Page 44 - Energize October 2021

TECHNICAL

Rooftop PV systems: Operation and

maintenance issues

by Mike Rycroft, Energize features writer

Rooftop PV has become a popular and cost effective behind-the-meter generation system, for both
residential and commercial/industrial consumers. Like any generation system, a rooftop PV system requires
regular maintenance to ensure that the system remains in an efficient and safe operational state and
achieves its expected lifetime.

ooftop solar systems (RTS) comprise a complex arrangement of RPS consists of these basic component groups (Figure 1):
mounting structures, solar panels, wiring, lightning and other • The panels, mounting structures, wiring and protection devices
Rprotection devices, charge controllers, batteries, inverters and • The charge controller and battery
grid interface units. Maintenance today consists of more than just • The AC inverter, which may incorporate grid connection units
cleaning the panels. Maintenance is aimed at keeping the RTS system in • Alternatively, a hybrid inverter which incorporates a charge controller
good working condition and achieving its design life.
Failure to do so can result in either complete failure of the system Any of these components can be responsible for failure or poor
or a significant decrease in the output or capacity of the system. performance.
Complete failure of the system means that some component has
failed and that there is no power output from the system. Reduction
in capacity over time is normal for all solar PV systems, and associated
batteries. Typical figures are 1% per annum of initial capacity for PV.
Any capacity reduction in excess of this means failure or maloperation
of some component and needs rectification.

A poor or ineffective maintenance regime can affect the system in
several ways:
• Decline in output greater than that expected due to ageing
• Damage to panels due to development of hotspots, glass cracking,
delamination (snail tracks) and encapsulant ageing
• Development of unsafe conditions
• Fire initiation and roof damage Figure 1: Rooftop solar system components
• Poor performance of associated equipment such as inverters,
batteries, etc. Most common problems encountered with RPS are:
• Poor overall system performance • Inverter problems
• Soiling and fouling of panels
Poor performance can negate the financial advantage that the system • Mounting system and roof damage
has and result in negative returns on investment, and this reason alone • Wiring and connection box corrosion or aging
is sufficient to justify a well-thought-out maintenance regime. • Panel damage
With the wider application of RTPs, building and personal • Bypass diode failure
safety has become a major concern. PV arcing risks caused by poor • Battery loss of capacity or failure
contacts in PV modules, poor connections from PV connectors, or
aged or broken cables, have become a matter of concern. Unsafe The two elements which will need the most attention are the solar
or non-compliant conditions resulting from poor maintenance can array and the batteries. Although inverters and charge controllers are
result in insurance claim rejection in the case of damage to the high on the list of failures they are generally reliable devices which will
system or property. self-check and flag any failure or mis-operation.

Roof top solar structure The PV array
A monitoring system can indicate that there are faults with the system, Soiling and fouling of PV panels
and to understand the location of correction of faults it is necessary to Soiling of panels means the accumulation of dust or grime on the panel
consider the structure of the system. surface due to dust and airborne pollutants. Soiling can reduce the output

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