Maintworld Magazine 4/2023

PHOTOVOLTAIC ENERGY
Possible causes alongside production
faults or damage in transit also include
errors in installation and planning. In
addition, age-related wear, accumulation
of dirt on the panels or weatherrelated
damage can also result in
impaired efficiency. When PV modules
are connected in a string, one defective
cell is all it takes to cause a significant
reduction in output.
Faults may reduce the system’s
efficiency, the service life and, in a
worst-case scenario, even cause a fire.
Many of these defects can be easily
remedied by, say, replacing defective
modules or cleaning panel surfaces.
Steps to prevent shading of the solar
modules by roof structures should
already be taken in the planning
stage. During PV system operation,
vegetation may have to be cut back
regularly.
TESTING AND INSPECTION –
BEFORE DAMAGE OCCURS
Early identification of deficiencies may
eliminate high secondary costs, and
even generate additional yield. Along
with economic advantages, testing
and inspection also serve to identify
safety-relevant defects. For this reason,
law and technical standards require
periodic electrical safety tests of PV
systems to be performed. In particular,
the accident prevention regulation
DGUV V3 and the standards EN 62446
(VDE 0126-23), IEC 62548 and DIN
VDE 0105-100/A1 do apply in Germany.
Depending on the age of the system and
other operating conditions, PV systems
TÜV SÜD
TÜV SÜD is a German certification
and inspection organization.
TÜV SÜD provides a wide range of
testing, inspection, certification,
and consulting services in various
sectors, including automotive,
industrial, energy, healthcare,
and more. Their primary focus is
on ensuring the safety, quality,
and sustainability of products,
processes, and systems.
may have to be tested and inspected
every one to four years.
Experts frequently identify simple
defects by means of visual testing performed
to evaluate a system’s actual
state of repair. Target-performance
comparison can be carried out with the
help of simulation software; it offers
indications of defects that may also impact
on the output of the PV systems.
By applying the voltage-current
characteristic, the software measures
the actual performance of the system
and compares it to the manufacturer’s
specifications. In case of deviations,
imaging processes are introduced to
provide more detailed information.
Defects increase electrical resistance,
and thus build up more heat.
The resulting hotspots are captured
by thermal imaging cameras. Inactive
modules, disconnected substrings and
performance degradation caused by
ageing, i. e. potential-induced degradation
(PID), are further anomalies that
can be identified using this method,
provided an adequate level of current
is produced by solar radiation.
HIGHEST PRECISION
ELIMINATES LOOPHOLES
By contrast, inverse thermography, also
known as reverse-current thermography,
is weather- independent. It detects even
the smallest defects at an early stage. In
this “reversed” method, current is fed
into the PV systems and the difference in
temperature is measured when current
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