8 Ways to Increase Solar Power Generation Efficiency | Power Output Improvement Guide

Table of Contents

• To improve solar power generation efficiency, it is important to identify generation losses

• Method 1: Check generation output data by time of day and by equipment unit

• Method 2: Separate the effects of weather, solar irradiance conditions, and seasonal differences

• Method 3: Manage dirt and deposits on panel surfaces

• Method 4: Reduce shading from weeds, trees, and structures

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

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

• Method 7: Improve drainage, terrain, and inspection routes

• Method 8: Continue improvements using inspection records and location information

• A mindset to avoid ending generation efficiency improvements as temporary measures

• Summary

Understanding generation losses is essential to improving solar power generation efficiency

When aiming to improve the efficiency of solar power generation, the first point to understand is that you cannot increase the amount of solar irradiance at the site. Solar power generation is affected by weather and seasons, so during periods with few sunny days or when solar conditions are poor, generation will decrease even if the equipment is functioning correctly. On the other hand, you can move closer to a state in which the incident sunlight is converted into electricity with as little waste as possible. In practice, improving generation efficiency means identifying the causes of missed generation potential and reducing those generation losses.

There is not a single cause of reduced power generation efficiency. Dirt on the panel surface, deposits such as bird droppings and fallen leaves, shading from weeds or trees, string-level abnormalities, faults in connection points, cable damage, stoppage of conversion equipment, output curtailment, temperature increases, poor drainage, and site environments that are difficult to inspect—multiple factors combine to reduce power output. Even when there appears to be no obvious visual problem, checking generation data by time of day or by equipment unit can reveal that only certain parts are continuously underperforming.

What operational staff searching for "how to increase power generation" should be careful about is not to rely on intuition when trying to improve generation efficiency. Deciding to clean because the panels look dirty, to remove weeds because the grass has grown, or to inspect because equipment appears to have stopped is not necessarily wrong. However, if the primary cause of the drop in power generation and the countermeasure do not align, the work may not yield the expected improvement. To improve generation efficiency, you should first confirm the pattern of the decline using data, identify the cause on site, and verify the effect after implementing countermeasures.

From here, we will explain eight practical methods to check on-site to improve solar power generation efficiency. Rather than treating cleaning, weeding, inspection, drainage, and record management as separate tasks, it is important to regard them as a single, continuous management process for identifying and improving generation losses.

Method 1: Check power generation data by time period and by equipment

The first step to improving power generation efficiency is to closely examine generation output data. If you only look at monthly or annual generation totals, you cannot tell when, where, or how generation losses are occurring. Even if nothing looks like a major anomaly on a monthly basis, there may be cases where output drops only during certain hours on sunny days, or where a specific piece of equipment remains underperforming. For improving generation output, it is more important to look at variations by time of day, by equipment unit, by day, and by season than to focus on aggregate totals.

If the morning generation is low, shading from trees on the east side, slopes, nearby structures, or adjacent equipment may be involved. If it is low in the evening, check for west-side shading and the influence of surrounding terrain. If the midday peak does not develop, candidates include soiling of the panel surface, temperature rise, limits of the power conversion equipment, output curtailment, or equipment shutdown. If the generation curve suddenly drops midway through a sunny day, you should cross-check shutdown logs and alarm history against the timestamps.

When comparing equipment on a per-unit basis, it's important to compare units under identical conditions. If you simply compare equipment with different orientations, tilts, numbers of panels, shading conditions, or connection configurations, you may mistake a normal difference for an anomaly. If, compared with adjacent rows or equipment facing the same direction, a specific area is consistently lower, suspect localized soiling, partial shading, poor connections, cable damage, or an equipment-side fault.

If you don't have a habit of checking power generation data, you'll be slow to notice losses. Short outages or partial equipment degradation may not be noticeable in the monthly total. However, if stoppages or performance drops occur during periods of strong solar irradiance, generation losses can be significant. To improve generation efficiency, it's essential to use data to narrow down targets before on-site work and to clarify which locations and time periods should be checked.

Method 2: Isolate weather, solar radiation conditions, and seasonal differences

When you feel that power generation is low, before suspecting an equipment malfunction you should check the weather, sunlight conditions, and seasonal variations. Solar power generation is heavily influenced by solar irradiance, so output will drop during periods with many cloudy or rainy days even if there is no equipment problem. If you compare only the monthly generation with the same month of the previous year or with the previous month and immediately conclude an equipment failure, the main cause may actually have been differences in the weather.

On the other hand, we must avoid overlooking genuine anomalies by attributing them to the weather. If the entire plant’s output is uniformly reduced in line with regional weather conditions, the influence 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 output is clearly lower compared with other sites in the same region, the weather alone cannot account for it. In such cases, it is necessary to check for soiling, shading, poor connections, shutdowns of power conversion equipment, and output curtailment.

To isolate weather-related effects, it is effective to compare sunny days with other sunny days or days with similar weather. On cloudy or rainy days, power generation fluctuates greatly with cloud movement, making it difficult to distinguish from equipment abnormalities. If you select and compare generation curves from sunny days, features such as shading, shutdowns, curtailment, and string anomalies become easier to detect. Rather than looking only at days with low generation, it is important to compare with days that have similar conditions.

Seasonal variations should also be taken into account. In winter, the sun's altitude is lower, and shadows from surrounding trees and terrain tend to extend further. In summer, while solar irradiance is stronger, panel temperatures and temperatures around equipment rise, which can make it harder for output to increase. During periods with heavy rainfall, monthly power generation tends to be lower, and after strong winds or heavy rain attention should be paid to deposits, sediment, poor drainage, and the condition around cables. When improving generation efficiency, it is important to distinguish between natural variations and losses that can be addressed on-site.

Method 3: Manage Dirt and Deposits on Panel Surfaces

Contamination and deposits on the panel surface are a common cause of reduced power generation efficiency. Because solar panels generate electricity by receiving solar radiation at their surface, accumulated dirt reduces the light reaching the cells. The type of soiling varies with site conditions, including soil dust, pollen, yellow sand, bird droppings, fallen leaves, tree sap, dust from nearby construction, road-borne dust, and salt-containing deposits that readily adhere 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 if they cover only a small area.

Particular attention should be paid to strip-like dirt that remains along the lower edge of the panel and around the frame. It is often assumed that rain will wash it away naturally, but in reality the flow of rainwater can gather dirt at the lower edge and leave it there. On gently sloped panels, water does not drain easily 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 coloration of the panel but also the lower edge, the corners, and the area 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 areas densely and act as partial shading that inhibits power generation. If only some installations are producing less power, focus inspections on the panel surfaces around those installations. Rows near trees, around structures where birds tend to perch, rows that are often downwind, and areas near unpaved walkways are more prone to dirt and deposits.

When cleaning is carried out, 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 decrease in generation has been confirmed, rows where dirt is concentrated, areas where soiling at the lower edges is noticeable, and locations with frequent bird damage or fallen leaves. By comparing photos and power output before and after cleaning, it becomes easier to determine how much the soiling had affected power generation at that site.

Cleaning must be carried out so as not to damage the equipment. Avoid vigorously scrubbing with hard tools, performing sudden work during periods when panels are at high temperature, or working without confirming the electrical safety of the equipment. Cleaning to improve power generation efficiency is not a cosmetic task to improve appearance; it is maintenance work to restore the light-receiving condition and enable long-term, stable use of the equipment.

Method 4: Minimize shadows cast by weeds, trees, and structures

Shading management is essential for improving the efficiency of solar power generation. Because solar panels generate electricity by receiving sunlight, even a partial shadow on a panel can reduce its power output. Causes of shading include weeds, trees, fences, utility poles, nearby buildings, mounting structures, adjacent rows of panels, monitoring equipment, and other factors. 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 on site. Even if there is no problem in winter or immediately after installation, they can grow rapidly from spring through summer and cast shadows on the lower edge of panels and the front rows. Even when vegetation does not touch the panels, the low solar altitude in the morning and evening causes long shadows. Furthermore, when weeds proliferate, ventilation worsens, inspection walkways become blocked, and it becomes difficult to check around equipment. Because this affects not only energy output but also maintainability and safety, weed management is fundamental to improving power generation efficiency.

Shadows from trees are a factor that tend 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 depending on the time of day. At power plants near forests or slopes, the height of the terrain combined with the height of the trees can 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 trees and terrain together.

When checking shadows, it's easier to identify the cause if you align the power generation data with the time of the on-site inspection. If morning generation is low, check the site conditions in the morning; if it's low in the evening, inspect the evening shadows. Even if there is no apparent problem at noon, large shadows can appear in the morning or evening. Also, even if there is no issue in summer, shadows can lengthen in seasons when the sun angle is lower. Shadows need to be managed as something that changes with time and season, not as a single moment.

Be aware of shadows from nearby structures and additional equipment. Adding new equipment inside the power plant, or installing fences, signs, or monitoring poles can cast shadows at certain times of day. To improve power generation efficiency, it is important not only to reduce existing shadows but also to operate in a way that does not create new ones. When you discover a shadow, record the time it occurs, its source, the equipment affected, and photos—this information can be used to decide on weeding, pruning, or rearranging components.

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

To increase power generation efficiency, you need to check not only the panel surface and shading but also the pathways that extract the electricity. Even if photovoltaic panels are receiving sunlight properly, defects in connections or cables can prevent the generated electricity from being drawn out sufficiently. String-level differences in power generation, loose terminals, poor contacts, damage to cable sheathing, moisture intrusion, damage by animals, damage during mowing operations, and degradation due to aging are all significant causes of reduced power output.

When checking for anomalies at the string level, it is fundamental to compare units under the same conditions. If you simply compare systems that differ in number of panels, orientation, tilt, shading conditions, or connection configuration, you may mistakenly judge normal differences as abnormalities. Compare with adjacent rows or installations that have the same orientation to see if any are consistently lower. If only a particular string is lower, possible causes include soiling of the panels, partial shading, poor connections, cable damage, or equipment-side problems.

Pay attention to how the anomaly appears. If it is consistently lower than the surroundings even on sunny days, dirt or connection problems are suspected. If it is lower only in the morning and evening, check for 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 are also possible causes. Combining the power output waveform with on-site conditions makes it easier to narrow down the cause.

Inspection of electrical equipment must be carried out with safety as the highest priority. Instead of having on-site personnel forcibly touch equipment to make judgments, document the equipment showing abnormalities, the time of occurrence, changes in power output, site photographs, and the surrounding environment, and, when necessary, arrange for a professional inspection. You should avoid performing work that omits safety checks simply to improve power generation efficiency.

Faults in connection points and cables can sometimes be related to the surrounding environment. In areas with heavy weed growth, it becomes difficult to inspect the condition of cables. In locations with poor drainage, moisture and standing water can affect connection points. At power plants that are easy for animals to access, cable damage can also occur. When improving power output, it is important to review not only electrical faults but also the site conditions that can cause recurrence.

Method 6: Reassess shutdown/suppression of conversion equipment and the thermal environment

The causes of low power generation are not limited to panels and wiring. If the equipment that converts the generated electricity is stopped or its output is restricted, power generation will not increase even with sufficient solar irradiance. When considering improvements in generation efficiency, 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 stoppage history, confirm which equipment stopped, when, and for how long. Even a short stoppage can cause large losses if it occurs during the daytime when power generation is high. If stops and recoveries are repeating during the day, they may not stand out in the monthly total, but in reality they could be causing 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 is occurring, power generation can plateau even on sunny days. If the upper part of the generation curve appears flat, check operational data and historical records. However, a flat curve does not necessarily mean output is being curtailed. Similar shapes can be caused by equipment capacity limits, temperature rise, soiling, shading, or measurement anomalies. Do not rely solely on the generation curve; it is important to verify by comparing equipment records with on-site conditions.

Temperature conditions are also a point to review. While solar power generation tends to be higher when solar irradiance is stronger, output can become harder to increase as temperatures rise. If generation does not rise as much as expected on a clear summer day, check not only irradiance but also panel temperature and the temperature around equipment. If weeds are growing under the panels, grass or other obstacles are present around the equipment, or dust and deposits are making heat dissipation difficult, this may affect the increase in power generation.

It's also important not to confuse equipment-side faults with panel-side issues. Even if a panel appears dirty, the primary cause may actually be an equipment shutdown or output curtailment. Cross-check the time of the power drop with equipment logs, and choose countermeasures based on evidence rather than speculation—this is the key to preventing failures when improving power generation efficiency.

Method 7: Optimize Drainage, Topography, and Inspection Access Routes

To improve power generation efficiency, it is necessary to look not only at the panels and equipment but also at the plant’s overall drainage, topography, and inspection routes. Areas where water tends to accumulate, places where sediment can flow in, paths that easily become muddy, slope collapses, scouring around mounting structures, and locations where cables are likely to be exposed can directly or indirectly cause a decrease in power output. Poor drainage and changes in topography may at first seem unrelated to generation efficiency, 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 easily. When weeds grow, they create shade, reduce ventilation, and make inspections more difficult. Muddy walkways can slow work, and the frequency of cleaning and weeding may decrease. Where sediment flows in, it can accumulate under panels and around cables, causing dirt and damage. If the same problems recur in the same place despite cleaning and weeding, drainage or topography issues should be suspected.

When checking topography and drainage, on-site inspections after rain as well as during fine weather are effective. Determine where water flows in, where it pools, and where it drains out. Recording puddles, sediment deposition, vegetation overgrowth, pathway settlement, and changes to slopes will reveal locations prone to recurring issues. If poor drainage is left unaddressed, dirt and weeds will recur, resulting in the same power generation losses occurring repeatedly.

Checking inspection routes is also important. Locations that are difficult to inspect tend to delay the detection of anomalies. If grass has overgrown and areas are impassable, the ground is too muddy to get close, equipment identification numbers are hard to read, or it is difficult to share the locations of anomalies, on-site response will take longer. Even if equipment with low power generation is identified in the data, if it takes time to reach the corresponding location on site, improvements will be delayed.

Improvements to drainage, terrain, and inspection routes may not immediately show up as increased power generation. However, over the long term they can reduce soiling, weeds, connection failures, and delays in inspections. To increase generation efficiency consistently, it is necessary not only to improve the generation equipment itself but also to create an environment that makes the power plant easier to manage.

Method 8: Continue improving using inspection records and location information

Keeping inspection records is essential for continuing to improve power generation efficiency. Even if dirt, shadows, abnormalities, or poor drainage are found on site, if the location is not shared accurately, it takes time to implement countermeasures or to recheck. Especially in large power plants, where similar rows and equipment are lined up, photos alone can make it difficult to identify the location. By managing inspection results linked to location information, the practical work of improving power generation can be greatly streamlined.

What you should record are the locations of equipment with low power output, rows that are prone to soiling, places where shadows occur, areas where water pools, locations where connection failures occurred, spots that were repaired, and the areas where cleaning or weed removal was carried out. Leaving photos, the date and time, equipment numbers, work performed, descriptions of abnormalities, the status of responses, and whether reinspection is necessary will be useful for the next inspection. If you increase the number of recording items too much, it will be hard to maintain on site, so initially it is important to make records that, when reviewed later, make clear what happened and where.

Linking power generation data with on-site photographs makes it easier to determine causes. If the locations of low-output installations overlap with places where shading occurs or where drainage is poor, the basis for countermeasures becomes clear. If power output at a cleaned location improves, you can conclude that soiling had a significant impact at that site. If morning and evening output improves after weed removal, it is highly likely that shadows from weeds were the cause. Keeping records speeds up decision-making in future cases.

Neglecting to keep adequate records will lead to the same problems recurring. Even if there are patterns—grass growing in the same spot every year, dirt accumulating in the same rows, the same walkways getting muddy after rain, or shutdowns occurring on the same equipment—without records the next response will be ad hoc. To improve power generation efficiency, inspections should not end as mere checks; it is important to accumulate them as information that can be used for subsequent improvements.

When multiple people are responsible for management, it is important to be able to share the exact same location. By recording the equipment number, location information, and photos together, field personnel, managers, inspectors, and repair staff can more easily confirm the same location. Improving power generation efficiency is not only about noticing issues on site, but also about preserving that information in a form that stakeholders can share. By continuing to maintain records, operations can move closer to proactively preventing declines in power generation.

A Mindset to Prevent Power Generation Efficiency Improvements from Becoming Temporary Measures

Improving power generation efficiency cannot be completed with a single cleaning, weeding, or repair. Solar power plants are outdoor facilities, 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 regrow; trees will grow; and drainage routes will change due to sediment and fallen leaves. Therefore, rather than carrying out improvement measures once and considering the job done, they need to be operated as an ongoing management cycle.

First and foremost, compare the power generation before and after the measures. After cleaning, weeding, repairs, equipment inspections, and drainage checks, verify how the power generation has changed. It is difficult to completely eliminate the influence of weather, but by comparing clear-sky days with each other or comparing with facilities under the same conditions, you can identify consistent trends. Prioritize measures that produced a large effect for future work, and if an effect is not apparent, suspect other causes.

Next, keep recurring problem areas as items to be managed. If you record rows that easily accumulate dirt, time periods when shadows are likely to occur, places where water pools, passages prone to damage, and equipment that tends to show abnormalities, you can inspect them before power output falls significantly. To steadily improve generation efficiency, it is important not only to respond after power output declines but also to identify conditions that are likely to cause declines in advance and take countermeasures.

When managing multiple power plants, it is also important to standardize the format of inspections and records. If the recording methods differ at each site, information sharing takes more time. If power generation data, on-site photos, location information, and work histories are managed with the same approach, it becomes easier to compare trends in generation decline. Improving generation efficiency is not only about measures at individual sites but also an effort to raise the overall quality of management operations.

Summary

To increase the efficiency of solar power generation, it is important to identify the causes of generation losses in order and address them starting with the areas that have the greatest impact on output. In solar power generation you cannot increase the amount of solar irradiance on site itself; however, you can improve output by bringing the system closer to a state that converts the received irradiance into electricity without waste. To do that, power output data, weather and irradiance conditions, dirt on panel surfaces, shading from weeds and trees, strings and connections, power conversion equipment, drainage and terrain, and inspection records need to be checked in order.

When you feel the power output is low, don't immediately carry out cleaning or repairs; first separate and examine the data. Identify when the output is low, which equipment is underperforming, and whether there are differences compared with equipment under the same conditions. With that information, an on-site inspection will clarify where cleaning is needed, what areas require weed removal, which connections should be checked, which devices should be inspected, and what drainage or access routes need to be reviewed. To maximize the effect of improving generation efficiency, it's important to make decisions by linking data with on-site conditions rather than relying on intuition.

Also, improving power generation efficiency is not something that can be completed in a single operation. Even after cleaning, dirt will return; even after weeding, grass will regrow; trees will grow; and equipment and wiring will change condition with age. By comparing power generation before and after countermeasures, keeping on-site photos and work records, and using them in the next inspection, the accuracy of improvements increases. To achieve a stable improvement in power generation, it is essential not only to eliminate the causes but also to create a site environment and management system that make the same causes less likely to occur.

Particularly at large power plants, a system for accurately sharing locations of issues is important. If dirt-prone rows, locations where shadows occur, places where water pools, abnormal strings, repair locations, cleaning areas, and inspection photos are recorded together with location information, stakeholders can more easily confirm the same place. By combining power generation data with on-site location information, it becomes easier to explain the priorities for cleaning, weeding, and repairs, and follow-up checks for recurrence on subsequent inspections can also be streamlined.

If you want to continue efforts to increase solar power generation efficiency based on on-site data, using LRTK is also effective. LRTK, an iPhone-mounted high-precision GNSS positioning device, is useful for recording inspection locations, areas prone to soiling, locations where shadows occur, poor drainage locations, abnormal equipment, repair locations, cleaning ranges, and on-site photos within a solar power plant together with high-precision location information. By advancing efficiency improvements using on-site records with location information rather than by intuition, it becomes easier to establish these efforts as practical guides for improving power output.