Check Your PV System in Autumn: What to Inspect Before Storms, Frost, and Winter

Autumn is a good time to take a closer look at your photovoltaic system. Not because every PV system needs special "winter maintenance" before winter, but because it's an opportunity to identify damage and weak points before storms, persistent moisture, frost, or snow put additional strain on the system.

A sensible autumn check doesn't start on the roof, but with the operational data. This is followed by modules, the mounting system, cables, and inverters.

Many things can be checked by system owners themselves – provided the relevant areas are safely accessible. As soon as electrical measurements, work on connectors, or interventions in the system are required, a specialist should take over.

Why should a PV system be checked in autumn?

PV systems are designed for long-term outdoor operation and are generally low-maintenance. However, they are not maintenance-free.

Regular checks help to detect changes early. Autumn is particularly suitable for this: damage or abnormalities from the current operating year can be discovered before a period with more precipitation, storms, frost, and potential snow loads begins.

Additionally, a check is recommended after unusual events – for example, after a severe storm, hail, work on the roof, or recurring error messages.

The goal is not to preemptively dismantle the entire system. The first step is rather to ask:

Has anything changed since the last check that should be examined more closely?

1. Check monitoring: Look for abnormalities in operational data first

The easiest way to start the autumn check is where the system is already monitored: in the inverter portal, the monitoring app, or the system monitoring.

Pay particular attention to the following points:

• Are there new or recurring error messages?
• Have inverters or individual strings temporarily failed?
• Are there unusual interruptions in system operation?
• Do comparable strings show noticeable deviations from each other?
• Is the yield lower than would be expected under comparable conditions?

A lower daily yield in autumn is not in itself an indication of a defect. Days get shorter, the sun's position changes, and irradiation fluctuates more.

Therefore, comparisons with similar periods, neighboring strings, or existing reference values are more meaningful.

It's also important: monitoring detects abnormalities but doesn't automatically provide the cause. Unusual performance can be caused by shading, soiling, a module defect, an electrical fault, or other factors, for example.

Monitoring primarily shows where a closer look is needed.

2. Check solar modules for visible damage

The next step is a visual inspection of the modules – but only from a safe location. No one should climb onto a roof unsecured for an autumn check.

Look for:

• broken or cracked module glass
• unusual discolorations
• delaminations or blistering
• damaged or deformed frames
• visibly shifted modules
• damage from branches, hail, or other objects
• abnormalities on module backsides, as far as they are safely visible

Module edges and areas around the clamps deserve special attention. Glass breakage on solar modules can be more easily overlooked there.

Not all module damage is visible

An inconspicuous module surface does not automatically mean that the module is technically flawless.

Microcracks and cell fractures, for example, can remain invisible to the naked eye. If there is a concrete suspicion due to a storm, conspicuous performance data, or another event, further testing procedures may be useful.

Depending on the type of defect, these include, for example:

• Thermography
• I-V curve measurement
• Electroluminescence (EL) testing
• electrical measurements

Which method is useful depends on the specific suspicion. For example, the professional testing of PV modules at the SecondSol PV Test Center can be used to examine performance, microcracks, cell fractures, and certain other module defects in more detail.

3. Check for leaves, soiling, and new shading

In autumn, not only the weather changes, but often also the immediate surroundings of the PV system.

Leaves can accumulate on modules or parts of the substructure. Trees and shrubs may have grown since the last check. In addition, there may be bird droppings, dust, mosses, lichens, or other deposits.

Therefore, check:

• Are leaves permanently lying on individual modules?
• Have stubborn dirt accumulations formed?
• Are there heavy deposits in the edge areas?
• Has a grown tree or shrub now shaded parts of the system?
• Has the vegetation significantly changed in ground-mounted systems?

Not every dirty system needs to be cleaned immediately. Rain can often remove loose deposits itself. More problematic are stubborn or localized dirt, if individual module areas are shaded for a longer period as a result.

Therefore, PV cleaning should be done according to the actual condition of the system and not solely according to the calendar.

When cleaning is useful and what to look out for is explained in more detail in our guide "Cleaning PV Systems: When, How Often, and Why Solar Cleaning Really Pays Off".

4. Inspect frames, module clamps, and mounting system

Before the stormy season, the mechanical fastening deserves special attention.

From a safe location, for example, the following abnormalities may be visible:

• visibly shifted modules
• missing or unusually seated module clamps
• bent components
• significant corrosion
• loose covers or wind deflectors
• changes to elevated structures
• noticeable shifts in flat roof or ground-mounted systems

Wind stresses a PV system through both pressure and suction. Whether the mounting system can withstand these loads depends, among other things, on the planning, the location, the components used, and the fastening or ballasting.

Do not simply retighten module clamps yourself

A noticeable clamp should not be preemptively "tightened by feel."

Manufacturers may provide precise specifications for clamping areas, fastening, and tightening torques. Incorrectly installed or overtightened clamps can, in turn, cause problems.

If there is a suspicion that parts of the mounting system have loosened or shifted, the fastening should be professionally checked.

5. Check cables and connectors: look, yes; open, no

DC cables and connectors are among the particularly important inspection points. At the same time, a clear distinction must be made here between a visual inspection and work on the electrical system.

As far as the cable routes are safely visible, operators can, for example, pay attention to the following abnormalities:

• hanging or loose cables
• cables rubbing over roof surfaces or sharp edges
• pinched cables
• visible damage
• animal bites
• damaged cable fastenings
• externally noticeable connectors

Particular attention should be paid to error messages that occur mainly after rain, in high humidity, or on a damp morning. This could indicate an insulation fault in the PV system. However, the exact cause must be professionally determined.

Operators should not disconnect, open, or reconnect connectors themselves.

Insulation measurements and work on DC or AC wiring also belong in expert hands.

6. Moisture and water: Take abnormalities seriously

Autumn often means more rain, dew, and longer periods of moisture. This can reveal weak points that did not appear during dry summer weeks.

For example, pay attention to:

• Insulation fault messages after rain
• Moisture in unintended places
• Visible damage to housings or cable glands
• Water accumulation near electrical components
• Noticeable areas on connection or distribution boxes

For flat roofs, it should also be ensured that leaves and other deposits do not impair roof drainage. Noticeable water accumulations should be clarified early.

Important: An error message is not automatically resolved just because it disappears after drying.

Recurring moisture-dependent insulation faults should be professionally investigated. Our technical article on insulation faults in PV systems explains which components may be involved and how such faults can be narrowed down.

7. Check inverter and ventilation

The inverter is particularly easily accessible in many systems and should therefore be part of the autumn check.

Check:

• Does the device display warnings or errors?
• Are ventilation openings visibly dirty or blocked?
• Have dust, leaves, or foreign objects accumulated?
• Is the area around the device, as specified by the manufacturer, clear?
• Are unusual noises occurring?
• Are there repeated shutdowns?

For inverters with fans or other active cooling systems, dirty ventilation areas can impair heat dissipation.

Which cleaning and maintenance work is permissible depends on the specific device. Therefore, manufacturer specifications are decisive.

Opening the inverter or working on its electrical connections is not part of the operator's autumn check.

If a professional diagnosis reveals that the inverter is indeed defective, SecondSol offers support for the repair and replacement of inverters

8. Check PV system for storms

An autumn check cannot prevent exceptionally strong storms from causing damage. However, it can help to identify existing weak points beforehand.

Before the storm season, therefore, check:

• Are the modules visibly in their intended position?
• Are clamps or parts of the mounting system noticeable?
• Are cables hanging freely and could they rub in the wind?
• Are there loose objects or problematic branches in the immediate vicinity?
• Are changes to elevated structures or wind deflectors visible in flat roof systems?

After a severe storm, another visual inspection is recommended.

Particular attention should be paid to shifted modules, glass breakage, altered fastenings, and damage from flying objects.

What exactly needs to be done after a storm, what typical damages are, and how they can be classified, we discuss in more detail in the article "Storm Damage to Photovoltaic Systems – Causes, Solutions, and Tips for Operators".

9. Prepare PV system for frost and snow

A technically intact PV system, correctly designed for its location, does not automatically require special measures as soon as temperatures drop.

More important is to identify existing weak points before winter.

Mechanical damage to modules or the mounting system should ideally not become apparent only under additional snow load. Moisture and temperature changes can also make existing problems more pronounced.

The permissible mechanical load of a specific module and mounting system cannot be answered with a universally valid value. Key factors include:

• Manufacturer specifications
• Mounting system used
• Installation situation
• Roof and module inclination
• Location
• Static design of the system

Does snow need to be preemptively removed from solar modules?

No, not as a general rule.

Whether snow removal is even sensible or necessary depends on the specific system, the amount of snow, the construction, and local conditions.

How snow affects PV yield and when removal is an option is explained in detail in the article "Snow on the PV System? How to Clear Your Photovoltaics of Snow".

However, in case of unusually heavy snow loads, visible deformations, or other abnormalities, improvisation should be avoided. We cover damage due to heavy snow loads separately in the article "What to Do in Case of Snow Pressure Damage to Your Photovoltaic System".

10. What can operators check themselves?

A simple rule of thumb helps with the distinction:

Observe and inspect: often yes. Open, disconnect, measure, or repair: specialist.

Operators can usually check themselves:

• Monitoring and error messages
• Noticeable yield deviations
• Visible glass breakage
• Leaves and dirt
• New shading
• Visibly shifted modules
• Externally noticeable module clamps
• Loose or hanging cables
• External abnormalities on the inverter
• Clear ventilation areas
• Recognizable water accumulations
• The visible condition after a storm or hail

The prerequisite is always that the check can be carried out from a safe location.

When should a specialist check the PV system?

A more extensive check is particularly useful if:

• Error messages occur repeatedly
• Insulation faults are reported
• The yield deviates significantly without an identifiable cause
• Glass breakage or other module damage is present
• Modules or parts of the mounting system appear shifted
• Cables or connectors appear damaged
• There is a concrete suspicion of damage after a storm, hail, or heavy snow load
• Electrical measurements are required
• Connectors need to be disconnected or components removed
• The condition cannot be reliably assessed by a purely visual inspection

Depending on the findings, electrical measurements, thermography, I-V curve measurements, or an electroluminescence test may then be useful.

Not every system automatically requires all testing procedures. The diagnosis should be based on the specific fault pattern.

Anyone who wants to have module damage investigated more closely can find information on the professional testing of photovoltaic modules at SecondSol.

PV Autumn Check: The Compact Checklist

Conclusion: Check in autumn instead of generally "winterizing"

A PV system does not need to be preemptively dismantled, completely cleaned, or subjected to general winter maintenance in autumn.

A systematic check is more sensible:

Check monitoring, inspect the system, identify changes, and have noticeable findings professionally investigated.

Particular attention should be paid to visible damage to modules and the mounting system, damaged cables, recurring error messages in damp conditions, new shading, and abnormalities on the inverter.

This makes the autumn check a practical part of preventive maintenance: problems are identified as early as possible, before storms, frost, and snow bring additional stresses.

Discovered damage during the autumn check?

Not every abnormality means that an entire system or a whole string needs to be replaced. Defective components can be checked, repaired, or specifically replaced depending on the type of damage.

At the SecondSol PV Test Center, solar modules can be examined using performance measurement and electroluminescence, among other methods. Operators and specialist companies can also find suitable modules, inverters, and other PV components via the SecondSol marketplace.

Frequently Asked Questions about the PV Autumn Check

Does a PV system need to be maintained before winter?

Not every PV system automatically requires special annual winter maintenance. However, regular, condition-based checks are useful. In autumn, monitoring, modules, mounting system, visible cable routes, and inverters can be checked. Manufacturer specifications and the maintenance concept of the respective system are also decisive.

Can I check my PV system myself?

Yes, many points can be checked yourself, as long as no dangerous access or intervention in the electrical system is required. This includes, for example, monitoring, error messages, visible glass breakage, soiling, shading, and externally recognizable changes.

Electrical measurements, opening devices, and working on connectors should be left to specialists.

Should leaves be removed from solar modules?

Leaves permanently lying on the modules should not be ignored. Whether active cleaning is necessary depends on the quantity, position, module tilt, and natural cleaning by rain and wind. The actual condition of the system is decisive – not just the season.

Further information can be found in our guide to cleaning PV systems.

Does snow need to be removed from solar modules?

No, not as a general rule. Whether snow removal is necessary or useful depends on the amount of snow, construction, module and roof pitch, and the mechanical design of the system. We cover this topic in detail in the guide "Snow on the PV System?".

How do you recognize storm damage to a PV system?

Visible signs can include broken module glass, shifted modules, noticeable clamps, damaged cables, or deformed parts of the mounting system. However, not all damage is externally recognizable.

If there are performance deviations or a concrete suspicion of damage after a severe storm, a more extensive check may be useful. More information can be found in our detailed guide to storm damage to photovoltaic systems.

How often should a PV system be checked?

A general interval does not suit every system. The scope and frequency depend on factors such as system type, location, manufacturer specifications, operating conditions, and maintenance concept.

In addition to planned checks, an unscheduled inspection after unusual events such as storms or hail may be useful.