- TPedge solar PV module with 2 mm thick glass undergoing distributed load test
The TPedge concept reduces the material
and production costs of solar photovoltaic (PV) modules, since
encapsulation foils and the lamination process are no longer needed. At
the same time, the aging stability of the PV module increases
appreciably.
In the project “TPedge,” researchers at
Fraunhofer ISE (Freiburg, Germany) together with their partners have
developed processes so that the innovative PV modules can be
manufactured on an industrial scale.
TPedge modules are edge-sealed, double-glass PV
modules, similar in construction to insulating glass windows. The solar
cells are fixed in the gas-filled space between the two glass panes with
special adhesive pins.
Processes for the industrial production of novel solar module concepts
The TPedge module forgoes the conventional
encapsulation foils as well as the traditional module frame. This not
only saves material costs but also avoids the time-consuming lamination
process.
In the project “TPedge – Development of a Technology
for Edge-Sealed Solar PV Modules,” Fraunhofer ISE and the company
Bystronic glass together developed processes for the industrial
production of novel solar module concepts.
“We have successfully transferred the lab prototype
to an industrial-scale module (with 60 solar cells),” says a pleased Max
Mittag, project head at Fraunhofer ISE.
At the PV Module-TEC (Module Technology Center) at
Fraunhofer ISE, the researchers put automated production systems into
operation with which they were able to produce numerous prototypes of
TPedge PV modules with different setups.
As a next step, the industrial production processes
were developed further and optimized. By substituting the 3 mm thick
glass with glass that is only 2 mm thick, the weight of the TPedge
modules could be reduced by 30 percent.
The module prototypes jointly produced with
Bystronic glass underwent many tests based on the standards IEC 61730
and 61215, and the results confirmed the high reliability and technical
maturity of the TPedge module concept.
Many different design setups were tested, using the
conventional glass-foil-laminate and glass-glass-laminate modules as a
reference. As part of the procedure, the PV modules were tested for
their resistance to hail and distributed loads.
Aging Stability
In the humidity-heat test, various TPedge modules
containing different types of commercial solar cells were subjected to a
relative humidity of 85 percent at a temperature of 85°C for over
4,000 hours.
After the test, the module power showed no change
compared to the initial values measured before exposure. Conventional
module concepts, however, with glass-foil-laminate and
glass-glass-laminate demonstrated, in part, large degradation effects
after undergoing the same test.
The TPedge modules also successfully passed the
thermal cycle durability test. Fraunhofer ISE’s TestLab PV Modules
verified the durability of the TPedge modules by exposing them to 400
temperature cycles (-40°C to +85°C) in the testing process.
Mechanical Durability
Using commercially available mounting systems,
durability tests for mechanical loads and hail were carried out at
Fraunhofer ISE. The tested modules successfully passed the tests in
which pressure loads up to 5,400 Pa were applied to the modules in
different mounting configurations.
Although the tests were repeatedly carried out, no
changes in the module power were detected. The TPedge concept was also
tested for its resistance to hail. Even the modules with the thinner
2 mm thick glass passed the tests successfully.
In the procedure, large hail stones of 25 mm
diameter were also aimed at especially critical parts of the module, for
example, the glass edges. The modules passed the hail tests without
being damaged and could be used further in the following tests.
Cost Savings
With a special model developed at Fraunhofer ISE to
determine the cost of ownership according to the SEMI standard, a highly
precise cell-to-module power analysis (CTM), and measurements from the
CalLab PV Modules, the specific module costs (€/Wp) for TPedge and
relevant competitive module technologies were calculated.
“The results show that the specific module costs of
the TPedge concept are approximately 2 percent less than the
conventional glass-foil-laminate concept,” says Mittag.
“The cost reduction is mostly due to lower material
costs. Material costs are crucial since they are responsible for about
90 percent of the total module production costs, including cells.”
The TPedge concept also lowers material costs compared to the glass-glass-laminate concept.
The project “TPedge” started at the beginning of
2013 and was funded by the German Federal Ministry for Economic Affairs
and Energy (BMWi). Fraunhofer ISE and its project partner Bystronic
glass developed the TPedge module technology and the possibilities for
industrial production followed.
Fraunhofer ISE has installed 70 TPedge modules on
the façade of one of its lab buildings; these have been operating in a
field test for three years now. Further research explores promising
approaches to increase the module power and addresses the particular
suitability of this technology for building-integrated photovoltaics. An
industrial implementation of this technology is a future aim and
partners are being sought.
source: http://www.solarserver.com
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