5 Items to Check First if You Want to Increase Power Generation

When you want to increase the output of a solar power generation system, it's premature to immediately consider adding panels or replacing equipment. Causes of stagnant output are not limited to panel performance; shade, dirt, temperature, orientation, tilt, wiring, equipment condition, seasonal variation, lack of maintenance, and other factors are interrelated in complex ways. If you check the wrong items first, you may find that cleaning brings no improvement, adding equipment only increases surplus, or you suspect the equipment when the real cause was winter shading. This article explains, for practitioners searching for "how to increase power generation," the five items people who want to increase output should check first, presented in an order that can be used on site.

Table of Contents

• Why decide the order of checks before increasing power generation

• Item 1: Check power generation by month and time of day

• Item 2: Check shadows, obstacles, and the surrounding environment

• Item 3: Check surface obstructions such as dirt, fallen leaves, and snow

• Item 4: Check orientation, tilt, and temperature conditions

• Item 5: Check equipment, wiring, and maintenance arrangements

• Decisions to avoid when trying to increase power generation

• Summary

Why you should decide the order of checks before increasing power generation

When you want to increase power generation, the most important thing is not to assume a cause. The output of solar power generation naturally fluctuates with weather and seasons. If clear weather continues, output tends to rise, while during periods with many cloudy or rainy days, output falls. In winter, because daylight hours are shorter and the sun's altitude is lower, output tends to be lower than in summer. Although summer brings higher solar irradiance, panel temperatures can rise and cause output to decrease.

Therefore, it is not appropriate to immediately judge that the equipment is faulty simply because the power generation for a given month was low. Conversely, if you assume it's seasonal variation and leave it unchecked, you may miss the real causes such as shading, soiling, equipment shutdowns, or wiring faults. To increase power generation, you need to distinguish between natural declines caused by weather and declines that can be improved.

There are broadly two approaches to increasing power generation. One is restoring existing equipment to the level it was originally capable of generating. Measures such as reducing shading, removing dirt, repairing equipment malfunctions, and addressing snow accumulation and fallen leaves fall into this category. The other is reviewing design and operation to increase opportunities for generation. Orientation and tilt, layout, expansion, energy storage, and how loads are used are among the related factors.

What beginners and operations personnel should do first is to check the former, not the latter. In other words, before adding anything new, verify whether any generation is being lost from the existing equipment. If output has decreased due to dirt or shading, adding panels will have limited effect if the same problems remain. If the cause is a fault in the equipment or wiring, cleaning alone will not resolve it.

Also, increasing power generation is not the same as increasing the effectiveness of the installation. Even if power generation increases, it becomes surplus if that electricity cannot be used within the facility. If the goal is to reduce electricity bills or purchased electricity, you need to look not only at generation but also at self-consumption. Even if generation occurs during the daytime, if the facility is not using power at that time, an increase in generation may not directly translate into practical benefits.

That is precisely why those who want to increase power generation should decide on the order in which to inspect things. First, review the generation data to understand when, where, and how the power output is dropping. Next, check causes that are easy to confirm on site, such as shading and soiling. After that, verify orientation, tilt, temperature, equipment, wiring, and maintenance arrangements. If you follow this order, you will reduce unnecessary measures and make it easier to find points with high improvement potential.

Item 1: Check power generation by month and time of day

The first thing people who want to increase power generation should look at is power generation by month and time of day. Looking only at the total annual generation does not reveal the causes of low output. The annual total is useful for seeing overall trends, but it is difficult to tell in which season it is falling, at what time of day it is falling, or whether only a particular installation surface is weak.

Looking at monthly power generation reveals seasonal variations. If the output is significantly lower only in winter, check not only the shorter sunshine hours but also winter shadows and snowfall. If it does not increase in summer as expected, check for output reduction due to high temperatures, soiling, equipment condition, and output capping. If declines are notable in spring or autumn, suspect seasonal factors such as pollen, dust, fallen leaves, and bird droppings.

One thing to be careful about here is not to judge solely by comparison with the previous month. Solar power generation fluctuates seasonally, so a drop from the previous month does not necessarily indicate an anomaly. If you want to check, it is easier to grasp the actual situation by comparing with the same month in the previous year, sunny days in the same season, the simulation values at the time of installation, and the generation per unit of installed capacity. Low generation in a month with poor weather is natural, but if generation is low even on sunny days, there is a higher likelihood that there are causes that can be corrected.

Generation by time of day is also important. If morning generation is weak, consider shadows from buildings, trees, or rooftop equipment on the east side. If generation drops off early in the evening, check for shadows on the west side. If there is an unusual dip around midday, you should check for shadows from nearby rooftop equipment such as penthouses and piping, equipment output limitations, and the condition of power conversion equipment.

Time-of-day generation curves are extremely useful for inferring the causes of reduced power output. If the drop is due to cloudy or rainy conditions, generation typically decreases across the board. Conversely, shading or a localized equipment fault can cause dips at similar times each day. If generation falls at the same time even on sunny days, it is worth checking site conditions and equipment status.

If you have data categorized by mounting surface or by system, it becomes even easier to narrow down the issue. The causes differ depending on whether the entire system is performing poorly or only a part is. If the overall performance is low, suspect the weather, general soiling, common equipment, or output limits. If only a part is performing poorly, focus checks on that surface’s shading, soiling, orientation, tilt, wiring, and connections.

The first step to increasing power generation is to examine the data in detail. If you know when output is low and where it is low, the site conditions you need to check next become clear. Rather than starting cleaning or replacements based on intuition, narrowing down the cause from the generation data makes it easier to achieve effective improvements.

Item 2: Check shadows, obstacles, and the surrounding environment

The second item to check is shadows, obstacles, and the surrounding environment. In solar power generation, if shadows fall on the panels they cannot receive sufficient sunlight and power output decreases. Shadows are a typical cause of reduced power generation, yet because they change with the season and time of day they are easily overlooked if on-site inspections are insufficient.

Causes of shading include surrounding buildings, rooftop equipment, rooftop penthouses, handrails, piping, air conditioning equipment, ventilation equipment, utility poles, signs, trees, slopes, and differences in terrain elevation. On roofs, even small pieces of equipment located near panels can cast long shadows in winter or at dawn and dusk. For land projects, it is necessary to check the shadows cast by trees on neighboring properties, utility poles, surrounding structures, and slopes.

What requires particular attention is shadows in winter. In winter the sun's altitude is low, and shadows that did not reach the panels in summer can extend to them. Even if the site looks unshaded when visited during a summer day, long shadows may occur in winter. If generation is significantly lower only in winter, it is important to check for winter shading as well as the shorter sunlight hours.

Shadows also change depending on the time of day. If power output does not increase in the morning, shadows on the east side may be the cause; if it falls early in the evening, shadows on the west side may be the cause; if there is an unnatural drop around midday, shadows from nearby equipment may be the cause. By combining power generation data with on-site inspection, it becomes easier to identify which obstacle is casting a shadow at which time of day.

Changes in the surrounding environment must not be overlooked. Trees that were small at the time of installation can grow and create shade. New equipment or piping may be added to rooftops. Buildings or other structures may be erected on neighboring land. Because solar power generation equipment is used for long periods, the on-site conditions at the time of installation may not remain unchanged.

As countermeasures, identify the sources of shading and record the areas affected by shadows. If trees are the cause and are within a manageable range, consider pruning or branch management. If rooftop equipment or nearby buildings are the cause, avoid heavily shaded areas when adding new installations or changing the layout. Major layout changes may be difficult for existing equipment, but understanding the cause helps explain reductions in power generation and supports future improvements.

Even when adding panels to increase generation, you should avoid forcefully adding them in shaded areas. Although installed capacity may increase, generation per unit of capacity can decrease, and total generation may not grow as much as expected. In shadow mitigation, it is important not only to eliminate shadows but to prioritize managing those shadows that have the greatest impact on generation.

Item 3: Check for surface obstructions such as dirt, fallen leaves, and snow

The third item to check is dirt, fallen leaves, snow, and other obstructions on the panel surface. Solar panels generate electricity by receiving sunlight on their surface, so if the surface is covered, their power output will decrease. Dirt and fallen leaves may seem like minor issues at first, but if left unaddressed they can cause a reduction in power generation.

Causes of soiling include sand and dust, pollen, yellow sand, bird droppings, exhaust-related dirt, particulate matter, and residues remaining after snowfall. In locations with many trees nearby, surfaces are more likely to be affected by falling leaves and birds. In areas near unpaved land, construction sites, farmland, material storage yards, or roads with heavy traffic, soil dust and particulates tend to adhere more easily. On rooftops, panels located near exhaust equipment or vents may become dirty more readily.

Soiling can occur suddenly, but in many cases it accumulates gradually. Therefore, if the power output is gradually declining, it is worth checking the condition of the panel surface. If output does not recover after rain, or if only a particular installation surface has lower output, check whether that surface is subject to conditions that make it prone to soiling.

Fallen leaves occur not only in autumn but also on windy days or depending on the condition of surrounding trees. If leaves are dry they may be blown away, but when wet from rain they can stick to the surface of panels. When they accumulate at the lower edge of panels or around the frame, they not only block sunlight but also lead to a buildup of dirt. For rooftop projects, when leaves collect in drains they can affect building maintenance, so inspections are necessary not only from the perspective of power generation but also from the standpoint of drainage management.

In snowy regions, periods occur during which power generation cannot take place because snow covers the panels. Not only the time when it is snowing, but also the time after snowfall during which snow remains on the panels affects power output. When the tilt angle is small, snow is less likely to slide off, and fallen snow can accumulate on the front or lower parts of the panels, causing shading. If winter power generation is low, check for the effects of snowfall and residual snow.

As a remedial measure, first check the surface condition within a range that can be inspected safely. If cleaning is necessary, choose a method that will not damage the panels and ensure safety. Rooftop work carries risks, so avoid attempting tasks that are unsafe. After cleaning or removal, confirm with data whether power generation has improved.

Addressing dirt, fallen leaves, and snow is fundamental not only to temporarily restore power generation but also to maintain it over the long term. Scheduling inspections by season makes it easier to detect declines in power generation early.

Item 4: Check orientation, tilt, and temperature conditions

The fourth item to check is orientation, tilt, and temperature conditions. When you want to increase power generation, it is important not only to check for shading and dirt but also to review whether the panels are installed under conditions that allow them to receive sunlight easily. In particular, when considering new installation, expansion, replacement, or layout changes, verifying the orientation and tilt can lead to improved power generation.

Orientation indicates which direction the panels face. Surfaces that face closer to south tend to produce more electricity over the year, but east- or west-facing surfaces are not necessarily at a disadvantage. East-facing panels tend to generate more in the morning, and west-facing panels tend to generate more in the afternoon. If a facility’s power demand is skewed toward the morning or afternoon, generation from east- and west-facing surfaces can help with self-consumption.

The tilt affects how sunlight is received throughout the seasons. A steeper angle can increase winter solar exposure, but it also influences inter-row shading, wind effects, snow accumulation, and installation spacing. A shallower angle can make it easier to fit more panels, but dirt and snow are more likely to remain. When reconsidering the tilt to increase energy production, check not only annual generation but also monthly generation, the number of panels to be installed, and maintenance requirements.

In roof projects, installations are often carried out to match the pitch of the existing roof, so the angle cannot always be freely changed. In that case, it is important to check the power generation of each roof surface and prioritize the surfaces with better conditions. If you force installation onto a poorly conditioned surface when expanding, the increase in power generation may be less than expected.

Temperature conditions also affect power generation. Even in summer, when solar irradiance is high, output can decrease if panel temperatures rise. Heat can build up on roofs, and if ventilation behind the panels is poor, temperature losses can become significant. If generation appears more stable in spring and autumn, check for temperature losses during the summer.

As a countermeasure, check generation data for monthly and time-of-day trends and examine their relationship with orientation, tilt, and temperature conditions. Major changes may be difficult for existing installations, but this becomes an important factor when adding capacity or upgrading equipment. To increase power generation, it is important not simply to move the angle closer to the theoretical optimum, but to choose installation conditions that match local site conditions and the facility’s demand.

Item 5: Check equipment, wiring, and the maintenance system

The fifth item to check is equipment, wiring, and the maintenance system. To increase power generation, you need to confirm not only the panels themselves but also that the generated electricity is in a usable state for the facility. Solar power generation functions as an integrated system of panels, wiring, connection points, power conversion equipment, monitoring, and maintenance.

Even if there is no problem on the panel side, power generation will decrease if there are faults in the wiring or equipment. Wiring losses vary depending on wiring distance and the condition of connections. If the wiring route is long, connection points are difficult to inspect, or the route is complex, defects may be discovered late. If power generation is low in only some parts of the system, the wiring and connection points need to be checked.

The condition of the power conversion equipment is also important. If the equipment has stopped or is not operating normally, the amount of usable electricity will decrease even if the panels are generating power. When generation suddenly drops, you should suspect not only shading or dirt but also equipment shutdown. If output levels off around midday, check the equipment capacity and output conditions.

We also inspect the equipment’s installation environment. If equipment is located in places prone to high temperatures, exposed to rain or snow, or in locations that are difficult to inspect, the risks for long-term operation increase. We check whether the equipment is easily accessible, whether there is space for inspection and replacement, and whether it is easy to verify conditions in the event of an anomaly.

Maintenance arrangements are also indispensable for maintaining power generation. Confirm whether there are inspection walkways, whether cleaning can be carried out, whether drains and rooftop equipment can be accessed, and whether weeding and drainage management can be performed on land projects. Even if you try to increase power generation by adding more panels, if you arrange them in a way that makes maintenance difficult, generation may decline in the long term.

Performance tracking is also important. Record monthly generation, generation by time of day, generation by installation surface, self-consumption, and surplus electricity so they can be compared with expected values and past performance. If you have a system that can isolate causes—weather, shading, soiling, equipment, wiring, or changes in demand—when generation declines, corrective actions can be taken more quickly.

To increase power output, merely inspecting the panels is insufficient. You must also check the path the electricity takes to reach the facility and the maintenance regime that keeps it running.

Decisions to avoid when trying to increase power generation

What you should avoid when trying to increase power generation is considering adding or replacing equipment without first identifying the cause. If the low power generation is due to shading, dirt, or equipment shutdowns, on-site inspection and maintenance can be more effective than adding more panels. First, it is important to confirm where the power is being lost.

You should also avoid judging solely by annual power generation. Even if annual power generation increases, if the additional output is not used within the facility and simply becomes surplus, improvements in the effectiveness of the installation will be limited. You need to distinguish whether you want to increase generation or increase self-consumption.

Be cautious about forcing additional panels into shaded or hard-to-maintain locations. Even if the installed capacity increases, the generation per unit of capacity may decrease. In configurations where inspection and cleaning are difficult, dirt and defects may be discovered late, which can lead to a long-term decline in power generation.

Also, it is important not to be satisfied with improvements shown only in simulations. Even if the layout appears to increase power generation on paper, unless you confirm whether that arrangement can actually be implemented on site and whether there are any issues with wind, snow accumulation, drainage, waterproofing, or maintenance access, problems may arise after installation.

You should avoid underestimating loss rates. If you evaluate improvement effects without sufficiently accounting for temperature, shading, dirt, snow accumulation, wiring, power conversion, and aging, the gap between projected and actual performance after installation can be large. To increase power generation, it is important to make decisions based on realistic figures that match site conditions rather than on optimistic numbers.

Improving power generation is not about trying seemingly good countermeasures one after another. It is about reviewing the data, inspecting the site, isolating the causes, and verifying the effects after improvements. Even if it may seem like taking the long way around, adhering to this sequence will ultimately bring you closer to increasing power generation.

Summary

The five items that people who want to increase power generation should check first are: monthly and time-of-day power generation, shading/obstructions/surrounding environment, dirt/fallen leaves/snow accumulation, orientation/tilt/temperature conditions, and equipment/wiring/maintenance arrangements. By checking these in order, it becomes easier to isolate the causes of low power generation and to select effective improvement measures.

In Item 1, check power generation by month and by time of day. By identifying which season, which time of day, and which installation surface is experiencing a drop in output, you can narrow down the cause. In Item 2, check for shadows, obstacles, and the surrounding environment. Nearby buildings, rooftop equipment, trees, utility poles, and differences in terrain elevation can be major causes of reduced power generation. In Item 3, check for surface obstructions such as dirt, fallen leaves, and snow. If sunlight does not reach the panel surface, the same equipment will produce less power.

In Item 4, we check the orientation, tilt, and temperature conditions. We look at whether the orientation and angle are favorable for power generation, whether there are temperature-related losses in summer, and whether the facility’s demand periods align with the power generation periods. In Item 5, we check the equipment, wiring, and maintenance arrangements. We verify whether the generated power is available for use at the facility and whether there is a plan for long-term inspections and cleaning.

When you want to increase power generation, things to avoid are adding equipment without checking the causes, judging solely by annual generation, and cramming layouts while ignoring shading and maintainability. Improving power generation is not about increasing the apparent installed capacity, but about recovering the generation that is actually being lost on site.

Accurate on-site information forms the foundation for increasing power generation. If you can accurately grasp the installation area, rooftop equipment, obstructions, trees, site boundaries, orientation, slope, inspection routes, and candidate connection points, it becomes easier to organize issues such as shading, soiling, temperature, wiring, and maintainability.

If you want to accurately record on-site installation areas, obstacles, trees, rooftop equipment, site boundaries, orientation, tilt, and inspection/maintenance access routes, and organize the items to check first to increase power generation, using LRTK, an iPhone-mounted GNSS high-precision positioning device, is effective. If you can obtain on-site location information with high precision, it becomes easier to identify causes of shading, areas prone to soiling, feasible installation ranges, wiring routes, and maintenance access lines, and to carry out a seamless process from on-site verification for power generation improvement and simulation comparisons to post-installation performance management. When aiming to increase power generation, it is important not to rely solely on desk-based estimates but to accurately understand the site and address, in order, the causes that are reducing generation.