Technical article
March 2014
191
Development of the cable
for photovoltaic power
generation systems
By Arifumi Matsumura*, Masaki Nishiguchi Shigeru Kubo, Fitel Photonics Laboratory, Furukawa Electric Co Ltd, Japan
Abstract
Furukawa has developed a cable for
photovoltaic power generation systems,
which meets the requirements of the
TÜV 2Pfg1169/2007 Standard
[1]
and the
JCS4517 Standard
[2]
.
A cable for photovoltaic power generation
systems, which meets the requirements of
these standards, requires that insulating
materials and sheath materials be made of
halogen-free materials.
In addition to that, the cable requires
vertical incombustibility, high-temperature
heat resistance, low-temperature charac-
teristics, and acid resistance.
Furthermore, a temperature index is
required to be more than 120ºC, because
temperatures in the working environment
range from −40ºC to +90ºC. A temperature
at which an aging residue percentage
reaches 50 per cent after 20,000 hours
is required to be higher than 120ºC. In
particular, excellent heat-deterioration
characteristics are required.
At this time, cross-linked polyethylene was
used as an insulator of the cable; highly
incombustible cross-linked polyolefin was
used as sheath materials. As a result, this
made it possible to meet the requirements
of the above-mentioned standards.
In addition, it was confirmed that there
is no problem in putting this cable
to practical use in terms of peeling
characteristics and bleed characteristics.
Furthermore, it is possible to manufacture
this cable without using special bridging
equipment
such
as
electron-beam
irradiation machines.
This cable is very advantageous in terms of
costs and response to mass production.
1 Introduction
In recent years, while there has been
a growing interest in environmental
problems all over the world, power
generation activities by using renewable
energy such as wind power generation,
photovoltaic
power
generation
and
biomass power generation have become
very active.
For photovoltaic power generation, power
generation facilities on the scale of more
than 1 megawatt, called ‘mega solar,’ have
rapidly begun to become widespread.
In the future, demand for the cables to be
used in these power generation facilities is
expected to increase.
At present, unique standards are used
in each region to ensure the reliability
of electric wires used for these power
generation facilities.
In Europe, there are the TÜV 2Pfg1169
standards while the UL4703 standards
[3]
are
available in North America.
In recent years, the JCS4517 standards
have been established in Japan on the
basis of the TÜV 2Pfg1169 standards.
Unique standards were established in
each region, and there is an increasing
demand for compatible cables that meet
all standards.
On the other hand, the development of
less expensive cables is called for greater
proliferation. At present, demand for
low-cost cables is much higher than
demand for integrated cables.
Against the background of the above-
mentioned
circumstances,
Furukawa
has developed a cable that meets the
requirements of the TÜV standards and the
JCS standards.
2 A Newly Developed
Cable for Photo-
voltaic Power
Generation
There is a hot-set property as one of the
mainly required properties of a cable for
photovoltaic power generation, which
corresponds to the TÜV standards and
the JCS standards. In an incombustible
halogen-free electric wire of polyolefin,
electron beams are usually irradiated to
satisfy the standard of hot-set properties.
However, in a future mega solar facility,
the capacity of an electric current will
become larger. Namely, the size of a cable
is expected to become larger. There is a
limit to the response by electron-beam
irradiation.
In addition, as far as a small size of a low
electric current is concerned, the cost of
irradiation equipment itself is high, and
non-electron beam bridging is called for.
Therefore, this cable meets the standard of
hot-set properties in the bridging method
that did not perform electron beam
irradiation in polyolefin materials.
The main physical properties of a newly
developed cable for photovoltaic power
generation are introduced below.
3 Test Method
3.1 Hot-set Test
A hot-set test was performed in
conformance
to
the
IEC60811-2-1
standards. An insulating tube-shaped
piece and a sheath tube-shaped piece
were cut out from a cable. The test pieces
were hung at 20ºC in an oven. A load of
20 N/cm
2
was applied to the test pieces.
