6 Inspections That Effectively Increase Power Output | How to Quickly Detect Losses

Table of Contents

• Increasing power generation begins with inspections that quickly detect losses

• 点検項目1：発電量データと発電カーブを確認する

• 点検項目2：パネル表面の汚れと付着物を確認する

• 点検項目3：雑草・樹木・周辺構造物の影を確認する

• 点検項目4：ストリング・接続部・ケーブルの異常を確認する

• 点検項目5：変換機器の停止・抑制・温度環境を確認する

• 点検項目6：排水・地形・点検動線を確認する

• 発電量アップを継続するための点検記録の残し方

• Summary

Increasing power output begins with inspections that detect losses early

When considering increasing the output of a solar power system, the most important initial step is not to implement major countermeasures after output has declined, but to establish an inspection system that detects early signs of loss. In solar power generation, you cannot increase the incident solar irradiance at the site. However, you can bring the system closer to a state that converts the received irradiance into electricity as efficiently as possible. In practice, then, increasing generation means quickly identifying the causes of lost potential generation and taking steps to minimize generation losses.

There is not a single cause for reduced power generation. Dirt on the panel surface, deposits such as bird droppings and fallen leaves, shading from weeds and trees, string-level abnormalities, faults in connections, cable damage, stoppage of power conversion equipment, output curtailment, temperature rises, poor drainage, and site conditions that make inspection difficult — multiple factors overlap to lower power generation. Even when there appears to be no major problem visually, checking generation data by time of day or by equipment unit can reveal that only part of the system is underperforming.

What operations personnel searching for "how to increase power generation" need to understand is that the work to raise output is not limited to cleaning and repairs. Cleaning, weeding, and repairs are all important, but if you carry out work without confirming where losses are occurring, you may end up spending time on areas that have little impact on power generation. Conversely, if you can first identify the equipment or time periods where output is declining, you can narrow down the locations to inspect and more easily choose measures that lead to improvement.

Inspections that effectively increase power generation check, in order, the generation data, panel surfaces, shading, electrical paths, power conversion equipment, drainage, and inspection routes. Rather than looking at only one element, it is important to link the data with on-site conditions. Whether output is low only in the morning, the midday peak fails to extend, it drops only in the evening, it becomes unstable after rain, or only specific equipment shows low output, the suspected causes will differ. The purpose of inspections is not only to find abnormalities but to create a situation where countermeasures can be taken before generation losses spread.

Inspections are not a one-time task. Solar power plants are outdoor installations, and their condition changes with the seasons, weather, surrounding environment, and equipment aging. Even after cleaning, dirt will return; even after weeding, grass will regrow; trees will grow; and drainage channels will change due to sediment. That is why regular inspections and record management are essential to sustain improvements in power generation. Below, we explain six inspection items you should check in practice to detect losses early.

Inspection Item 1: Check power generation data and the power curve

The first step in inspections that effectively boost power generation is to check the generation data before going to the site. When you suspect low output, looking only at monthly or annual generation won’t tell you when or where losses are occurring. Even if nothing looks abnormal on a monthly basis, output may drop only during certain hours on sunny days, or only specific equipment may remain at a low level. To improve inspection accuracy, it is important to first narrow down the locations and times of the declines using data.

Examining the power generation curve makes it easier to identify the direction of the cause. If generation is low in the morning, 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 develop, candidates include soiling of the panel surface, temperature rise, limitations of conversion equipment, output curtailment, or equipment shutdown. If the generation curve suddenly drops during a sunny day, it is necessary to correlate alarm histories and shutdown histories with the timestamps.

Comparisons at the equipment level are also essential. If you only look at the plant’s total power output, some anomalies can be concealed by the average. Compare systems with the same orientation, the same tilt, a similar number of panels, and the same shading conditions, and check whether any particular rows or strings are consistently lower. If only a portion is lower compared with systems under similar conditions, local soiling, partial shading, poor connections, cable damage, or equipment-side faults may be suspected.

There are two types of declines in power generation output: sudden drops and gradual declines. Sudden drops can be related to equipment shutdowns, wire breaks, poor connections, or the emergence of obstructions. Gradual declines that progress little by little may be related to the accumulation of dirt, the growth of weeds and trees, deterioration of site conditions due to poor drainage, or the aging of equipment. By reading the pattern of decline, you can identify what to prioritize for on-site inspection.

If you neglect checking the data, you will be slow to notice losses. Short-term stoppages or partial declines in equipment performance may not be noticeable in the monthly total. However, if stoppages or declines occur during periods of strong solar irradiance, generation losses can be significant. To increase power generation, it is important to detect small deviations early rather than respond only after anomalies become large and obvious. Regular checks of power generation data and power curves are the starting point for inspections and the foundation for increasing output.

Inspection Item 2: Check the panel surface for dirt and contaminants

In inspections aimed at boosting power output, always check the panel surface for dirt and deposits. Because solar panels generate electricity by receiving sunlight at the surface, accumulated dirt reduces the light reaching the cells. The type of soiling varies with the site environment: dust and soil, pollen, yellow sand, bird droppings, fallen leaves, sap, dust from nearby construction, road-derived dust, and salt-containing grime that tends to adhere in coastal areas. Even light soiling spread over a wide area can affect power output, and localized deposits can act as strong shading even over a small area.

Particular attention should be paid to the band-like dirt that remains on the lower edge of panels and around the frames. It is often assumed that rain will naturally wash the dirt away, but in reality rainwater flow can collect dirt at the bottom edge and leave it there. On panels with a shallow incline, 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. During inspections, you need to carefully check not only the overall color of the panel but also the lower edge, corners, and the areas around the frame.

Localized deposits such as bird droppings and fallen leaves should not be overlooked. Unlike dirt that spreads thinly across the entire surface, these cover specific spots thickly and act as partial shading that reduces power generation. If only some installations show reduced output, focus on inspecting the panel surfaces around those installations. Rows close to trees, areas around structures where birds are likely to perch, rows that tend to be downwind, and areas near unpaved access ways are more prone to dirt and deposits.

During inspections, it is important not only to check for dirt but also to examine its relationship with power generation data. If areas with heavy soiling coincide with equipment locations showing low power output, cleaning should be given high priority. Conversely, if dirt appears conspicuous but a decline in power generation cannot be confirmed, other causes should be investigated first. To increase power output, it is essential to make judgments by comparing the data with on-site conditions rather than relying solely on visual impressions.

When cleaning, preventing damage to the equipment is a basic prerequisite. Avoid vigorously scrubbing with hard tools, performing sudden work during periods when panels are at high temperature, and carrying out tasks without first verifying electrical safety. Cleaning is not a cosmetic task but maintenance work intended to restore the light-receiving condition and to enable long-term, stable use of the equipment. Areas where soiling repeatedly occurs should be recorded as locations to focus on during the next inspection, as this makes it easier to detect losses early.

Inspection Item 3: Check for shadows from weeds, trees, and surrounding structures

Checking for shading is essential in inspections aimed at increasing power generation. Because solar panels generate electricity from sunlight, even partial shading of a panel can reduce power output. Causes of shading are varied and include weeds, trees, fences, utility poles, surrounding buildings, mounting structures, adjacent rows of panels, and monitoring equipment. Since shadows move with the time of day and the seasons, the absence of visible shading at the time of inspection does not necessarily mean there is no problem.

Weeds are a common cause of power generation loss at sites. Even if there are no problems 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 when vegetation does not touch the panels, the low sun angles in the morning and evening cause shadows to lengthen. Furthermore, when weeds proliferate, ventilation is reduced, inspection pathways become blocked, and it becomes more difficult to check around equipment. Because weed control affects not only generation output but also maintainability and safety, weed management is fundamental to improving power generation.

Shading from trees is a factor that can become problematic during long-term operation. Even trees that had little impact at the time of installation can grow over several years and reduce power generation. Trees located on the south, east, and west sides in particular cast shadows on panels at different times of day. At 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 generation is low only in winter, or if there is a large drop in the morning and evening, it is necessary to check both the trees and the terrain.

When checking shadows, it's easier to identify the cause if you align the power generation data with the times of on-site inspections. If generation is low in the morning, check the site in the morning; if it's low in the evening, look at the evening shadows. Even if nothing appears wrong at noon, large shadows can occur in the morning and evening. Also, even if there are no problems in summer, shadows can lengthen in seasons when the sun's altitude is lower. Shadows should be considered as something that changes over time and with the seasons, not at a single point in time.

Shadows cast by surrounding structures are also subject to inspection. Adding new equipment within the power plant, or installing fences, signs, or monitoring poles, can create shadows at certain times of day. If power generation data shows a drop at the same time each day, suspect the influence of a fixed shadow. To increase power output, it is important not only to reduce existing shading but also to operate in a way that avoids creating new shadows. When you find a shadow, record a photo, the time, the shadow’s source, and the equipment being shaded—this will make future inspections and countermeasures easier.

Inspection Item 4: Check for abnormalities in strings, connection points, and cables

In inspections aimed at increasing power output, it is necessary to check not only panel surfaces and shading but also the pathways that extract the electricity. Even if solar panels are receiving sunlight normally, problems with connections or cables can prevent the generated electricity from being fully extracted. Differences in generation at the string level, loose terminals, poor electrical contacts, damage to cable sheathing, moisture ingress, animal damage, damage during grass‑cutting operations, and deterioration due to aging are all important causes of reduced power output.

When checking for abnormalities at the string level, it is fundamental to 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 abnormalities. Compare with adjacent rows or equipment with the same orientation to see if any are consistently lower. If only a particular string is lower, possible causes include panel soiling, partial shading, poor connections, cable damage, or equipment-side problems.

Pay attention to how anomalies appear. If a reading is consistently lower than its surroundings even on sunny days, dirt or connection problems may be suspected. If it is lower only in the morning and evening, check for the effect of shadows. If anomalies tend to occur after rain, moisture ingress or the condition of connection points may be involved. If it becomes unstable during periods of high ambient temperature, poor contact or the thermal environment around the equipment are also possible causes. Combining the power output waveform with on-site conditions makes it easier to narrow down the cause.

Checks of electrical equipment must be carried out with safety as the top priority. Rather than having on-site personnel forcibly handle equipment to make a judgment, it is important to organize the equipment showing abnormalities, the time of occurrence, changes in power generation, on-site photos, and the surrounding environment, and to escalate to a professional inspection when necessary. If faults in connection points or cables are left unaddressed, not only will the reduction in power generation continue, but the risks to the safety of the equipment will also increase.

Also, faults in connection points and cables can be related to the surrounding environment. In areas with heavy weeds, it becomes difficult to check the condition of cables. During mowing operations there is also a risk of coming into contact with cables. In locations with poor drainage, humidity and standing water can affect connection points. In power plants that are easily accessed by animals, cable damage can also occur. When performing inspections to increase power generation, it is important to assess electrical faults together with the site environment rather than treating them separately.

Even a small difference in power generation can become a large loss if it continues over a long period. Rather than assuming there is no problem because the overall output has not fallen significantly, detecting declines in individual equipment early can lead to increased power generation. For locations suspected of abnormalities, recording the equipment number, location, photos, and time of occurrence makes it easier to hand them over for the next inspection or specialist verification.

Inspection Item 5: Verify the Shutdown, Suppression, and Thermal Environment of the Converter Equipment

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 limited, power generation will not increase even when solar radiation is sufficient. Inspections aimed at increasing power output must check the conversion equipment's operating status, shutdown history, alarm history, and whether output curtailment has been applied.

When reviewing downtime history, confirm which equipment stopped, when it stopped, and for how long. Even short stoppages can cause significant losses if they occur during daytime when power generation is high. If equipment repeatedly stops and resumes during the day, it may not stand out in the monthly totals but can still result in lost generation. Whether only a specific piece of equipment stops or multiple pieces stop simultaneously will change which causes you should suspect.

If output curtailment occurs, power generation can hit a ceiling even under clear-sky conditions. If the top of the power generation curve appears flat, check operational data and history. However, a flat curve does not necessarily indicate output curtailment. Similar patterns can result from equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not judge based solely on the generation curve; it is important to verify with equipment records and on-site conditions.

The surrounding environment of conversion equipment is also important. Conditions such as weeds growing around the equipment, poor ventilation, excessive dust or deposits, and a tendency for heat to build up can affect operating efficiency and the risk of shutdown. Even if there are no abnormalities in the equipment itself, poor surrounding conditions can hinder stable operation. It is important to keep the area around the equipment in a condition that allows for easy inspection, good airflow, and immediate confirmation if an abnormality occurs.

Solar power generation tends to produce more electricity the stronger the sunlight, but when temperatures rise, output may not increase as much. If on a clear summer day the power generation does not reach expected levels, check not only the solar irradiance but also the panel temperature and the temperature around the equipment. If weeds are growing under the panels, there is grass or obstacles around the equipment, or dust and deposits are preventing heat dissipation, these can affect the increase in power generation.

Stops of power conversion equipment or problems with the thermal environment cannot be determined from the appearance of the panel surface alone. That is why it is important to cross-check the time of the power generation drop with the equipment history. If the time when power generation fell matches the time of a shutdown or an alarm, it becomes easier to narrow down the possible causes. If the equipment logs show no anomalies, check other causes such as the panels themselves, wiring, shading, soiling, and solar irradiance conditions. Inspections based on data and history rather than on guesswork are the quickest way to detect losses early.

Inspection Item 6: Check drainage, terrain, and inspection routes

In inspections aimed at increasing power generation, it is necessary to check not only the panels and equipment but also the plant’s overall drainage, terrain, and inspection routes. Areas where water tends to pool, places where sediment can flow in, paths that easily become muddy, slope failures, scour around mounting structures, and locations where cables are prone to exposure can directly or indirectly lead to reduced power output. Poor drainage and changes in terrain may at first appear unrelated to power generation, but they are important factors that contribute to soiling, weed growth, connection faults, and decreased ease of inspection.

Areas where puddles remain after rain are prone to weed growth. When weeds grow, they cast shadows, reduce ventilation, and make inspections more difficult. Muddy pathways slow down work and can lower the frequency of cleaning and weeding. Where sediment flows in, it can accumulate beneath panels and around cables, causing dirt and damage. If cleaning and weeding repeatedly fail to prevent problems in the same location, drainage or terrain issues should be suspected.

For checking terrain and drainage, it is effective to carry out on-site inspections not only in fine weather but also after rain. Determine where water flows in, where it pools, and where it drains away. Recording puddles, sediment accumulation, weed growth, pathway settlement, and changes to slopes will reveal locations prone to recurrence. If poor drainage is left unaddressed, soiling and weeds will recur, resulting in the same power generation losses occurring repeatedly.

Verifying inspection routes is also important. Areas that are difficult to inspect tend to delay the detection of abnormalities. If grass has overgrown so you cannot pass, if it's too muddy to approach, if equipment numbers are hard to read, or if abnormal locations are difficult to share, on-site responses will take longer. Even if you identify equipment with low power generation from the data, improvement will be delayed if it takes time to reach the relevant location on site.

Inspections of drainage, topography, and inspection routes may not immediately appear as increases in power generation. However, over the long term they reduce dirt, weeds, poor connections, and inspection delays. To stably increase power generation, it is necessary not only to improve the generation equipment itself but also to create an environment that makes the power plant easy to manage. To detect losses quickly, you need not only an eye for equipment but also the perspective to see the whole site.

How to Keep Inspection Records to Maintain Increased Power Output

To sustain increased power generation, it is essential to keep inspection results recorded. Even if dirt, shading, abnormalities, or poor drainage are found on site, if the location is not shared accurately, implementing countermeasures and re-inspections will take time. In large power plants in particular, similar rows and equipment can make it hard to identify locations from photos alone. Managing inspection results linked with location information can greatly streamline the practical work of improving power generation.

What you should record are the locations of equipment with low power output, rows that get dirty easily, places where shadows occur, areas where water accumulates, locations of connection failures, places that have been repaired, and the areas where cleaning or weeding was carried out. Keeping photographs, dates and times, equipment numbers, work performed, details of abnormalities, the status of responses, and whether reinspection is needed will be useful at the next inspection. Because adding too many items to record makes it hard to sustain in the field, it is important to start by ensuring that, when viewed later, it is clear what happened and where.

Linking power generation data with on-site photographs makes it easier to identify causes. If the locations of systems with low output coincide with areas where shadows occur or where drainage is poor, the rationale for countermeasures becomes clear. If power generation at a cleaned location improves, you can conclude that soiling had a significant impact at that site. If morning and evening generation improves after weeding, it is likely that shadows from weeds were the cause. Keeping records speeds up future assessments.

When inspection records are lacking, the same problems will recur. Even if there are trends—grass growing in the same places every year, dirt accumulating in the same rows, the same walkways turning muddy after rain, or the same equipment experiencing stoppages—without records the next response will be ad hoc. To increase power generation, it is important not to end inspections as mere checks but to accumulate them as information that can be used for future improvements.

When multiple people are responsible for management, it is important that they can accurately share the same location. If you record the equipment number, location information, and photos together, on-site personnel, managers, inspectors, and repair staff will find it easier to confirm the same location. Improving power output is not just about noticing it on site, but also about keeping that information in a form that relevant parties can share. By continuing to maintain records, you can move closer to inspections that prevent declines in power generation before they occur.

Inspection records also provide the basis for prioritizing improvements in power generation. If you can identify locations prone to soiling, times of day when shadows are likely to occur, areas with poor drainage, and equipment that tends to develop faults, you can focus on those during the next inspection. Rather than responding after a large drop in output, checking places that are likely to decline in advance makes it easier to detect losses early. Inspections that effectively increase power generation should combine the work of finding issues with the work of recording them.

Summary

In inspections aimed at increasing power generation, it is important to detect signs of generation loss early and connect them to appropriate countermeasures for each cause. In solar power generation, you cannot increase the amount of solar irradiance at the site itself. However, you can reduce generation losses by bringing the system closer to a state that converts the received sunlight into electricity without waste. To do this, it is necessary to check, in order, generation output data, panel surfaces, shading, strings and connection points, conversion equipment, drainage, and inspection routes.

The first things to look at are the power output data and the generation curve. Determine when output is low, which equipment is underperforming, and whether there is a discrepancy compared with equipment under the same conditions. If you then inspect the site, it becomes clear where cleaning is needed, what areas require weeding, which connections should be checked, which devices need verification, and what drainage or access routes should be reviewed. To increase the effectiveness of inspections, it is important to make judgments by linking data with on‑site conditions rather than relying on intuition.

Losses from reduced power generation may not appear significant at first. Minor soiling, brief shading, anomalies in part of a string, or short equipment outages can become large generation losses if they persist over time. That is why it is important to detect small changes early through regular inspections, record them, and link them to corrective measures. Keeping inspection records allows you to identify locations where the same problems recur and to address them before power output falls significantly in future.

At particularly large power plants, a system for accurately sharing problem locations is important. If you record soiling-prone rows, areas where shading occurs, places where water accumulates, 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 priority of cleaning, weeding, and repairs, and to streamline follow-up checks for recurrence.

If you want to continue inspections that effectively increase power generation based on on-site data, using LRTK can also be effective. As an iPhone-mounted GNSS high-precision positioning device, LRTK is useful for recording inspection positions within a solar power plant, areas prone to soiling, locations where shadows occur, spots with poor drainage, abnormal equipment, repair locations, and on-site photos together with high-precision location information. By accumulating inspections that quickly detect losses as records with location information, it becomes easier to continue practical efforts to increase power generation.