8 Operational Techniques to Increase Solar Power Output | Commonly Overlooked Causes

Table of Contents

• Operations to increase solar power generation start with discovering overlooked causes

• Operational Technique 1: View generation data by time of day

• Operational Technique 2: Narrow down abnormal ranges by comparing with equipment under the same conditions

• Operational Technique 3: Separate the effects of weather, solar irradiation conditions, and seasonal differences

• Operational Technique 4: Manage dirt and deposits on panel surfaces

• Operational Technique 5: Mitigate shadows from weeds, trees, and structures early

• Operational Technique 6: Do not overlook abnormalities in strings, connection points, and cables

• Operational Technique 7: Check power conversion equipment, temperature environment, and ventilation

• Operational Technique 8: Organize drainage, terrain, and inspection records to prevent recurrence

• Operational design to sustain improvements in generation output

• Summary

Operational efforts to increase solar power generation begin with identifying the causes of oversights

When you want to increase solar power generation, the first thing to check is not adding equipment but whether the existing equipment is able to deliver its intended generation capacity. In solar power, you cannot increase the site’s incident irradiance. You cannot increase the number of sunny days, nor can you change the sun’s altitude with the seasons. However, you can move toward a state in which the received solar radiation is converted into electricity with as little waste as possible. In other words, in practical terms, operations to increase generation involve finding the causes of lost potential generation and reducing generation losses.

The causes of underperforming power generation are not necessarily limited to major failures. Light soiling on the panel surface, banded deposits remaining at the lower edge, bird droppings and fallen leaves, partial shading at certain times from weeds or trees, loose connections, cable damage, short-term stoppages of conversion equipment, output curtailment, summer temperature rises, recurrence of sediment and weeds due to poor drainage, and insufficient inspection records — these easily overlooked factors can accumulate and reduce power output.

What practical staff searching for "how to increase power generation" should be careful about is not deciding countermeasures based solely on the on-site appearance. Deciding to clean because the panels look dirty, to remove weeds because the grass has grown, or to suspect a malfunction because the equipment looks old can be appropriate in some cases. However, if the main cause of the drop in power generation lies elsewhere, those actions will not lead to sufficient improvement. Even if you clean, if shadows remain in the morning and evening the power output is unlikely to recover, and even if you remove weeds, if brief stoppages of the power conversion equipment continue, daytime generation will not increase.

To increase solar power generation, it is important to link generation data with on-site conditions and systematically isolate causes. Check when output is low, which equipment is underperforming, whether there is a difference compared with equipment under the same conditions, whether output is low even on sunny days, and whether it becomes unstable after rain. Then review soiling, shading, connections, equipment, temperature, drainage, and inspection records. The mere result of low generation does not tell you what should be prioritized. By checking each easily overlooked cause one by one, you can more easily improve generation while reducing unnecessary work.

Operational Tip 1: View power generation data by time of day

The first step in operations to increase solar power generation is to look at generation data by time of day. If you only look at monthly or annual generation totals, you can’t tell when generation losses are occurring. Even when overall generation is low, the causes to suspect differ depending on whether it’s low only in the morning, the midday peak isn’t reaching its potential, it drops only in the evening, or there are sudden dips during the day. Rather than judging by aggregate values alone, it’s important to read the shape of the generation curve.

If morning generation is low, shadows from trees on the east side, slopes, 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 soiling of the panel surfaces, temperature rise, limitations of conversion equipment, output curtailment, or equipment shutdowns. If the generation curve suddenly drops during a clear day, it is necessary to cross-check shutdown histories and alarm histories with the timestamps.

For time-of-day checks, it is important to use data from sunny days as much as possible. On cloudy or rainy days, power generation fluctuates greatly due to cloud movement. For that reason, it becomes difficult to determine whether an issue is an equipment fault or an effect of the weather. By looking at the generation curve on sunny days, it is easier to find patterns such as the effect of shadows that fall at the same time every day, equipment stoppages that occur only at specific times, and output curtailment that flattens the upper part of the curve.

There are two patterns in declines in power generation: sudden drops and gradual decreases. If the drop is sudden, suspected causes include equipment shutdowns, wiring breaks, poor connections, or the emergence of obstructions. If it is decreasing gradually, factors such as accumulation of dirt, growth of weeds or trees, deterioration of site conditions due to poor drainage, and aging of equipment may be involved. By reading the pattern of the decline, you can narrow down the locations on site that should be checked intensively.

If you don't make a habit of checking power generation data by time of day, inspections tend to become broad and shallow. Even if you inspect many locations on site, if the time of the on-site check doesn't match the time when the generation drop occurs, you may miss causes such as shading or equipment shutdowns. If output is low in the morning, check on-site conditions in the morning; if it's low in the evening, check for evening shading. Time-of-day data checks are the first operational practice for determining the direction of power generation improvement.

Operational Technique 2: Narrow down the abnormal range by comparing with equipment under the same conditions

To increase power generation, it is essential not only to consider the overall plant figures but also to make comparisons at the equipment level. Even if nothing appears abnormal overall, there may be cases where only certain rows, certain strings, or areas connected to specific conversion devices have lower power output. Such partial generation losses may be difficult to notice in monthly totals, yet if they persist for a long time they can result in significant losses.

When comparing, choose installations with similar orientation, tilt, number of panels, shading conditions, and connection configuration. If you simply compare installations with different conditions, you may misinterpret normal differences as abnormalities. Even within a power plant, power generation changes if orientation or tilt differs. The purpose of the comparison is to find locations that are consistently producing less among installations that should normally have similar generation.

If only part of an installation is lower compared with equipment under the same conditions, localized soiling, partial shading, poor connections, cable damage, or problems on the converter side may be suspected. For example, if a particular row is lower than adjacent rows even on sunny days, possible causes include grass growing in front of that row, concentrated soiling on the lower edge, or a fault in the wiring route. Narrowing down the abnormal range in the data before inspecting the site increases the accuracy of the inspection.

When narrowing down the affected area, it is also important to be able to pinpoint the exact location on site. At sites where equipment numbers or row numbers are unclear, even if an anomaly is detected in the data, it can take time to locate the corresponding spot in the field. A photo alone may not always convey the location. When improving power generation, being able to accurately share the location among stakeholders is just as important as finding the anomaly.

Even a small difference in power output can become a significant loss if it persists day after day. Rather than concluding there is no problem because the total generation hasn’t dropped significantly, continuously monitor the difference compared with equipment under the same conditions. This comparison makes it easier to narrow down the areas that need cleaning, the spots that require weeding, the connection points to inspect, and the devices to check. For operational improvements, it’s important to adopt a perspective that detects localized declines early, rather than relying on the overall average.

Operational Technique 3: Separate Weather, Solar Radiation Conditions, and Seasonal Differences

When you feel that solar power generation is low, the things you should check before suspecting an equipment malfunction are the weather, solar irradiance conditions, and seasonal differences. Because solar power generation is greatly affected by the amount of sunlight, generation will decrease during periods with frequent clouds or rain even if there is no problem with the equipment. If you compare only the monthly generation with the same month of the previous year or with the previous month and immediately judge it to be abnormal, it may turn out that differences in weather were the main cause.

On the other hand, we must avoid overlooking real anomalies by attributing them to the weather. If the entire power plant is declining uniformly in line with regional weather, the impact of solar irradiance conditions is likely significant. However, if only part of the plant is underperforming while other equipment in the same plant is operating normally, or if there is a clear difference compared with equipment under the same conditions, 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-related ones, it is effective to compare sunny days with each other and days with similar weather. Cloudy or rainy days cause large fluctuations in power generation, making it difficult to discern the characteristics of anomalies. If you select and inspect the generation curves for sunny days, you can more easily find the impact of shadows that occur at the same time every day, string-level anomalies where only certain equipment shows low output, and equipment stoppages that cause output to drop only for specific periods.

Seasonal variations are also an important factor to consider. In winter, the sun’s altitude is lower, and shadows from surrounding trees and terrain tend to be longer. In summer, although solar irradiance is stronger, panel temperatures and temperatures around equipment rise, which can reduce output. During rainy periods, monthly power generation tends to be lower, and after strong winds or heavy rain attention is needed for fallen leaves, sediment, deposits, poor drainage, and the condition around cables.

To increase power generation, you need to separate natural variability from on-site generation losses that can be improved. If weather is the primary cause, cleaning or repairs will not significantly improve generation. Conversely, if output remains low even on sunny days, it is highly likely that there is room for improvement on site. By operating in a way that isolates weather and seasonal differences, you can reduce unnecessary measures and focus on the causes that lead to improved generation.

Operational Technique 4: Managing Dirt and Deposits on Panel Surfaces

Dirt and deposits on panel surfaces are a common cause of reduced solar power generation. Because solar panels generate electricity by receiving sunlight at their surface, when dirt accumulates the light reaching the cells is reduced. The way panels become soiled varies with site conditions and includes dust, pollen, yellow sand (Asian dust), bird droppings, fallen leaves, sap, dust from nearby construction, road-derived dust, and salt-containing grime that tends to accumulate in coastal areas. Even a thin layer of dirt can affect power output if it spreads over a wide area, and localized deposits can act as strong shading even over a small area.

One easy-to-overlook issue is the banded dirt that remains along the lower edge of the panel and near the frame. People tend to assume that rain will naturally wash it away, but in reality rainwater flow can collect the dirt at the lower edge and leave it there. On panels with a gentle tilt, water does not drain well 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 over the entire surface, these cover specific spots more densely and hinder power generation by causing partial shading. If only some installations have low power output, focus on inspecting the panel surfaces around those installations. Rows close to trees, areas around structures where birds tend to perch, downwind rows, and locations near unpaved walkways are more prone to dirt and deposits.

When performing cleaning, it is practical to prioritize areas that have the greatest impact on power generation. Instead of cleaning all panels at the same frequency, focus on equipment where a drop in power generation has been confirmed, rows with concentrated dirt, areas where soiling is conspicuous at the lower edge, and locations with frequent bird damage or fallen leaves. Comparing photos and power output before and after cleaning makes it easier to determine how much the soiling was affecting power generation at that site.

When cleaning, it is also important not to damage the equipment. Avoid scrubbing vigorously with hard tools, performing sudden work during times when panels are at high temperatures, or skipping safety checks for electrical equipment. Cleaning to increase power generation is not a cosmetic task but a maintenance operation to restore light-receiving conditions and to keep the equipment operating stably for a long time. By recording the location and extent of dirt and the causes that tend to produce it, you can apply that information to future inspections.

Operational Tip 5: Control Shadows from Weeds, Trees, and Structures Early

Shadow management is essential for operations that aim to increase power generation. Because solar panels generate electricity from sunlight, even a partial shadow on a panel can reduce output. Causes of shading vary and include weeds, trees, fences, utility poles, nearby buildings, mounting structures, adjacent panel rows, and monitoring equipment. Shadows shift with the time of day and the seasons, so the absence of visible shadows at the time of inspection does not necessarily mean there is no problem.

Weeds are an easily overlooked cause of power generation loss. 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 the panels and the front rows. Even if the vegetation does not touch the panels, shadows lengthen when the sun is low in the morning and evening. Furthermore, when weeds become overgrown, ventilation worsens, inspection aisles become blocked, and it becomes difficult to check around equipment. Because it affects not only power generation but also maintainability and safety, weed management should be carried out early.

Shading from trees is a factor that tends to become problematic in long-term operation. Trees that had little impact at installation can grow over several years and reduce power generation. Trees located on the south, east, and west sides in particular cast shadows on solar panels at different times of day. At solar power plants near forests or slopes, the elevation of the terrain and the height of trees can combine to create long shadows in winter. If power 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 terrain together.

When checking shadows, it is important to match them to the time periods where power generation data shows a drop. If output is low in the morning, check the on-site conditions in the morning; if it is low in the evening, inspect the shadows in the evening. Even if there is no problem at noon, large shadows can appear in the morning and evening. Also, even if there is no problem in summer, shadows will lengthen in seasons when the sun's elevation is low. When you find a shadow, record the time it occurs, the source, the equipment that is shaded, and take photographs.

Attention must also be paid to shadows from nearby structures and additional equipment. Adding new equipment within the power plant, or installing fences, signs, or monitoring poles, can cast shadows at certain times of day. To prevent reduced power generation, it is important not only to reduce existing shading but also to operate in ways that avoid creating new shading. Shade management is not something that ends with a single round of weed control; it must be continued while monitoring seasonal changes.

Operational Tip 6: Don't Overlook Abnormalities in Strings, Connections, and Cables

To increase solar power generation, you need to check not only the panel surfaces and shading but also the routes that extract the electricity. Even if the solar panels are receiving sunlight normally, if there are faults in the strings, connections, or cables, the generated electricity cannot be fully extracted. Loose terminals, poor contacts, damage to cable sheathing, ingress of moisture, damage caused by animals, damage during grass-cutting work, and deterioration due to aging are major causes of decreased power generation.

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

Connection point or cable faults are suspected when only certain equipment has low power output, when abnormalities tend to occur after rain, when power generation suddenly drops, or when output fluctuates unstably. Even if there is no visible dirt or shading but only some parts are underperforming, electrical faults should be considered. If there is a persistent difference compared with a string under the same conditions, prioritize checking the connection points and cables.

When inspecting electrical equipment, safety must be the highest 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 a judgment. Document the equipment showing abnormalities, the time of occurrence, changes in power output, on-site photographs, and the surrounding environment, and, when necessary, arrange for a professional inspection. At the stage of identifying the cause, it is important to clarify where and what type of abnormality is suspected.

Faults in cables and connections are also related to the surrounding environment. In areas overgrown with weeds, it becomes difficult to inspect the condition of cables. In locations with poor drainage, moisture and standing water can affect connections. At sites where animals can easily enter, cable damage may occur. For improving power generation, it is essential not only to carry out repairs but also to check site conditions that could lead to recurrence.

Operational Tip 7: Check conversion equipment, temperature environment, and ventilation

The causes of low power generation are not limited to the panels and wiring. If the equipment that converts the generated electricity is stopped or its output is being restricted, power generation will not increase even when solar irradiance is sufficient. In operations to increase solar 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 reviewing downtime history, check which equipment stopped, when it stopped, and for how long. Even a short stoppage can cause a large loss if it occurs during daytime when power generation is high. If stoppages and recoveries repeat during the day, they may not stand out in the monthly totals, but you may actually be losing generated power. Whether only specific equipment stops or multiple pieces of equipment stop simultaneously changes which causes should be suspected.

When output curtailment occurs, power generation can plateau even on sunny days. If the top of the generation curve looks flat, check the operating data and history. However, a flat curve does not necessarily mean output curtailment. Similar shapes can result from equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not judge solely from the generation curve; it is important to confirm by comparing equipment records with on-site conditions.

Temperature conditions are another point that should be reviewed. While solar power generation generally benefits from stronger solar irradiance, increases in panel temperature or in the temperature around equipment can make it harder for output to rise. If generation is lower than expected on a clear summer day, you need to check not only the solar irradiance but also the thermal environment. If weeds are proliferating under the panels, if grass or obstacles are present around the equipment, or if dust and deposits are hindering heat dissipation, these conditions can affect the growth of generated power.

Maintaining the environment around equipment is an easily overlooked operational practice. Keeping the area around equipment clear and visible, reducing vegetation and debris that obstruct ventilation, and keeping it in a condition where abnormal indicators and the external appearance are easy to inspect enables earlier detection of stoppages and anomalies. To avoid conflating equipment-side faults with panel-side problems, it is important to cross-check the timing of power output declines with the equipment’s history and isolate causes based on solid evidence.

Operational Technique 8: Prevent Recurrence by Organizing Drainage, Topography, and Inspection Records

In operations aimed at increasing solar power generation, it is necessary to consider not only panels and equipment but also the plant’s overall drainage, topography, and inspection/maintenance access routes. Places where water tends to accumulate, where sediment flows in, muddy or easily waterlogged pathways, slope failures, scouring around the racking, and locations where cables are prone to exposure can directly or indirectly cause reductions in power generation. Poor drainage and changes in terrain may at first seem unrelated to power output, but they are important factors that lead to soiling, weeds, faults in connections, and reduced ease of inspection.

In locations where puddles remain after rain, weeds tend to grow easily. When weeds grow, they create shading, reduce airflow, and make inspections more difficult. Muddy walkways slow down work, and the frequency of cleaning and weeding may decrease. Where sediment flows in, it accumulates under panels and around cables, causing dirt and damage. If the same problems recur in the same locations despite cleaning and weeding, drainage or topography issues should be suspected.

When checking terrain and drainage, on-site inspections after rain as well as during fair weather are effective. Determine where water flows in from, where it accumulates, and where it drains out. Recording puddles, sediment deposits, vegetation overgrowth, pathway settlement, and changes to slopes will reveal locations prone to recurrence. If drainage problems are left unaddressed, soiling and weeds will recur, resulting in the same power generation losses happening repeatedly.

Inspection records are also indispensable for preventing recurrence. If you record the locations of equipment with low power output, rows that tend to get dirty, spots where shadows occur, places where water pools, locations where connection faults have occurred, areas that were repaired, and the extent of cleaning or weeding performed, it will be clear what to check at the next inspection. If records are insufficient, you won’t be able to learn the causes even if the same problems recur, and you’ll have to verify everything from scratch each time.

To prevent recurrence, it is also important to compare power generation before and after countermeasures. After carrying out cleaning, weeding, repairs, equipment inspections, and drainage checks, record the power generation before and after the work, on-site photos, the scope of work, and weather conditions. Prioritize measures that proved highly effective for future interventions, and if an effect is hard to see, consider other possible causes. To increase solar power generation, rather than investigating causes from scratch each time, use past records to streamline subsequent inspections.

Operational Design for Sustaining Improvements in Power Generation

Efforts to increase solar power generation cannot be completed with a single cleaning or repair. Solar power plants are outdoor installations, and their condition changes with the seasons, weather, surrounding environment, and the aging of equipment. Even if you clean them, dirt will return; even if you remove weeds, grass will grow back; trees will grow; and equipment and wiring will change in condition over long-term operation. To consistently improve power generation, a system is needed to sustain inspections and countermeasures.

First and foremost, it is important to define the criteria for checking power output. Decide how often you will review generation data, at what level of decline you will perform an on-site inspection, and to which equipment unit you will apply comparisons; doing so will speed up anomaly detection. Relying solely on an operator’s intuition leads to oversights and inconsistent judgments. Standardizing the sunny-day generation curve, comparisons with equipment under the same conditions, checks of shutdown histories, and the recording of on-site photographs will stabilize the accuracy of improvements.

Next, clarify the priority of countermeasures. If you try to solve all issues at the same time, the workload increases and countermeasures that have a large impact on power generation may be postponed. Prioritize checking equipment that shows a clear decline in power generation data, shadows with long-duration impacts, recurring soiling or poor drainage, and devices that experience frequent stoppages even for short periods. To increase power generation, it is practical to implement measures in order from locations with the largest generation losses.

When multiple people share management responsibilities, a system that allows them to accurately share the exact same location is also necessary. In large power plants, similar rows and equipment are lined up, so photos alone can make it difficult to identify the location. If equipment numbers, location information, photos, and work histories are recorded together, on-site personnel, managers, inspectors, and maintenance staff can more easily confirm they are referring to the same location. Improving power generation is also about creating a system that applies observations made on-site to the next set of improvements.

In operation planning, it is important not only to respond after power output declines but also to identify in advance the conditions that are likely to cause declines. If you record rows that tend to accumulate dirt, times of day when shading is likely to occur, locations where water pools, walkways that are prone to damage, and equipment that tends to show abnormalities, you can check them before power output falls significantly. Recording causes that are easy to overlook and prioritizing them in subsequent inspections is the basic practice for continuously improving power output.

Summary

What's important in operational practices for increasing solar power generation is to check, in sequence, the causes that are easy to overlook and to make improvements beginning with the areas that have the greatest impact on output. In solar power generation, you cannot increase the solar irradiance itself on-site. However, you can improve output by bringing the system closer to a state where received sunlight is converted into electricity without waste. To do this, you need to verify, in order, generation data, comparisons with equipment under the same conditions, weather and irradiance conditions, dirt on panel surfaces, shadows from weeds and trees, string wiring and connection points, power conversion equipment, and drainage and inspection records.

When you feel that power output is low, rather than immediately carrying out cleaning or repairs, it is important to first break down and examine the data. Determine when it is low, which equipment is underperforming, and whether there is a difference compared with equipment under the same conditions. By then inspecting the site, you will be able to identify the places that should be cleaned, the areas where weeds should be removed, the connection points that should be checked, the equipment that should be inspected, and the drainage or access routes that should be reconsidered. When improving power output, it is important to make decisions by linking data with on-site conditions, not by intuition.

Also, efforts to increase solar power generation are not completed with a single operation. Even if you clean, dirt will return; even if you remove weeds, they will grow back; trees will continue to grow; and equipment and wiring will change condition with age. Comparing generation before and after countermeasures, keeping on-site photos and work records, and using them for the next inspection will increase the precision of improvements. To consistently increase generation, it is essential not only to eliminate 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 essential. If you record dirt-prone rows, locations where shadows occur, places where water accumulates, abnormal strings, repair locations, cleaning areas, and inspection photos together with location information, stakeholders can more easily verify the same spot. By combining power generation data with on-site location information, it becomes easier to explain the priority of cleaning, weeding, and repairs, and to streamline subsequent rechecks for recurrence.

If you want to continue operations to increase solar power generation based on on-site data, utilizing LRTK is also effective. As an iPhone-mounted GNSS high-precision positioning device, LRTK is useful for recording inspection locations, areas prone to dirt, locations where shadows occur, locations with poor drainage, abnormal equipment, repair positions, cleaning coverage, and on-site photos at a solar power plant together with high-precision location information. By recording causes that are easy to overlook with location information attached, it becomes easier to implement power generation improvements based on on-site data rather than on intuition.