5 Cleaning Methods to Increase Solar Panel Power Generation

When you want to increase the power output of solar panels, cleaning is one of the relatively easy measures to undertake. However, just because the output is low doesn’t mean you should immediately spray water or scrub the surface. If the cause of the output drop is not dirt but shade, snowfall, equipment malfunction, wiring losses, or temperature rise, cleaning alone will not lead to sufficient improvement. To increase generation through cleaning, it is important to check generation data, determine the type and extent of soiling, choose a method that allows safe work, and verify the effect after cleaning. This article explains five cleaning methods from a practical perspective for professionals searching "how to increase power generation," aimed at raising the power generation of solar panels.

Table of Contents

• Things to check before increasing power generation by cleaning

• Determining the need for cleaning from power generation data

• Basic cleaning to safely remove surface dirt

• Cleaning focused on fallen leaves and bird droppings

• Regular cleaning for sites with high dust or pollen

• Condition checks after snowfall or after rain

• Verify effectiveness by comparing power generation after cleaning

• Dangerous decisions to avoid when cleaning

• Summary

What to check before increasing power generation through cleaning

To increase a solar panel's power output through cleaning, you first need to confirm whether the output has actually fallen due to dirt. When dirt accumulates on the panel surface, sunlight has more difficulty reaching the active area, reducing output. However, dirt is not the only cause of reduced output. Shading from nearby buildings or trees, the low solar altitude in winter, snow cover, temperature increases, faults in wiring or power conversion equipment, and output limitations can also affect power generation.

Before starting cleaning, check when the drop in power generation is occurring. It is important to distinguish whether the output is low for only one day, low over several weeks, lower compared with the same month of the previous year, or low even on sunny days. Low generation during months of continued rain or cloud cover is a natural fluctuation. On the other hand, if output does not increase even on sunny days, if only a specific roof surface shows low output, or if generation does not recover after rain, it is worth checking for soiling or the condition of the equipment.

Dirt that is easily removed by cleaning includes sand and dust, pollen, yellow dust, particulate matter, fallen leaves, bird droppings, and exhaust-related grime. If there are trees nearby, the area is more susceptible to fallen leaves and birds, and if unpaved land, construction sites, farmland, or roads are nearby, particulate matter and soil dust are more likely to adhere. On rooftops, panels located near vents and exhaust equipment can become locally soiled.

However, safety considerations are indispensable when cleaning. Solar panels are often installed on rooftops or at height, and getting too close recklessly can lead to falls or equipment damage. You should avoid actions such as climbing onto roofs with poor footing, working on wet roofs, vigorously scrubbing the panel surface, or carelessly spraying water around electrical equipment just to try to increase power output.

Cleaning is an effective measure to increase power generation, but the purpose is not cosmetic. The objective is to identify the soiling that is reducing power generation, remove it safely, and confirm improvement using generation data from before and after cleaning. Rather than treating cleaning as a one-off task, it is important to position it as part of power generation management.

Determining the Need for Cleaning from Power Generation Data

To determine whether solar panels need cleaning, first check the power generation data. Even if the power output seems low, cleaning is not necessary in every case. It is important to use the data to distinguish whether the decline is a natural decrease due to weather or seasonal factors, caused by shading or equipment problems, or caused by soiling.

By examining monthly power generation, you can identify seasonal causes of declines. If generation in spring falls short of expectations, pollen or dust deposition may be a factor. If a decline is noticeable in autumn, check for fallen leaves, bird droppings, and soiling after typhoons. If generation is low in winter, you should consider not only soiling but also snow accumulation, winter shading, and shorter daylight hours together. If generation is low in summer, check for temperature-related losses and equipment condition.

Time-of-day generation data is also useful for deciding whether to clean. If dirt is attached across the entire array, total daily generation may be slightly reduced. If there is localized dirt or fallen leaves, generation may be reduced on specific strings or installation surfaces. If output is low only in the morning or only in the evening, shading is more likely the cause than dirt. If output is generally low, including around midday, it is worth checking for dirt and the condition of the equipment.

If you have data by installation surface or by system, it becomes easier to narrow down cleaning targets. If only a specific roof surface, rather than the entire system, shows reduced power generation, check whether that surface is in an environment prone to soiling. Surfaces near exhaust vents, close to trees, in places where birds tend to gather, or on sides facing the direction dust is easily blown are more likely to experience reduced power generation due to soiling.

When reviewing power generation data, compare not only with the previous month but also with the same month of the previous year and with sunny days in the same season. Because solar power generation varies greatly by season, being lower than the previous month alone does not allow you to determine the need for cleaning. If generation is lower even when compared on sunny days, or is clearly lower than past performance in the same season, an on-site inspection is worth carrying out.

By determining the need for cleaning from data, you can reduce unnecessary cleaning and hazardous work. If soiling is not the cause, you should check for other causes such as shading, equipment, wiring, temperature, or snow accumulation. Cleaning to increase power generation is more likely to be effective when carried out after reviewing the generation data.

Basic cleaning to safely remove surface dirt

The basic principle of cleaning to increase the power output of solar panels is to remove dirt safely without damaging the panel surface. The panel surface is an important part that receives sunlight, and cleaning methods that could cause scratches or deterioration of the coating should be avoided. The purpose of cleaning is to restore the surface so that sunlight can more easily reach the power-generating area.

In basic cleaning, you first identify the type of dirt. The approach varies depending on whether it is light dirt such as sand dust or pollen, dirt that contains bird droppings or oil, or fallen leaves that are stuck. Light dust may be washed away naturally by rain, but on panels with a low slope or on surfaces where dirt tends to remain locally, dirt can accumulate.

When cleaning, take care not to scrub too hard. Using hard tools or abrasive materials can damage the panel surface. If the surface is scratched, not only will dirt be more likely to remain, but it may also affect long-term power generation efficiency. Also avoid using inappropriate detergents or chemicals. Because they can adversely affect equipment, roofing materials, and waterproofing layers, cleaning methods should be chosen carefully.

Take care when using water. Avoid spraying water carelessly around electrical equipment, and exercise particular caution near wiring, connection points, and power conversion devices. Also, suddenly applying cold water during the height of summer heat can put stress on components, so pay attention to the timing of cleaning. Cleaning work is carried out not only to increase power generation but also to protect the equipment.

There are safety risks when cleaning on roofs. Sloped roofs, wet roofs, locations without scaffolding, and working at height are extremely dangerous. What operational staff should do is not to force themselves onto the roof, but to assess the condition of soiling within a range that can be safely inspected and to clarify the scope of necessary measures. If hazards are present, it is important to perform inspections and cleaning under an appropriate arrangement.

After cleaning, check how much the power generation has improved. If the weather conditions differ before and after cleaning, a simple comparison is not possible. Comparing on similar sunny days, during the same time period, and on the same installation surface makes it easier to judge the cleaning effect. Basic cleaning is the first step toward improving power generation, but it only becomes a practical measure once you carry out effectiveness verification.

Cleaning that focuses on checking fallen leaves and bird droppings

When cleaning to increase the power output of solar panels, particular attention should be paid to fallen leaves and bird droppings. These can easily block sunlight locally and may repeatedly occur in the same place. If power generation is low only on certain panels or strings, fallen leaves or bird droppings may be the cause.

Fallen leaves are a common issue at sites with nearby trees. Dry leaves can be blown away by the wind, but when they get wet from rain they can stick to the surface of panels. When they accumulate at the lower edges of panels or near frames, they can not only block sunlight but also lead to moisture and dirt buildup. On roof projects, if leaves collect around drainage outlets they can cause poor drainage and potential building management problems.

Bird droppings are one of the types of soiling that are particularly likely to affect power generation. When there are trees, power lines, railings, or rooftop equipment nearby that attract birds, droppings can repeatedly accumulate in the same area. Bird droppings can be difficult to remove by rain alone, and if left untreated they can cause localized reductions in power output. Even if they look small, they can cover part of a panel for a long time, so caution is necessary.

When checking for fallen leaves or bird droppings, it is important to compare the power generation data with the location. If only a specific roof surface has low output, check whether there are trees or structures nearby that tend to attract birds. If that surface underperforms throughout the day rather than just in the morning or evening, surface soiling may be responsible rather than shading.

When cleaning, choose methods that do not damage the panels rather than forcibly scrubbing off fallen leaves or bird droppings. If you aggressively scrub stuck-on dirt, you may scratch the surface. Also, because working on the roof is hazardous, prioritize safety when determining the cleaning scope and work methods. Check for fallen leaves around drainage outlets as well, and it is desirable to consider panel cleaning and roof management together.

Fallen leaves and bird droppings can recur even after being cleaned once. Therefore, we check not only the cleaning but also the surrounding environment that causes them. If tree branches are nearby, consider managing them, and if there are places where birds tend to congregate, record the patterns of soiling. Repeated soiling should be managed as part of regular inspections, as this helps maintain power generation.

Regular cleaning at sites with high dust and pollen

At sites with high levels of dust and pollen, regular cleaning and inspections help maintain power output. Dust and pollen are fine and gradually accumulate on the surface of panels. Even when the dirt is not visually noticeable, it can make it harder for sunlight to reach the panels, causing power output to decline gradually. Rather than increasing power output, management aimed at maintaining the panels' original power output is important.

Environments prone to dust generation include unpaved land, construction sites, farmland, material storage yards, roads with heavy traffic, and areas around facilities that handle powders or processed materials. Depending on wind direction, soiling can be concentrated on particular roof surfaces or rows of panels. If power generation data show that only a specific surface has lower output, check whether that surface faces a direction that is more susceptible to dust.

Pollen and yellow sand are highly seasonal and can sometimes cause power generation to be lower in early spring. They may be washed away by rain, but during periods of low rainfall or on panels with a small tilt they can remain on the surface. Powdery dirt can also accumulate along the lower edge of panels or near the frame. If spring power generation is lower than the simulation or the same month of the previous year, check for pollen and dust.

When planning regular cleaning, determine inspection timing based on local conditions. At sites with a lot of dust, check power generation data seasonally, after strong winds, and after nearby construction. In areas with a lot of pollen, check whether power generation has recovered after the pollen season. If power generation recovers after rain, natural washing may be sufficient, but if it remains low after rain, suspect residual dirt.

To assess the effectiveness of regular cleaning, compare power generation before and after cleaning. Rather than looking only at the month when cleaning was performed, comparing output on similar sunny days and during the same time of day makes the effect easier to see. If generation does not improve despite cleaning, check for other causes such as shading, temperature, equipment, or wiring.

Measures to deal with dust and pollen are highly dependent on site-specific environmental conditions. Rather than carrying out routine cleaning uniformly, it is important to determine a cleaning frequency suited to each site while recording power generation data, the occurrence of soiling, the surrounding environment, and the effects after cleaning.

Condition checks after snowfall and after rain

Checking conditions after snowfall or rain is also an important method that should be included in cleaning and inspection to increase power generation. Because solar panels are installed outdoors, their surface condition changes due to rain and snow. Rain can wash away dirt, but it can also cause dirt to accumulate in certain spots or fallen leaves to stick. After snowfall, snow may remain, causing periods when power generation is not possible.

After rain, check whether dirt has been washed away or whether any debris remains at the bottom edge of the panels. Rain can sometimes clean the entire surface, but on low-tilt panels water does not run off easily and dirt can remain. If bird droppings or dust have adhered, they may be difficult to remove with rain alone. If power output does not recover after rain, suspect residual dirt.

After snowfall, check how long snow remains on the panels. While snow is on the panels they cannot receive solar radiation, and power generation drops significantly. If the tilt angle is low or cold temperatures persist, snow may remain for a long time. Even after the snow has fallen off, accumulated snow beneath or in front of the panels can cast shadows. If winter power generation is lower than expected, you need to check the effects of snowfall and residual snow.

After snowfall, safety is the top priority for inspections. Going onto the roof to remove snow is highly dangerous and can also damage equipment and the roof. Avoid forcing snow removal; first understand the situation using power generation data and by checking only the areas that can be inspected safely. Recording surfaces where snow tends to remain, areas where snow may fall, snow storage spaces, and inspection routes will help with winter measures in future seasons.

Checks after rain or snowfall are opportunities to assess how much dirt and snow are affecting power generation. You can determine whether a drop is one that will recover naturally or one that requires cleaning or inspection. In particular, at sites where power generation falls in the same season every year, it is important to record the conditions after rain and snow and compare them with the generation data.

Rain and snow are natural phenomena, but they are factors that cannot be ignored in power generation management. By checking conditions after snowfall or after the rain has stopped, you can better determine the timing for cleaning and inspections.

Compare power generation after cleaning to verify effectiveness

After cleaning, always compare the power generation to verify the effectiveness. If you are satisfied with merely having cleaned, you won't know whether the power generation actually improved or whether another cause still remains. Cleaning intended to increase power generation is considered complete only after verification following the work.

In verification, we compare power generation before and after cleaning. However, simply comparing the day before cleaning with the day after cleaning is insufficient. If the weather, season, temperature, or solar irradiance conditions differ, power output will naturally change. It is important to compare data from as similar sunny days as possible, the same time of day, the same installation surface, and the same season.

If data are available by installation surface or by system, check whether the power output from the cleaned area has improved. Even if the total power output has increased slightly, the change may be due to factors other than the cleaned surface. If only a specific surface was cleaned, it is easier to judge the effect by looking at how the power output of that surface changed.

If power generation improves after cleaning, it becomes more likely that dirt was the cause of the reduced output. If the improvement is small, the effect of dirt may have been limited, or other causes such as shading, equipment, wiring, temperature, or snowfall may remain. If cleaning does not lead to improvement, it is important to proceed to the next inspection items.

Also keep cleaning records. Recording the cleaning date and time, weather, cleaned area, type of dirt, cleaning method, power generation before and after cleaning, photos, and location information will help with future decision-making. If the same spot gets dirty in the same season every year, this can be reflected in periodic inspections and cleaning plans. By recording cleaning effectiveness, it becomes easier to determine the appropriate cleaning frequency for each site.

Cleaning intended to increase power generation should not be carried out based solely on experience or intuition. By comparing pre- and post-cleaning data and distinguishing cleanings that are effective from those that have little effect, you can reduce unnecessary work and manage operations in ways that directly improve power generation.

Dangerous decisions to avoid during cleaning

What you should avoid when cleaning solar panels is starting work without first identifying the cause of low power output. If the cause of the drop in power output is shading, equipment malfunction, wiring losses, or a rise in temperature, cleaning alone will not improve it. First check the generation data and determine whether dirt is likely the cause.

Avoid attempting unsafe work on roofs. Solar panels are often installed on roofs or at height, posing a risk of falls and equipment damage. Working on wet roofs, sloped roofs, areas with poor footing, or during strong winds is especially dangerous. Cleaning to increase power generation is pointless if it leads to accidents. Areas that cannot be safely checked should be inspected with appropriate measures and personnel in place.

You must also avoid cleaning that can damage the panels. Actions such as scrubbing vigorously with hard tools, using detergents that are not suitable for the surface, applying high-pressure water, or carelessly spraying water around electrical equipment can lead to deterioration or malfunction of the equipment. Cleaning is a means to increase power generation, but if done in a way that stresses the equipment, it will be counterproductive.

Also, caution is needed when continuing regular cleaning without confirming its effectiveness. At some sites cleaning can have a large effect, while at others the impact of dirt may be small and shadows or equipment may be the primary causes. If you do not compare power generation before and after cleaning, you cannot determine whether the cleaning was truly effective.

Furthermore, it is also a judgment we should avoid to think that cleaning alone can increase power generation. Cleaning is important, but power generation is also affected by shade, orientation, tilt, temperature, snow accumulation, wiring, equipment, and maintenance practices. If cleaning does not lead to improvement, other causes need to be checked.

Cleaning carried out without consideration for safety, equipment protection, and data verification can not only fail to improve power output but also increase risk. Cleaning should be performed safely and only to the extent necessary, based on generation data and on-site inspections.

Summary

When it comes to cleaning methods to increase solar panel power output, you need to consider the whole process—not only removing dirt but also determining whether cleaning is necessary, identifying the type of soiling, ensuring safe work, and verifying effectiveness after cleaning. Cleaning can be an effective measure to improve power output, but it will not yield sufficient results if soiling is not the cause. It is important to combine power generation data with on-site inspection.

First, determine the need for cleaning from power generation data. Check monthly generation, generation by time of day, and generation by installation surface to assess whether dirt may be the cause. Next, inspect the panel surface for dirt, fallen leaves, and bird droppings. Localized or encrusted dirt can lead to reduced power output. For sites with high levels of dust or pollen, consider regular cleaning tailored to local conditions.

After snowfall or rain, check whether snow and dirt have been naturally cleared. Some dirt will be washed away by rain, but it can remain on low-tilt panels or as stubborn, stuck-on grime. After cleaning, verify the effect by comparing power output. It is important to confirm that, under similar weather conditions, the power output from the cleaned area has improved.

Things to avoid during cleaning are performing work without confirming the cause, undertaking unsafe work on the roof, using methods that could damage the panels, and failing to verify the cleaning effect with data. Cleaning intended to increase power generation must be carried out with safety and equipment protection as prerequisites.

Furthermore, precise on-site information is indispensable for improving the accuracy of cleaning and inspection. If you can ascertain the installation area, rooftop equipment, obstacles, trees, site boundaries, orientation, slope, inspection routes, and potential connection points, it becomes easier to identify areas prone to dirt, causes of shading, and areas that are difficult to clean.

Using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective when you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, tilt, inspection routes, and efficiently carry out cleaning and inspections to increase solar panel power output. If you can acquire high-precision location information on site, it becomes easier to organize areas prone to soiling, causes of shading, feasible installation ranges, wiring routes, and maintenance routes, and you can consistently proceed from cleaning records and verification of power output improvements to post-installation performance management. To increase solar panel power output through cleaning, it is important not to rely on intuitive work but to accurately understand the site and respond appropriately to the soiling and obstructions that are reducing power output.