7 Ways to Increase Solar Power Generation｜From Causes of Decline to Improvement Measures

When you want to increase the power output of a solar photovoltaic system, the first important step is not simply to look for “ways to generate more.” It is essential to break down the causes of low output and separate factors that can be improved from those that are difficult to control, such as season and weather. Generation is determined by a combination of factors including solar irradiance, temperature, shading, soiling, equipment condition, installation quality, the surrounding environment, and the quality of maintenance management. For that reason, you should avoid deciding that a single measure will produce a large improvement without inspecting the site.

In this article, aimed at practitioners searching for information on "how to increase power generation," we organize seven improvement methods that are easy to verify on-site while identifying declines in photovoltaic power output. The content is intended to be more useful for managers of industrial and commercial solar power plants than for residential systems, and is designed for use during inspection, maintenance, and improvement planning.

Table of Contents

• Isolate the causes of reduced solar power generation before increasing output

• 1. Assess power generation by separating the effects of solar irradiance and temperature

• 2. Check panel surface soiling and decide on cleaning based on on-site conditions

• 3. Determine the locations and times of shading to reduce losses

• 4. Inspect for faults in wiring, connections, and at the string level

• 5. Review the operating status of power conditioners and protective devices

• 6. Manage the surrounding environment such as vegetation, debris accumulation, and drainage

• 7. Compare design values, actual performance, and on-site conditions, and continue making improvements

• Continuous management is more important than one-time measures to increase power generation

Isolate the Causes of Reduced Solar Power Generation Before Increasing Output

To increase solar power generation, you must first clarify why the output is low. It is premature to conclude there is an equipment fault just because there are days with low generation. Output can vary greatly due to natural conditions such as cloudy skies, rain, snowfall, yellow sand (Asian dust), the rainy season, periods before and after typhoons, and shorter sunlight hours in winter. In particular, solar power performance can differ even with the same installed capacity depending on the season, installation angle, orientation, and surrounding environment.

On the other hand, there are declines that cannot be easily explained by weather alone. For example, if power generation is clearly lower compared with days with similar solar irradiance conditions; if output drops only during specific time periods; if only some of the multiple circuits exhibit weaker generation; or if there is a history of equipment shutdowns, the cause may lie with the equipment or the on‑site environment. To avoid overlooking these changes, it is important to look not only at the total power generation but also at breakdowns by day, by time period, by circuit, and by device.

The phrase "increasing power generation" mainly has two meanings. One is bringing equipment closer to a condition where it can deliver its intended performance. This approach is about reducing losses by removing dirt, shading, weeds, poor electrical contacts, equipment outages, and so on. The other is reexamining the equipment layout and system configuration to create better generation conditions. However, at existing power plants, it is not easy to make large changes to panel tilt or orientation. Therefore, at many sites, maintenance improvements that reduce losses are the most realistic starting point.

A common cause of failure when trying to improve power output is proceeding with cleaning or parts replacement without confirming the root cause. If dirt is not the cause, cleaning will have only limited effect. If shading is the main cause, inspecting only the equipment will not fix the time-of-day output drop. If equipment shutdowns are occurring but you assume it’s due to the weather, lost opportunities for selling power or self-consumption may continue. To increase power generation, it is important to combine on-site observation, checking generation data, and checking equipment condition to progressively narrow down the cause of the decrease.

1. Evaluate power generation by separating the effects of solar irradiance and ambient temperature

When you want to increase the power output of a solar power system, the first thing to check is whether the decline in output is caused by equipment problems or by solar irradiance conditions. Because solar power generation produces electricity by receiving sunlight, on days with low solar irradiance the power output also decreases. It is natural for output to be low on cloudy or rainy days. Also, even when it is sunny, sunlight may not be as strong as it appears due to moisture in the air, thin clouds, yellow dust, or haze.

On the other hand, the effect of ambient temperature is another easily overlooked factor. Solar panels tend to produce more power when solar irradiance is stronger, but their output tends to decrease as panel temperature rises. Therefore, even on sunny summer days with strong sunlight, if the air temperature or panel temperature is high, the efficiency can look worse than on clear spring or autumn days. In practice, rather than simply judging “it’s sunny but generation is low,” you need to compare conditions while taking both irradiance and temperature into account.

When evaluating power generation, rather than comparing only yesterday and today, it is easier to make a judgment if you compare against past performance in the same season or days with similar weather. If records of solar irradiance are available, check generation together with the irradiance conditions. If irradiance is sufficient but generation does not increase, this becomes a reason to suspect equipment-related losses. Conversely, if generation is low but irradiance is also low, the variation may be due to natural conditions rather than an equipment abnormality.

By making this distinction, you can reduce unnecessary on-site interventions. If you immediately perform cleaning or equipment replacement in response to a temporary decline caused by weather factors, you only increase effort and make the improvement harder to see. Conversely, leaving a situation where solar irradiance is sufficient but power generation is low will cause you to lose generation opportunities you should have obtained. The first step to increasing power generation is to understand the relationship between solar irradiance, temperature, and power generation, and to separate declines that should be suspected as anomalies from normal fluctuations.

Especially at power plants with multiple sections, you can compare generation trends within the same site. If only one section has lower output, local soiling, shading, wiring, or equipment faults are more likely than weather. If the entire plant is declining similarly, check the weather, output control, overall equipment shutdowns, and conditions of the receiving equipment. When aiming to increase generation, prioritizing countermeasures based on such comparisons improves the accuracy of on-site responses.

2. Check the panel surface for dirt and make cleaning decisions based on site conditions

One method widely considered at many sites to increase solar power generation is panel cleaning. When dirt adheres to the panel surface, sunlight has difficulty reaching the cells, which can lead to a decrease in power generation. The types of soiling vary depending on the site: soil dust, yellow sand, bird droppings, fallen leaves, pollen, exhaust-derived deposits, salt-containing contaminants in coastal areas, and dust near farmland or development sites.

However, cleaning should not be decided simply because something looks dirty; it is important to judge based on the impact on power generation and the risks of the work. Light dust may be washed away to some extent by rainfall. On the other hand, bird droppings, caked-on mud, and stripe-like dirt that accumulates along the lower edge of panels can be difficult to remove with rain alone. In particular, if dirt is localized on part of a panel, it can obscure a portion of the power-generating surface and potentially affect output at the circuit level.

When inspecting on-site, observe not only the overall appearance of the panels from a distance but also the pattern of soiling by row, accumulation at the lower edges, drainage flow, areas of concentrated bird damage, and how dust from surrounding roads enters the site. On sloped terrain or newly developed sites, panels in lower positions can become dirtier due to rain splash and inflow of sediment. Also, dust after grass cutting or temporary increases in soiling caused by nearby construction may occur.

To increase power generation through cleaning, it is important to compare before and after. Recording the power output before cleaning, the area cleaned, and the power output after cleaning will help inform decisions for future occasions. Rather than cleaning all panels uniformly, start by checking sections with heavy dirt, circuits showing reduced output, and locations with concentrated bird damage, as this makes it easier to set work priorities. Safety management is also necessary for the cleaning work itself. When working at heights, on slopes, on wet walkways, or around electrical equipment, measures to avoid the risks of falls and electric shock are essential.

Also, cleaning alone may not significantly improve power generation. In such cases, you need to consider causes other than soiling. If the reduction in power generation is due to shading, equipment shutdowns, wiring faults, panel degradation, or output control, cleaning alone will not resolve the issue. Cleaning is one effective improvement measure, but it is not a universal solution. Combining on-site conditions with generation data to identify where and when cleaning should be carried out will lead to improved power generation.

3. Reduce losses by identifying where and when shadows occur

One of the major factors that reduces the output of solar power generation is shading. Even if shading occurs only briefly over part of a plant, depending on the circuit configuration it can affect power generation more than expected. In particular, reductions in output are more likely during periods of low solar elevation in the morning and evening, in winter, at sites where nearby trees or buildings are close, and where utility poles or racking members cast shadows.

The troublesome aspect of shadows is that their appearance can change significantly depending on the time of day when an on-site inspection is carried out. Even if an inspection during the daytime seems to show no problems, there are cases where tree shadows occur only in the morning, shadows from adjacent structures lengthen only in the evening, or shadows from mountains or slopes reach the site only in winter. Therefore, when checking for shadows, it is important not to make a judgment based on a single on-site visit. If power generation data shows a drop in output only during specific time periods, check whether shadows are occurring during those times.

A common cause of shading is the growth of surrounding trees. Trees that posed no problem at the time of installation can extend their branches after a few years and cast shadows seasonally. Even weeds and low shrubs can affect power generation if they grow to the height of the bottom edge of the panels or to the level of the front row. In addition, structures on adjacent land, temporary installations, fences, signs, utility poles, communications equipment, and parts of mounting racks can also create shadows. Because a solar power plant is a long-term facility, it is necessary to continuously check not only the shadows present at installation but also any new shadows that arise during operation.

Shading countermeasures to increase power generation depend on the cause. If trees or weeds are the cause, consider tree removal, pruning, mowing, and reviewing the management area. If structures or equipment are the cause, separate items into those that can be relocated and those that cannot. Even if relocation is difficult, understanding when shadows occur and the extent of their impact will help explain the causes of reduced generation and support improvement planning.

When checking for shadows, it is also important to keep photos and location information. Recording which column and which section, around what time, and from which direction the shadows fall makes later comparisons easier. If the extent of shading changes with the seasons, management should account for changes across spring, summer, autumn, and winter. Rather than roughly attributing low power output to “poor sun exposure,” specifically understanding the time shadows occur, their length, the objects causing them, and the circuits affected leads to effective improvements.

4. Inspect wiring, connectors, and string-level faults

To increase power output, you need to check not only the panels themselves but also the condition of the wiring and connection points. In solar power generation systems, multiple panels are connected as a circuit and linked to junction boxes, combiner/collection equipment, and power conditioners. If there are poor connections, broken wires, deterioration, water ingress, loose terminals, or cable damage along this path, the generated electricity may not be fully extracted.

Faults in wiring or connections can be difficult to detect from appearance alone. Even if the panel surface looks clean and there appear to be no shadows, if only a specific string shows low output, suspect an anomaly at the circuit level. If you only look at the power generation of the entire plant, reductions in some circuits can be masked. In facilities with multiple circuits, it is important to compare strings under the same conditions and look for locations where the output differences are large.

At connection points, loosening and corrosion due to aging, intrusion of rainwater, defective handling during installation, and cable damage caused by animals can occur. Vegetation overgrowth can place loads on cables, and ground subsidence, deformation of mounting racks, or deterioration of wiring supports can cause cables to rub or be pulled. Because this affects not only power output but also safety, any areas suspected of abnormalities require professional inspection.

The basics of inspection are visual checks and comparing measurement results. Confirm that cable jackets show no damage, that junction boxes show no signs of water ingress, that terminals show no discoloration or traces of overheating, and that wiring routes have no excessive bends or sagging. In addition, checking the voltage and current of each string, the insulation condition, and the equipment's records makes it easier to narrow down the area where a problem exists. Because electrical measurements and terminal inspections are hazardous, involve qualified personnel or maintenance staff as necessary.

From the perspective of increasing power output, early detection of wiring faults is important. Unlike dirt or shading, problems with wiring or connections, if left unaddressed, will not only continue to reduce power output but may also lead to equipment failures. In particular, if power output suddenly drops, tends to decrease after rain, only certain circuits show unstable readings, or a device has an abnormal event history, prioritize checking the wiring and connection points. If you make a habit of closely monitoring generation data, it helps lead to early detection of such abnormalities.

5. Review the operating status of power conditioners and protective devices

In solar power generation systems, power conditioners play an important role in converting the electricity generated by panels into a usable form. Even if there are no problems with the panels, if the power conditioner is stopped, subject to output restrictions, or showing abnormal logs, the amount of power generated will not increase. To raise power generation, it is essential to check not only the generating side but also the condition of the equipment that converts and sends out the power.

When inspecting the power conditioner, check the operating status, shutdown history, error/fault indications, the presence of any output limitations, temperature rise, ventilation condition, and the surrounding environment. In particular, in summer the temperature around the equipment tends to rise, and poor ventilation can cause the output to be reduced by protective operations. Situations such as objects placed around the equipment, dust or fallen leaves accumulating in the intake or exhaust vents, or installation in locations strongly exposed to sunlight or wind and rain can also affect operation.

Power generation installations also include devices that affect output and safety, such as circuit breakers, switches, protective devices, junction boxes, and collection equipment. If any of these devices malfunction, generation for the entire system or part of it may stop. On site, people tend to blame the panels alone for low generation, but in reality the operation of protective devices, device settings, or conditions on the grid side may be involved. It is important to check abnormal event histories and alarms and to determine whether the same fault is recurring.

To improve power generation, managing to shorten downtime is also effective. If a power plant’s outage is prolonged, generation opportunities are lost during that period. By putting in place a monitoring system that can detect outages immediately, procedures for on-site checks, and a clear flow for recovery decisions, you can more easily curb annual declines in power generation. This is especially necessary when managing multiple power plants, where outages or anomalies are more likely to be overlooked, so operations that regularly review generation data are required.

When reviewing equipment, it is also important not to change settings recklessly. Settings of power conditioners and protective devices affect safety and grid interconnection conditions, so changing them without expert knowledge can cause other problems. Even with the aim of increasing power generation, it is desirable not to make decisions based solely on on-site personnel, but to coordinate with qualified personnel or maintenance staff as necessary. It is important to consider improving power generation not merely as increasing output, but as management to ensure the system safely delivers its intended performance.

6. Arrange the surrounding environment, such as vegetation, accumulated deposits, and drainage

The power generation of a solar power plant is influenced not only by the equipment itself but also by the management of the surrounding environment. Especially for ground-mounted plants, weeds, low shrubs, fallen leaves, sediment, poor drainage, bird damage, small animals, and the condition of areas around fences can affect power generation and equipment maintenance. To increase power generation, site environmental upkeep must be given as much priority as inspections of the generation equipment.

Weeds are an obvious cause of reduced power output, yet they are a factor that tends to be neglected in maintenance. When vegetation grows in front of panels it casts shadows and can reduce power output. Especially on low-mounted racks or sloped ground, even a slight increase in grass height can cast a shadow on the lower edge of a panel. Also, when weeds become entangled in wiring or around racks, they can hinder inspections and may lead to cable damage or provide hiding places for pests.

Mowing should not be treated as something that can be done just a few times a year. The timing and rate of growth vary depending on the local climate, the site’s soil conditions, rainfall, surrounding vegetation, and the layout of the power plant. If vegetation management is carried out to increase power generation, it is important to act before shading occurs. Rather than mowing after power output has dropped, creating a management plan before output declines makes it easier to reduce annual losses.

Drainage conditions should not be overlooked. In areas with poor drainage, rainwater can pool, making mud splash and sediment accumulation more likely. If mud adheres to the lower edges of panels, it can lead to reduced power generation due to soiling. Also, when the ground becomes muddy, the safety of inspection and mowing operations is reduced, which can cause maintenance delays. At power plants on developed or sloped land, changes in rainwater flow can cause sediment inflow that was not present at the time of installation.

When maintaining the surrounding environment, it is important to walk the site regularly to inspect it. Relying on monitoring data alone can make it difficult to discern grass height, mud buildup, drainage flow, fence damage, signs of animal intrusion, and the accumulation of fallen leaves. When investigating the causes of low power generation, keeping records that include site photos and location information as well as the data makes it easier to compare conditions before and after improvements.

Environmental management aimed at increasing power output depends more on the quality of routine maintenance than on special capital investment. Continuously managing vegetation, checking drainage, removing accumulated debris, inspecting around fences, and keeping access routes clear makes it easier to reduce losses caused by shading, soiling, and delayed inspections. When small lapses in maintenance accumulate, they can lead not only to decreased power generation but also to equipment failures and safety issues. For long-term, stable operation of a power plant, it is necessary to treat the surrounding environment as part of the power generation equipment.

7. Reconcile design values, actual results, and on-site conditions to sustain continuous improvement

An important factor in increasing solar power generation is continuously comparing design values, actual performance, and on-site conditions. In plant operations, the expected generation at the time of installation and simulation results are sometimes used as benchmarks. However, actual generation varies depending on weather, the surrounding environment, age-related changes, maintenance status, and equipment condition. Therefore, it is necessary to regularly check the difference between the design assumptions and actual results, and investigate the cause if the difference is large.

Design values are useful as a guideline for power generation, but they do not fully reproduce every aspect of the site. Various conditions are assumed, including installation angle, orientation, shading, snowfall, soiling, topography, equipment efficiency, and wiring losses. After operation begins, surrounding trees may grow, ground or drainage conditions may change, and soiling or weeds may have an impact, causing deviations from the design assumptions. If the generated power is lower than expected, it is important not just to look at the difference from the design value but to check which assumptions have changed at the site.

When reviewing actual performance data, check trends not only in monthly or annual totals but also by time of day and by section. Relying solely on monthly generation can cause you to miss short-term stoppages, shading during specific time periods, or drops in particular circuits. To increase generation, it is more effective to divide the system into smaller units and compare them, rather than searching for anomalies in the overall totals. For example, compare sections under similar conditions within the same plant; if only some sections perform lower, prioritize checking shading, soiling, wiring, and equipment condition in those sections.

Recording on-site conditions is also important. If you record the dates when cleaning or grass cutting was performed, the dates when equipment abnormalities occurred, the parts or locations that were repaired, spots where shading was observed, and areas with poor drainage, it becomes easier to correlate these with changes in power generation. If power generation improves, you can identify what produced the effect. Conversely, if measures do not lead to improvement, you can quickly switch to investigating other causes.

Improving power generation is not something that can be completed with just one inspection. Solar power plants are outdoor facilities, and environmental conditions change with the seasons. In spring there is pollen and yellow dust; in summer high temperatures and weeds; in autumn falling leaves; in winter shorter sunlight hours and snowfall; and after strong winds or typhoons there can be debris and changes around the mounting structures. Creating a year-round maintenance plan that takes these changes into account is the approach to steadily increase power generation.

Also, when deciding the priority of improvement measures, it is important to address the areas that have the greatest impact on power generation first. If you only deal with areas that are visually noticeable, you may end up spending time on tasks with little effect. By combining generation data, site photos, location information, and inspection records, it becomes easier to determine which locations should be prioritized. In practical work to increase power generation, it is important to shift from instinctive on-site responses to record-based improvements.

Continuous management is more important than one-off measures to increase power generation

Methods for increasing solar power output span many areas, such as cleaning, shade mitigation, vegetation management, wiring inspections, equipment checks, drainage improvements, and data analysis. However, performing any single measure alone does not always yield sufficient results. Causes of reduced output arise from a combination of hard-to-control factors like weather and improvable factors like dirt, shading, and equipment condition. Therefore, increasing output requires a continual approach of isolating causes and implementing site-appropriate measures.

What operations personnel should first work on is creating a state that allows them to quickly notice changes in power generation. By checking generation trends by day, time of day, section, and equipment, and by comparing them with past performance and installations under the same conditions, it becomes easier to spot signs of anomalies. Next, perform on-site inspections to check for soiling, shading, weeds, drainage, wiring, and equipment condition. Then, after taking action, record how power generation changed and reflect that in the next maintenance plan. By repeating this cycle, it becomes easier to grasp the condition of the plant and to improve power generation while reducing unnecessary interventions.

Especially at industrial or commercial solar power plants, sites are large and the number of installations is high, so it becomes difficult to identify the causes of reduced power output by visual inspection alone. If you cannot organize where shadows are appearing, which sections have noticeable weeds or dirt, and where inspection records have been logged, corrective measures tend to become dependent on individual staff. To increase power generation, it is important to record site conditions together with their locations and manage them by linking them to generation data.

If you want to continuously improve power generation, it is effective to establish a system that integrates on-site inspections, recording, sharing, and decision-making for improvements. Rather than judging the causes of low generation by intuition alone, recording on-site conditions and sharing them among stakeholders to connect to countermeasures makes it easier for equipment to perform at its intended capacity. The shortcut to increasing solar power generation is not forcibly raising output, but creating a management system that quickly identifies causes of decline and continuously reduces losses.