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Technology Talks

TRACK 4: ENERGY CONVERSION & STORAGE

THURSDAY, AUGUST 31, 2017 2:15 pm – 3:45 pm
Room: Jackson, Second Floor

Dr. Michael D. 8-4-1 - Packaging Challenges and Opportunities for Photovoltaics and Thermoelectrics
Kempe
Session Organizers: Dr. John Reifenberg, Alphabet Energy, Dr. Matthew Reese, National
National Renewable Energy Laboratory
Renewable Energy
Laboratory (NREL) The two technical talks in this Session will focus on the state of the art, challenges, opportuni-
ties, and future directions in the packaging of photovoltaic cells and modules, as well as in
thermoelectric-based devices for space and terrestrial power systems and waste-heat recovery
applications.

Dr. Michael D. Kempe is a senior scientist and studies the factors that affect the longevity of PV
cells and modules. His work concerns primarily modeling and measuring moisture ingress into
PV modules and studying the effect of moisture on polymer adhesion, device performance, and
component corrosion. His work also includes the development of a technique for measuring the
moisture permeation rates in films at levels around 10-6 g/m2/day and the evaluation of edge
seal materials. He is also studying the effects of ultraviolet radiation and heat on the mechani-
cal, chemical, and electrical stability of PV packaging components. This effort is tied into
creating qualification tests that accurately assess safety and predict long-term durability.

Packaging Needs and Considerations for Photovoltaic Modules

The packaging materials used in PV modules serve multiple purposes. They physically hold
components in place, provide electrical insulation, optically couple superstrate materials (e.g.,
glass) to PV cells, protect components from mechanical stress by mechanically de-coupling
components via strain relief, and protect materials from corrosion. To do this, the packaging
materials must adhere well to all surfaces, remain compliant, protect against electric shock at up
to 1500 V DC, and transmit light after exposure to temperature, humidity, and UV radiation
histories. The safety and durability standards, IEC 61730 and IEC 61215, are primarily responsible
for much of the determination of the suitability of a material for a PV application. However, there
is still much work being done on these standards to enable them to more accurately determine
if a module will be safe and durable for the 25 y warranty period.

Here we describe common materials and configurations of PV modules and the reasons behind
the choices. In some cases this is determined by historical data as opposed to the qualification
standards. In recent years, cost pressures have led manufacturers to select inadequate
materials which fail in the field despite passing the qualification tests. This highlights the need
for modification of testing standards and the need for testing beyond the qualification tests for
new designs and materials used in the PV industry.

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