don't assume it's caused by just one factor

When solar power generation is not increasing, the first thing you need to do is avoid assuming a single cause and instead sequentially isolate where generation losses are occurring. Even if you feel that output is low, not growing as expected, or has declined compared to the previous year, the reasons vary by site. Sometimes the issue can be explained solely by weather conditions, while other times multiple factors overlap, such as dirt on panel surfaces, shadows from weeds or trees, faults at connection points, equipment shutdowns, poor drainage, or insufficient record-keeping.

For practitioners searching "how to increase power generation," the first point to grasp is that with solar power generation you cannot increase the amount of incoming solar irradiance at the site itself. However, you can move closer to a state in which the received sunlight is converted into electricity with as little waste as possible. In other words, the practical work of increasing generation is to identify the causes of lost potential generation and reduce generation losses.

A condition in which power generation does not increase cannot be judged by appearance alone. Even if the panels are lined up and show no major damage from a distance, there may be cases where only some rows are dirty, shadows occur only in the morning and evening, generation becomes unstable only after rain, only certain strings have low output, or power conversion equipment repeatedly stops for short periods. If you only look at monthly generation figures, these kinds of partial losses tend to be overlooked.

Also, to determine the cause of low power generation, it is necessary to link generation data with on-site conditions. From data alone, you cannot tell whether the issue is shading, soiling, equipment faults, or drainage. Even site photos alone make it difficult to judge how much these factors affect generation. By checking the time periods, equipment, and locations where generation is falling in the data, and then inspecting those sites on the ground, the points that need to be improved become clear.

Efforts to increase power generation do not end with a single cleaning or weeding. Outdoor solar power plants are constantly affected by the seasons, weather, the surrounding environment, and the condition of equipment. Even after cleaning, dirt returns; even after weeding, grass grows back; trees grow; and drainage paths change. That is why it is important to operate the identification of causes, implementation of countermeasures, verification of effects, and updating of records as a single continuous process.

Cause 1: Missing anomalies by viewing power generation data only roughly.

One of the first things to check when power generation isn’t improving is whether the way you view generation data is too coarse. If you only look at monthly or annual generation figures, you won’t know when, where, or how generation losses are occurring. Even if nothing looks significantly abnormal on a monthly basis, there may be cases where output drops only during certain hours on sunny days, or where a particular piece of equipment consistently performs worse than the surrounding units.

It is important to view power generation data broken down by time of day, by equipment unit, by day, and by season. If generation is low only in the morning, shadows from trees, structures, slopes, or terrain on the east side are suspected. If it is low only in the evening, check for west-side shading and influences from surrounding equipment. If the midday peak does not reach expected levels, candidates include soiling on panel surfaces, temperature rise, limits of the power conversion equipment, shutdowns, and output curtailment. If there is a sudden drop in the generation curve, you need to cross-check alarm and shutdown histories against the time.

When comparing by equipment unit, it is important to compare equipment under the same conditions. If you simply compare installations with different numbers of panels, orientation, tilt, shading conditions, or connection configurations, you may misinterpret normal differences as abnormalities. If only some sections remain consistently lower compared with adjacent rows or equipment facing the same direction, you should suspect on-site causes rather than the weather. You can narrow down the range to check—such as soiling, shading, poor connections, cable damage, or equipment faults.

Declines in power generation can be sudden or gradual. Sudden declines may be related to equipment shutdowns, wire breaks, poor connections, the emergence of obstructions, or similar issues. When the decline is gradual, it may be related to the buildup of dirt, the growth of weeds or trees, changes in equipment condition due to aging, or deterioration of site conditions caused by poor drainage. By observing the pattern of the decline, you can see what should be prioritized for inspection on site.

As a countermeasure, it is effective to establish criteria for reviewing power generation data. Decide how often to check, how large a discrepancy should trigger an on-site inspection, and down to which equipment unit to monitor; doing so allows anomalies to be detected sooner. Relying solely on the intuition of personnel leads to oversights and inconsistent judgments. To increase power generation, it is important to narrow down targets using data before conducting on-site work.

Cause 2: Mistaking declines caused by weather or solar irradiance conditions for equipment malfunctions

When you feel your power generation is underperforming, before suspecting equipment faults you should check the weather and solar irradiance conditions. Solar power generation is heavily influenced by the amount of sunlight, so during periods with many cloudy or rainy days, power output will decline even if there is no equipment problem. If you compare only monthly generation with the same month last year or with the previous month and immediately conclude there is a malfunction, you may find that differences in weather were the main cause.

On the other hand, you must avoid overlooking a real anomaly by attributing it to the weather. If the entire power plant shows a similar decline consistent with local weather, the impact of solar irradiance conditions is likely significant. However, if only part of the plant is performing below normal while other equipment in the same plant is operating as usual, or if outputs are clearly lower compared with other sites in the same region, weather alone cannot explain it. In such cases, it is necessary to check for soiling, shading, poor connections, converter/inverter shutdowns, output curtailment, and so on.

To separate weather-related differences, it is effective to compare sunny days with each other, days with similar weather, and generation trends within the same region. On cloudy or rainy days, generation can fluctuate greatly due to cloud movement, making it difficult to distinguish from equipment faults. By selecting and comparing generation curves from sunny days, features such as shading, shutdowns, curtailment, and string anomalies become easier to detect.

Seasonality should also be taken into account. In winter, solar elevation is lower, and shadows from surrounding trees and terrain tend to extend farther. In summer, although solar irradiance is stronger, panel temperatures and the temperatures around equipment rise, which can make it harder for output to increase. During periods of heavy rainfall, monthly power generation tends to be lower, and after strong winds or heavy rain attention should be paid to soiling, sediment, poor drainage, and the condition around cables.

As a countermeasure, record separately the natural variations caused by weather and the generation losses that can be improved on-site. For days when generation was low, review the weather, the generation curve, comparisons with other facilities, and the on-site conditions together. Establishing a system that, after understanding the impact of weather, prevents overlooking equipment abnormalities is fundamental to increasing power generation.

Cause 3: Soiling and deposits on the panel surface are reducing the amount of light received

Dirt and deposits on the panel surface are a common cause of reduced power generation. Because solar panels generate electricity by receiving solar radiation at the surface, when dirt adheres, the light reaching the cells is reduced. Soil dust, pollen, yellow sand, bird droppings, fallen leaves, tree sap, dust from nearby construction, road-derived dust, and salt-containing deposits that readily adhere in coastal areas — how panels become soiled varies greatly depending on the site environment.

Particular attention should be paid to the band-like dirt that remains at the lower edge of panels and around the frame. It is often assumed that rain will wash it away naturally, but in reality the flow of rainwater can collect dirt at the lower edge and leave it there. On panels with a gentle slope, water does not drain well and dirt is more likely to accumulate. Even dirt that is not noticeable from a distance can affect power generation if it covers part of a cell.

Adhesions such as bird droppings and fallen leaves should not be overlooked. Unlike uniform soiling, these accumulate heavily in specific spots and create partial shading. If only some equipment is producing less power, check the panel surfaces in that area. Rows near trees, around structures where birds are likely to perch, leeward rows, and areas near unpaved walkways tend to be more prone to dirt and debris accumulation.

As a countermeasure, it is pragmatic to prioritize cleaning areas that have the greatest impact on power generation. Instead of cleaning all panels at the same frequency, focus on rows where dirt is concentrated, equipment where a decrease in power output has been confirmed, areas where soiling is noticeable along the lower edges, and locations with heavy bird damage or fallen leaves. By comparing photos and power generation before and after cleaning, it becomes easier to determine how much the soiling at that site was affecting power output.

Cleaning must be carried out so as not to damage the equipment. Avoid vigorously scrubbing with hard tools, performing sudden work during periods when the panels are at high temperature, and working without first confirming the electrical safety of the equipment. Cleaning to increase power generation is not a cosmetic task to improve appearance, but a maintenance operation to restore the panels' light-receiving condition and to keep the equipment operating reliably over the long term. By identifying the causes that make dirt likely to accumulate and by reviewing access paths, surrounding vegetation, and locations where birds tend to gather, it becomes easier to prevent recurrence of reduced power generation.

Cause 4: Some power generation is being obstructed by shadows from weeds and trees

One thing you should always check when power generation is not increasing is shading. Because solar panels generate electricity from sunlight, even a shadow over part of a panel can reduce output. Causes of shading include weeds, trees, fences, utility poles, nearby buildings, mounting racks, adjacent rows of panels, monitoring equipment, and other factors. Shadows move with the time of day and the seasons, so the absence of visible shading at the time of inspection does not necessarily mean there is no problem.

Weeds are a common cause of power generation loss at sites. Even if there is no problem in winter or immediately after installation, they can grow rapidly from spring to summer and cast shadows on the lower edges of panels and the front row. Even when vegetation does not touch the panels, the low sun angles in the morning and evening create long shadows. Furthermore, when weeds become overgrown, ventilation deteriorates, inspection walkways become blocked, and it becomes difficult to check around equipment. Because they affect not only power output but also maintainability and safety, weed management is fundamental to improving power generation.

The shadows cast by trees are a factor that can become problematic during long-term operation. Even trees that had little impact at the time of installation can grow over several years and reduce power generation. Trees located especially on the south, east, and west sides cast shadows on panels depending on the time of day. At power plants near woodland or slopes, the elevation of the terrain combined with the height of trees can overlap and create long shadows in winter. If generation is low only in winter, or if there are large drops in the morning and evening, it is necessary to check both the trees and the topography.

As a countermeasure, it is effective to align the power generation data with the timing of on-site inspections. If generation is low in the morning, check the site conditions in the morning; if it is low in the evening, check for shadows in the evening. Even if a noon inspection finds no problems, there can be large shadows in the morning and evening. Also, even if there are no issues in summer, shadows can lengthen in seasons when the sun angle is lower. Shadows need to be managed not as a single point in time but as something that changes with time and season.

When carrying out weeding and pruning, prioritize the areas that have the greatest impact on power generation. Rather than simply grooming the entire site uniformly, focus especially on the front of the panels, areas around equipment, inspection walkways, and directions where shadows are likely to extend. After work, record whether shadows were actually eliminated, whether inspections became easier, and whether airflow improved. Because shadow problems tend to recur, do not treat it as a one‑time task; annual management that anticipates grass and tree growth is important.

Cause 5: Not noticing string-level differences in power output

To increase power generation, it is important to check for anomalies at the most granular level possible, not just the overall plant-level figures. Even if the plant's total output doesn't appear to show a major problem, some strings may be experiencing reduced output. If left unaddressed, these partial declines can continue to cause generation losses over the long term.

When checking for anomalies at the string level, it is fundamental to compare items under the same conditions. If you simply compare ones with different panel counts, orientation, tilt, shading conditions, or connection configurations, you may mistake normal differences for anomalies. Check whether any string is consistently lower compared with adjacent rows or installations with the same orientation. If only a specific string is low, potential causes include dirty panels, partial shading, poor connections, cable damage, or equipment-side issues.

Pay attention to how anomalies appear. If the output is consistently lower than the surroundings even on sunny days, dirt or connection problems may be suspected. If it’s lower only in the morning and evening, check for shading effects. If anomalies tend to occur after rain, moisture ingress or the condition of connection points may be involved. If instability appears during periods of high temperature, poor electrical contact or the temperature environment around the equipment are also possibilities. Combining the power generation waveform with on-site conditions makes it easier to narrow down the cause.

As a countermeasure, put in place management practices that allow precise on-site identification of strings suspected to be abnormal. If the management drawings do not match the equipment numbers on site, if row numbers are hard to understand, or if photos alone do not convey the location, inspections and repairs will take longer. Even if a drop in power output is detected in the data, if you cannot reach the relevant location on site, it will take a long time to implement improvements.

Even small differences in power generation can result in significant losses if they continue over a long period. Furthermore, if poor connections or cable damage are involved, this can lead to safety risks as well as reduced power output. Instead of assuming there is no problem because the overall generation hasn’t dropped significantly, it is necessary to manage and detect localized anomalies early.

Cause 6: Unable to draw power due to faults in connectors or cables

In solar power generation, even if panels are receiving sunlight normally, faults in connection points or cables can reduce power output. There are many causes that impede the flow of electricity, such as loose terminals, poor contact, damage to cable sheathing, moisture ingress, damage by animals, damage during grass-cutting operations, and deterioration due to aging. Because these issues can be difficult to detect from appearance alone, it is necessary to narrow down the range of anomalies using power generation data and make a judgment by comparing it with on-site conditions.

You should suspect faults in connections or cables when only specific equipment shows low power generation, when abnormalities tend to occur after rain, when generation suddenly drops, or when output fluctuates unstably. If only part of the system is underperforming despite no dirt or shading being evident, electrical faults should also be considered. If there is a persistent difference compared with a string under the same conditions, prioritize checking the connections and cables.

Cables are components that are highly susceptible to site conditions. In areas with heavy weeds, it becomes difficult to inspect the condition of cables. There is also a risk that mowing work may come into contact with cables. In locations with poor drainage, moisture and puddles can affect connection points. At power plants where animals can easily enter, cable damage may also occur. It is important not to consider connection faults in isolation but to inspect them together with the surrounding environment.

As a countermeasure, compile the equipment showing abnormalities, the time of occurrence, changes in power output, on-site photographs, and the surrounding environment, and, when necessary, connect this to specialized inspections. Checks of electrical equipment must be carried out with safety as the highest priority. Rather than having on-site personnel forcibly touch equipment to make a judgment, it is important to organize the information so the cause can be identified using the correct procedures.

A perspective of preventing recurrence is also indispensable. Even if connection points are repaired, if water still pools in the same spot, vegetation becomes overgrown, cables are prone to exposure, animals can easily enter, or the area remains difficult to inspect, a fault may occur again. Recording where and why faults happened and reviewing the surrounding environment will lead to management that is less likely to cause repeated decreases in power generation.

Cause 7: Power generation has plateaued due to shutdowns or output curtailment of power conversion equipment

The causes of stagnant power output are not limited to the panels and wiring. If the equipment that converts the generated electricity has stopped or its output is being restricted, power output will not increase even if solar irradiance is sufficient. If you want to increase power output, you must always check the operating status of the conversion equipment, shutdown history, alarm history, and whether output curtailment is in effect.

When checking stoppage history, confirm which equipment was stopped, when, and for how long. Even short stoppages can cause large losses if they occur during the daytime when power generation is high. If stops and recoveries are repeated during the day, it may not stand out in the monthly totals, but you may actually be missing generation. Whether only specific equipment stops or multiple units stop simultaneously will change the possible causes you should consider.

If output curtailment is occurring, generation can level off even on sunny days. If the top of the generation curve appears flat, check curtailment records and operational data. However, a flat curve does not necessarily indicate output curtailment. Similar shapes can be caused by equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not judge based solely on the generation curve; it is important to isolate causes by comparing equipment records with on-site conditions.

The surrounding environment of the conversion equipment is also a point that should be checked. Conditions such as weeds growing around the equipment, poor ventilation, excessive dust or deposits, and a tendency for heat to accumulate can affect operational efficiency and increase the risk of shutdown. Even if there are no abnormalities in the equipment itself, poor surrounding conditions can hinder stable operation.

As a countermeasure, compare the drop in power output with the shutdown time to narrow the range of possible causes. If the time when output dropped coincides with an alarm or shutdown time, it becomes easier to identify the cause. Conversely, if there are no abnormalities in the equipment records, suspect other causes such as the panels, wiring, shading, dirt, or solar irradiance conditions. Choosing countermeasures based on generation data and equipment history, rather than on guesswork, is essential for improving power output.

Cause 8: Power generation losses are recurring due to poor drainage and changes in terrain

When power output isn't increasing, it's necessary to check not only the panels and equipment but also the drainage, topography, and inspection access routes of the entire power plant. Places where water tends to accumulate, spots where sediment flows in, paths that easily become muddy, slope collapses, scour around the mounting racks, and locations where cables are likely to be exposed can directly or indirectly cause a decrease in power generation.

Poor drainage may seem to have little direct connection to power generation. However, in places where puddles remain after rain, weeds tend to grow more easily. When weeds grow, they cast shadows, reduce ventilation, and make inspections more difficult. On muddy walkways, work is delayed and the frequency of cleaning and weeding may decrease. In areas where sediment flows in, it accumulates beneath panels and around cables, causing soiling and damage.

When checking topography and drainage, on-site inspections after rain as well as in fair weather are effective. Determine where water flows in, where it pools, and where it drains out. Recording puddles, sediment accumulation, vegetation overgrowth, pathway settlement, and changes in slopes will reveal locations prone to recurrence. If dirt or weeds repeatedly return to the same spots despite cleaning or weeding, you should suspect drainage or topographical problems rather than merely surface-level issues.

Inspection routes also affect power generation improvement. Locations that are difficult to inspect tend to delay the detection of anomalies. If grass has overgrown so you cannot pass, if the ground is muddy and you cannot approach, if equipment numbers are hard to identify, or if it is difficult to share information about abnormal locations, on-site response will take more time. Even if you find low-producing equipment from the data, if it takes time to reach the corresponding spot on site, improvements will be delayed.

As a countermeasure, manage not only the power generation equipment but also the site environment as a whole. Record poor drainage, sediment accumulation, pathway defects, and slope changes, and correlate them with declines in power output and inspection delays. Even if it does not immediately appear as a large improvement in power generation, reducing dirt, weeds, connection faults, and inspection delays helps curb long-term generation losses.

Review Steps for Advancing Practical Measures to Increase Power Generation

To increase power generation, it is important not only to address each cause individually but also to have a review procedure that is practical for day-to-day operations. The first thing to do is to check the generation data. Check not only the monthly totals but also the generation curve on sunny days, declines by time of day, differences by equipment unit, outage history, and alarm history. Here, identify whether the decline is plant-wide, limited to certain equipment, or occurring during specific time periods.

Next, isolate weather and solar irradiance conditions. Check whether the decline occurs during periods with frequent clouds or rain, or if output is low even on sunny days. Compare with generation trends in the surrounding area and with other units at the same plant to identify any equipment-side generation losses that can be corrected. If a decline remains after excluding weather factors, prioritize an on-site inspection.

During on-site inspections, first check for dirt and shading. Look for dirt on the panel surface, accumulation along the lower edge, bird droppings, fallen leaves, weeds, trees, and shadows from structures. If you inspect the site at the times when power generation drops, it becomes easier to find the cause. If output is low in the morning, check for morning shadows; if low in the evening, check for evening shadows; if it doesn’t increase at midday, focus on dirt, temperature, and the area around the equipment.

Next, inspect the strings, connectors, cables, and power conversion equipment. If only some units show lower performance, compare them with units under the same conditions to narrow down the range of abnormalities. If instability occurs after rain, check the environment around connectors and cables. If the power generation curve plateaus or suddenly drops, check for power conversion equipment shutdowns, alarms, output curtailment, and the temperature conditions. When checking electrical equipment, prioritize safety and, if necessary, arrange for a professional inspection.

Finally, review drainage, topography, and inspection records. If dirt or weeds repeatedly appear in the same location, poor drainage or sediment flow may be involved. Abnormalities are discovered late in areas that are difficult to inspect. If inspection results are recorded as photos, date and time, equipment number, location information, and action history, subsequent checks will be faster. Increasing power generation is not a one-off task but an operational practice that links data, on-site conditions, countermeasures, and records.

Summary

There is not a single cause for underperforming power generation. Coarse interpretation of generation data, misjudging the effects of weather or solar irradiance conditions, dirt on panel surfaces, shadows from weeds or trees, generation differences at the string level, faults in connections or cables, stoppage of conversion equipment or output curtailment, poor drainage or changes in terrain—multiple factors combine to reduce generation. In solar power generation, the site cannot increase the solar irradiance itself, but it can move closer to a state in which the received solar irradiance is converted into electricity without waste.

When you want to increase power output, rather than immediately considering major renovations, it’s important to first break the data down and examine it. Check when output is low, which equipment is underperforming, and whether there are differences compared with equipment under the same conditions. Then, by inspecting the site, you can identify where cleaning is needed, the areas that require weeding, connection points that should be inspected, equipment that should be checked, and drainage and traffic flow that should be reviewed. Improving power output should be driven by linking data with on-site conditions, not by intuition.

Also, efforts to increase power generation are not something that can be completed in a single operation. Even if you clean, dirt will return; even if you remove weeds, grass will regrow; trees will grow; drainage routes will change; and equipment and wiring will alter in condition with age. By comparing power generation before and after countermeasures, keeping on-site photos and work records, and applying them to the next inspection, the accuracy of improvements is enhanced. To increase power generation consistently, it is essential not only to remove the causes but also to establish a site environment and management system that are less prone to deterioration.

In particularly large power plants, a system for accurately sharing the locations of problem areas is necessary. If shadowed areas, rows prone to soiling, places where water pools, anomalous strings, repair locations, and inspection photos are recorded together with location information, stakeholders can more easily confirm the same spot. By combining power generation data with on-site location information, it becomes easier to explain the priority of countermeasures and to streamline future inspections and recurrence checks.

If you want to accurately identify the reasons why power generation is not increasing and continue review procedures on site, using LRTK is also effective. As an iPhone-mounted GNSS high-precision positioning device, LRTK is useful for recording inspection locations within a solar power plant, shadow occurrence points, locations of poor drainage, abnormal equipment, repair locations, and onsite photos together with high-precision location information. To embed methods for increasing power generation into routine practice, it is important to accurately find the causes and manage the ability to repeatedly check the same locations. By using LRTK, it becomes easier to advance power generation improvements based on field data, from confirming eight causes through rechecking after improvements.