12 Concrete Measures to Improve the Efficiency of Solar Power Generation

When you want to improve the efficiency of solar power generation, the first things that may come to mind are replacing panels with higher-performance ones or expanding the system. However, actual power generation is not determined solely by panel performance. Shading, dirt, orientation, tilt, temperature, snow accumulation, wiring, equipment condition, maintenance planning, and how generation data is interpreted—multiple factors together determine output. In other words, to improve solar power efficiency, it's important to check whether your current equipment is performing as it should before adding more capacity. This article explains, from 12 perspectives, concrete measures to increase generation efficiency for practitioners who search for "発電量 上げ方".

Table of Contents

• Key Concepts to Grasp Before Improving Solar Power Generation Efficiency

• Analyze Generation Data to Identify Causes of Efficiency Loss

• Reduce Shading and Obstacles to Maximize Sunlight

• Manage Panel Surface Soiling to Minimize Generation Losses

• Review Orientation, Tilt, and Layout to Optimize Sunlight Utilization

• Mitigate Performance Losses Due to Temperature, Snow, and Wind Conditions

• Inspect Wiring, Equipment, and Output Conditions

• Enhance Efficiency Including Self-Consumption and Maintenance Planning

• Summary

Key Considerations Before Improving the Efficiency of Solar Power Generation

The phrase "improving the efficiency of solar power generation" can have several meanings. While it can refer to increasing the conversion efficiency of an individual panel, in practice you need to consider obtaining more generation from installed equipment, using the generated electricity as effectively as possible, and limiting long-term declines in output.

What matters for practitioners examining ways to increase generation is not the performance on a datasheet but increasing the amount of electricity actually generated on site and usable within the facility.

When you notice low power output, it's premature to immediately assume the panels are underperforming or that the system lacks capacity. In reality, causes such as shading, dirt accumulation, longer shadows in winter, temperature-related losses in summer, losses in wiring or equipment, or generated power not being used for self-consumption may be hidden. Adding equipment without checking for these causes first may not lead to improved efficiency.

The first step to improving efficiency is to identify the factors that are reducing power generation. Solar power generation varies with solar irradiance, weather, season, temperature, installation conditions, and the surrounding environment. A low output in a given month does not necessarily indicate an anomaly. However, if output is clearly lower than the same month in the previous year or than simulated values, if it fails to increase even on sunny days, or if it drops only during specific time periods, there may be causes that can be remedied.

When improving efficiency, we consider not only short-term power generation but also the long-term maintenance of power output. Solar power systems are operated outdoors for long periods. Dirt, fallen leaves, snow accumulation, equipment degradation, tree growth, additions of rooftop equipment, and similar factors can cause power losses that did not exist at the time of installation. It is important not to rely solely on the condition at installation but to accurately verify the current on-site conditions.

Also, increasing power generation efficiency and improving the benefits of deployment are not exactly the same. Even if generation increases, that electricity becomes surplus if it cannot be used within the facility. For facilities aimed at self-consumption, you need to look not only at the total amount generated but also at whether generation occurs during the times when the facility uses electricity. By separating and checking the generated amount, the usable electric energy, and the excess electric energy, you can correctly assess the practical improvement effects.

Isolate the Causes of Efficiency Decline by Reviewing Generation Data

One concrete measure to improve the efficiency of solar power generation is to check monthly generation. The total annual generation alone does not reveal which season’s output is falling. By confirming whether it’s low in winter, fails to rise in summer, or drops during the rainy season or prolonged rain, you can narrow down the causes. If the decline occurs in winter, check for short sunshine duration, low solar altitude, shading, and snow. If the decline occurs in summer, check for temperature-related losses, soiling, high equipment temperatures, and output curtailment.

The second concrete measure is to look at power generation by time of day. If generation is low only in the morning, consider shading on the east side; if it falls early in the evening, consider shading on the west side; if there is an unnatural dip around midday, consider shading from rooftop equipment or nearby structures, equipment output limitations, or problems with wiring or connections. If generation drops in the same time period even on sunny days, the cause may be local site conditions or equipment conditions rather than the weather.

The third specific measure is to check power generation by installation surface and by system. Whether the total power generation is low or only certain surfaces or systems are underperforming changes what should be checked. If generation is low overall, suspect the weather, overall soiling, common equipment, output limitations, and temperature losses. If only a particular roof surface is low, check that surface for shading, soiling, orientation, tilt, and the tendency for leaves to accumulate. If only a particular system is low, check the wiring, connection points, and the condition of the power conversion equipment.

When reviewing generation data, it's also important not to get the comparison baseline wrong. Comparing only with the previous month is affected by seasonal variations. Comparing with the same month in the previous year, sunny days in the same season, the simulation values from the time of installation, and generation per unit of installed capacity makes it easier to determine whether a drop in generation is a natural fluctuation or an anomaly that should be corrected. Measures to increase generation should be pursued only after isolating the cause from the data.

Organizing power generation data is not a flashy improvement measure, but it is the most important starting point. If you can identify which months, which times of day, and which surfaces have low generation, it becomes easier to prioritize cleaning, shading countermeasures, equipment inspections, and layout adjustments. Efficiency improvements should be pursued based on data, not on intuition.

Reduce shadows and obstacles to secure solar radiation

The fourth specific measure is to identify obstacles that cast shadows and reduce power generation losses. In solar power generation, when panels are shaded they cannot receive sufficient sunlight and power output decreases. Sources of shading include surrounding buildings, rooftop equipment, roof penthouses, handrails, piping, air-conditioning equipment, ventilation equipment, utility poles, signs, trees, slopes, and variations in terrain elevation.

Shadows change with the seasons and the time of day. In summer shadows are short, and a site visit may make it appear that there is no problem. However, in winter the sun’s altitude is lower and shadows become longer. Even locations that had no shadow during summer daytime can cast shadows on panels on winter mornings and evenings. If generation is significantly lower only in winter, you should check not only the sunshine duration but also winter shadows.

In shadow mitigation, first determine at what times of day and over what areas shadows fall. If morning power generation is weak, check the east side; if it drops early in the evening, check the west side; if there is a dip around midday, check for shadows from nearby equipment. By cross-referencing not only site photographs but also generation data, it becomes easier to identify shadows that significantly affect power output.

The fifth concrete measure is to manage the growth of trees and plantings. Trees grow over time, and areas that had no shade at installation may become shaded after several years. In addition to shade, trees can cause fallen leaves, bird droppings, and branches to blow onto the site. If the trees are on the property and can be managed, consider pruning and managing branches. If neighboring trees cannot be dealt with freely, the impact of their shade should be reflected in power generation simulations and maintenance plans.

It is also important not to force adding panels into shaded areas. Increasing system capacity can sometimes make annual generation look higher in simulations. However, in heavily shaded areas the energy produced per unit of capacity is lower, so it may not lead to the expected improvement in efficiency. To increase generation, prioritize areas that receive sunlight and treat heavily shaded areas cautiously.

Shadow mitigation is an important improvement that can be implemented before adding more equipment. Whether restoring the power output of existing installations or revising plans for new installations or expansions, accurately assessing shadows is fundamental to improving efficiency.

Manage soiling on panel surfaces to reduce generation losses

The sixth specific measure is to manage soiling on panel surfaces. Solar panels generate electricity by receiving sunlight on their surfaces, so when dirt accumulates it reduces the amount of light reaching the panels and lowers their power output. Soiling often builds up gradually and can be difficult to notice as the cause of reduced generation.

Causes of soiling include sand and dust, pollen, yellow dust, fallen leaves, bird droppings, exhaust-related grime, particulate matter, and residues remaining after snowfall. Areas with many trees nearby are more susceptible to fallen leaves and bird-related contamination. If unpaved land, farmland, construction sites, or roads with heavy traffic are nearby, soil dust and particulates are more likely to adhere. On rooftops, panels located near exhaust equipment or vents may become dirty more easily.

When addressing soiling, compare trends in declining power generation with the on-site conditions. If power generation is gradually declining, if it does not recover after rain, or if only specific panels show reduced output, suspect soiling. In particular, bird droppings, fallen leaves, and dust that have adhered may not be removed by rain alone. If the panels have a low tilt, dirt may also be more likely to remain.

The seventh specific measure is to set the timing for cleaning and inspections. To increase power generation, rather than hastily responding after dirt appears, it is effective to determine inspection timing according to local environmental conditions. Conducting inspections during periods of high pollen or dust, during leaf-fall, after snowfall, and at times when birds are likely to have an impact makes it easier to detect declines in power generation early.

However, for cleaning work, safety and the protection of equipment are given top priority. Rooftop work involves a risk of falling, and methods that could damage panel surfaces may be counterproductive. Actions such as scrubbing vigorously with hard tools, using unsuitable detergents, applying high-pressure water, or carelessly spraying electrical equipment with water should be avoided. The necessity of cleaning will be determined after checking the power generation data and the on-site conditions.

Soiling management is a fundamental measure for improving power generation efficiency. Before adding more panels, checking whether existing panels can receive sufficient sunlight is a shortcut to improving power output.

Reassess Orientation, Tilt, and Layout to Maximize Solar Exposure

The eighth specific measure is to reassess orientation, tilt, and layout. The efficiency of solar power generation varies depending on the direction panels face, the angle at which they are installed, and the area over which they are arranged. Especially when considering new installations, expansions, replacements, or layout changes, reviewing orientation and tilt can potentially improve power output.

Generally, surfaces that are closer to south-facing tend to produce more power over the year. However, east- or west-facing orientations are not necessarily disadvantageous. East-facing surfaces tend to generate more in the morning, and west-facing ones in the afternoon. If a facility's power demand is concentrated in the morning or afternoon, utilizing east- and west-facing surfaces can increase self-consumption. To improve generation efficiency, check not only the annual generation but also how well it matches the times when the facility uses electricity.

The tilt angle is also important. Increasing the angle can make panels more exposed to winter solar radiation, but it affects inter-row shading, wind, snow accumulation, and installation spacing. Decreasing the angle can make it easier to install more panels in the same area, but soiling and snow are more likely to remain. Decisions should be based not only on power generation but also on soiling, snow accumulation, wind, and maintainability.

The ninth specific measure is to reduce waste in layout. Forcing panels into areas with heavy shading, surfaces with unfavorable orientation, locations that are difficult to inspect, or areas that are too close to drains or rooftop equipment may not increase power generation as much as expected. It is important not only to increase system capacity but also to check the generation per unit of capacity.

On rooftop projects, we check the power generation for each roof surface. We separate areas such as the south, east, and west faces and flat-roof sections to understand which surface is contributing to generation. For land projects, we revisit the layout considering inter-row spacing, maintenance aisles, drainage, terrain, and shading. Tightening the panel rows increases capacity, but can worsen inter-row shading and maintainability.

When reviewing the layout, compare before and after with simulations. Confirm not only total generation but also generation per unit capacity, month-by-month generation, self-consumption, and surplus electricity. If generation increases but only the surplus grows, the practical benefit is limited. To improve generation efficiency, it is important to choose a layout that captures sunlight easily, is convenient to use within the facility, and is easy to maintain.

Suppressing losses due to temperature, snow, and wind conditions

The tenth specific measure is to reduce output losses caused by rising temperatures. Solar power systems tend to generate more electricity with greater solar irradiance; however, when panel temperatures get high, output can decline. Especially in summer and for rooftop installations, generation may not increase as much as expected despite strong sunlight.

To minimize temperature loss, check the ventilation conditions around the panels. If the roof surface tends to get hot, if the space behind the panels is small, or if nearby equipment restricts airflow, heat is likely to become trapped. Even for ground-mounted installations, temperature conditions can be affected if overgrown grass blocks ventilation or nearby structures cause air to stagnate.

In power generation data, attention is paid to summer power output. If output does not increase despite expected high solar irradiance, or if spring and autumn produce more stable output, check for the influence of temperature losses. Temperature countermeasures include arranging components so as not to obstruct ventilation, managing vegetation, and ensuring heat dissipation around equipment. However, changes to racking height or tilt angle affect wind loads and constructability, so they need to be evaluated comprehensively.

The eleventh specific measure is dealing with snow and fallen leaves. In snowy regions, snow accumulating on panels creates periods when they cannot generate electricity. When the tilt is low, snow tends to remain, and after snow slides off it can accumulate in front of or beneath the panels and cast shadows. Fallen leaves likewise, when they build up on the panel surface or around drainage outlets, can lead to reduced power generation and building-management problems.

Wind conditions should not be overlooked. Increasing the tilt angle or using taller mounting structures can make installations more susceptible to wind. If measures against wind are insufficient, safety and constructability can be affected. On the other hand, good ventilation can help reduce temperature increases. To improve power generation efficiency, temperature, snow accumulation, and wind should be evaluated together as integrated site conditions, rather than separately.

Temperature, snowfall, and wind may not be fully apparent from the numbers in a power generation simulation alone. It is important to check local roof and site conditions and seasonal variations, and to establish installation and maintenance conditions that can sustain power generation over the long term.

Inspect wiring, equipment, and output conditions

The twelfth specific measure is to inspect the wiring, equipment, and output conditions. The electricity generated by solar panels is used within the facility after passing through wiring and power conversion equipment. Even if there are no problems on the panel side, losses or malfunctions in the wiring or equipment will reduce the amount of electrical energy actually available for use.

Wiring losses vary depending on wiring distance and the condition of connections. When wiring is long, connection points are difficult to inspect, or the route is complex, it becomes harder to identify the causes of decreased power output. When installing new systems or expanding existing ones, it is necessary to plan not only the panel layout but also the wiring routes and equipment installation locations rationally. For existing installations, wiring and connection points should be included among the items checked when there is a drop in power output.

The condition of the power conversion equipment is also important. If equipment is offline or some circuits are not operating normally, the amount of electricity available to the facility will be reduced even if the panels are generating. If generation suddenly drops, if only certain circuits are low, or if there is an unnatural plateauing of output around midday, check the equipment and the connections.

Also check the output conditions. Even if you increase panel capacity, the output may reach an upper limit depending on equipment capacity and connection conditions. The fact that output is capped is not necessarily bad in itself, but even if you think you have increased generation, the actual usable amount of electricity may not have increased. Also check whether the generation peak coincides with facility demand or whether the surplus has become too large.

The installation environment of the equipment also affects power generation efficiency. Locations prone to high temperatures, exposed to rain or snow, or difficult to inspect increase long-term operational risks. Check whether there is space for inspection and replacement, and whether access is possible in the event of an abnormality.

Inspection of wiring, equipment, and output conditions is not so much intended to increase power output as it is to prevent the loss of the electricity that should be produced. If cleaning the panels and implementing shading countermeasures do not improve power output, you need to check whether there is an issue in the electrical path.

Improve efficiency by including self-consumption and maintenance planning

To improve the efficiency of solar power generation, you need to consider not only the amount of power generated but also self-consumption and maintenance planning. If the electricity generated is not used within the facility, increasing generation may have only a limited effect. In self-consumption systems, it is more important that generation occurs during hours when it can be used than how much can be generated.

Power generation, self-consumption, and surplus electricity are checked separately. Even if power generation is sufficient, if a facility’s demand is concentrated at night, self-consumption tends not to increase. At facilities where there is demand on weekdays but little demand on weekends, surplus may increase. When implementing measures to improve generation efficiency, confirm whether the resulting improvement will be allocated to self-consumption or become surplus.

Maintenance planning is also essential for improving efficiency. Solar PV systems are operated outdoors for long periods. Shadows, dirt, fallen leaves, snow accumulation, equipment malfunctions, wiring faults, and tree growth must be continuously checked even after installation. If there are no inspection walkways, cleaning cannot be performed, or equipment is inaccessible, it will take longer to identify the causes of reduced power output.

Under the maintenance plan, monthly generation, generation by time of day, generation by installation surface, self-consumption, and surplus energy are recorded and compared with expected values and with the same month of the previous year. Changes in generation after cleaning, after shade mitigation, and after equipment inspections are checked. Recording the effects of improvements makes future maintenance decisions easier.

When it comes to improving power generation efficiency, attention tends to focus on equipment performance and design conditions. However, in practice, having an operational framework that regularly checks system condition and quickly addresses the causes of reduced power output is extremely important. Rather than temporarily boosting efficiency, establishing mechanisms to maintain it over the long term greatly influences the outcomes of solar power generation.

Summary

To improve the efficiency of solar power generation, it is necessary to comprehensively review not only panel performance but also generation data, shading, soiling, orientation, tilt, temperature, snow, wind, wiring, equipment, self-consumption, and maintenance planning. Efficiency improvements should not start by adding more equipment; they should start by confirming whether the current equipment is able to deliver its intended generation output.

As specific measures, first check the monthly power generation to identify seasonal factors causing declines. Next, examine time-of-day power generation to investigate possible shading or equipment abnormalities. Checking data by installation surface and by system makes it easier to isolate which areas are experiencing drops in generation. Inspect for shadows, trees, and obstacles, and prioritize countermeasures for the areas that have the greatest impact on power generation. Manage dirt on panel surfaces, fallen leaves, and bird droppings, and perform safe cleaning and inspections as necessary.

Furthermore, we will review orientation, tilt, and layout to consider arrangements that maximize solar exposure and are easy to maintain. We will also assess temperature rise, snowfall, and wind conditions, and consider installation conditions that can sustain power generation over the long term. It is also important to inspect wiring, equipment, and output conditions to ensure that the power generated by the panels remains usable by the facility. Finally, check self-consumption and surplus electricity separately, and by continuing maintenance planning and performance management, link efficiency improvements to long-term outcomes.

When trying to increase power generation, what you should avoid are adding equipment without identifying the cause, judging only by annual generation, and cramming in layouts while ignoring shading and maintainability. The purpose of improving efficiency is not to increase apparent installed capacity, but to recover generation opportunities lost on site and to make the generated electricity effectively usable.

Accurate on-site information is the foundation for improving the efficiency of solar power generation. If the installation area, rooftop equipment, obstructions, trees, property boundaries, orientation, slope, inspection access routes, and potential connection points can be accurately understood, it becomes easier to sort out issues related to shading, soiling, temperature, wiring, and maintainability.

If you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, slope, inspection access routes, and so on, and identify improvement points to increase solar power generation efficiency, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. By obtaining high-precision location information on site, you can more easily organize causes of shading, areas prone to soiling, feasible installation ranges, wiring routes, and maintenance access, making it easier to carry out a consistent process from on-site verification for efficiency improvements and simulation comparisons to post-installation performance management. To truly improve solar power generation efficiency, it is important not only to pursue desk-based measures but also to accurately grasp the site and appropriately address the causes that are reducing power output.