6 Basic Items to Increase Power Generation | Explained: Causes of Decline and How to Improve

Table of Contents

• Start increasing power generation by isolating the causes of decline

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

• Basic item 2: Inspect panel surfaces for dirt and deposits

• Basic item 3: Manage shadows from weeds, trees, and structures

• Basic item 4: Check for abnormalities in strings and connection points

• Basic item 5: Review stoppages, curtailment, and the temperature environment of power conversion equipment

• Basic item 6: Organize terrain, drainage, and inspection access routes

• Record management to sustain increased power generation

• Summary

Increasing power output starts with isolating the causes of decline

When considering an increase in solar power generation output, the first thing you need to do is not add more equipment but confirm whether the existing equipment is able to deliver its intended generation capacity. In solar power generation you cannot increase the amount of incident solar irradiance at the site. However, you can reduce generation losses by keeping the surfaces that receive sunlight clean, minimizing shading, ensuring the electrical extraction paths are functioning properly, and maintaining equipment in a stable operating condition. In practical terms, increasing output means finding the causes of lost potential power and taking measures to minimize those losses.

There is not a single cause for reduced power generation. Dirt on the panel surface, shadows from weeds or trees, faults at connection points, cable damage, stoppages of conversion equipment, output curtailment, temperature increases, poor drainage, and inspection-unfriendly access routes are among multiple factors that combine to lower power output. Even if there appear to be no visible problems, checking generation data by time of day or by equipment unit can reveal that only certain parts have experienced a significant drop. Conversely, even when generation looks low, considering weather and solar irradiance conditions may show that it is not an equipment fault.

Therefore, when working to increase power generation, it is important not to jump straight into cleaning or repairs, but to systematically isolate the causes of the decline. Check when the 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 the issue is skewed toward particular seasons or times of day. By carrying out these checks, you can determine whether you need to clean, remove weeds, inspect wiring, review equipment histories, or even revisit drainage and topography.

Increasing power generation is not a one-off task but an activity to improve operational precision. Even if you clean, dirt will return; even if you remove weeds, grass will regrow; trees will grow; and equipment and wiring will change condition with age. Because these are outdoor installations, on-site conditions are constantly changing. That is why it is important to record power generation data, on-site photos, inspection results, and work history, and to use them to inform future decisions. Below, we explain the six basic items that operational staff should grasp to promote increases in power generation, presented in a flow from causes of decline to improvements.

Basic Item 1: Viewing power generation data by time period and by facility

The first step to increasing power generation is to examine generation data in detail. If you only look at monthly or annual totals, you may misidentify the cause. Monthly generation is heavily influenced by the weather, so months with many cloudy or rainy days will be lower even if there are no equipment faults. Conversely, even if the monthly total does not look significantly abnormal, generation losses may persist during certain hours on sunny days or with specific equipment. To increase generation, it is important to check changes not only in totals but also by time of day, by day, and by individual equipment.

Viewing by time of day makes the likely direction of the cause easier to identify. If generation is low only in the morning, shadows from trees, structures, or terrain on the east side are suspected. If it is low only in the evening, check for shadows on the west side or impacts from nearby equipment. If the midday generation peak does not extend, candidates include dirt on the panel surface, temperature rise, inverter shutdown, output curtailment, or capacity constraints. If the generation curve suddenly drops midway on a sunny day, equipment shutdowns or connection failures may also be possible.

Comparisons at the equipment unit level are also essential. If you look only at the overall plant figures, abnormalities in some equipment can be hidden by the averages. Compare equipment with the same orientation, the same tilt, a similar number of panels, and the same shading conditions, and check whether a particular area remains consistently low. If only a part is lower compared with equipment under similar conditions, the cause is more likely on-site rather than the weather. Conversely, if the entire plant is similarly low, you need to consider the influence of weather or solar irradiance conditions.

When looking at the data, consider sudden drops and gradual declines separately. If power output suddenly falls, suspect equipment shutdown, disconnection, poor connections, or the emergence of obstructions. If it is declining gradually, accumulation of dirt, growth of weeds or trees, aging-related degradation, or deterioration of site conditions due to poor drainage may be involved. By reading the shape of the decline, you can narrow down the locations that should be checked on site.

If you enter the site without checking the data, inspections tend to be broad and shallow. If you know in advance the times of day or equipment where power generation is falling, you can focus on the east side if output is low in the morning, the west side if it’s low in the evening, and on equipment, temperature, or soiling if it’s low at midday. In practical work to increase power generation, cleaning and weeding are not the only improvement measures. Verifying the data to find where generation losses are occurring is the first improvement measure.

Basic Item 2: Inspect the panel surface for dirt and deposits

Soiling on the panel surface is a common cause of reduced power generation. Because solar panels generate electricity by receiving sunlight on their surface, dirt and deposits reduce the light reaching the cells. The type of soiling varies by site and includes soil dust, pollen, yellow sand, bird droppings, fallen leaves, sap, road-derived dust, dust from nearby construction, and salt-containing dirt that adheres in coastal areas. Even light dirt spread over a wide area can affect power generation, 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 lower edges of panels and around the frames. It is often thought that rain will wash it away naturally, but in reality, after rainwater flows, dirt can collect at the lower edge and remain. Panels with a shallow tilt do not shed water easily, making dirt more likely to accumulate. Although edge dirt is not very noticeable from a distance, it can affect power generation. During on-site inspections, it is important to carefully check not only the overall coloration but also the edges, corners, and areas around the frames.

Bird droppings and fallen leaves can reduce power generation by causing partial shading. There are site-specific tendencies, such as bird damage being concentrated on certain rows, fallen leaves tending to accumulate near surrounding trees, and dust tending to collect on downwind rows. If power generation data shows that only some equipment has lower output, focus inspections on dirt and deposits in that area. If locations with dirt overlap with locations of reduced power generation, cleaning should be given high priority.

When cleaning, it is more practical to prioritize areas that have the greatest impact on power generation rather than cleaning all panels at the same frequency. Focus on rows near unpaved access paths, rows on the leeward side, places where birds tend to gather, areas where rainwater does not drain well, and installations where a drop in power generation has been confirmed. Recording before-and-after photos, the date the work was performed, the scope of the work, and changes in power generation makes it easier to determine how much soiling at that site is affecting power output.

However, cleaning must be carried out in a way that does not damage the equipment. Avoid scrubbing hard with rigid tools, performing sudden tasks during periods when panel temperatures are high, and working without conducting safety checks. Cleaning to increase power generation is not merely a task to make things look clean; it is maintenance to restore light-receiving conditions and prolong the service life of the equipment. In addition to removing dirt, understanding why soiling tends to occur and reviewing access routes, surrounding vegetation, and areas where birds tend to gather will make it easier to prevent recurrence.

Basic Item 3: Manage shading from weeds, trees, and structures

When increasing power generation, shadow management is extremely important. Solar panels generate electricity by receiving sunlight, so even partial shading can reduce their output. Causes of shading vary and include weeds, trees, fences, utility poles, surrounding buildings, mounting structures, adjacent rows of panels, and monitoring equipment. Because shadows move with the time of day and season, a single on-site inspection can overlook them.

Weeds are a cause of power generation loss that deserve particular attention in power plant operations. 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 solar panels and on the rows in front. Even if the vegetation does not touch the panels, shadows lengthen when the sun is low in the morning and evening. In addition, when weeds become overgrown, ventilation deteriorates, inspection walkways are blocked, and it becomes harder to check around equipment. Because it affects not only power output but also maintainability and safety, weed management is a basic mitigation measure.

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

When checking shadows, it is effective to match power generation data with the timing of on-site inspections. If power output is low in the morning, check the site conditions in the morning; if it is low in the evening, observe the evening shadows. Even if shadows are not visible at noon, large shadows can appear in the morning and evening. Even if there is no problem in summer, shadows can lengthen in seasons when the sun’s altitude is low. Measures to mitigate shading to increase power generation should be undertaken with attention to time of day and season.

When carrying out weeding or pruning, prioritize the areas that have the greatest impact on power generation. Rather than aiming solely to uniformly tidy the whole site, focus on the areas in front of the panels, around equipment, inspection walkways, and directions in which shadows are likely to extend. After the work, record whether the shadows have actually been eliminated, whether inspections have become easier, and whether ventilation has improved. Because shading problems tend to recur, do not treat this as a one-off task; annual management that anticipates the growth of grasses and trees is necessary.

Basic Item 4: Inspect strings and connection points for abnormalities

To increase power generation, it is important to check for anomalies not only in the overall figures for the power plant but also at the smallest possible units. Even if the total generation does not appear to show a significant anomaly, only some strings may be underperforming. Such partial declines, if left unaddressed, will continue to cause generation losses over a long period. To achieve higher generation, do not be reassured by overall averages; you need the perspective to detect differences at the equipment level and at the string level.

When comparing at the string level, the basic principle is to compare items under the same conditions. Simply comparing ones that differ in panel count, orientation, tilt, shading conditions, or connection configuration can lead to mistaking normal differences for anomalies. Check whether any are consistently lower than adjacent rows or installations with the same orientation. If only a particular string is low, possible causes include panel soiling, partial shading, poor connections, cable damage, or problems on the equipment side.

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

Faults in connection points and cables are also an important cause of reduced power output. Loose terminals, poor contact, damage to cable sheathing, ingress of moisture, damage by animals, damage during mowing operations, and deterioration with age are among the many factors that can impede the flow of electricity. Because these can be difficult to detect from appearance alone, it is necessary to narrow down the abnormal range using power generation data and determine the cause by cross-checking with on-site photographs and work history.

Checks of electrical equipment are conducted with safety as the highest priority. Rather than having on-site personnel forcibly handle equipment to make a judgment, we review the equipment showing abnormalities, the time of occurrence, changes in power generation, on-site photos, and the surrounding environment, and, when necessary, arrange for specialized inspections. Even if connection points are repaired, if conditions such as water pooling in the same place, vegetation overgrowth, cables that are easily exposed, or easy access for animals remain, there is a possibility of recurrence. Increasing power generation involves not only fixing abnormalities but also creating an environment in which abnormalities are less likely to occur.

Basic Item 5: Review Shutdown, Suppression, and Thermal Environment of Conversion Equipment

Low power generation is not caused solely by the panels and wiring. If the equipment that converts the generated electricity is stopped or its output is limited, generation will not increase even when solar radiation is sufficient. When considering increasing power generation, it is essential to check the operating status of the conversion equipment, shutdown history, alarm history, and whether any output curtailment is in place.

When reviewing stop histories, check which equipment stopped, when it stopped, and for how long. Even short stops can cause significant losses if they occur during the daytime when power generation is high. If stops and recoveries are repeatedly occurring during the day, they may not appear significant in the monthly total but can actually result in missed generation. Depending on whether only a specific piece of equipment stops or multiple pieces stop simultaneously, the suspected causes will differ.

If output curtailment is occurring, power generation can plateau even on sunny days. If the top of the generation curve looks flat, check curtailment logs and operational data. However, a flat curve does not necessarily mean output curtailment. Similar shapes can be caused by equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not judge based on the generation curve alone; it is important to isolate the cause by combining equipment records with on-site conditions.

Temperature conditions should also be reviewed. Solar power generation performs better with stronger sunlight, but when panel temperatures or the temperatures around equipment rise, output tends to drop. If, on a clear summer day, generation does not increase as expected, you need to check not only solar irradiance but also the effects of temperature rise and poor ventilation. If weeds are growing under the panels, there are grasses or obstacles around the equipment, or dust and deposits are making heat dissipation difficult, they can potentially affect power generation.

The area around conversion equipment should be kept easy to inspect, well ventilated, and in a condition that allows immediate confirmation of any abnormalities. If the surroundings of the equipment are overgrown with grass, passageways are narrow, or debris has accumulated, both the operating environment and the ease of inspection deteriorate. In practical work to increase power output, it is important, in addition to checking the equipment itself, to prepare the surrounding environment so the equipment can operate stably.

Basic Item 6: Organize Terrain, Drainage, and Inspection Access Routes

If you are thinking about increasing power output over the long term, you need to check not only the panels and equipment but also the plant’s overall topography, drainage, and inspection/maintenance access routes. Areas where water tends to accumulate, where sediment flows in, paths that easily become muddy, slope failures, scouring around mounting structures, and places where cables are likely to be exposed can directly or indirectly cause reductions in power output. Poor drainage and changes in topography may at first seem unrelated to power output, but they are important factors that lead to soiling, weeds, connection faults, and reduced ease of inspection.

In areas where puddles remain after rain, weeds tend to grow more easily. When weeds grow, they create shade, reduce ventilation, and make inspections more difficult. Muddy walkways slow down work, which can lead to less frequent cleaning and weeding. Where soil and sediment flow in, it can accumulate under panels and around cables, causing dirt and damage. To consistently increase power output, it is important to maintain not only the power generation equipment but also the site environment.

When checking topography and drainage, on-site inspections after rain as well as during fair weather are effective. Identify where water flows in, where it pools, and where it drains away. Recording puddles, sediment accumulation, vegetation overgrowth, pathway settlement, and slope changes will show locations that are prone to recurrence. If dirt or vegetation repeatedly appear in the same spot despite cleaning or weeding, you should suspect drainage or topographical problems rather than only surface-level causes.

Inspection routes also affect power generation. Locations that are difficult to inspect tend to delay the detection of abnormalities. When grass has overgrown so you cannot pass, when the ground is muddy and you cannot get close, when equipment numbers are hard to read, or when it is difficult to share the location of an anomaly, on-site response takes longer. Even if underperforming equipment is identified in the data, improvements will be delayed if it takes time to reach the corresponding site.

Reviewing topography, drainage, and site layout and access routes may not immediately translate into a significant increase in power generation. However, reducing dirt, weeds, poor connections, and delayed inspections helps suppress long-term generation losses. To prevent power generation improvements from remaining only temporary, it is essential to create a site environment that is less prone to problems, easy to inspect, and easy to address.

Record Keeping to Sustain Increased Power Generation

Efforts to increase power output are greatly affected not only by the work itself but also by how records are managed. Even if dirt, shadows, abnormalities, or drainage problems are found on site, if the exact location is not shared, it takes time to implement countermeasures or recheck. This is especially true at large power plants, where similar rows and equipment are lined up and a location can be hard to identify from photos alone. Managing inspection results linked to location information streamlines the practical work of improving power output.

Items that should be recorded are the locations of equipment with low power generation, places where shadows occur, rows that are prone to soiling, locations where water accumulates, points where connection failures occurred, places that were repaired, and the areas where cleaning or weeding was carried out. If these can be managed on a map, generation data and on-site conditions can be overlaid and checked. If areas of low generation overlap with poor drainage or locations where shadows occur, the rationale for countermeasures becomes clear.

It is effective to include photos, date and time, equipment number, work performed, details of any abnormalities, response status, and whether reinspection is necessary in inspection records. However, if you add too many record items, it becomes difficult to use in the field. What matters is that, when viewed later, you can see where and what happened and how it was addressed. If power generation drops again, checking past records makes it easier to determine whether the same problem is occurring in the same location or whether it is a new cause.

When managing multiple power plants, standardizing record-keeping methods is also important. If each site differs in how inspection photos are taken, how equipment numbers are labeled, and the format of anomaly records, information sharing takes longer. Managing generation data, on-site photos, location information, and work histories under a unified approach makes it easier for stakeholders to share the situation. Improvements in power generation become more reproducible not only through the experience of on-site personnel but also by using records at the organizational level.

By continuing to keep records, the weaknesses of each power plant become visible. If you can identify patterns — grass growing in the same spots every year, dirt accumulating in the same rows, the same walkways getting muddy after rain, or the same equipment causing shutdowns — you can take preventive measures before problems occur. To increase power generation, it is important not only to respond after output declines but also to understand the conditions that tend to cause declines and manage proactively to prevent them.

Summary

The basics of increasing power output are to correctly identify the causes of decline and to reduce generation losses one by one. In solar power generation, you cannot increase the amount of solar irradiance itself, but you can move the system closer to a state where the incident solar radiation is converted to electricity without waste. To do so, you need to check generation data by time of day and by equipment unit, and review in order: soiling, shading, string abnormalities, poor connections, equipment stoppages, output curtailment, temperature conditions, poor drainage, and inspection access routes.

If you feel the power generation is low, instead of immediately considering major renovations, first separate and review the data. Check when output is low, which equipment is underperforming, and whether there is a difference compared with equipment under the same conditions. Then, by inspecting the site, you can identify where cleaning is needed, the areas that require weed removal, connection points that need inspection, devices to check, and drainage or access routes to reconsider. Increasing power generation should be driven by linking data with on-site conditions, not by intuition.

Also, increasing power generation is not something that can be completed with a single operation. Even if you clean, dirt will return; even if you remove weeds, grass will regrow; trees will grow; drainage paths will change; and equipment and wiring will change condition with age. By comparing generation before and after countermeasures, keeping on-site photos and work records, and using them for the next inspection, the accuracy of improvements increases. To raise power generation stably, it is essential not only to remove the causes but also to create a site environment and management system that are less likely to deteriorate.

In large power plants, a system for accurately sharing the locations of problems is also important. If the locations of shadowing, dirt-prone rows, water-accumulation areas, abnormal strings, repair sites, and inspection photos are recorded with location information, stakeholders will find it easier to verify the same spot. By combining power generation data with on-site location information, it becomes easier to explain the prioritization of countermeasures, and future inspections and recurrence checks can be made more efficient.

If you want to strengthen efforts to increase power generation using on-site records and location information, using LRTK is also effective. LRTK, an iPhone‑mounted high-precision GNSS positioning device, is useful for recording inspection points within a solar power plant—such as locations where shadows occur, areas with poor drainage, abnormal equipment, repair sites, and on-site photos—together with highly accurate location information. To raise power generation, it is important to accurately identify causes and to manage ongoing verification of the same locations. By using LRTK, you can more practically carry out the on-site management necessary for boosting power generation, from identifying causes of decline to confirming conditions after improvements.