9 Ways to Deal with Low Solar Power Generation and Precautions

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What to Check First If You Feel Your Solar Power Output Is Low

When you have a solar power system installed, you may sometimes feel, "It seems to be generating less than before," "It's sunny but it's not generating as much as I expected," or "my revenue from selling electricity has decreased." Because solar power generation is greatly affected by weather and seasons, a lower output does not necessarily mean there is a fault.

However, if power generation is clearly decreasing, leaving it unaddressed may cause your revenue from selling electricity and the electricity bill savings from self-consumption to continue to decline. In particular, if the cause is panel soiling, shading, a power conditioner malfunction, or wiring problems, prompt inspection and corrective action are important.

First, we need to confirm whether the power output is actually abnormal. The power output from a solar power system is not the same every day. Even on sunny days, it can vary due to temperature, cloud movement, solar irradiance, wind, panel angle, and the installation environment. If today's output is only lower than yesterday's, it is often within the range of natural variation.

However, you should exercise caution if any of the following conditions persist.

• Even on sunny days, power generation is only about half of what it used to be.

• Power generation is significantly lower compared with the same season of the previous year.

• An error message is displayed on the monitor.

• The power conditioner has stopped

• Power generation drops dramatically only during specific time periods.

• The power output suddenly dropped after rain or a typhoon.

• The balance between electricity sold and electricity purchased suddenly changed.

When you feel that power generation is low, it’s important not to rely on impressions alone but to compare with past data. Check the generation monitor, HEMS, your utility’s online account page, and electricity sales (feed-in) statements, and look at changes on a monthly and yearly basis. In particular, checking the year-over-year comparison for the same month makes it easier to account for seasonal differences.

Main causes of low solar power generation

The causes of low solar power generation are not necessarily limited to a single factor. Some are natural, such as the weather, while others may be related to equipment malfunctions or insufficient maintenance. By correctly identifying the cause, you can more easily restore generation while avoiding unnecessary repair costs.

Temporary decline due to seasons and weather

Solar power generation increases as the amount of sunlight rises. Therefore, power output tends to be lower on rainy days, cloudy days, during the rainy season, in typhoon season, and in winter. In particular, in winter, because daylight hours are shorter and the sun’s altitude is lower, generation can be reduced compared with summer and spring.

Also, being midsummer doesn't necessarily mean that power generation will be at its maximum. Solar panels tend to lose generation efficiency when they get hot, so on days when the temperature is too high the amount of power generated may not increase much. Even with high solar irradiance, if the panel surface temperature rises too much it may not produce as much electricity as expected.

Dirt on solar panels

When dirt adheres to the surface of solar panels, sufficient light cannot reach them, causing a decrease in power generation. Causes of dirt include yellow sand, pollen, bird droppings, fallen leaves, sand and dust, exhaust gases, and salt from sea breezes.

General dirt is washed away to some extent by rain, but bird droppings, oil-containing grime, and dirt that has accumulated over a long period may not come off naturally. In particular, if a part of a panel becomes heavily soiled, it can affect not only that area but also the power generation efficiency of the entire connected circuit.

Shading by the Surrounding Environment

One often-overlooked cause of low solar power generation is "shading." When panels are shaded by neighboring houses, trees, utility poles, antennas, roof protrusions, or building extensions, power generation decreases.

Even if there were no problems at the time of installation, power generation can decrease after a few years if trees grow or buildings are erected on neighboring land. Also, because the sun’s elevation is lower in winter, shadows can extend into places that were not shaded in summer and affect power generation.

Power conditioner malfunction

The electricity generated by solar panels cannot be used directly in the home. A power conditioner converts direct current into alternating current, allowing it to be used in the home or sold to the grid.

Therefore, if the power conditioner has a fault, the power output may appear low even if the solar panels themselves are functioning normally. The power conditioner is an important component of a solar power generation system, and its lifespan is generally considered to be shorter than that of the panels. If around 10 years have passed since installation, consider the possibility of deterioration or failure.

Wiring and connection issues

Solar photovoltaic systems consist of panels, junction boxes, power conditioners, distribution boards, and metering equipment connected by wiring. Deterioration of wiring, poor connections, broken wires, loose terminals, or rainwater intrusion can reduce power output or cause the system to stop.

If the power output suddenly drops after a typhoon, heavy rain, snowfall, or an earthquake, there may be a problem with the wiring or connection points. Because there is a risk of electric shock or fire, avoid touching the wiring yourself and request an inspection from a qualified professional.

Decline in power generation efficiency due to aging

Solar panels are durable equipment that can be used for many years, but their power output gradually decreases over time. This is a natural aging-related degradation and cannot be completely avoided.

However, declines due to aging are usually gradual. If power output suddenly drops on a particular day, you need to suspect causes other than simple aging, such as panel damage, power conditioner failure, faulty wiring, or the effects of shading.

9 Ways to Deal with Low Solar Power Generation

From here, we will introduce nine measures to check when solar power generation is low. Because a drop in generation can involve multiple causes, go through them in order as far as you can.

1. Check the power generation monitor for error messages

The first thing to check is the displays on the power generation monitor and the power conditioner. If error codes, warning lights, or shutdown indicators are shown, they can provide clues to the cause of low power generation.

If an error is displayed, check the instruction manual for details. The displayed messages vary by manufacturer, but may include system abnormalities, voltage rises, power conditioner stoppage, communication errors, and stand‑alone operation mode.

What you should be careful about is that even if an error appears, do not immediately disassemble the unit or touch the wiring. Solar power systems handle high-voltage electricity, so it is dangerous to work on them without the necessary knowledge. First, record what is displayed and report it to the installer or the manufacturer's support.

When checking, noting the following information will make consultation go more smoothly.

• Error code

• Date and time the error occurred

• The period when power generation decreased

• Weather and power outage status

• Operating status of the power conditioner

• Power generation displayed on the monitor

Providing this information will make it easier for the service provider to infer the cause.

2. Compare with the power generation in the same month of the previous year

To determine whether power generation is low, it is effective to compare the data with the same month of the previous year. Because solar power generation varies greatly with the seasons, simply comparing January and July, or the rainy season and clear autumn weather, does not allow for an accurate assessment.

For example, even if this month's power generation is lower than last month's, it may be within a natural range due to weather or seasonal effects. However, if it is significantly lower compared to the same month in the previous year, there may be some problem with the equipment or the environment.

When comparing, it's recommended to look at a reasonably aggregated period—preferably not day-by-day but over a week, a month, three months, etc. Just because it was cloudy for one day or rained for several days doesn't necessarily mean it's abnormal. Check over a monthly period to see whether there is a clear decline.

Ways to check power generation data include a power generation monitor, HEMS, the utility company's feed-in statements for electricity sold, and the manufacturer's cloud service. If no records have been kept, noting the monthly generation going forward will make it easier to detect abnormalities.

3. Check the panel surface for dirt

When power output is low, also check the solar panels for dirt. You don't need to get up close to the panels on the roof, but from the ground you can check whether bird droppings, fallen leaves, mud, yellow sand, pollen, and similar debris are noticeable.

If the soiling is minor, it can sometimes be washed away by rain. However, dirt that tends to adhere, such as bird droppings, or leaves that have accumulated for a long time can affect power generation. In particular, even if only some panels are dirty, the overall power generation efficiency may decrease depending on the connection method.

However, avoid climbing onto the roof to clean them yourself. The risk of falling is high, and you may damage the panels or harm the waterproofing. Also, methods such as pouring large amounts of tap water, scrubbing with a stiff brush, or using a pressure washer at close range can cause damage to the panels and mounting racks.

If you're concerned about dirt, consult a professional company that handles solar panel cleaning. Although there is a cleaning fee, it is safer and better for protecting your equipment than attempting to do it yourself.

4. Check for shadows at different times of day

Shading is a very important factor causing low solar power generation. Because the sun’s position changes in the morning, at noon, and in the evening, if generation drops significantly during only a certain time of day, shading may be responsible.

When inspecting, observe the area around the panels at several times during the day. In particular, check whether any of the following are casting shadows.

• Neighboring houses and nearby buildings

• Trees and hedges

• Utility poles and power lines

• television antenna

• Roof level differences and chimneys

• Balconies and handrails

• Extensions and carports

Even if there are no problems at the time of installation, trees may grow or new buildings may be constructed nearby after a few years, increasing shading. It is also important to note that shadows tend to be longer in winter because the sun’s angle is lower.

If trees are the cause, pruning may improve the situation. If antennas or rooftop equipment are the cause, consult a specialist to see whether they can be relocated. If the cause is something difficult to resolve on your own, such as shading from buildings, you need to understand the impact of reduced power generation and then review your operational methods.

5. Check the operating status of the power conditioner

The power conditioner is often described as the heart of a solar power generation system. When power generation is low, check whether the power conditioner is operating normally.

Points to check include the operation indicator light, stop indicator light, error displays, abnormal noises, unusual odors, overheating, and fan operation. If you hear sounds that are different from normal, smell something like burning, experience frequent shutdowns, or repeated restarts, there may be a malfunction or deterioration.

Also, the installation location of the power conditioner is important. When installed outdoors, it can be affected by direct sunlight, rain and wind, humidity, dust, and insect intrusion. Even when installed indoors, locations with poor ventilation or those that tend to become hot can put stress on the equipment.

When a power conditioner nears the end of its lifespan, its conversion efficiency may decline and it may become more prone to shutdowns. If about ten years have passed since installation and power generation is low, it may be time to consider an inspection or replacement.

6. Verify that voltage-rise suppression is not occurring

When it's sunny but power output doesn't increase, voltage rise suppression may be involved. Voltage rise suppression is a function in which the power conditioner reduces its output when the grid-side voltage becomes high.

In residential areas with many solar power installations, on sunny days a large number of households may simultaneously sell power back to the grid, which can cause the voltage to rise. As a result, power conditioners may reduce their output for safety, making the generation and sold electricity appear lower.

Whether voltage rise suppression is occurring can sometimes be confirmed from the monitor display or the power conditioner's history. If suppression is occurring frequently, consult the installer or the power company. Depending on the situation, checking the settings or an investigation on the grid side may be necessary.

However, work involving voltage requires specialized knowledge. Please refrain from changing settings or touching wiring yourself. Incorrect handling can lead to equipment failure or safety hazards.

7. Check the condition of breakers and junction boxes

If your power output suddenly drops, or it appears not to be generating, check the breakers and junction boxes. If the breaker for the solar power system has tripped, the electricity generated may not flow into your home or to the grid for selling.

If there is a breaker dedicated to the solar power generation system in the distribution board, check whether it is turned off. However, repeatedly resetting a breaker without knowing why it tripped is dangerous. Because the breaker may have tripped due to a ground fault or equipment malfunction, if it trips repeatedly consult a qualified professional immediately.

With junction boxes, you can also check the exterior for damage, scorch marks, unusual odors, or signs of rainwater intrusion. However, opening the junction box and touching the interior is dangerous. If you notice any abnormalities from the outside, limit yourself to taking photos and reporting them to a professional.

If power generation is reduced after a typhoon or heavy rain, after lightning strikes, or after power is restored following an outage, breakers or protective devices may have tripped. Prioritize safety checks and avoid performing any unsafe operations.

8. Request an inspection from the installer or manufacturer

There are limits to what you can check yourself. If low power generation persists or an error message appears, request an inspection from the installer or the manufacturer.

In an inspection by a professional contractor, they will check the appearance of the panels, the mounting racks, wiring, junction boxes, power conditioners, the insulation condition, and power generation data. By using specialized equipment, faults that are not visible to the naked eye can also be detected.

When requesting an inspection, it will go more smoothly if you prepare the following information in advance.

• Installation period

• Manufacturer name and model number

• Periods when power generation decreased

• Error codes and display information

• Historical power generation data

• Presence or absence of typhoons, heavy rain, lightning strikes, construction work, etc.

• Warranty certificates and contracts

If the item is still within the warranty period, repair costs may be reduced. Check which warranty applies—manufacturer warranty, installation warranty, or natural disaster coverage. Because inspection fees may apply, it's wise to confirm the charges and scope of service before making a request.

9. Review Power Generation Simulations and Actual Performance

If you feel the power generation is low, it may be that the output you were expecting simply does not match the actual installation conditions. Solar power generation simulations are calculated based on solar irradiance, panel capacity, roof orientation, tilt, the presence or absence of shading, regional conditions, and other factors.

However, actual power output varies depending on the weather, the surrounding environment, and the condition of the equipment. If there is a difference between the output you were told before installation and the actual results, reconfirm the simulation conditions. In particular, if the impact of shading was not fully reflected or if the surrounding environment changed after installation, the output may be lower than expected.

When reviewing, it is recommended to evaluate based on annual power generation. Monthly fluctuations are large, so judging based on only a short period can easily be misleading. If generation is significantly below expectations over the course of a year, check for equipment malfunctions or design problems.

Also, it's important to be cautious about judging solely by revenue from selling electricity. If household self-consumption increases, the amount of electricity sold will fall, but that may lead to lower electricity bills. Separating and checking power generation, electricity sold, electricity purchased, and self-consumption makes it easier to understand the actual effect.

Precautions: What Not to Do When Power Generation Is Low

You may feel anxious if your solar power output is low, but taking dangerous actions on your own can lead to accidents or equipment failures. When you want to restore power generation, it is especially important to check things using the correct procedures.

Do not climb onto the roof to inspect it yourself.

Solar panels are often installed on roofs, and climbing onto the roof yourself for inspection or cleaning is extremely dangerous. Roofs are sloped, footing can be slippery, and even a momentary lapse in caution can lead to a fall.

The risk is particularly high after rain, during times when morning dew remains, on windy days, and during high temperatures in summer. Also, walking on roofing materials or panels can damage the roof or crack the panels.

Even if the cause of low power generation appears to be dirty or damaged panels, leave work on the roof to qualified professionals. Considering safety equipment, work experience, and whether insurance covers it, the risks of doing it yourself are too great.

Do not attempt to repair panels or wiring yourself.

Solar power systems continue to generate electricity during the daytime. Even if you think you have turned the switch off, electricity may still be present on the panel side. Therefore, it is dangerous to touch wiring, junction boxes, or the inside of the power conditioner based on your own judgment.

There is a risk of electric shock, short circuit, fire, and equipment malfunction, and it may also void the warranty. If you notice symptoms such as burn marks, unusual odors, strange noises, smoke, or the circuit breaker tripping repeatedly, stop using the product immediately and consult a qualified technician.

Do not clean with a pressure washer or a stiff brush.

When you're concerned about dirt on the panels, you might be tempted to clean them with a high-pressure washer or a stiff brush. However, strong water pressure and friction can damage the coating on the panel surface.

When small scratches form, dirt adheres more easily, which can actually reduce power generation efficiency. Also, if water gets into the gaps or connection points of the panels, it can sometimes cause a malfunction.

Solar panels are precision equipment. Even if they appear robust, cleaning them in a DIY manner can reduce their performance. If cleaning is necessary, hire a professional who knows the methods suitable for solar panels.

Don't Assume It's a Malfunction Based Solely on Power Output

When power generation is low, it's easy to immediately suspect a fault. However, causes of reduced power generation include various factors such as weather, season, temperature, shading, voltage rise suppression, and increased self-consumption.

Especially in months with a lot of cloud cover or rain, power generation can drop significantly. If you judge a fault based only on short-term generation, it can lead to unnecessary inspection costs and anxiety.

First, compare with the same month of the previous year and with the annual results, and check for any error messages or equipment abnormalities. If you find any clear anomalies, it is most efficient to consult a specialized contractor.

Daily Checks to Prevent Power Output Decline

Solar power systems are not equipment you can completely ignore once installed. Although you don't need to perform large-scale maintenance frequently, checking the system's power output on a daily basis allows you to notice abnormalities early.

Check power generation once a month

To detect a decline in power generation early, it is recommended to check the generation roughly once a month. You don't need to check it in detail every day, but keeping monthly records of generation makes it easier to compare with the same month in the previous year.

Items to check include generated power, electricity sold, electricity purchased, and self-consumption. In households that have storage batteries or electric vehicles, it is particularly difficult to judge generation status based on electricity sold alone. Also check how much of the generated electricity is being used within the household.

Recording power generation is fine with a dedicated app, spreadsheet software, or handwritten notes. The important thing is to create a state in which you can notice abnormalities.

Inspect the exterior after typhoons or heavy rain.

After typhoons, heavy rain, strong winds, snowfall, or lightning strikes, solar power generation equipment may be affected. You don't need to climb onto the roof, but check from the ground within the visible range for any shifted panels, abnormalities in the mounting structure, flying debris, or damage.

Also, if power generation suddenly decreases after a disaster, there may be a fault in the wiring or equipment. Check for error messages and the condition of the breakers, and if you find any abnormalities, consult a professional.

Damage caused by natural disasters may be covered by fire insurance or natural disaster compensation. If damage is suspected, keeping photos and power generation data can be helpful when filing insurance claims or consulting about repairs.

Observe changes in surrounding trees and buildings

To stabilize solar power generation, managing shade is also important. As garden trees and neighboring trees grow, shadows can appear in places that were not a problem a few years ago.

Trees located on the south or west side in particular are likely to affect power generation. Regularly check how the branches are growing and consider pruning if necessary. Trees within your own property are easier to deal with, but if trees or buildings on neighboring land are the cause, you cannot take action without permission. To avoid disputes, it is important to consult carefully when necessary.

Also, home renovations, carport installation, or antenna installation can also cause shading. When adding new equipment around solar panels, be sure to check in advance how it will affect power generation.

Understand the warranty coverage and inspection schedule

Solar power generation systems may come with multiple warranties, such as manufacturer warranties, installation warranties, output warranties, and equipment warranties. However, the coverage and duration of these warranties vary depending on the manufacturer and the terms of the contract.

To avoid panicking when power generation is low, keep your warranty certificates and contracts and make sure to check what is covered by the warranty. Coverage varies by warranty and may include reduced panel output, power conditioner failures, installation defects, natural disasters, and so on.

Also, not having undergone periodic inspections may affect warranty support. If you have received an inspection notice from the installer, do not ignore it—check the details.

Symptoms That Warrant Consulting a Professional

When power generation is low, many people may be unsure when they should consult a service provider. If it's just minor bad weather, it's fine to wait and see, but if you experience any of the following symptoms, it's recommended to consult as soon as possible.

Significantly lower power output even on sunny days

If power generation is clearly low despite a stretch of sunny days, there may be an equipment problem. In particular, if output has fallen significantly compared with the same month last year, or is unnaturally low compared with typical generation trends in the same region, consider arranging an inspection.

If it's due to temporary clouds or temperature effects, the changes will be limited to day-to-day fluctuations; however, if low levels persist for consecutive days, there may be a problem with the panels, power conditioners, wiring, junction boxes, or similar.

Error messages or warning lights are displayed

If an error is displayed on the power generation monitor or power conditioner, do not ignore it. Depending on the content of the error, power generation may have stopped or safety devices may have been activated.

Make a note of the error code, check the user manual, and consult the installer or the manufacturer. Even if the error temporarily disappears, an inspection is necessary if it occurs repeatedly.

Unusual noises, strange odors, or scorch marks

If you notice abnormal noises, unusual odors, scorch marks, or signs of smoke coming from the power conditioner or junction box, consult a qualified professional immediately. Abnormalities in electrical equipment can lead to fires or serious malfunctions if left unaddressed.

When you experience these kinds of symptoms, it is important not to disassemble the device yourself or to repeatedly restart it based on your own judgment. Prioritize safety, and if necessary, seek instructions from a professional or the manufacturer regarding breaker operation.

Power generation dropped after typhoons, lightning strikes, and earthquakes

If power output is reduced after a natural disaster, there may be physical damage to the equipment. Cracked panels, loosened mounts, damaged wiring, water ingress into junction boxes, and failure of the power conditioner are possible.

After a disaster, even if there are no visible signs of damage, internal faults may have occurred. If reduced power generation continues, request an inspection promptly. Because there may be time limits for insurance or warranty claims, it is also important to save photos of the damage and the power generation data.

Tips for dealing with low power generation while keeping costs down

When solar power output is low, inspection and repair costs are a concern. While some causes do require spending, by carefully choosing the order in which you check things you may be able to reduce unnecessary expenses.

First, check—within the range you can safely inspect yourself—things like the power generation monitor, a comparison with the same month last year, the effects of the weather, and whether any error messages are displayed. If an abnormality appears likely, consult a service provider; this will make it easier to explain the situation.

Next, check the warranty periods. Coverage varies depending on the type of warranty, such as panels, power conditioners, installation, and natural disaster coverage. If a warranty is still in effect, you may be able to reduce repair or replacement costs.

Also, when requesting an inspection, check the fee structure in advance. Confirm whether there are charges for travel, inspection, repairs, parts, and estimates so you won’t be surprised by unexpected costs later.

Consulting multiple service providers can also be effective. However, rather than choosing based only on price, check their track record in inspecting solar power systems, the manufacturers they support, warranty support, and the clarity of their explanations. If you prioritize low cost alone, the cause may not be correctly identified, and you may end up needing re-inspection or additional repairs.

Risks of Leaving Low Power Output Unaddressed

If low power output is left unaddressed, it can lead not only to financial losses but also to the worsening of equipment problems. Minor faults may be resolved with early intervention, but if left unattended for a long time, repair costs can become significant.

Decreased income from electricity sales and reduced electricity bill savings

When solar power generation is low, the amount of electricity that can be sold decreases. Also, because the electricity available for self-consumption is reduced, purchases from the power company increase, and the effect of reducing electricity bills is diminished.

Especially during periods when electricity costs are soaring, the savings from self-consumption are important. If a decline in power generation is left unaddressed, losses will accumulate gradually each month. Even a small decrease can make a big difference when viewed over the course of a year.

The malfunction may worsen

If power generation is declining due to abnormalities in the power conditioner, faulty wiring, or deterioration of connection points, leaving it untreated can allow the fault to worsen. Even if the initial drop in power output is only slight, it can ultimately lead to a system shutdown.

Abnormalities in electrical equipment also have safety implications. If there are scorch marks, unusual odors, or abnormal noises, you need to consider not only problems with power generation but also the risk of fire.

There is a possibility that it will exceed the warranty period.

If you notice low power generation but leave it unaddressed, the warranty period may expire. Even faults that could have been handled free of charge or at low cost within the warranty period may become your responsibility once the period has passed.

If you notice anything unusual, check the warranty certificate and contract, and seek advice promptly. In particular, if several years have passed since installation, pay attention to the power conditioner's warranty period.

Operational Points for Stabilizing Solar Power Generation

To stabilize solar power generation, not only inspections of the equipment itself but also daily usage and management are important. Rather than increasing generation, the key is to quickly identify factors causing declines and to use electricity efficiently without waste.

Use electricity during the hours when power is being generated.

Solar power generation produces most of its electricity during the daytime. If you can consume the electricity you generate yourself, you can reduce the amount you need to buy from the power company. For households where the feed-in tariff has fallen, using the electricity rather than selling it can be more advantageous.

If you have appliances that can be operated during the daytime—such as a washing machine, dishwasher, EcoCute, a storage battery, or charging for an electric vehicle—using them during solar generation hours can enhance the effectiveness of your solar power generation.

However, if you use too much electricity when generation is low, the amount of electricity you need to buy may increase. While watching the generation monitor, it is important to use electricity in line with the amount being generated.

If you have a storage battery, check the settings

In households that have battery storage installed, the battery’s charge and discharge settings affect the amounts of electricity sold and purchased. Even if you feel that the amount of power generation is low, the electricity that was generated may actually be being stored in the battery, making the amount sold only appear small.

Battery operation modes include economic-priority, disaster-prevention-priority, environment-priority, and peak-cut, among others. Because the flow of electricity changes depending on the settings, check generated electricity, the amount sold to the grid, and the amount stored separately.

Also, under settings that prioritize protection against power outages, a certain amount of electricity is always kept in storage, so patterns of self-consumption and electricity sales may differ from usual. Before concluding that power generation is low, please also review the settings on the storage battery.

Plan to receive periodic inspections

Because solar power generation systems are equipment used over long periods, regular inspections are especially important. Even if there are no visible abnormalities, wiring deterioration, loose terminals, and power conditioner malfunctions can gradually progress.

Undergoing inspections not only enables early detection of the causes of reduced power generation, but also helps prevent equipment failures. Check the inspection schedule recommended by your installer or manufacturer, and arrange inspections on a planned basis as needed.

Especially if about ten years have passed since installation, it is important to check the condition of the power conditioner. If the time for replacement is approaching, it is reassuring to consider the costs and model options in advance to prepare for sudden failures.

Frequently Asked Questions

Is a day with low solar power generation a malfunction?

It does not necessarily indicate a malfunction. Power generation can fluctuate due to clouds, rain, snowfall, yellow sand, pollen, rising temperatures, seasonal differences in hours of sunlight, and other factors. If power generation is low for just one day, it is often caused by the weather or reduced solar irradiance.

However, if power output remains low even on sunny days, or has fallen sharply compared with the same month of the previous year, there may be an equipment problem. If you see error messages or notice unusual noises or odors, contact your service provider promptly.

Is it normal for power generation to be low on rainy days?

It's natural for power generation to be lower on rainy days because there is less solar radiation. Solar panels still generate electricity on cloudy days, but output drops considerably compared with sunny conditions. During the rainy season and the typhoon season, monthly power generation also tends to be lower.

However, if power generation does not recover even after it clears up following rain, make sure to check for dirty panels, wiring faults, abnormalities in the power conditioner, and so on.

Will cleaning the panels restore power generation?

If power generation is low due to dirt, cleaning may improve it. In particular, if bird droppings, fallen leaves, yellow sand, pollen, or sand and dust are noticeable, they may be blocking the light.

However, not all decreases in power generation are solved by cleaning. If shading, a malfunctioning power conditioner, wiring trouble, or voltage rise suppression is the cause, cleaning may not lead to any improvement. It is important to identify the cause.

When should a power conditioner be replaced?

Power conditioners often have a shorter lifespan than solar panels, and inspections or replacements are sometimes considered around 10 years after installation. Of course, because lifespan varies with the operating environment and the model, they do not necessarily fail at 10 years.

If you experience symptoms such as low power output, frequent errors, unusual noises, or repeated shutdowns, the unit may be due for replacement. Check the warranty period and have a qualified professional perform an inspection.

Who should I contact if power generation is low?

First, consult the retailer or installer who performed the installation. They have the installation details and warranty information, so handling will be smoother. If you don't know who the installer is or cannot contact them, consult the manufacturer's support or a solar power inspection contractor.

When seeking consultation, having the power generation data, error messages, years since installation, manufacturer name, model number, and warranty certificate ready will make it easier to identify the cause.

Summary

If you feel that your solar power generation is low, it is important to first confirm whether it is actually abnormal. Since generation varies with weather, season, temperature, and solar irradiance, a drop of only one day does not necessarily indicate a fault.

On the other hand, if power generation remains low even on sunny days, is substantially lower than in the same month of the previous year, displays error messages, produces unusual noises or odors, or if generation suddenly drops after a typhoon or lightning strike, there may be an equipment malfunction.

When power generation is low, check the following 9 items in order.

• Check the power generation monitor for error messages

• Compare power generation with that of the same month in the previous year

• Check the panel surface for dirt

• Check for shadows at each time of day

• Check the operating status of the power conditioner

• Verify that voltage rise suppression is not occurring

• Check the condition of circuit breakers and junction boxes

• Request an inspection from the installer or manufacturer

• Review power generation simulations and actual results

In particular, avoid climbing onto the roof to inspect the system yourself or attempting to repair wiring or equipment on your own. Solar power generation systems handle high voltages, so incorrect actions can lead to electric shock, fire, or equipment failure.

To prevent a decline in power generation, monthly generation checks, visual inspections after typhoons or heavy rain, shadow management, understanding warranty coverage, and regular inspections are effective. If low power generation is left unaddressed, not only will revenue from electricity sales and savings on electricity bills decrease, but there is also a risk that faults will worsen.

If you feel that your power generation may be low, first check the data and, within what you can do safely, narrow down the cause. If you suspect any abnormality, consult a professional as soon as possible — that is the quickest way to keep using your solar power system safely and with confidence for a long time.