Five Priorities for Improving Power Generation | Where to Start, Explained

Table of Contents

• Improving power generation starts with establishing priorities

• Priority 1: Use power generation data to pinpoint the time windows and scope of declines

• Priority 2: Separate weather, solar irradiance conditions, and seasonal variations

• Priority 3: Check on-site visible losses such as soiling, shading, and weeds

• Priority 4: Check for abnormalities in connections, cables, and power conversion equipment

• Priority 5: Use drainage management, terrain assessment, and inspection records to prevent recurrence

• Practical decision-making to avoid incorrect prioritization

• Summary

Improving Power Generation Starts with Setting Priorities

When you want to improve the power generation of a solar power system, the first thing you need to do is not to immediately start cleaning or making repairs. Even if you feel that generation is low, not growing as expected, or down compared with the same month last year, the cause is not necessarily a single one. Dirt on the panel surface, bird droppings and fallen leaves, shading from weeds or trees, faults in connection points, cable damage, stoppage of conversion equipment, output curtailment, temperature rise, poor drainage, lack of inspection records, and so on—multiple factors may be combining to reduce power generation.

For practitioners searching "how to increase power generation," the important thing is to view increasing generation as bringing the system closer to a state in which no electricity that could have been generated is lost. In solar power generation, you cannot increase the amount of solar irradiance at the site itself. You cannot increase the number of clear days, nor change the seasonal solar altitude. However, you can move closer to a state in which the received irradiance is converted into electricity with as little waste as possible. In other words, improving generation is the work of finding the generation losses on site and reducing their causes one by one.

A common pitfall when trying to improve power generation is addressing problems in the order they catch your eye. Cleaning because the panels are dirty, trimming weeds because the grass has grown, or suspecting the equipment because it looks old are decisions that can be necessary in some situations. However, if the main cause of the drop in generation lies elsewhere, carrying out those tasks will not lead to sufficient improvement. For example, even if you clean the panels, generation will be hard to restore if morning and evening shadows remain, and even if you remove weeds, daytime generation will not increase if short interruptions of the conversion equipment continue.

That is why prioritization is important when improving power generation. First, review the generation data to identify when, on which equipment, and what kind of declines are occurring. Next, distinguish whether the changes are natural variations due to weather and solar irradiance conditions, or losses that can be mitigated on site. Then, check in order: soiling, shading, weeds, connection points, cables, power conversion equipment, drainage, and inspection records. The simple fact of low generation does not tell you where to start. By linking the data with on-site conditions, you can implement measures starting with those most likely to be effective.

Also, improving power output is not something that can be completed with a single task. A solar power plant is an outdoor facility, and its condition changes with the seasons, weather, the surrounding environment, and equipment aging. Even if you clean, dirt will return; even if you remove weeds, grass will grow; trees will grow; and drainage paths will change due to sediment and fallen leaves. To consistently improve power output, you need operational practices that identify causes, implement countermeasures, verify their effects, and use the records for the next inspection. Setting priorities is not about reducing work, but a basic principle for addressing the areas with the greatest generation losses correctly.

Priority 1: Use power generation data to narrow down the time periods and range of the decline

The first thing to do when improving power generation is to check the generation data. Rather than going to the site and inspecting the panels first to look for causes, start by using the data to understand when, where, and how generation is declining. If you only look at monthly or annual generation, you cannot identify the timing of generation losses or differences by equipment unit. Even if it does not appear to be a major anomaly on a monthly basis, there may be cases where generation drops only during certain hours on sunny days, or where only a specific row, a specific string, or the area connected to a particular converter remains at a low level.

Viewing generation by time of day makes it easier to identify the likely direction of the cause. If morning generation is low, shadows from trees on the east side, slope faces, nearby structures, or adjacent equipment may be involved. If it is low in the evening, check for shadows on the west side and the effects of surrounding terrain. If the midday peak does not develop, candidates include soiling of the panel surfaces, temperature rise, limitations of power conversion equipment, output curtailment, or equipment shutdowns. If, even on sunny days, the generation curve suddenly drops partway through, you should correlate shutdown histories and alarm logs with the times.

It is also essential to compare on a per-unit basis. If you only look at the total generation of the entire plant, some abnormalities can be buried in the average. Compare units with the same orientation, the same tilt, a similar number of panels, and the same shading conditions to check whether any particular unit is performing lower than the others. Simply comparing units with different conditions risks mistaking normal differences for abnormalities. The purpose of comparison is to find locations that are consistently lower among units that should have similar generation.

Also pay attention to the pattern of the decline. If power output drops suddenly, possible causes include equipment shutdown, broken wiring, poor connections, or the appearance of obstructions or shading. If it is declining gradually, factors may include accumulation of dirt, growth of weeds or trees, deterioration of site conditions due to poor drainage, and aging of equipment or components. The areas to inspect on site and the priority of countermeasures differ between sudden declines and gradual declines.

At this stage, what’s important is to turn the perception that power generation is low into verifiable information. If you can clarify when output is low, which equipment is underperforming, and whether there are differences compared with equipment under the same conditions, you can narrow down the targets for on-site inspection. Rather than wandering aimlessly around a large power plant, it is easier to decide on cleaning, weeding, repairs, and equipment checks if you first understand the time periods and areas where declines occur. In prioritizing power generation improvements, data verification is the initial entry point.

Priority 2: Separate weather, solar radiation conditions, and seasonal variations

When a decline is seen in power generation data, the next step is to isolate weather, sunlight (solar irradiance) conditions, and seasonal differences. Because photovoltaic power generation is strongly affected by the amount of solar radiation, output will decrease during periods with many cloudy or rainy days even if there is no problem with the equipment. If you compare only monthly generation with the same month of the previous year or with the previous month and immediately conclude equipment failure, the main cause may actually have been differences in the weather.

On the other hand, we must not overlook real anomalies by attributing them to the weather. If the entire plant is declining in the same way in line with local weather, the impact of irradiance conditions is likely significant. However, if only part of the plant is underperforming while other equipment within the same plant is operating normally, or if there is a clear difference compared with equipment under the same conditions, weather alone cannot explain it. In such cases, it is necessary to check for on-site causes such as soiling, shading, poor connections, equipment shutdowns, and output curtailment.

To separate weather-related causes from equipment-side causes, compare sunny days with other sunny days or days with similar weather whenever possible. Cloudy or rainy days have large fluctuations in power generation, making anomaly characteristics harder to see. If you select and check the generation curves from sunny days, it becomes easier to identify the effects of shadows that occur at the same time each day, string anomalies where only specific equipment shows lower output, and equipment stoppages that cause drops only for certain periods. Rather than isolating only days with low generation, it is important to compare them with days under similar conditions.

Seasonal differences should not be overlooked. In winter, the sun's elevation is lower and shadows from surrounding trees and terrain tend to stretch longer. In summer, although solar radiation is stronger, panel temperatures and equipment ambient temperatures rise, which can reduce output. During rainy seasons, monthly power generation tends to be lower, and after strong winds or heavy rain attention is needed for fallen leaves, soil and debris, deposits, poor drainage, and the condition around cables. Because the causes of generation declines change with the seasons, relying on the same inspection methods alone can lead to oversights.

By making this distinction, you can reduce unnecessary measures. If the weather is the main cause, cleaning or repairs will not greatly improve power generation. Conversely, if a particular area continues to show low output even on sunny days, it is highly likely there is room for improvement on site. To determine where to begin improving power generation, you must separate natural variability from generation losses that can be addressed on site.

Priority 3: Check on-site visible losses such as dirt, shadows, and weeds

After isolating weather and irradiance conditions, next check for visible losses at the site. The first things to look for are dirt on the panel surfaces, deposits such as bird droppings and fallen leaves, and shading from weeds and trees. These causes of reduced power output are often easy to spot, and if addressed appropriately the improvement can be readily observed. However, do not judge by appearance alone; it is important to cross-check with generation data to identify the affected equipment and time periods.

Dirt on the panel surface is a common factor that reduces the amount of light received. The way panels become dirty varies with the site environment, including soil dust, pollen, yellow sand (Asian dust), bird droppings, fallen leaves, sap, dust from nearby construction, road-derived dust, and salt-containing deposits that easily adhere in coastal areas. Of particular concern are band-like deposits that remain at the lower edge of the panel or near the frame. It is often assumed that rain will naturally wash them away, but in reality the flow of rainwater can collect dirt at the lower edge and leave it there. Even dirt that is not noticeable from a distance can affect power generation if it covers part of a cell.

Localized deposits such as bird droppings and fallen leaves should not be overlooked. Unlike dirt that thinly covers the entire surface, these concentrate heavily in specific spots and impede power generation by causing partial shading. Rows near trees, structures where birds tend to perch, rows that are frequently downwind, and areas near unpaved access paths are more prone to dirt and deposits. If only some systems show low power output, focus inspections on the panel surfaces around those systems.

We also check for shadows at the same time. Causes of shadows include weeds, trees, fences, support posts, surrounding buildings, mounting structures, adjacent panel rows, and other factors. Because shadows move with the time of day and season, the absence of visible shadows at the time of inspection does not necessarily mean there is no problem. If shading occurs in the morning, check the site in the morning; if it occurs in the evening, observe the evening shadows. Even if there is no problem at noon, long shadows may appear in the morning and evening.

Weeds are an issue that must not be overlooked when prioritizing improvements to power generation. Even if vegetation is not touching the panels, shadows lengthen when the sun is low in the morning and evening. Furthermore, when weeds become overgrown, airflow is reduced, inspection walkways become blocked, and it becomes difficult to inspect the areas around equipment. Dirt, shadows, and weeds are relatively easy to detect, but if left unattended the resulting generation losses can become prolonged. It is important to perform cleaning and weeding starting with areas that have the greatest impact on power output, and to compare before-and-after photos and power output.

Priority 4: Check for abnormalities in connectors, cables, and conversion devices

If visible dirt or shading on site does not clearly identify the cause, or if cleaning or weeding does not restore generation, check the routes that extract the electricity and the power conversion equipment. Even if the solar panels are receiving sunlight normally, faults in the connections, cables, strings, or power conversion equipment can prevent the generated power from being fully extracted. When improving power output, it is necessary to inspect not only the light‑receiving surface but also the components that support the flow of electricity.

When checking for anomalies at the string level, compare strings under the same conditions. If you simply compare systems that differ in panel count, azimuth, tilt, shading conditions, or connection configuration, you may mistakenly judge normal differences as anomalies. Check whether any are persistently lower compared to adjacent rows or equipment with the same orientation. If only a specific string is low, candidates include soiling, partial shading, poor connections, cable damage, or equipment-side problems.

Issues with connection points and cables include loose terminals, poor contact, damage to cable sheathing, moisture ingress, damage caused by animals, damage during grass-cutting operations, and deterioration due to aging. These can be difficult to detect from appearance alone. If only certain equipment has low power output, abnormalities tend to occur after rain, power output suddenly drops, or output fluctuates unstably, prioritize checking the connection points and cables.

For conversion equipment, check the operating status, shutdown history, alarm history, and whether output curtailment is in effect. Even brief outages can cause large losses if they occur during daytime when generation is high. If the generation curve levels off on sunny days, check for output curtailment, equipment capacity limits, temperature rises, measurement anomalies, and so on. It is important not to judge based only on the generation curve, but to review equipment records together with on-site conditions.

Also check the temperature environment and ventilation. Solar power generation tends to produce more electricity the stronger the sunlight, but when panel temperatures or the temperatures around equipment rise, output can become harder to increase. Conditions such as weeds proliferating under panels or around equipment, grass or obstacles that impede heat dissipation, or areas around equipment that are difficult to inspect can affect power generation and the detection of anomalies. When inspecting electrical equipment, prioritize safety: rather than having on-site personnel forcibly touch internal components, it is important to organize which equipment is suspected of being faulty, the time of occurrence, changes in generation, on-site photos, and the surrounding environment so that necessary inspections can be carried out.

Priority 5: Prevent recurrence through drainage, topography, and inspection records

The items most easily overlooked toward the end of the priority list for improving power generation are drainage, topography, and inspection records. These may not seem to directly affect power output in the same way cleaning, weed removal, or repairs do. However, at sites where the same generation losses recur, it is not uncommon for the cause to be the overall environment of the power plant. Areas where water tends to pool, places where sediment washes in, paths that easily become muddy, slope failures, scouring around mounting racks, and locations where cables are likely to become exposed can lead to soiling, weed growth, connection faults, and reduced accessibility for inspection.

In areas where puddles remain after rain, weeds are more likely to grow. When weeds grow, they create shade, reduce ventilation, and make inspections more difficult. Muddy access paths can slow work and may reduce the frequency of cleaning and weeding. Where soil and debris flow in, they can accumulate beneath panels and around cables, causing soiling and damage. If cleaning and weeding repeatedly fail to prevent problems in the same locations, drainage or terrain issues should be suspected.

When checking topography and drainage, on-site inspections after rain as well as in fair weather are useful. Identify where water flows in, where it pools, and where it drains out. Recording puddles, sediment accumulation, vegetation overgrowth, subsidence of paths, and changes to slopes will reveal locations that are prone to recurrence. If poor drainage is left unaddressed, dirt and weeds will recur, resulting in repeated power generation losses.

Inspection records are also essential for preventing recurrence. If you record the locations of equipment with low power output, rows that are prone to soiling, locations where shadows occur, places where water accumulates, spots where connection faults have occurred, areas that have been repaired, and the scope of cleaning and weeding performed, the places to check at the next inspection will be clear. If records are insufficient, even if the same problem repeats you will not be able to learn the cause and will have to check everything from scratch each time.

By adopting a perspective focused on preventing recurrence, power generation improvement shifts from a temporary task to continuous operation. Rather than simply cleaning dirt, confirm why that location is prone to soiling. Rather than merely cutting grass, examine why grass tends to grow there. Rather than only repairing connection points, verify background factors such as moisture, drainage, and cable exposure. When prioritizing power generation improvements, it is important to record the causes of recurrence at the end and tie them to the next inspection.

How to Decide Priorities Before Spending Money

To determine where to start improving power generation, it is important to consider together the impact on output, the likelihood of the cause, the ease of countermeasures, and the likelihood of recurrence. Rather than addressing the most conspicuous problems in sequence, inspect the areas with the largest generation losses first. Equipment that shows a clear decline in output in the generation data, shading with a long duration of impact, recurring soiling or drainage problems, and equipment that experiences frequent short stoppages are all priorities to check.

First, before moving on to measures that involve significant additional costs, narrow down the causes using data and on-site verification. Whether to clean should be decided not only by the presence of dirt but also by whether the area of soiling corresponds with the decrease in power generation. Whether to carry out weeding should be decided not only by whether vegetation is overgrown but also by whether shadows appear during periods of reduced generation. Whether to prioritize equipment inspection should be determined by checking whether the timing of the generation drop matches shutdown logs or alarm history.

Confirming the effects after countermeasures is also important when deciding priorities. After performing cleaning, weeding, repairs, equipment checks, and drainage checks, record the power generation before and after the work, on-site photos, the scope of work, and the weather conditions. It is difficult to completely eliminate the influence of weather, but by comparing clear-sky days with each other or comparing with installations under the same conditions, certain trends can be identified. Prioritize measures that produced large effects in future work, and if effects are hard to see, suspect other causes.

Also, improving power generation is not something that can be completed with a single operation. Even if you clean, dirt will accumulate again; even if you remove weeds, grass will grow back; trees will grow; and equipment and wiring will change condition with age. That is why it is necessary to record the results of each inspection and identify the conditions that tend to reduce power generation. Rather than responding after generation has dropped significantly, if you can check in advance the places that are prone to declines, it will be easier to keep losses small.

When multiple people are responsible for management, a mechanism to share priorities is also necessary. If equipment numbers, location information, photos, and work histories are recorded together, field staff, managers, inspection personnel, and repair personnel can more easily verify the same location. Clarifying and sharing priorities reduces missed checks and duplicated work, making it easier to sustain improvements in power generation.

Summary

The first priority when improving power generation output is to narrow down, using generation data, the time periods and equipment range where the decline occurs. Next, determine whether the variation is a natural fluctuation due to weather and solar irradiance conditions or a generation loss that can be corrected on site. Then check for visible on-site losses such as soiling, shading, and weeds, and, if necessary, inspect connections, cables, power conversion equipment, and temperature conditions. Finally, organize drainage, terrain, and inspection records, and manage them to prevent the same causes from recurring.

When you feel the power output is low, rather than immediately carrying out cleaning or repairs, it's important to first separate and examine the data. Identify when the output is low, which equipment is underperforming, and whether there is any difference compared with equipment under the same conditions. Then, by checking the site you can clarify where cleaning is needed, the areas that require weeding, the connections that need inspection, the equipment that must be checked, and the drainage and access routes that should be reviewed. When improving power output, it's crucial to make decisions by linking the data with on-site conditions, not by intuition.

Also, improving power output is not something that can be completed in a single operation. Even if you clean, dirt will accumulate again; even if you remove weeds, grass will grow; trees will grow; and equipment and wiring will change condition over time. By comparing power output before and after countermeasures, keeping on-site photos and work records, and using them for the next inspection, the precision of improvements will increase. To consistently raise power output, it is essential not only to eliminate causes but also to create a site environment and a management system that make the same causes less likely to recur.

In particularly large power plants, a system for accurately sharing locations of problems is important. If you record rows prone to soiling, locations where shadows occur, spots where water accumulates, abnormal strings, repair locations, cleaning areas, and inspection photos 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 priority of cleaning, weeding, and repairs, and it also streamlines verification of recurrence in subsequent inspections.

If you want to continuously manage the priority of power generation improvements based on field data, using LRTK is also effective. LRTK, as an iPhone-mounted high-precision GNSS positioning device, is useful for recording inspection locations within solar power plants, areas prone to soiling, locations where shadows occur, drainage problem spots, abnormal equipment, repair locations, cleaning coverage, and on-site photos together with high-precision location information. By organizing what to start with using location information, it becomes easier to carry out power generation improvements based on field data rather than on intuition.