What to do to increase power output? 8 items to check on site

Table of Contents

• To increase power generation, it is important to identify on-site inefficiencies

• Item 1: Check power generation data by time of day

• Item 2: Compare with equipment under the same conditions to narrow down the range of decline

• Item 3: Separate weather, solar irradiance conditions, and seasonal differences

• Item 4: Check panels for surface dirt and deposits

• Item 5: Check for shading from weeds, trees, and structures

• Item 6: Check strings, connection points, and cables for abnormalities

• Item 7: Check power conversion equipment for shutdowns, curtailment, and temperature conditions

• Item 8: Check drainage, terrain, and inspection records

• On-site management to continue improving power generation

• Summary

To increase power generation, it is important to identify on-site waste

When considering what to do to increase the power output of solar power generation, the first thing you need is not to add more equipment but to check whether the existing equipment is performing at its intended capacity. In solar power generation, you cannot increase the amount of solar irradiance at the site. You cannot increase the number of clear-sky days, nor can you alter the seasonal solar altitude. However, you can move the system closer to a state in which the incident solar radiation is converted into electricity with as little waste as possible. In other words, in practical terms, increasing power output means finding the causes that lead to losing power that should be generated and reducing generation losses.

The cause of low power generation is not necessarily a single factor. Dirt on the panel surface, deposits such as bird droppings and fallen leaves, shading from weeds or trees, faults at connection points, cable damage, stoppage of conversion equipment, output curtailment, temperature rise, poor drainage, lack of inspection records, and other factors may combine. Even if there appears to be no major visible abnormality, checking power generation data by time of day or by equipment unit can reveal that only some parts are continuously declining.

For practitioners searching "how to increase power generation", the important thing is not to decide countermeasures based solely on on-site impressions. Judgments such as cleaning because the panels are dirty, weeding because the grass has overgrown, or suspecting equipment degradation because the devices look old are necessary in some cases. However, if the primary cause of the decline in power generation lies elsewhere, those actions will not lead to sufficient improvement. Even if you clean, if morning and evening shadows remain, power generation is unlikely to recover; and even if you remove weeds, if short stoppages of the power conversion equipment continue, daytime generation will not increase.

To increase power generation, it is important to link generation data with on-site conditions to isolate causes. Check when output is low, which equipment is affected, whether there is a difference compared to equipment under the same conditions, whether output 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 fact that generation is low alone does not tell you what to prioritize. If you organize the items to check on site, you will more easily find causes that lead to improved generation even within limited inspection time.

Also, improving power output is not something that can be completed in a single operation. A solar power plant is an outdoor facility, and its condition changes with the seasons, weather, surrounding environment, and the aging of equipment. Even after cleaning, dirt will return; even after weeding, grass will regrow; trees will grow; and drainage routes will change due to sediment and fallen leaves. To reliably increase and stabilize power output, it is necessary to identify causes, implement countermeasures, verify their effectiveness, and use the records in the next inspection as part of ongoing operations.

Item 1: Check power generation data by time of day

The first thing to examine to increase power generation is the generation data, not the on-site panels. If you only look at monthly or annual generation, you cannot tell when generation losses are occurring. Likewise, even when overall generation is low, the potential causes change depending on whether it is low only in the morning, the midday peak does not rise, it drops only in the evening, or there is a sudden dip during the day. To increase generation, the starting point is to look at the generation curve by time of day rather than the totals.

If power generation is low in the morning, shadows from trees on the east side, slopes, surrounding structures, or adjacent equipment may be responsible. 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 surfaces, a rise in temperature, limitations of power conversion equipment, output curtailment, or equipment shutdowns. If the generation curve suddenly drops during a sunny day, you should cross-check shutdown logs and alarm histories against the times.

When checking by time of day, it is important to use data from sunny days whenever possible. On cloudy or rainy days, power output can fluctuate greatly due to cloud movement, making it difficult to determine whether the cause is an equipment fault or the weather. By looking at the generation curve on sunny days, it becomes easier to find patterns such as the effect of shadows that occur at the same time each day, equipment stoppages that happen only at specific times, and output curtailment that flattens the top.

When looking at power generation data, consider abrupt declines and gradual declines separately. If output suddenly drops, equipment shutdowns, broken wiring, poor connections, or the emergence of obstructions are suspected. If output is decreasing gradually, accumulation of dirt, growth of weeds or trees, deterioration of the site environment due to poor drainage, or equipment degradation may be involved. By interpreting the pattern of the decline, you can narrow down the areas on site that should be checked intensively.

If you go on-site without checking the data, inspections tend to be broad and shallow. Even if you walk around the entire plant, if the timing of the on-site check doesn't match the time when power output drops, you may miss the causes of shading or stoppages. If output is low in the morning, check the on-site conditions in the morning; if it's low in the evening, look for evening shading. On-site checks to increase power generation start with data verification before going to the site.

Item 2: Narrow the range of decline by comparing with equipment under identical conditions

To identify the causes of low power generation, looking only at the total for the entire plant is insufficient. Even if there is no major anomaly overall, there may be cases where only certain rows, certain strings, or areas connected to specific power conversion equipment show reduced generation. Such localized generation losses are difficult to notice in monthly totals, but if they persist over long periods they can lead to significant losses. To increase generation, it is important to narrow down the areas of decline by comparing them with equipment under the same conditions.

When making comparisons, select installations with similar orientation, tilt, number of panels, shading conditions, and connection configuration. Simply comparing installations with different conditions can cause you to misinterpret normal differences as abnormalities. Even within the same power plant, power generation changes if orientation or tilt differs. The purpose of the comparison is to identify locations that are consistently underperforming among installations that should normally have similar output.

If only a specific part is underperforming compared with installations 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 column is lower than adjacent columns even on sunny days, possible causes include grass growing in front of that column, concentrated soiling at the lower edge, or a fault in the wiring route. Narrowing down the abnormal range in the data before inspecting the site improves the accuracy of the inspection.

When narrowing the scope of the decline, it is also important to be able to accurately identify the relevant location on site. At sites where equipment numbers or row numbers are hard to read, even if an anomaly is found in the data, it can take time to locate the corresponding spot on site. A photo alone may not convey the location. When improving power output, being able to accurately share the location among stakeholders is as important as finding the anomaly.

Even a small difference in power generation can become a large loss if it continues every day. Rather than assuming there is no problem because the total power generation has not dropped significantly, continuously check the difference compared with equipment under the same conditions. This comparison makes it easier to narrow down the areas that need cleaning, the places that need weeding, the connection points that need inspection, and the equipment that needs checking.

Item 3: Separating weather, solar radiation conditions, and seasonal differences

When you feel that power generation is low, before suspecting equipment failure you should check the weather, solar irradiance conditions, and seasonal differences. Solar power generation is greatly affected by the amount of sunlight, so during periods with many cloudy or rainy days generation can decrease even if there are no equipment problems. 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, the main cause may actually be differences in weather.

On the other hand, one must avoid overlooking real anomalies by attributing them to the weather. If the entire power plant shows reduced output consistent with regional weather, the impact of solar irradiance conditions is likely significant. However, if only part of the plant is underperforming while other equipment at 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 for on-site causes such as soiling, shading, poor connections, equipment shutdowns, or output curtailment.

To distinguish between weather-related causes and equipment-related causes, it is effective to compare clear-sky days with each other or days with similar weather. On cloudy or rainy days, power output varies greatly, making the characteristics of anomalies harder to see. By selecting and checking the power output curves of clear-sky days, you can more easily find effects such as shadows that fall at the same time every day, string anomalies where only certain equipment shows low output, and equipment shutdowns that cause drops only during specific periods.

Seasonal differences are also an important factor to consider. In winter the sun’s altitude is lower, so shadows from surrounding trees and terrain tend to stretch farther. In summer, although solar radiation is stronger, panel and equipment temperatures rise, which can make it harder for power output to increase. During periods of heavy rain, monthly power generation tends to be lower, and after strong winds or heavy rain you should also pay attention to fallen leaves, sediment, deposits, poor drainage, and the condition around cables.

To increase power generation, you need to distinguish between natural variability and generation losses that can be improved on-site. If the cause is the weather, cleaning or repairs will not significantly improve output. Conversely, if output remains low even on sunny days, it is likely that there is room for improvement at the site. To improve the accuracy of identifying causes, it is important not to ignore solar irradiance conditions and to carefully separate them from equipment-side issues.

Item 4: Inspect the panel surface for dirt and deposits

One common cause of low power generation that should be checked at many sites is dirt and deposits on the panel surface. Because solar panels generate electricity by receiving sunlight at their surface, when dirt adheres the amount of light reaching the cells is reduced. Soil dust, pollen, yellow sand, bird droppings, fallen leaves, tree sap, dust from nearby construction, dust from roads, and salt-containing dirt that easily adheres in coastal areas—how panels become soiled varies depending on the site environment. Even light soiling, if spread over a wide area, can affect power generation, and localized deposits can act as a strong shade even over a small area.

Particular attention should be paid to the banded dirt that remains along the lower edges of panels and around the frames. It is often assumed that rain will naturally wash it away, but in reality rainwater flow can gather the dirt at the lower edge and leave it there. Panels with a shallow tilt do not drain well, making it easier for dirt to accumulate. Even dirt that is not noticeable from a distance can affect power generation if it covers part of a cell. On-site inspections need to carefully check not only the overall coloration of the panels but also the lower edges, corners, and areas around the frames.

Localized deposits such as bird droppings and fallen leaves should not be underestimated. Unlike dirt that spreads thinly across the entire surface, these cover specific areas heavily and act as partial shading that hinders power generation. If only some installations show reduced output, focus inspection on the panel surfaces around those installations. Rows close to trees, areas around structures where birds tend to perch, rows that are often downwind, and locations near unpaved walkways are more likely to accumulate dirt and deposits.

When 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 output has been confirmed, rows with concentrated soiling, areas where soiling along the lower edge is conspicuous, and locations with heavy bird damage or fallen leaves. Comparing photos and power output before and after cleaning makes it easier to judge how much the soiling at that site had affected generation.

However, 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, or working without first verifying the electrical safety of the equipment. Cleaning to improve reduced power generation is not a cosmetic task but a maintenance activity to restore the light-receiving condition and keep the equipment operating stably over the long term. By recording the locations, extent, and likely causes of the soiling, you can make use of that information in subsequent inspections.

Item 5: Check for shadows cast by weeds, trees, and structures

When investigating low power output, shading must always be checked. Because solar panels generate electricity from sunlight, even a shadow covering part of a panel can reduce its output. Causes of shading include weeds, trees, fences, utility poles, nearby buildings, mounting structures, adjacent rows of panels, monitoring equipment, and more. 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 on-site power generation losses. Even if there is no issue in winter or immediately after installation, they can grow rapidly from spring into 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 angle in the morning and evening lengthens shadows. Furthermore, when weeds become overgrown, ventilation deteriorates, inspection walkways become blocked, and it becomes more difficult to check around equipment. Because it affects not only power output but also maintenance and safety, weed management is fundamental to improving generation performance.

Tree shading is a factor that can become problematic during long-term operation. Trees that had little effect at the time of installation can grow over several years and reduce power generation. Trees located on the south, east, and west sides in particular cast shadows on panels at different times of day. At plants near forests or slopes, the heights of the terrain and the 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 terrain together.

When checking shadows, it is important to match the times to the periods when power generation data is declining. 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 are no problems at noon, large shadows can appear in the morning and evening. When you find a shadow, record the time it occurred, the source, the equipment affected, and photos. Weed control and pruning should be prioritized in the areas that have the greatest impact on power generation.

Attention must also be paid to shadows cast by surrounding structures and added equipment. Adding new equipment within the power plant, or installing fences, signs, or surveillance poles, can create shadows depending on the time of day. To increase power output, it is important not only to reduce existing shadows but also to operate in a way that does not create new ones. Shadow management is not something that can be completed with a single weeding; it must be carried out continuously while monitoring seasonal changes.

Item 6: Check for abnormalities in connectors, cables, and conversion devices

The causes of low power generation are not limited to panel surfaces or shading. Even if solar panels are receiving sunlight normally, faults in connection points, cables, or power conversion equipment can prevent the generated electricity from being fully extracted. Differences in generation at the string level, loose terminals, poor contacts, damage to cable sheaths, moisture ingress, animal damage, stoppage of power conversion equipment, and output curtailment are important causes of reduced power generation.

When checking for abnormalities at the string level, compare strings that are under the same conditions. If you simply compare strings with different panel counts, orientations, tilts, shading conditions, or connection configurations, you may mistakenly interpret normal differences as abnormalities. Compare with adjacent rows or with equipment facing the same direction to see if any are persistently low. If only a particular string is low, possible causes include soiling, partial shading, poor connections, cable damage, or issues on the equipment side.

Suspicion of faults in connection points or cables arises when only certain equipment has low power output, when abnormalities are more likely to appear after rain, when generation suddenly drops, or when output fluctuates unstably. In areas with heavy weeds, it becomes difficult to check the condition of cables. In locations with poor drainage, moisture and puddles can affect the connections. At sites prone to animal intrusion, cable damage may also occur.

For conversion equipment, check the operating status, shutdown history, alarm history, and whether output curtailment is in effect. Even short shutdowns can cause large losses if they occur during the daytime when generation is high. If the generation curve flattens on clear days, check for output curtailment, the equipment capacity limit, temperature rise, measurement anomalies, and so on. Do not judge based only on the generation curve; it is important to review equipment records together with on-site conditions.

When checking 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 inside of equipment to make a judgment. Organize the equipment that is showing abnormalities, the time of occurrence, changes in power generation, on-site photos, and the surrounding environment, and, if necessary, arrange for specialist inspection. At the stage of determining the cause, it is important to make clear where and what kind of abnormality is suspected.

Item 7: Check the shutdown, suppression, and temperature environment of the conversion equipment

For power conversion equipment, it is important to check not only shutdowns and output curtailment but also the temperature environment. Solar power generation tends to increase as solar irradiance strengthens, but when panel temperatures or the temperatures around equipment rise, output may not increase as much. If, on a clear summer day, the amount of power generated does not rise as expected, you need to check the temperature environment as well as the solar irradiance.

Panels exposed to strong sunlight outdoors can reach high surface temperatures. When surrounding ventilation is poor, or weeds are growing thickly beneath the panels, heat can become trapped. Output reductions due to temperature may not appear as abrupt shutdowns but as a slowdown in the growth of power output. Especially at sites where power output tends to plateau around noon in summer, it is worth checking the ventilation conditions.

Conversion equipment is also affected by temperature. If grass or other objects around the equipment hinder heat dissipation, it can lead to reduced efficiency or activation of protective functions. The area around the equipment must be kept easy to inspect, allow airflow, and be arranged so that any abnormalities can be checked immediately. Conditions in which weeds or accumulated debris make the area around the equipment difficult to see are undesirable not only for power generation output but also for inspectability and safety.

It is also important not to confuse equipment-side faults with panel-side issues. Even if the panels appear dirty, the primary causes may actually be equipment shutdowns, output curtailment, or temperature conditions. Correlating the times of generation drops with equipment history, and choosing countermeasures based on evidence rather than guesswork, is the key to avoiding failure when improving power generation.

What you should check on site is not limited to the equipment's history. Vegetation around the equipment, ventilation, inspection access routes, the effects of rainwater and sediment, and the ease of visual inspection are also important. Maintaining an environment that allows equipment to operate stably is one of the basic management practices for increasing power generation.

Item 8: Check drainage, topography, and inspection records

To increase power generation, you need to check not only the panels and equipment but also the plant’s overall drainage, topography, and inspection routes. Areas where water tends to accumulate, places where sediment can wash in, paths prone to becoming muddy, slope collapses, scouring around the racking, and locations where cables are likely to be exposed can directly or indirectly cause a decrease in power generation. These are important factors that lead to soiling, weeds, defects in connections, and reduced accessibility for inspection.

Areas where puddles remain after rain tend to encourage weed growth. When weeds grow, they create shading, reduce ventilation, and make inspections more difficult. Muddy walkways slow work and can lead to less frequent cleaning and weeding. In places where sediment flows in, it can accumulate beneath panels and around cables, causing soiling and damage. If cleaning or weeding repeatedly fails to resolve problems in the same locations, drainage or terrain issues should be suspected.

When checking terrain and drainage, it is effective to inspect the site not only in fair weather but also after rain. Determine where water flows in, where it accumulates, and where it drains out. Recording puddles, sediment accumulation, overgrowth of vegetation, pathway subsidence, and changes to slopes will reveal locations prone to recurrence. If drainage problems are left unaddressed, dirt and weeds will return repeatedly, resulting in the same power generation losses occurring again and again.

Inspection records are also important for identifying causes of recurrence. If you can check whether dirt has appeared in the same location in the past, whether weeds have grown in the same row, or whether the same equipment has experienced stoppages, you can narrow down the cause more quickly. If records are insufficient, start keeping photos, date and time, equipment number, location, details of abnormalities, and the status of responses from this inspection so they can be used for the next check.

By identifying the factors that cause recurrence, countermeasures change from one-time tasks to ongoing improvement. Rather than just cleaning dirt, check why that location is prone to soiling. Rather than simply mowing grass, look at why grass tends to grow there. Rather than only repairing connections, verify background factors such as humidity, drainage, and cable exposure. With this perspective, it becomes easier to sustain the effects of power generation improvements over the long term.

On-site Management to Sustain Power Output Improvements

Efforts to increase power generation are not 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 if you clean them, dirt will return; even if you remove weeds, grass will grow; trees will grow; and equipment and wiring will change condition during long-term operation. To stably improve power generation, a system for ongoing inspections and corrective measures is necessary.

First, the important thing is to compare power output before and after the measures. After performing cleaning, weeding, repairs, equipment checks, and drainage inspections, check how the power output has changed. It is difficult to completely eliminate the influence of weather, but by comparing sunny days with each other or comparing installations under the same conditions, you can identify certain trends. Prioritize measures that showed a large effect for future work, and if an effect is not apparent, consider other possible causes.

Next, keep locations that tend to recur as management targets. By recording rows that easily accumulate dirt, times of day when shadows are likely to occur, places where water pools, passageways that are prone to damage, and equipment that tends to show abnormalities, you can check them before power generation drops significantly. To consistently increase power generation, it is important not only to respond after output falls but also to identify conditions that are likely to cause declines in advance and take measures.

When multiple people are involved in management, it is also important that they can accurately share the same location. In large power plants, similar rows and equipment are often arranged, so a photo alone can make it difficult to identify the location. If equipment numbers, location information, photos, and work histories are recorded together, field staff, managers, inspectors, and repair personnel can more easily confirm the same location. Improving power output is also about creating a system that leverages on-site observations for subsequent improvements.

It is also important to clarify the priorities for improving power generation. Trying to resolve all issues at once can increase workload and cause measures that have a large impact on power output to be postponed. Prioritize checking equipment that shows a clear decline in generation data, shadows with a long duration of impact, recurring soiling or drainage failures, and devices that experience frequent shutdowns even for short periods. To increase power generation, it is practical to implement measures in order, starting from locations with the largest generation losses.

Summary

When organizing what should be done to increase power output, the important thing is to systematically check the causes of generation losses on site and 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 power output by bringing the system closer to a state in which the received irradiance is converted into electricity without waste. To do this, it is necessary to check, in order, power generation data, comparisons with equipment under the same conditions, weather and irradiance conditions, panel surface soiling, shading from weeds and trees, connections and conversion equipment, temperature environment, drainage, and inspection records.

When you suspect generation output is low, don’t rush into cleaning or repairs; first separate and analyze the data. Determine when output is low, which units are underperforming, and whether there is a difference compared with equipment under the same conditions. With that information, a site inspection will clarify where to clean, the areas that need weed control, which connection points require inspection, which devices need checking, and which drainage or flow paths should be reconsidered. When improving generation output, it is important to make decisions by linking data with on-site conditions, not by intuition.

Furthermore, efforts to increase power generation are not completed with a single action. Even if you clean, dirt will return; even if you remove weeds, grass will grow back; trees will continue to grow; and equipment and wiring will change condition over time. 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 will increase. To consistently increase power generation, 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.

In particularly large power plants, a system for accurately sharing problem locations is essential. If you record frequently soiled rows, shadowed areas, water accumulation spots, abnormal strings, repair locations, cleaning areas, and inspection photos together with location information, stakeholders can more easily confirm the same locations. By combining power generation data with on-site location information, it becomes easier to explain the priorities for cleaning, weeding, and repairs, and it also streamlines verification of recurrence in subsequent inspections.

If you want to continuously manage the eight on-site items to check in order to increase power generation as records with location information, leveraging LRTK is also effective. LRTK, an iPhone-mounted GNSS high-precision positioning device, is useful for recording inspection locations within a solar power plant, areas prone to soiling, locations where shading occurs, sites of poor drainage, abnormal equipment, repair locations, cleaning scope, and on-site photos together with high-precision location information. By keeping the results of on-site inspections with location information, it becomes easier to pursue power generation improvements based on field data rather than on intuition.