7 Habits to Steadily Increase Power Generation｜Basics of Daily Inspections

Table of Contents

• Making daily inspections a habit is important for steadily increasing power output

• Habit 1: Detect small declines in the daily power generation curve

• Habit 2: Narrow down abnormal ranges by comparing with equipment under the same conditions

• Habit 3: Regularly check the panel surface for dirt and deposits

• Habit 4: Promptly manage shading from weeds, trees, and structures

• Habit 5: Don’t overlook abnormalities in connections, cables, and conversion equipment

• Habit 6: Keep drainage, access routes, and areas around equipment in a condition that makes inspection easy

• Habit 7: Use inspection records and location information to build up improvement effects

• How to proceed with daily inspections to stabilize power output

• Summary

Making daily inspections a habit is essential to steadily increase power generation

When you aim to stably increase the power output of a solar photovoltaic system, the first thing to focus on is not large equipment additions or a one-time major upgrade. It is important to monitor daily generation, detect small losses early, and accumulate countermeasures tailored to the causes. In solar power generation, you cannot increase the solar irradiance itself at the site. You cannot increase the number of sunny days or change the seasonal solar altitude. However, you can put the system in a state that converts the received irradiance into electricity with as little waste as possible. In other words, in practical terms, efforts to raise generation mean reducing on-site loss factors so that the power that should be generated is not left untapped.

There is not a single cause for a drop in power generation. Dust on the panel surface, pollen, bird droppings, fallen leaves, soiling at the lower edge, shading from weeds or trees, faults at connection points, cable damage, stoppage of power conversion equipment, output curtailment, rising temperatures, poor drainage, insufficient inspection records, and other factors can combine to reduce power output. Moreover, these factors do not necessarily appear as sudden major abnormalities. They often show up as small signs: the generation curve on clear days is slightly lower, output falls only in the morning and evening, or only part of a system is lower compared with equipment under the same conditions.

For practitioners searching "how to increase power generation", the important thing is not to rush into countermeasures after output has fallen, but to detect signs of decline during daily inspections. Deciding to clean panels because they are dirty, to remove weeds because grass has grown, or to inspect equipment because it looks old is sometimes necessary. However, if the main cause of the power drop lies elsewhere, those actions will not lead to sufficient improvement. Even if you clean the panels, if morning and evening shadows remain the power output is unlikely to recover, and even if you remove weeds, daytime generation will not increase if short interruptions of the conversion equipment continue.

To reliably increase power generation, daily inspections must be designed as habits rather than tasks. Look at the daily generation curve, compare with equipment under the same conditions, keep on-site photos, check for seasonal dirt and weeds, review the history of power conversion equipment and connection points, ensure drainage and inspection walkways are in order, and apply inspection records to the next inspection. With these habits, it becomes easier to detect drops in power output at an early stage. Below, the basics of daily inspections to steadily increase power generation are explained as seven habits.

Habit 1: Detect small declines in the daily power generation curve

The first habit for steadily increasing power generation is to check the daily generation curve. If you only look at monthly or annual generation, you won’t know when generation losses occur. Likewise, even if overall generation is low, the causes you should suspect differ depending on whether it’s only low in the morning, the midday peak doesn’t develop, it drops early in the evening, or there are sudden troughs during the day. In routine inspections, it’s important to look not only at total values but also at generation curves by time of day.

If morning generation is low, shadows from trees on the east or southeast, slopes, weeds, surrounding structures, or adjacent equipment may be involved. If generation falls off early in the evening, check for shadows on the west or southwest, surrounding terrain, and tree growth. If the midday peak does not extend, candidates include soiling of the panel surface, temperature rise, limitations of power conversion equipment, output curtailment, equipment shutdowns, or abnormalities at the string level. If the generation curve suddenly drops partway through, it is necessary to correlate the shutdown history and alarm logs of the conversion equipment with the times.

When analyzing a power generation curve, use sunny days as a baseline whenever possible. On cloudy or rainy days, power output can fluctuate greatly due to moving clouds, making it difficult to determine whether the cause is an equipment fault or weather. If you consistently see a drop at the same time period on sunny days, you should suspect fixed shading or system-side limitations. Conversely, if the entire plant shows a similar decline, the impact of weather or solar irradiance conditions is likely significant.

In daily inspections, it is important not to view changes in power generation solely as 'abnormal or not.' Picking up small anomalies—slightly lower output than yesterday, a peak that doesn't reach as high as on a sunny day in the same season, a delayed morning ramp-up—leads to early detection of generation losses. Even a small decrease in output can become a significant loss if it continues every day. To steadily increase power generation, it is fundamental to make a habit of looking at the generation curve and quickly identify the time periods and shapes of declines.

Habit 2: Narrow down the range of abnormalities by comparing with equipment under the same conditions

The next habit to establish is comparing equipment under the same conditions. If you look only at the plant’s total generation, some anomalies will be buried by the average. Even if the plant as a whole does not appear to have a major problem, there can be cases where only a particular row, a particular string, or the area connected to a particular inverter is generating less. Such localized generation losses are hard to notice in monthly totals, but if they persist over a long period they can become a significant loss.

When making comparisons, choose installations with similar azimuth, tilt, number of panels, shading conditions, and connection configuration. If you simply compare installations with different conditions, you may mistake normal differences for abnormalities. The purpose of the comparison is to identify locations that are consistently underperforming among installations that should have similar generation. If only a portion is lower compared with installations under the same conditions, suspect local soiling, partial shading, string faults, connection failures, cable damage, or problems on the power-conversion equipment side.

When comparing equipment under the same conditions, also check whether the drop is temporary or persistent. If the difference appears on only one day, it may be due to clouds, a temporary shadow, fallen leaves, or similar effects. If the same area is lower on multiple sunny days, there is a higher likelihood of a persistent cause on site. If the same string or the area connected to the same equipment is lower every time, it should be treated as a location to prioritize in routine inspections.

Once you narrow down the anomaly range, make sure the location can be accurately verified on site. At sites where equipment numbers or row numbers are hard to read, even if you detect an anomaly in the data, it can take time to find the corresponding spot on site. A photograph alone may not convey the location. When improving power generation, being able to share the exact location among stakeholders is as important as finding the anomaly. In routine inspections, performing equipment-level comparisons together with on-site location management helps stabilize power output.

Habit 3: Regularly check the panel surface for dirt and deposits

To reliably increase power generation, it is necessary to make a habit of regularly checking the panel surface for dirt and deposits. Because solar panels generate electricity by receiving sunlight on their surface, accumulated dirt reduces the light reaching the cells. The type of soiling varies by site environment, such as soil dust, pollen, yellow sand, bird droppings, fallen leaves, sap, dust from nearby construction, dust from roads, and contamination containing salt that tends to adhere in coastal areas. Even light dirt can affect power generation if it spreads over a wide area, and localized deposits can act as a strong shadow even over a small area.

Particularly important to watch for are band-like stains that remain along the panel bottom edge and near the frame. It is often assumed that rain will naturally wash them away, but in reality the flow of rainwater can gather dirt at the bottom edge and leave it there. Panels with a shallow tilt do not drain well, making it easier for dirt to accumulate. Even dirt that is not noticeable from a distance can affect power generation if it covers part of a cell. During routine inspections, it is important to check not only the overall color of the panel but also the bottom edge, the 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 densely, creating partial shading that hinders power generation. Dirt and deposits are more likely to occur in rows close to trees, around structures where birds commonly perch, in rows that tend to be downwind, and near unpaved paths. If only some installations have reduced power output, focus inspections on the panel surfaces around those installations.

When deciding whether to perform cleaning, check whether the soiling coincides with areas of reduced power generation. If areas with low generation overlap with visibly soiled areas, cleaning should be given high priority. Conversely, if soiling is visible but does not match the areas of reduced output, you need to investigate other causes such as shading, connections, power conversion equipment, or temperature conditions. Cleaning is not merely cosmetic; it is a measure to reduce generation losses. By recording before-and-after photos of the cleaning, the scope of work, weather conditions, and changes in power output, you can more easily determine how much the soiling affected generation.

Habit 4: Manage shadows cast by weeds, trees, and structures early

In daily inspections aimed at reliably increasing power output, making shadow management a habit is essential. Because solar panels generate electricity from sunlight, even a shadow covering part of a panel can reduce power output. Causes of shadows vary and include weeds, trees, fences, support posts, nearby buildings, mounting racks, adjacent rows of panels, monitoring equipment, and more. Since shadows move with the time of day and the seasons, the absence of visible shadows at the moment of inspection does not necessarily mean there is no problem.

Weeds are a common cause of losses at sites. Even if there is no problem in winter or immediately after installation, they can grow rapidly from spring to summer and cast shadows on the lower edge of panels and on the front rows. Even when the weeds do not touch the panels, the low sun angles in the morning and evening can produce long shadows. Furthermore, when weeds proliferate, ventilation worsens, inspection walkways become blocked, and it becomes more difficult to inspect around equipment. Because it affects not only power generation but also maintainability, managing vegetation height is a basic part of routine inspections.

Shadows from trees are also a factor that can become problematic in long-term operation. 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 panels at different times of day. At plants near forests or slopes, the heights of the terrain and the trees can combine to 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 both the trees and the terrain together.

When checking shadows, it is important to inspect the site at the times corresponding to the periods of reduced output shown in the power generation data. If output is low in the morning, check the site in the morning; if it is low in the evening, observe the shadows in the evening. Even if there is no problem at noon, significant shadows can appear in the morning and evening. Also, even if there is no issue in summer, the sun’s altitude is lower in winter, causing shadows from the same structures to extend farther. Recording the time shadows occur, their sources, and the equipment they affect makes it easier to decide on weed removal, branch pruning, or layout adjustments.

Habit 5: Don't Overlook Abnormalities in Connectors, Cables, and Conversion Devices

To reliably increase power generation, you need to check not only the panel surface and shading but also the electrical pathways that extract the electricity and the power conversion equipment. Even if the solar panels are generating normally, faults in the strings, connection points, cables, or conversion equipment can prevent the generated power from being fully extracted. Loosened terminals, poor contacts, damaged cable sheathing, moisture ingress, animal damage, damage during mowing operations, aging-related deterioration, and stoppage or output curtailment of conversion equipment can all lead to reduced power generation.

When checking for abnormalities at the string level, compare strings under the same conditions. If you simply compare strings that differ in panel count, orientation, tilt, shading conditions, or connection configuration, you may mistakenly interpret normal differences as faults. Check whether any string is consistently lower compared with adjacent rows or strings with the same orientation. If only a particular string is lower, candidates include soiling, partial shading, poor connections, cable damage, panel faults, or issues on the inverter/power conversion equipment side.

Regarding the power conversion equipment, check the operating status, shutdown history, alarm history, and whether output curtailment is in effect. Even short stops can cause significant losses if they occur during daytime when generation is high. If shutdowns and restarts are repeating during the daytime, you may be losing generation even if it does not stand out in the monthly totals. If the upper part of the generation curve is flat and capped, check for output curtailment, equipment capacity limits, temperature rise, insufficient input, and measurement abnormalities.

Thermal conditions and ventilation are also important. Solar power generation tends to be greater with stronger sunlight, but when panel temperatures or the temperatures around equipment rise, output can be suppressed. Conditions such as overgrown weeds beneath panels or around equipment, accumulated deposits, or poor ventilation can affect power generation and the detection of anomalies. During routine inspections, check that the area around equipment is easy to see, easy to access, and has good airflow.

When inspecting electrical equipment, safety is the highest priority. Even if there is pressure to increase power generation, on-site personnel should avoid forcing themselves to touch connection points or the interior of equipment to make a judgment. First, document the equipment suspected of malfunction, the time of occurrence, changes in power generation, on-site photos, and the surrounding environment. If necessary, arrange for a professional inspection; this helps identify the cause while maintaining safety.

Habit 6: Keep drains, walkways, and areas around equipment accessible for inspection

To reliably increase power generation, it is important not only to maintain the panels and equipment but also to keep the power plant’s drainage, walkways, and areas around equipment in a condition that makes them easy to inspect. These may seem unrelated to power output, but in fact they are factors that lead to soiling, weeds, connection faults, and making inspection more difficult. Locations where water tends to collect, places where sediment flows in, walkways that easily become muddy, slope failures, erosion around mounting structures, and spots where cables are easily exposed can repeatedly cause decreases in power generation.

Areas where puddles remain after rain tend to encourage weed growth. When weeds grow, they create shading, reduce airflow, and make inspections more difficult. In places where sediment flows in, dirt tends to accumulate at the lower edges of panels and around cables. If the same problems recur in the same locations despite cleaning and weeding, it is necessary to check for drainage and terrain issues. During routine inspections, checking conditions after rain as well as in clear weather makes it easier to identify spots prone to recurrence.

The condition of inspection access routes also affects efforts to improve power generation. If grass has overgrown and paths become impassable, if it's too muddy to approach, if equipment numbers are hard to see, or if a location can't be conveyed by photos alone, discovery and sharing of anomalies will be delayed. Even if low-output equipment is identified from the data, if it's difficult to reach the corresponding site on the ground, corrective measures will be delayed. Keeping the power plant in a condition that makes inspections easy is the foundation for maintaining routine inspections.

We also check the area around the equipment. If grass, fallen leaves, soil, or other obstacles are around converters and junction boxes, visual inspection can become difficult and ventilation may be affected. When the area around equipment is hard to see, abnormal indicators or changes in appearance are harder to notice. Poor ventilation can lead to reduced output and unstable operation due to rising temperatures. To stably increase power generation, it is necessary to maintain not only the power generation equipment itself but also a surrounding environment that is easy to inspect.

Habit 7: Accumulate Improvement Effects Using Inspection Records and Location Information

To turn daily inspections into improvements in power output, keeping a habit of recording inspection results is essential. Even if dirt, shadows, anomalies, or poor drainage are found on site, if the exact location is not shared, implementing countermeasures or rechecking can take time. Especially at large power plants, where similar rows and equipment are lined up, it can be difficult to identify a location from photos alone. By linking inspection results with location information and managing them, the practical work of improving power output becomes easier to carry out.

What you should record are the locations of equipment with low power generation, rows that tend to get dirty, places where shadows occur, areas where water accumulates, locations suspected of connection faults, spots where conversion equipment has stopped, places that were repaired, and the areas where cleaning or weeding was carried out. Keeping photos, date and time, equipment numbers, work performed, details of abnormalities, response status, and whether reinspection is necessary will be useful for the next inspection. Because adding too many items to record makes it hard to keep up on site, it is important to start by making records that, when reviewed later, clearly show where and what happened.

Linking power generation data with on-site photos makes it easier to determine causes. If the locations of equipment with low power output overlap with areas where shadows occur or where drainage is poor, the rationale for corrective actions becomes clear. If power generation at a cleaned location improves, you can conclude that soiling had a significant impact at that site. If generation in the morning and evening improves after weeding, it is likely that shadows from weeds were the cause. Having records speeds up decision-making in future cases.

If you neglect inadequate record-keeping, the same problems will repeat. Even if there are recurring patterns—grass growing in the same spot each year, dirt accumulating in the same row, the same pathway becoming muddy after rain, or stoppages occurring on the same equipment—without records you'll respond in an ad hoc way next time as well. To steadily increase power generation, it is important to narrow down where to check using past records rather than searching for the cause from scratch each time.

Also record power generation after countermeasures. After 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. Prioritize measures that had a large effect in future work, and investigate other causes for measures that had little effect. Repeating this process establishes the foundation for improving the quality of routine inspections and prevents power generation improvements from being only temporary.

How to Conduct Daily Inspections to Stabilize Power Generation

To stabilize power generation, it is important to design daily inspections as continuous operations rather than one-off checks. First, determine the frequency and the criteria for reviewing generation data. Decide in advance how large a drop will trigger an on-site inspection, up to which equipment unit comparisons should be made, and which items to focus on in each season; doing so can reduce variability in judgments among staff. To prevent overlooking declines in generation, it is important to make the inspection criteria clear.

Next, link power generation data with on-site inspections. If a morning dip is visible in the generation curve, check for morning shading; if the midday peak does not reach its expected level, check for soiling, temperature, and the history of conversion equipment, and if there is a difference compared with equipment under the same conditions, inspect the relevant area on site. Do not judge based on data alone, and do not judge based on on-site findings alone; by combining both, it becomes easier to identify the cause of generation losses.

We also incorporate seasonal inspections. In spring, pay attention to pollen and yellow sand; in summer, to weeds and high temperatures; after typhoons, to sediment and falling debris; in autumn, to fallen leaves; and in winter, to shadows and frost caused by the sun’s lower altitude. If power generation declines in the same place at the same time each year, there may be a seasonal cause. By keeping seasonal inspection records, you can take measures in subsequent years before power generation falls significantly.

What's important in daily inspections is not just responding after power output drops, but identifying in advance the conditions that make drops likely. By recording rows that tend to collect dirt, times when shadows are likely to occur, places where water pools, walkways prone to damage, and equipment likely to develop abnormalities, you can carry out inspections before power output falls significantly. To steadily increase power output, it is necessary to establish a management system that builds on small daily checks and detects generation losses early.

Summary

To stably increase power generation, it is important to make daily inspections a habit and to detect small signs of generation loss early. In solar power generation, you cannot increase the solar irradiance itself on site. However, you can improve power output by bringing the system closer to a state that converts received solar irradiance into electricity without waste. To do this, it is necessary to routinely check generation data, comparisons with installations under the same conditions, dirt on panel surfaces, shading from weeds or trees, connections and conversion equipment, drainage and access ways, and inspection records.

When you notice that power generation is low, don’t immediately proceed with cleaning or repairs; first, it is important to segment and review the data. Determine when the output is low, which equipment is underperforming, and whether there is a difference compared with equipment under the same conditions. With that information, an on-site inspection will clarify which areas need cleaning, the extent of weeding required, which connection points should be inspected, which equipment should be checked, and which drainage or access routes should be reconsidered. When improving power generation, it is crucial to make decisions by linking data with on-site conditions rather than relying on intuition.

Also, routine inspections are not something that can be completed in a single operation. Even if you clean, dirt will return; even if you remove weeds, grass will grow back; trees will grow; and equipment and wiring change with age. By comparing power generation before and after measures, keeping on-site photos and work histories, and using them for the next inspection, the precision of improvements increases. To consistently increase 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.

Especially at large power plants, a system for accurately sharing the locations of issues found during routine inspections is important. If dirty-prone rows, areas where shadows occur, places where water accumulates, abnormal strings, locations where connection abnormalities are suspected, shutdown points of power conversion equipment, cleaning areas, repair locations, and inspection photos are recorded together with location information, stakeholders can more easily confirm the same spots. By combining power generation data with on-site location information, it becomes easier to explain and prioritize cleaning, weeding, repairs, and specialized inspections, and it also streamlines follow-up checks for recurrence on subsequent visits.

If you want to continue daily inspections that stably increase power output based on on-site data, using LRTK can also be effective. As an iPhone-mounted high-precision GNSS positioning device, LRTK is useful for recording inspection locations within a solar power plant, places prone to soiling, shadow occurrence points, areas of poor drainage, abnormal equipment, connection points and equipment surroundings, cleaning ranges, repair locations, and onsite photos together with high-precision location information.

By retaining the results of routine inspections with location information, it becomes easier to pursue improvements in power output based on on-site data rather than on intuition.