Where should you start to increase power generation? 6 steps

When you want to increase the power output of a photovoltaic system, it's premature to immediately consider adding panels or upgrading equipment. The reasons output isn't increasing often involve multiple factors beyond panel performance—weather, season, shading, dirt, temperature rise, snow accumulation, wiring, equipment condition, orientation, tilt, and lack of maintenance. If you check things in the wrong order at the outset, you may clean and see no improvement, add equipment only to increase surplus, or suspect the equipment when the real cause was shading. This article explains, in six steps, what to start with to increase generation, aimed at practitioners searching for "how to increase power generation".

Table of Contents

• Do not assume the cause before increasing power generation

• Step 1: Check monthly power generation to see whether the variation is natural or abnormal

• Step 2: Check time-of-day power generation for shading or equipment abnormalities

• Step 3: On-site, check for external factors such as shading, soiling, or snow accumulation

• Step 4: Review orientation, tilt, and layout conditions

• Step 5: Inspect wiring, connection points, and power conversion equipment

• Step 6: Record the power generation after improvements and use it to guide the next actions

• Decisions to avoid when trying to increase power generation

• Summary

Don't assume the cause before increasing power output

When you aim to increase power generation, the first important thing is not to attribute low output to a single cause. Solar power systems do not always generate the same amount of electricity even on sunny days. Output varies day to day depending on solar irradiance, temperature, weather, solar altitude, shading, dirt, snow cover, equipment condition, and so on. Therefore, if output was low in only a particular month, it is not appropriate to immediately conclude there is a fault or degradation.

For example, in winter, daylight hours are shorter and the sun’s altitude is lower, so power generation tends to decrease compared with summer. Furthermore, in winter the shadows cast by buildings, trees, and rooftop equipment extend farther, so power generation can decline in places that were unaffected in summer. In summer, although solar irradiance is greater and power generation tends to increase, output may fall if panel temperatures rise. In spring, pollen and yellow dust, and in autumn, fallen leaves and post-typhoon dirt can affect power generation.

To increase power output, you need to clarify what the current output is being compared to. Whether it is lower than the previous month, lower than the same month last year, lower than the simulation value at installation, or lower even on sunny days will change which causes you should investigate. Because comparing only with the previous month can lead to misunderstanding seasonal variations, it is important to compare with the same month last year or with sunny days in the same season.

Also, even if you feel that power generation is low, the issue may not be the generation itself but that self-consumption or the benefits of the installation have not increased. If the electricity generated is not used within the facility and becomes surplus, you may feel that, even with sufficient generation, "the effect is not being seen." If you do not check power generation, self-consumption, and surplus electricity separately, you may target the wrong area for improvement.

The starting point for thinking about how to increase power generation is to systematically review the data and on-site conditions without presuming the cause. Rather than instinctively moving to cleaning or adding equipment, understanding when, where, and why generation is declining makes it easier to choose effective measures.

Step 1: Check whether monthly electricity generation reflects natural variation or an anomaly

The first step is to check the monthly power generation. When you want to increase generation, looking only at the annual total won’t reveal the cause. The annual total is useful for grasping overall trends, but it makes it hard to see which seasons generation is falling and when countermeasures are needed.

By looking at monthly power generation, you can identify seasonal characteristics. If it is low in winter, check for short sunshine hours, reduced solar elevation, shading during winter, and the effects of snow. If generation does not increase as expected in summer, check for rising panel temperatures and high-temperature conditions of equipment. If generation struggles to increase in spring, deposition of pollen, yellow sand, or dust may be involved. If a decline is observed in autumn, check for fallen leaves, dirt after typhoons, and debris blown in by strong winds.

When checking monthly power generation, simply comparing it to the previous month is insufficient. Solar power generation fluctuates significantly with the seasons, so a lower output than the previous month is not necessarily abnormal. For example, a drop in generation from autumn to winter is a natural trend. Conversely, if output is clearly lower even compared with the same month of the previous year or with sunny days in the same season, there may be hidden causes that are reducing generation.

If simulation values from the time of installation are available, compare the expected monthly power generation with the actual generation. Even if the annual total shows little difference, certain months may be lower. Check whether that month experienced shading, soiling, snow cover, equipment outages, or changes in facility operation. By comparing month by month, it becomes easier to determine whether the lower generation is naturally occurring or a decline that can be improved.

Also, monthly generation data is useful for maintenance planning. If a site underperforms in spring due to soiling, you can plan inspections and cleaning in early spring. If a site has many fallen leaves in autumn, schedule inspections during the leaf-fall season. If a site is heavily affected by shading or snowfall in winter, focus on reviewing winter generation data. To increase power generation, it is important to identify monthly trends and implement measures tailored to the seasonal causes.

Step 2: Search for shading and equipment anomalies using time-of-day generation

The second step is to check power generation by time of day. After understanding seasonal trends from monthly generation, next look at which times of day the generation is underperforming. Checking by time of day makes it easier to spot issues such as shading, equipment faults, output limits, and orientation-related problems.

If the morning power output is weak, consider shading on the east side caused by buildings, trees, utility poles, rooftop equipment, etc. If power output drops rapidly in the evening, check for shadows on the west side. If there is an unusual dip around midday, suspect shading near the panels from rooftop structures, piping, air-conditioning equipment, railings, etc., or abnormalities in power conversion equipment or connections, or the output reaching its limit.

When analyzing power generation by time of day, it is important to use data from sunny days. Cloudy or rainy days generally see lower generation overall, so they are not suitable for isolating shading effects or equipment abnormalities. If generation consistently drops at the same time of day even on sunny days, it is more likely that local site conditions or equipment issues, rather than the weather, are involved.

If data are available by mounting surface or by circuit, you can investigate in more detail. Whether the overall performance is low, only some roof surfaces are low, or only specific circuits are low will change where you need to inspect. If only certain roof surfaces are low, check the shading, soiling, orientation, and tilt of those surfaces. If only specific circuits are low, you need to check the wiring, connection points, and power conversion equipment.

Time-of-day generation is also useful for judging self-consumption. If a facility uses a lot of power in the morning but morning generation is reduced by shading, it will be difficult to increase self-consumption. If a facility has high demand in the afternoon and there is strong shading on the west side, that will similarly affect the effectiveness of the installation. To not only raise generation but also increase the amount of usable energy, it is important to check the time-of-day generation curve.

Checking data by time of day improves the accuracy of estimating the cause. Measures to increase power generation—such as cleaning, shading mitigation, equipment inspection, and layout review—are varied, but to determine which to prioritize you need to know when power generation is falling.

Step 3: Check on-site for external factors such as shadows, dirt, and snow

The third step is to check external factors on site. If you detect a downward trend in generation data, inspect the actual site for shading, dirt, fallen leaves, snow accumulation, and changes in the surrounding environment. Many causes of underperformance in power generation cannot be identified without visiting the site.

The first thing to check is shadows. Sources of shadows include surrounding buildings, rooftop equipment, roof penthouses, handrails, piping, air-conditioning equipment, ventilation equipment, trees, utility poles, signs, slopes, and differences in terrain elevation. Even if there were few shadows at the time of installation, shadows can increase due to tree growth, additions of rooftop equipment, or changes in surrounding buildings.

Shadows change with the seasons and time of day. Even if there are no shadows when seen during summer daytime, long shadows can reach the panels on winter mornings and evenings. If generation data shows weak output in the morning, prioritize the east side; if it’s weak in the evening, prioritize the west side; if there’s a dip around midday, focus on equipment close to the panels. On-site inspections are more efficient when carried out with attention to the time periods and orientations that look suspicious in the data.

Next, check the panel surface for soiling. Sand and dust, pollen, yellow sand, bird droppings, fallen leaves, exhaust-related grime, and particulate matter can adhere, making it harder for sunlight to reach the panels and reducing power output. If output does not recover after rain, or if only a specific surface shows reduced output, soiling may be the cause. Even when cleaning is necessary, rooftop work is hazardous, so prioritize safety when making decisions.

In snowy regions, check whether snow remains on the panels and whether fallen snow is casting shadows on the front or underside of the panels. Not only the period during which it is snowing, but also the duration that snow remains after snowfall affects power generation. In autumn, check for fallen leaves; after typhoons, check for debris and dust; and after strong winds, check for changes in trees and surrounding structures.

During on-site inspections, record photos, locations, dates and times, and their relationship to power generation data. If you note which locations have which obstructions, which surfaces are dirty, and during which time periods shadows are likely to appear, you can use that information for future inspections and when consulting with contractors. To increase power output, it is important to organize the external factors found on site by linking them to the data.

Step 4: Review Orientation, Tilt, and Placement Conditions

The fourth step is to review the orientation, tilt, and placement conditions. Power output is affected not only by the panels' performance but also by the direction they face, the angle at which they are installed, and the area over which they are arranged. While existing installations may not be able to be changed immediately, this is an essential factor for identifying causes and deciding on expansion, replacement, or layout improvements.

Surfaces that face close to south tend to produce more electricity over the year. However, east- and west-facing surfaces are not necessarily always inferior. East-facing surfaces tend to generate more in the morning, and west-facing ones in the afternoon. If a facility's demand is high in the morning or afternoon, generation from east- or west-facing surfaces can help self-consumption. If the goal of increasing generation is to reduce the amount of purchased electricity, you need to check not only annual generation but also how the generation time periods match the demand time periods.

Tilt angle also affects power generation. A larger tilt can make it easier to receive solar radiation in winter, but it affects inter-row shading, wind, snow shedding, and installation spacing. A smaller tilt can make it easier to increase the number of panels installed, but dirt and snow may be more likely to remain. For flat roofs and ground-mounted installations, it is important to check the balance among angle, row spacing, number of panels, and maintainability.

We will also review the placement conditions. Check whether panels are being forced into heavily shaded areas, places prone to soiling, around drains or inspection ports, or locations that are difficult to maintain. Increasing installed capacity may appear to increase generation, but placing panels in poor-condition locations can reduce the energy produced per unit of capacity. To increase generation, rather than simply adding more panels, you need to prioritize areas that are conducive to generation and easy to manage.

Even when it is difficult to change the layout of existing equipment, it is worthwhile to understand the orientation, tilt, and layout conditions. If you can identify which surfaces are contributing to power generation and which are causing reductions, it becomes easier to make decisions about cleaning, inspection, shading countermeasures, expansion, and replacement/upgrades. To increase power generation, it is important to accurately understand the site's layout conditions.

Step 5: Inspect wiring, connection points, and power conversion equipment

The fifth step is to inspect the wiring, connection points, and power conversion equipment. If the panel surfaces are clean and shading or snow have little effect but power output remains low, the cause may lie in the electrical pathways. The electricity generated by the solar panels is routed through wiring and equipment to be converted into a form usable by the facility. For that reason, looking at the panels alone may not reveal the cause.

Wiring losses vary depending on wiring distance and the condition of connections. When the wiring is long, connection points are difficult to inspect, or the wiring route is complex, faults tend to be detected more slowly. If only a specific circuit has low power generation, or if there are large differences in power output between installation surfaces, the wiring and connections need to be checked.

The condition of power conversion equipment is also important. If equipment is stopped or not operating properly, even if the panels are generating, sufficient power cannot be delivered to the facility. If generation suddenly drops, if output plateaus around midday, or if there are differences in generation between systems, check the equipment and output conditions. If equipment is located in places prone to high temperatures, poorly ventilated areas, or locations that are difficult to inspect, consider the risks for long-term operation.

Electrical inspections require specialized expertise and safety precautions, so on-site personnel should not attempt to perform them. What is important is to organize the power generation data and the on-site conditions, and to clarify the scope in which abnormalities are suspected. If you determine whether the output is low across the whole system, only in part, or only during specific time periods, you can carry out the necessary inspections more efficiently.

To increase power generation, it is necessary to check not only panel surfaces and shading but also the path the generated electricity takes to reach the facility. Inspecting wiring, connections, and power conversion equipment is an important procedure for recovering lost generation.

Step 6: Record the power output after improvements and use it to inform the next measures

The sixth step is to record the power generation after improvements and use the data to guide the next countermeasures. Efforts to increase power generation do not end with inspections or cleaning. You need to confirm how power generation changed as a result of cleaning, shade-mitigation measures, and equipment inspections.

To verify the effectiveness of measures, compare power generation before and after the measures. However, you cannot simply compare the figures if the weather or season is different. Comparing on similar sunny days, the same month of the previous year, the same time of day, the same installation surface, and the same system makes it easier to judge the effectiveness. Check whether power generation returned after cleaning, whether morning or evening generation improved after shadow mitigation, and whether generation on a specific system recovered after equipment inspection.

Items to record include the inspection date and time, weather, the inspected area, the status of power generation, the presence of dirt or shadows, the condition of snow or fallen leaves, the results of equipment and wiring checks, the actions taken, and power generation before and after countermeasures. Keeping photos and location information together makes it easier to verify the same location at the next inspection.

By continuing to keep records, site-specific trends become apparent. You can identify patterns such as heavy dust in spring, leaves tending to accumulate in autumn, strong shadows from a particular direction in winter, temperature loss tending to occur in summer, and power output on certain surfaces tending to drop after typhoons. Once these tendencies are understood, inspections and cleanings can be moved forward for subsequent occasions, making it easier to prevent drops in power generation in advance.

In addition, records are also useful for internal briefings and consultations with contractors. Rather than explaining the reason for low power generation based on intuition, it is smoother to share the cause when power generation data, on-site photos, location information, and details of countermeasures are all available. To increase power generation, it is important to run inspection, countermeasures, verification, and recordkeeping as a single cycle.

Decisions to Avoid When Increasing Power Output

When trying to increase power generation, you should avoid proceeding with adding panels or upgrading equipment without first identifying the cause. If low output is due to shading, dirt, or equipment downtime, on-site inspection and maintenance may be more effective than expanding the system. First, confirm whether the existing equipment is able to deliver its expected generation.

You should avoid assuming that cleaning alone will solve the problem. If dirt is the cause, cleaning is effective, but if the cause is shading, snow, temperature, wiring, equipment, or output limits, cleaning alone will not improve the situation. If cleaning does not restore the power output, you need to investigate other causes.

Relying solely on annual power generation is risky. Even if annual generation increases, if the additional output only becomes surplus, the improvement in the effectiveness of the installation is limited. You should distinguish whether you want to increase power generation or increase self-consumption. It is important to check whether generation is increasing during the hours when the facility can use it.

Also, it is a decision to avoid layout improvements that sacrifice maintainability. If inspection walkways and cleaning space are reduced to add more panels, it may appear that power generation increases in the short term. However, if responses to soiling or equipment faults are delayed, power generation could decline in the long term. Increasing power generation presupposes a layout that can be continuously maintained.

The way to increase power generation is not to try measures you come up with one after another. It is to check the data, inspect the site, isolate the causes, and verify the results after making improvements. By following this process, you can reduce unnecessary measures and make it easier to sustain improvements in power generation.

Summary

The answer to the question of where to start to increase power generation is to begin by checking the generation data. Use monthly generation to identify seasonal declines, examine time-of-day generation to look for shading and anomalies, and inspect the site for external factors such as shade, dirt, and snow. Then review orientation, tilt, and layout conditions, and inspect wiring, connection points, and power conversion equipment. Finally, record the generation after improvements and use it to inform the next measures.

In Step 1, examine monthly power generation to determine whether the variations are natural or abnormal. In Step 2, examine generation by time of day to look for shading or equipment anomalies. In Step 3, inspect the site for shading, soiling, snow accumulation, and changes in the surrounding environment. In Step 4, review orientation, tilt, and layout conditions. In Step 5, inspect wiring, connection points, and power conversion equipment. In Step 6, record the post-improvement power generation and use it to drive continuous improvement.

When trying to increase power generation, things to avoid are adding equipment without identifying the causes, assuming that cleaning alone will solve the problem, judging solely by annual generation, and sacrificing maintainability. Improving power output is an effort to recover the generation actually lost on site. It must be pursued based on data and on-site verification, not on intuition.

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

If you want to accurately record on-site installation extents, obstacles, trees, rooftop equipment, property boundaries, orientation, inclination, inspection routes, and so on, and efficiently carry out the initial checks to increase power generation, leveraging LRTK, an iPhone-mounted high-precision GNSS positioning device, is effective. By obtaining high-precision location information on site, you can more easily sort out causes of shading, areas prone to soiling, feasible installation zones, wiring routes, and maintenance routes, making it easier to proceed seamlessly from on-site verification and simulation comparison to post-installation performance management. 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 factors that are lowering generation.