Solar maintenance intervals

How to set risk-based owner checks, professional inspection and electrical testing intervals for a domestic PV system.

A domestic PV system needs monitoring, visual checks and periodic competent inspection. It does not have one universal annual service interval. The schedule should reflect the equipment instructions, electrical-installation inspection regime, environment, roof access, system age, condition and any insurer or warranty requirements.

The aim is to find deterioration before it becomes unsafe or causes a long generation loss, without selling unnecessary roof visits.

Build the schedule from evidence

The handover pack should identify the maintenance requirements for modules, inverter, mounting system, isolators, surge protection, monitoring and any battery. Combine those with the property’s electrical inspection schedule and site risks.

The BS EN IEC 62446 series covers PV documentation, testing and maintenance. IET guidance notes that its recommended PV inspection and testing intervals should be no greater than those for the AC installation to which the PV is connected.

That is a ceiling, not a promise that every domestic array can wait until the next general inspection. Harsh exposure, a known connector issue, repeated faults or roof work can justify earlier attention.

Owner monitoring

Monitoring is the most frequent check because it does not require roof access. Review generation often enough to notice a persistent outage or step change rather than discovering it on an annual bill.

Useful checks include:

inverter normal-operation and fault indication
daily or interval generation compared with weather and season
unexpected zero output during daylight
changes between comparable strings or module channels
monitoring communications and correct date and time
unexplained import or export after system changes

One cloudy day is not a fault. A sustained deviation after accounting for weather, shade and curtailment deserves investigation.

Ground-level visual checks

Without climbing, look for:

obviously displaced or cracked modules
loose hanging cable or debris
failed bird mesh
vegetation or new permanent shade
roof damage, water entry or blocked gutters near the array
inverter warning lights, unusual noise or visible damage
discolouration or heat damage at accessible isolators

Binoculars or safe photography can help, but they do not prove the condition of hidden connectors or roof fixings.

Triggered inspection

Arrange a competent inspection after events that can change the installation, including:

roof repair, scaffolding impact or building work near cables
severe wind, flood, lightning or fire exposure
animal or bird damage
repeated inverter, insulation or arc-fault alarms
visible movement, scorching, cracking or water entry
replacement of the inverter or modules
unexplained sustained underperformance

Do not wait for a routine date where there is a present safety sign.

What a professional inspection covers

The scope should be agreed rather than described vaguely as a service. Depending on the system and risk, it can include:

documentation, labelling and circuit identification
module, frame, rail and roof-interface condition
cable support, UV exposure, routing and mechanical damage
connector compatibility, security and signs of heating
DC and AC isolators and protective devices
earthing and bonding arrangements where applicable
inverter ventilation, logs, settings and firmware status
electrical tests appropriate to the installation and fault history
comparison with commissioning baseline values
thermal imaging under suitable operating conditions where justified

Testing and isolation should follow the PV-specific safe system of work. Array DC voltage can remain present in daylight.

DC switch-disconnectors deserve attention

The IET identifies maintenance of PV DC switch-disconnectors as important because selection, configuration, terminals and environmental exposure can contribute to failure.

Inspection considers whether the device suits the maximum DC voltage and current, is correctly configured, remains suitable for its environment and has sound conductors and terminals. Operating or opening it is a competent-person task performed under the correct off-load procedure.

Thermal imaging can identify abnormal heating, but it needs sufficient and stable operating load and a trained interpretation. A normal image in weak sunlight is not strong evidence.

Cleaning is condition-based

Rain often removes loose dirt, while bird fouling, lichen or sheltered edge deposits can persist. Cleaning belongs in the schedule when inspection or performance evidence indicates it, or when the manufacturer requires it.

It is not automatically needed every year. Roof access and module damage risk may outweigh a small unproven energy gain. Use the module maker’s approved method and a proper work-at-height plan.

Inverter and monitoring maintenance

Keep vents and manufacturer-required clearances unobstructed. Filters or fans, where fitted and serviceable, follow the product instructions. Do not open the inverter or blow debris into it while energised.

Firmware can affect grid settings, monitoring and security. Updates should come through the supported route, with settings and behaviour checked afterwards. A lost cloud account should not prevent the owner from identifying a local fault or safely isolating the system.

Mounting and roof condition

PV maintenance and roof maintenance overlap. A roofer should know that DC cables can remain live, and a PV contractor should not claim to have inspected concealed roof structure without access.

Check fixings, rails, clamps and corrosion where safely visible. Module clamp position and torque are manufacturer-specific. Retightening everything as a routine action can be harmful if threads, frames or roof seals are disturbed without cause.

Keep a maintenance record

Record:

date, scope and competent person
weather and operating condition for performance tests
inspection and electrical results
photographs and thermal images where used
faults found and corrective work
replacement component make, model and serial number
updated settings, firmware and drawings
next interval and why it was selected

The original commissioning pack provides the baseline. Without it, the first competent inspection should reconstruct the system information needed for future maintenance.