7 Improvements to Boost Power Generation｜Countermeasures for Solar Power Losses

Table of Contents

• Improving power output starts with identifying the causes of losses

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

• Improvement 2：Isolate weather, solar irradiance conditions, and seasonal variations

• Improvement 3：Remove dirt and deposits from panel surfaces

• Improvement 4：Mitigate shading caused by weeds, trees, and structures

• Improvement 5：Check for abnormalities in strings, connection points, and cables

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

• Improvement 7：Organize drainage, terrain, and inspection records to prevent recurrence

• Operational points for sustaining increased power generation

• Summary

Increasing power generation starts with identifying the causes of losses

When aiming to increase the power output of a solar power system, the first thing to consider is not adding more equipment but verifying whether the existing equipment is performing at its intended capacity. With solar power, you cannot increase the amount of solar irradiance at the site. You cannot increase the number of sunny days, nor change the seasonal solar elevation. However, you can move the system closer to a state in which the received irradiance is converted into electricity with as little waste as possible. In other words, in practical terms, increasing generation means identifying the causes that are causing the system to miss out on power it should be generating and reducing generation losses.

There is not a single cause for decreased power generation. Dirt on the panel surface, deposits such as bird droppings and fallen leaves, shading from weeds or trees, faults at connection points, cable damage, failure of conversion equipment, output curtailment, temperature rise, poor drainage, and a lack of inspection records are among the multiple factors that can combine to reduce power generation. Even when no major abnormalities are apparent visually, viewing power generation data by time of day or by equipment can reveal that only certain parts are showing a continuous decline.

For operations personnel searching "how to increase power generation", it's important not to decide on countermeasures based solely on impressions at the site. Actions such as cleaning because the panels are dirty, cutting grass because it has grown, or suspecting a malfunction because equipment looks old can be necessary in some cases. However, if the main cause of reduced output lies elsewhere, those tasks will not lead to sufficient improvement. Even if you clean, generation is unlikely to recover if morning and evening shading remains, and even if you remove grass, daytime generation will not increase if short intermittent stoppages of the power conversion equipment continue.

To efficiently increase power generation, it is important to link generation data with on-site conditions to isolate the causes. Check when output is low, which equipment is underperforming, whether there is a difference compared with equipment under the same conditions, whether it is low even on sunny days, and whether it becomes unstable after rain. Then, review in order: soiling, shading, connections, equipment, temperature, drainage, and inspection records. The mere fact that generation is low does not tell you what should be prioritized. For solar loss mitigation, it is important to classify the causes of loss and implement countermeasures starting with the locations that have the greatest impact on generation.

Also, improving power output cannot be accomplished with a single action. Solar power plants are outdoor facilities, and their condition changes with the seasons, weather, surrounding environment, and equipment aging. Even if you clean them, dirt will return; even if you remove weeds, grass will grow back; trees will grow; and drainage channels will be altered by sediment and fallen leaves. To consistently improve power output, you need operational practices that identify causes, implement countermeasures, verify their effectiveness, and apply the records to the next inspection.

Improvement Measure 1: Check power generation data by time of day and by equipment unit

The first improvement to target for increasing power generation is to take a more granular look at the generation data. If you only look at monthly or annual generation totals, you can’t tell when, where, or how generation losses are occurring. Even if nothing appears to be a major anomaly on a monthly basis, output may drop during certain hours on sunny days, or low output may persist only in a specific row, a specific string, or the area connected to a particular power conversion device.

Viewing power generation by time of day makes it easier to determine the likely cause. If generation is low in the morning, shadows from trees, embankments, nearby structures, or adjacent equipment on the east side may be involved. If it is low in the evening, check for west-side shadows or the influence of surrounding terrain. If the midday peak does not reach expected levels, candidates include soiling of the panel surface, temperature rise, limitations of power conversion equipment, output curtailment, or equipment shutdowns. If the power curve suddenly drops during a sunny day, you should cross-check shutdown logs and alarm histories with the timestamps.

When comparing on a per-equipment basis, it is important to compare equipment under the same conditions. If you simply compare equipment that differ in azimuth, tilt, number of panels, shading conditions, or connection configuration, you may misinterpret normal differences as abnormalities. If, compared with adjacent rows or equipment with the same orientation, a specific area is consistently lower, suspect local soiling, partial shading, connection faults, cable damage, or abnormalities on the power conversion equipment side.

Pay attention to the pattern of power generation decline. If it drops suddenly, possible causes include equipment shutdown, wire breakage, poor connections, or the emergence of obstructions. If it falls gradually, accumulation of dirt, growth of weeds or trees, deterioration of site conditions due to poor drainage, or aging of equipment and components may be involved. For sudden drops versus gradual declines, both the locations to check on site and the priorities for countermeasures change.

As an approach to improvement, first use the power output curve from a sunny day as a baseline, and check the power output by time of day and by individual equipment units. By narrowing down the time periods and equipment ranges showing declines before going on site, you can reduce wasted inspections. Rather than aimlessly walking around a large power plant, focusing on the locations where output has dropped makes it easier to quickly identify the causes that will lead to increased power output.

Improvement Measure 2: Separate weather, solar radiation conditions, and seasonal differences

When you feel that power generation is low, before suspecting an equipment malfunction you should check the weather, solar irradiation conditions, and seasonal differences. Because solar power generation is greatly affected by the amount of sunlight, generation will decrease during periods with many cloudy or rainy days even if there is no problem with the equipment. If you compare only the monthly generation with the same month last year or the previous month and immediately conclude that there is an equipment failure, it may turn out that weather differences were the main cause.

On the other hand, we must avoid overlooking genuine abnormalities by attributing them to the weather. If the entire power plant is declining uniformly in line with regional weather, the effect of solar irradiance conditions can be considered significant. However, if only part of the plant is performing below normal while other equipment at the same plant is operating as usual, or if there is a clear difference compared with equipment under similar conditions nearby, the weather alone cannot explain it. In such cases, it is necessary to check on-site causes such as soiling, shading, poor connections, equipment shutdowns, and output curtailment.

To separate weather-related causes from equipment-side causes, it is effective to compare sunny days with each other or days with similar weather. On cloudy or rainy days, power generation fluctuates greatly, making it difficult to discern the characteristics of anomalies. By selecting and checking the generation curves on sunny days, it becomes easier to detect the impact of shadows that cause drops at the same time every day, string anomalies where only specific equipment shows low output, and equipment shutdowns that cause drops for only a certain period.

Seasonal differences are also an important consideration. In winter, the sun’s altitude is lower, and shadows from surrounding trees and terrain tend to extend farther. In summer, although solar irradiance is stronger, panel and equipment temperatures rise, which can make output less likely to increase. During rainy periods, 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.

When aiming to increase power generation, it is essential to distinguish between natural declines and losses that can be remedied. If weather is the main cause, cleaning or repairs will not significantly improve power generation. Conversely, if output remains low in a specific area even on sunny days, there is a high likelihood that on-site improvements are possible. By correctly isolating weather effects, you can reduce unnecessary measures and concentrate on loss-mitigation efforts that effectively improve power generation.

Improvement measure 3: Remove dirt and deposits from the panel surface

Dirt and deposits on the panel surface are a typical cause of reduced power generation. Because solar panels generate electricity by receiving sunlight on their surface, when dirt adheres the amount of light reaching the cells decreases. The types of soiling vary depending on site conditions, such as soil dust, pollen, yellow dust, bird droppings, fallen leaves, sap, dust from nearby construction, road-derived dust, and salt-containing deposits that tend to adhere in coastal areas. Even light soiling can affect power output if it spreads over a wide area, and localized deposits can act as a strong shadow even over a small area.

Particular attention should be paid to the band-like dirt that remains along the panel bottom edge 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 shallow tilt, water does not drain well, making dirt prone 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 or fallen leaves should not be overlooked. Unlike dirt that spreads thinly across the entire surface, these concentrate in specific spots and act as partial shading, hindering power generation. If only some systems show reduced power output, focus inspection on the panel surfaces around those systems. Rows near trees, areas around structures where birds tend to perch, rows that are often downwind, and locations near unpaved walkways are prone to dirt and deposits.

As an improvement, determine cleaning targets starting with the locations that have the greatest impact on power generation. Rather than cleaning all panels at the same frequency, prioritize installations where a drop in generation has been observed, rows with concentrated soiling, areas where lower-edge soiling 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 had been affecting generation.

However, cleaning must be carried out so as not to damage the equipment. Avoid vigorously scrubbing with hard tools, performing sudden work when panels are at high temperatures, or working without conducting safety checks for the electrical equipment. Cleaning aimed at increasing power generation is not a cosmetic task to improve appearance, but a maintenance activity to restore the panels’ light-receiving condition and to keep the equipment in long-term stable use. By recording the cleaned locations, types of dirt, and conditions prone to recurrence, you can make use of that information for future inspections.

Improvement Measure 4: Reduce shading from weeds, trees, and structures

When investigating causes of reduced power generation, the impact of shading should always be checked. Because solar panels generate electricity from sunlight, even a shadow on part of a panel can reduce its output. Shading can be caused by various things such as weeds, trees, fences, utility poles, nearby buildings, mounting structures, adjacent rows of panels, and monitoring equipment. Because shadows move depending on the time of day and season, just because no shadow was visible at the time of inspection doesn't necessarily mean there is no problem.

Weeds are a common cause of power generation losses on site. 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 rows. Even if the vegetation does not touch the panels, the low solar elevation in the morning and evening causes long shadows. Furthermore, when weeds proliferate, ventilation worsens, inspection pathways 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 generation performance.

Shading from trees is a factor that can become problematic during long-term operation. Even trees that had little impact when the system was first installed can grow over several years and reduce power generation. Trees located especially to the south, east, and west can cast shadows on panels at different times of day. At power plants near forests or slopes, the height of the terrain combined with tree height can overlap and create long shadows in winter. If generation is low only in winter, or there are large drops in the morning and evening, it is necessary to check trees and the terrain together.

As a countermeasure, check the site at the times when power generation data shows a decline. If output is low in the morning, inspect site conditions in the morning; if it is low in the evening, look for evening shadows. Even if there is no problem at noon, large shadows may appear in the morning or evening. Also, even if there is no issue in summer, shadows can lengthen in seasons when the sun altitude is low. When you find shadows, record the time of occurrence, the source of the shadow, the equipment affected by the shadow, and take photos.

Attention must also be paid to shadows from surrounding structures and additional equipment. Adding new equipment inside the power plant, or installing fences, signs, or monitoring poles, can cast shadows at certain times of day. To prevent a decrease in power generation, it is important not only to reduce existing shading but also to operate in ways that do not create new shadows. Shading management is not something that can be finished with a single weeding; it must be continuous, taking seasonal changes into account.

Measure 5: Check for abnormalities in strings, connection points, and cables

Declines in power generation do not necessarily appear uniformly across an entire plant. Even if the overall generation does not look abnormal, there may be cases where only some strings have reduced output. Such partial generation losses are hard to notice in monthly totals, but if they persist over a long period they can result in significant losses. If you are aiming to increase power output, it is important not to be reassured by the overall average and to check differences at the string level.

When checking for abnormalities at the string level, compare units under the same conditions. If you simply compare systems that differ in panel count, azimuth, tilt, shading conditions, or connection configuration, you may mistakenly interpret normal differences as abnormalities. Check whether any string is consistently lower compared with adjacent rows or installations with the same orientation. If only a particular string is lower, possible causes include soiling, partial shading, poor connections, cable damage, or equipment-side problems.

Faults in connections and cables are also a major cause of reduced power output. Loose terminals, poor contact, damage to cable sheathing, moisture ingress, animal damage, damage during grass-cutting operations, and deterioration with age can all impede the flow of electricity. These issues can be difficult to detect by appearance alone, so they need to be assessed by combining power output data with on-site conditions.

Faults in connection points and cables are suspected when only specific installations show low power output, when abnormalities tend to appear after rain, when power generation suddenly drops, or when output fluctuates unstably. Even if no dirt or shading is visible but only some sections are low, electrical faults should be considered. If there is a persistent difference compared with strings under the same conditions, prioritize checking the connection points and cables.

When inspecting electrical equipment, safety must be the top priority. Even if you want to increase power generation, on-site personnel should avoid forcibly touching connection points or the interior of equipment to make assessments. Organize the equipment showing abnormalities, the time of occurrence, changes in power generation, on-site photos, and the surrounding environment, and, when necessary, arrange for professional inspections. To reduce unnecessary losses, it is important to detect anomalies while they are still small and narrow down the cause before power generation losses become prolonged.

Improvement Measure 6: Review Shutdown, Suppression, and Temperature Environment of Conversion Equipment

The causes of low power generation are not limited to panels and wiring. If the equipment that converts the generated electricity is stopped or its output is restricted, power generation will not increase even with sufficient solar irradiance. For loss-mitigation measures aimed at increasing power generation, it is essential to verify the operating status of the conversion equipment, shutdown history, alarm history, and whether output curtailment is in effect.

When reviewing downtime history, check which equipment stopped, when, and for how long. Even a short stoppage can cause a large loss if it occurs during daytime when power generation is high. If equipment repeatedly stops and restarts during the day, it may not stand out in the monthly totals, but in reality you could be missing generated energy. Whether only a specific piece of equipment stops or multiple pieces of equipment stop simultaneously will change the causes you should suspect.

If output curtailment is occurring, power generation may plateau even on sunny days. If the upper part of the power generation curve appears flat, check the operating information and history. However, a flat curve does not necessarily indicate output curtailment. Similar shapes can result from equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not judge based only on the generation curve; it is important to verify equipment records together with on‑site conditions.

The thermal environment is also a point to review. While solar power generation tends to increase with stronger solar irradiance, higher panel or surrounding equipment temperatures can limit output. If generation does not rise as expected on a clear summer day, you should check the temperature environment as well as solar irradiance. Overgrown weeds beneath the panels, grass or obstacles around equipment, or dust and deposits that hinder heat dissipation can all affect power production.

As a countermeasure, correlate the time when power output declined with the equipment logs. If the time of the output drop matches the time of alarms or shutdowns, it becomes easier to narrow down the possible causes. If there is no anomaly in the equipment records, check other causes such as panels, wiring, shading, dirt, and solar irradiance conditions. Around the equipment, reducing grass and debris and ensuring ventilation and accessibility for inspection will help enable early detection of abnormalities and more stable operation.

Improvement Measure 7: Organize drainage, terrain, and inspection records to prevent recurrence

To prevent repeated declines in power generation, it is necessary to check not only the panels and equipment but also the power plant's overall drainage, terrain, and inspection access routes. Locations where water readily accumulates, sites where sediment can wash in, pathways prone to becoming muddy, slope failures, scour around mounting structures, and areas where cables are likely to be exposed can directly or indirectly cause reductions in power generation. These are important factors that lead to soiling, weeds, connection faults, and reduced inspectability.

Where puddles remain after rain, weeds are more likely to grow. When weeds grow, shading occurs, ventilation worsens, and inspections become more difficult. On muddy pathways, work can be delayed and the frequency of cleaning and weeding may decrease. In places where sediment flows in, it accumulates under panels and around cables, causing dirt and damage. If the same problems recur in the same locations even after cleaning or weeding, drainage or topography issues should be suspected.

When checking topography and drainage, on-site inspections after rain are useful as well as those in fine weather. Determine where water flows in, where it pools, and where it drains out. Recording puddles, sediment deposits, vegetation overgrowth, pathway subsidence, and changes to slopes helps identify areas 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 indispensable for preventing recurrence. By recording the locations of equipment with low power generation, rows prone to soiling, locations where shadows occur, areas where water accumulates, spots where connection failures occurred, places that were repaired, and the areas where cleaning or weeding was performed, you will make clear which locations should be checked at the next inspection. If records are insufficient, even if the same problem repeats you will not be able to learn the cause and will have to check everything from scratch each time.

As an improvement measure, use inspection records as a basis for decisions to improve power generation. Don’t just clean dirt; check why that location becomes dirty easily. Don’t just cut the grass; look into why grass tends to grow at that spot. Don’t just repair the connections; check background factors such as moisture, drainage, and cable exposure. By recording causes of recurrence and focusing on them during the next inspection, you can more easily reduce unnecessary losses.

Operational Approaches to Prevent Recurring Declines in Power Generation

Efforts to address causes of reduced power generation cannot be completed with a single cleaning or repair. Solar power plants are outdoor facilities, and their condition changes with the seasons, weather, surrounding environment, and equipment aging. Even after cleaning, dirt will reappear; even after weeding, grass will grow; trees will grow; and equipment and wiring will change condition during long-term operation. To achieve a stable improvement in power generation, a system for ongoing inspections and countermeasures is necessary.

The most important thing is to compare power generation before and after the measures. After performing cleaning, weeding, repairs, equipment inspections, and drainage checks, verify how the power generation has changed. It is difficult to completely remove the influence of the weather, but by comparing sunny days with one another or comparing systems under the same conditions, you can identify consistent trends. Prioritize measures that produced a large effect for future actions, and if an effect is not apparent, consider other possible causes.

Next, keep locations that are prone to recurring issues under management. If you record rows that easily accumulate dirt, time periods when shadows are likely to occur, places where water pools, areas where walkways are prone to deteriorate, and equipment that tends to show abnormalities, you can check them before power generation drops significantly. To prevent a decline in power generation, it is important not only to respond after output falls, but to identify in advance the conditions that make drops likely and take countermeasures.

When multiple people are managing a site, being able to share the exact location is also important. At a large power plant, similar rows and pieces of equipment can make it hard to identify a location from photos alone. If equipment numbers, location data, photos, and work histories are recorded together, field staff, managers, inspectors, and maintenance personnel can more easily confirm they are referring to the same place. Improving power generation is also about creating a system that uses observations made on site to inform future improvements.

Also, it is important to clarify the priority of measures to improve power generation. If you try to address all issues at once, the workload can become substantial and measures that have a large impact on power output may be postponed. Prioritize inspecting equipment that shows clear declines in power generation data, shadows that have long impact durations, recurring soiling or poor drainage, and devices that experience frequent short-duration stoppages. Practical countermeasures for reduced power generation involve classifying the causes and proceeding in order from locations with the largest generation losses.

Summary

When aiming to increase power generation, an important aspect of improvement measures is to identify, in sequence, the locations and causes of generation losses, and to make improvements starting with the areas that have the greatest impact on output. In solar power generation you cannot increase the solar irradiance itself at the site. However, you can improve output by bringing the system closer to a state in which the received solar irradiance is converted into electricity without waste. To do so, it is necessary to check, in order, the power generation data, weather and solar irradiance conditions, soiling of panel surfaces, shadows from weeds and trees, strings and connection points, conversion equipment, drainage, and inspection records.

When you notice that power generation is low, it's important not to jump straight into cleaning or repairs, but first to break down and analyze the data. Identify when output is low, which equipment is underperforming, and whether there is a difference compared with equipment under the same conditions. With that understanding, an on-site inspection will clarify where to clean, what areas to weed, which connections to check, what equipment to verify, and which drainage and access routes should be reconsidered. To improve reduced power generation, it's essential to make decisions by linking data with on-site conditions rather than relying on intuition.

Also, measures to increase power generation are not something that can be completed in a single operation. Even if you clean, dirt will reattach; even if you remove weeds, grass will grow back; trees will grow; and equipment and wiring will change condition over time. By comparing power generation before and after measures, keeping on-site photos and work histories, and applying them to the next inspection, the accuracy of improvements will increase. To raise power generation stably, it is essential not only to eliminate the causes but also to create a site environment and management system that make the same causes less likely to occur.

Especially at large power plants, a system for accurately sharing problem locations is important. If rows prone to soiling, areas prone to shading, places where water accumulates, abnormal strings, repair locations, cleaning coverage, and inspection photos are recorded together with positional information, stakeholders can more easily confirm the same locations. By combining power generation data with on-site positional information, it becomes easier to explain the prioritization of cleaning, weeding, and repairs, and it also streamlines subsequent checks for recurrence.

If you want to continue loss-mitigation measures aimed at increasing power generation based on field data, utilizing LRTK is also 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 soiling, locations where shadows occur, points of poor drainage, abnormal equipment, repair locations, cleaning areas, and on-site photos together with high-precision location information. By leaving the locations where improvement measures were implemented and their results with location information, it becomes easier to advance power generation improvements based on field data rather than intuition, and to continuously reduce unnecessary solar losses.