7 Ways to Improve Insufficient Power Generation｜Basics of Inspection and Countermeasures

Table of Contents

• To improve insufficient power generation, it is important to isolate the cause

• Method 1: Check power generation data by time of day and by equipment unit

• Method 2: Distinguish between weather, solar irradiance conditions, and seasonal variations

• Method 3: Check the panel surface for dirt and deposits

• Method 4: Manage shading from weeds, trees, and structures

• Method 5: Check for abnormalities in strings, connections, and cables

• Method 6: Review shutdowns, curtailment, and the temperature environment of the power conversion equipment

• Method 7: Address drainage, topography, and inspection records to prevent recurrence

• Basics for continuing inspections and countermeasures

• Summary

Isolating the causes is essential to improving power generation shortfalls

When you want to improve insufficient solar power generation, the first thing you need is not to immediately start cleaning or repairs. Even if generation is low, not growing as expected, or lower than the same month last year, the cause is not necessarily a single one. Dirt on the panel surface, bird droppings and fallen leaves, shading from weeds or trees, faulty connections, cable damage, inverter stoppages, output curtailment, rising temperatures, poor drainage, and insufficient inspection records are among the multiple factors that can combine to cause a shortfall in generation.

For practitioners responsible for operations who search for "how to increase power generation," it is important to regard the idea of increasing output as an effort to reduce generation losses. In solar power generation, you cannot increase the amount of sunlight 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, improving a shortfall in generated power means finding where the power that should be generated is being lost and reducing those wastes.

To pinpoint the cause of insufficient power generation, first examine how the decline appears. Whether the entire plant output is low, only certain equipment is underperforming, it is low only in the morning, the midday peak fails to develop, it drops in the evening, or it becomes unstable after rain will change the suspected causes. The single fact that generation is low does not tell you whether you should clean, remove weeds, inspect connection points, review equipment history, or reassess drainage and terrain.

One common pitfall when trying to improve insufficient power generation is deciding on the cause based solely on on-site appearance. Cleaning because the panels look dirty, weeding because the grass has grown, or inspecting because equipment looks old—these judgments may be necessary in some situations. However, if generation data is not linked with on-site conditions, you may end up prioritizing work that has little impact on power output. Effective improvements require a flow of data review, on-site inspection, countermeasures, verification of effects, and record updates.

Also, because solar power plants are outdoor facilities, their conditions are constantly changing. Even if you clean them, dirt will return; even if you remove weeds, grass will grow; trees will grow; and drainage paths will change due to sediment and fallen leaves. Equipment and wiring also change condition over long-term operation. Therefore, improving low power output cannot be completed with a single task; it needs to be treated as an ongoing operation of inspections and countermeasures. Below, we explain seven practical methods you should check to improve low power output.

Method 1: Check power generation data by time period and by facility

The first step to addressing a power generation shortfall is to check generation data by time of day and by individual equipment. If you only look at monthly or annual generation totals, you cannot tell when, where, or how generation losses are occurring. Even if nothing looks seriously abnormal on a monthly basis, there may be cases where generation falls only during certain hours on sunny days, or where a particular unit continues to perform worse than its surroundings. It is important to read the pattern of decline first, rather than the aggregate value.

Checking by time of day makes the likely causes easier to see. If generation is low in the morning, shadows from trees on the east side, slope faces, surrounding structures, or adjacent equipment may be involved. If it is low in the evening, check for shadows on the west side and the influence of surrounding terrain. If the midday peak does not reach expected levels, candidates include dirt on the panel surface, temperature rise, limits of power conversion equipment, output curtailment, or equipment shutdown. If, even on sunny days, the generation curve suddenly drops midway, you should cross-check stoppage logs and alarm logs with the timestamps.

When checking on a per-equipment basis, it is important to compare units under the same conditions. If you simply compare equipment with different orientations, tilts, numbers of panels, shading conditions, or connection configurations, you may mistake normal differences for abnormalities. If a specific area is consistently lower compared with adjacent rows or equipment with the same orientation, suspect local soiling, partial shading, poor connections, cable damage, or faults on the equipment side.

Pay attention to how the power output declines. If it drops suddenly, possible causes include equipment shutdown, wiring faults, poor connections, or the emergence of obstructions. If it is decreasing gradually, accumulation of dirt, growth of weeds or trees, deterioration of the site environment due to poor drainage, or aging-related changes in the equipment may be involved. By analyzing the pattern of decline, you can narrow down the locations that need to be checked on site.

When checking power generation data, use sunny days as the baseline whenever possible. On cloudy or rainy days, power output can fluctuate greatly due to cloud movement, making it difficult to distinguish from equipment faults. With a sunny day's generation curve, features such as shading, shutdowns, curtailment, and string faults are easier to identify. To improve insufficient power generation, the starting point is to first identify the time periods, equipment, and persistence of the generation losses.

Method 2: Separate weather, solar radiation conditions, and seasonal variations

When you notice a shortfall in power generation, the things you should check before suspecting an equipment fault are the weather, sunlight/solar irradiance conditions, and seasonal differences. Because solar power generation is greatly affected by the amount of solar radiation, generation can drop during periods with many cloudy or rainy days even if there is no problem with the equipment. If you compare only monthly generation with the same month of the previous year or with the previous month and immediately conclude there is a shortfall, the actual main cause may have been differences in the weather.

On the other hand, you must avoid overlooking a real anomaly by blaming the weather. If the entire power plant is declining in the same way in line with regional weather, the influence 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 there is a clear difference compared with equipment under similar conditions, the weather alone cannot explain it. In such cases, it is necessary to check for soiling, shading, poor connections, equipment shutdowns, and output curtailment.

To separate weather-related causes from equipment-related ones, it is effective to compare sunny days with other sunny days or days with similar weather. On cloudy or rainy days, power generation fluctuates greatly, making anomaly characteristics harder to see. By selecting and inspecting the generation curves for sunny days, it becomes easier to detect the impact of shadows that fall at the same time each day, string anomalies where only specific equipment is underperforming, and equipment shutdowns that cause drops only during certain periods.

Seasonal variations are also an important factor to consider. In winter, the sun's altitude is lower and shadows cast by nearby trees and terrain tend to be longer. In summer, although solar radiation is stronger, panel and equipment temperatures rise, which can make it harder for output to increase. During rainy seasons, monthly power generation tends to be lower, and after strong winds or heavy rain attention should be paid to fallen leaves, sediment, deposits, poor drainage, and the condition around cables.

The key to improving insufficient power generation is to separate natural variability from on-site generation losses that can be corrected. When you find a day with low generation, check not only the weather on that day but also differences from installations under the same conditions, the generation curve by time of day, site photos, and equipment history. By understanding the impact of weather and focusing on causes that can be improved, you can more easily reduce unnecessary work.

Method 3: Check the panel surface for dirt and deposits

Surface dirt and deposits on panels are a common cause of insufficient power generation. Because solar panels generate electricity by receiving sunlight on their surface, when dirt adheres the light reaching the cells is reduced. The type of soiling varies with the site environment, including soil dust, pollen, yellow sand, bird droppings, fallen leaves, tree sap, dust from nearby construction, road-derived dust, and salt-containing deposits that easily accumulate in coastal areas.

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

Localized deposits such as bird droppings and fallen leaves should not be overlooked. Unlike dirt that spreads thinly across the entire surface, these cover specific spots thickly and hinder power generation by causing partial shading. If only some systems show reduced power output, focus inspections on the panel surfaces around those systems. Rows near trees, around structures where birds tend to perch, rows that are often downwind, and areas near unpaved walkways are more prone to dirt and localized deposits.

When carrying out cleaning, it is practical to prioritize areas that have the greatest impact on power generation. Rather than cleaning all panels at the same frequency, focus on equipment where a decline in power generation has been confirmed, rows with concentrated soiling, areas where soiling along the lower edge is noticeable, and locations with heavy bird damage or fallen leaves. Comparing photos and power generation before and after cleaning makes it easier to judge how much the soiling at that site was affecting output.

However, cleaning must be performed in a way that does not damage the equipment. You should avoid scrubbing hard with rigid tools, carrying out sudden work during times when panels are at high temperature, or working without confirming electrical safety. Cleaning to improve reduced power output is not a cosmetic task but maintenance intended to restore the light-receiving condition and ensure long-term, stable use of the equipment. Recording the location, extent, and likely causes of soiling can also lead to early detection of recurrence.

Method 4: Manage shadows cast by weeds, trees, and structures

Managing shading is essential to improving insufficient power generation. Because solar panels generate electricity from sunlight, even a shadow over part of a panel can reduce power output. Causes of shading include weeds, trees, fences, utility poles, surrounding buildings, mounting structures, adjacent rows of panels, monitoring equipment, and others. Shadows move with the time of day and the seasons, so not seeing shadows at the time of an inspection does not necessarily mean there is no problem.

Weeds are a common cause of power generation losses on site. Even if they are not a problem in winter or immediately after installation, they can grow rapidly from spring to summer and cast shadows on the lower edges of the panels and on the front rows. Even if the weeds do not touch the panels, the low solar angles in the morning and evening cause long shadows. Furthermore, when weeds become overgrown, ventilation is impaired, inspection pathways are blocked, and it becomes more difficult to check around equipment. Because it affects not only power output but also maintainability and safety, weed management is fundamental to improving power generation.

Shadows from 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 to the south, east, and west in particular cast shadows on the panels depending on the time of day. At power plants near forests or slopes, the height of the terrain can combine with the height of the trees to create long shadows in winter. If power generation is low only during winter, or if there is a large drop in output in the mornings and evenings, it is necessary to check both the trees and the terrain together.

When checking shadows, aligning the power generation data with the times of on-site inspections makes it easier to find the cause. If morning generation is low, check the on-site conditions in the morning; if it’s low in the evening, look at the evening shadows. Even if there is no problem when checked at noon, large shadows can appear in the morning and evening. Also, even if there is no problem in summer, shadows can lengthen in seasons when the solar altitude is low. Shadows need to be managed as something that changes over time and with the seasons, not as a single point in time.

When performing weeding and pruning, prioritize areas that have the greatest impact on power generation. Rather than aiming only to make the entire site uniformly tidy, focus on the panel fronts, around equipment, inspection walkways, and directions where shadows are likely to extend. After work, record whether shadows have actually been eliminated, whether inspections have become easier, and whether ventilation has improved. If you record the sources of shadows, it will be easier to determine the timing of future weeding and pruning.

Method 5: Inspect strings, connections, and cables for abnormalities

To improve insufficient power generation, you need to inspect not only the panel surfaces and shading but also the pathways that carry the electricity. Even if solar panels are receiving sunlight normally, faults in connections or cables can prevent the generated electricity from being fully extracted. String-level differences in output, loose terminals, poor contacts, damaged cable sheathing, moisture ingress, damage by animals, damage during mowing, and age-related deterioration are all significant causes of reduced power generation.

When checking for string-level abnormalities, it is fundamental to compare items under the same conditions. If you simply compare systems that differ in number of panels, orientation, tilt, shading conditions, or connection configuration, you may mistakenly interpret a normal difference as an abnormality. Check whether any string is consistently lower compared to adjacent rows or installations with the same orientation. If only a particular string is low, possible causes include panel soiling, partial shading, poor connections, cable damage, or equipment-side problems.

Pay attention to how the anomaly appears. If it is consistently lower than the surroundings even on sunny days, dirt or connection problems are suspected. If it is lower only in the mornings and evenings, check for shadow effects. If anomalies tend to appear after rain, moisture ingress or the condition of the connections may be involved. If it becomes unstable during periods of high temperature, poor contact or the temperature environment around the equipment are also possible causes. Combining the power generation waveform with on-site conditions makes it easier to narrow down the cause.

If a fault in connections or cables is suspected, safety must be the top priority. Even if there is pressure to increase power generation, on-site personnel should avoid forcibly touching connections or the interior of equipment to make a judgment. Organize the affected equipment, the time of occurrence, changes in power output, on-site photos, and the surrounding environment, and, if necessary, arrange for a professional inspection. At the stage of identifying the cause, it is important to clearly specify where and what kind of abnormality is suspected.

Connection points and cable faults can be related to the surrounding environment. In areas with heavy weeds, it becomes difficult to inspect the condition of cables. In locations with poor drainage, moisture and standing water can affect connections. At power plants that are easily accessed by animals, cable damage can also occur. Rather than stopping at repairs, confirming on-site conditions that could lead to recurrence is essential for improving insufficient power generation.

Method 6: Review shutdown, suppression, and temperature environment of conversion equipment

The causes of insufficient power generation aren't limited to the panels and wiring. If the equipment that converts the generated electricity is stopped or its output is limited, power generation will not increase even if solar irradiance is sufficient. To improve insufficient power generation, it is essential to check the operating status of the conversion equipment, shutdown history, alarm history, and whether output curtailment is in effect.

When checking the downtime history, confirm which equipment stopped, when it stopped, and for how long. Even short stoppages can cause significant losses if they occur during the daytime when generation is high. If stops and recoveries are repeated during the day, they may not stand out in the monthly total, but you may actually be losing generated power. Whether only a specific piece of equipment stops or multiple pieces stop simultaneously will change which causes you should suspect.

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

Temperature conditions are also a point to review. Solar power generation tends to increase with stronger sunlight, but output can become less responsive as temperatures rise. If generation does not increase as expected on a clear summer day, check not only the solar irradiance but also the panel temperature and the temperatures around the equipment; weeds growing under the panels, grass or obstacles around the equipment, or dust and deposits that impair heat dissipation can affect the increase in power generation.

It is also important not to confuse equipment-side faults with panel-side problems. Even if the panels look dirty, the primary cause may actually be equipment shutdowns or output curtailment. Cross-check the time of the generation drop with equipment logs, and choose countermeasures based on evidence rather than conjecture—this is the key to avoiding failure when addressing insufficient power generation.

Method 7: Prevent recurrence by organizing drainage, terrain, and inspection records

To improve insufficient power generation, it is necessary to check not only the panels and equipment but also the plant’s overall drainage, terrain, and inspection routes. Locations where water tends to pool, where sediment flows in, pathways that easily become muddy, slope failures, scouring around mounting structures, and places where cables are prone to be exposed can all cause reductions in power output directly or indirectly. Poor drainage and changes in topography may at first seem unrelated to power output, but they are important factors that lead to soiling, weeds, connector faults, and degraded inspectability.

In areas where puddles remain after rain, weeds are more likely to grow. When weeds grow, they create shading, reduce ventilation, and make inspections more difficult. Muddy walkways can slow work and may reduce the frequency of cleaning and weeding. Where sediment flows in, it can accumulate under panels and around cables, causing dirt and damage. If the same problem keeps recurring in the same place despite cleaning and weeding, drainage or terrain issues should be suspected.

When checking terrain and drainage, on-site inspections after rain are as useful as inspections in fine weather. Determine where water flows in, where it pools, and where it drains out. By recording puddles, sediment accumulation, vegetation overgrowth, pathway subsidence, and changes to slopes, you can identify locations prone to recurrence. If poor drainage is left unaddressed, dirt and weeds will recur, resulting in the same power generation losses happening repeatedly.

Inspection records are also essential for preventing recurrence. If you record the locations of equipment with low power generation, rows prone to soiling, shaded areas, places where water accumulates, locations where connection faults occurred, repaired locations, and the areas where cleaning or weeding was carried out, the places to check during the next inspection will be clear. If records are insufficient, the same problems may recur without allowing you to learn their causes, and responses tend to become ad hoc.

To fundamentally address power generation shortfalls, it's necessary not only to fix the immediate abnormalities but also to create a site environment where the same abnormalities are less likely to occur. Rather than just cleaning dirt, verify why that location tends to get dirty. Rather than just mowing grass, examine why grass grows easily in that spot. Rather than just repairing connections, check underlying factors such as humidity, drainage, and cable exposure. Adopting this perspective makes it easier to sustain the effects of power generation improvements over the long term.

Fundamentals for continuing inspections and countermeasures

Addressing insufficient power generation cannot be completed with a single inspection or countermeasure. A solar power plant is an outdoor installation, and its condition changes with the seasons, the weather, the surrounding environment, and equipment aging. Even after cleaning, dirt will accumulate again; after weeding, grass will regrow; trees will grow; and drainage paths will change. Equipment and wiring also change over long-term operation, so continuous inspections and record-keeping are necessary.

First and foremost, compare the power output before and after the measures. After performing cleaning, weeding, repairs, equipment inspections, and drainage checks, confirm how the power output has changed. It is difficult to completely eliminate the impact of weather, but by comparing sunny days with each other or comparing systems under the same conditions, you can identify consistent trends. Prioritize measures that had a large effect for future work, and if an effect is hard to see, suspect other causes.

Next, keep locations that tend to recur as management targets. If you record rows that easily accumulate dirt, time periods when shadows are likely to occur, spots where water pools, walkways prone to damage, and equipment likely to show anomalies, you can inspect them before power generation falls significantly. To reliably improve insufficient power generation, it is important not only to respond after generation has dropped but also to identify in advance the conditions that tend to cause drops and take countermeasures.

When multiple staff members are involved in management, it is important to be able to share the exact same location. In large power plants, rows and equipment that look similar can make it difficult to identify a location from photos alone. By recording equipment numbers, location information, photos, and work history together, on-site personnel, managers, inspectors, and repair staff can more easily confirm the same location. Improving insufficient power generation is also about building a system that leverages observations made on site for subsequent improvements.

Also, it is important to clarify the priority of inspections and countermeasures. Trying to solve all issues at once can increase the workload and cause measures that would significantly affect power output to be postponed. Prioritize checking equipment that shows a clear decline in power generation data, shading that lasts for long periods, recurring soiling or drainage problems, and equipment that experiences frequent stops even for short durations. To address power shortfalls, it is practical to implement countermeasures in order from the locations with the largest generation losses.

Summary

To improve insufficient power generation, it is important not to assume a single cause but to sequentially isolate where and why generation losses occur. In solar power generation, the site cannot increase the solar irradiance itself. However, generation can be improved by bringing the system closer to a state that converts the received irradiance into electricity without waste. To do this, it is necessary to check, in order, the generation output data, weather and irradiance conditions, panel surface soiling, shadows from weeds and trees, strings and connection points, conversion equipment, drainage and terrain, and inspection records.

When you feel that power generation is low, rather than immediately carrying out cleaning or repairs, it is important to first segment and review the data. Identify when the output is low, which equipment is underperforming, and whether there is a difference compared with equipment under the same conditions. With that information, an on-site inspection will make clear where cleaning is required, the areas that need weed removal, which connection points should be inspected, which pieces of equipment should be checked, and which drainage or access routes should be reconsidered. In addressing insufficient power generation, it is crucial to make decisions by linking data with on-site conditions, not by relying on intuition.

Also, improving insufficient power generation is not something that can be completed with a single operation. Even if you clean, dirt will return; even if you remove weeds, grass will grow back; trees will keep growing; and equipment and wiring will change condition as they age. Comparing power generation before and after countermeasures, keeping on-site photos and work history, and using them for the next inspection will increase the accuracy of improvements. To raise power generation stably, it is essential not only to remove the causes but also to create a site environment and management system that make the same causes less likely to occur.

Especially in large power plants, a system for accurately sharing problem locations is important. By recording rows prone to soiling, locations where shadows occur, areas where water accumulates, abnormal strings, repair locations, cleaning areas, and inspection photos together with location information, stakeholders can more easily confirm the same spot. Combining power generation data with on-site location information makes it easier to explain the priorities for cleaning, weeding, and repairs, and also streamlines checking for recurrence in future inspections.

If you want to continue inspections and countermeasures for power generation shortfalls based on field data, using LRTK can also be effective. As an iPhone-mounted high-precision GNSS positioning device, LRTK is useful for recording inspection locations within a solar power plant, areas prone to dirt, locations where shadows occur, areas with poor drainage, malfunctioning equipment, repair locations, cleaning areas, and onsite photos together with high-precision location information. By documenting the causes of power generation shortfalls with location information, inspections and countermeasures can be advanced based on field data rather than intuition.