PDMS (Polydimethylsiloxane) film: composition and application
PDMS is the abbreviation of Polydimethylsiloxane which is an organic based polymer that is used as a backsheet material in solar modules.
Backsheet and encapsulant materials
The solar module backsheets contain multiple layers of barrier films and adhesives. The backsheet construction is critical in protecting the solar cells from different environmental conditions like moisture, UV exposure and other performance threats while also improving solar module efficiency by aiding the reduction of partial module cost. The encapsulation film protects the solar cell and ensures its reliability and performance; its role is providing optical and electrical transmissivity and keeping the moisture out. Encapsulants provide an opportunity for realizing greater efficiencies in the module manufacturing process.
What is PDMS?
Polydimethylsiloxane is an organic based polymer that is from the silicone group. PDMS has the following properties: optically clear material, inert, non-flammable and non-toxic.
In addition, PDMS has different applications ranging from contact lenses, elastomers, medical devices to lubricants and heat resistant tiles. PDMS is also used as encapsulant for solar panel backsheets.
PDMS use in solar panels
When photovoltaic panels were ﬁrst introduced in the 1960s and 1970s,the dominant encapsulants were based on PDMS. PDMS is used more in encapsulants than backsheets.
PDMS was chosen due to its properties mainly exceptional intrinsic stability against thermal and ultraviolet light, induced stress and good mechanical properties over a wide range of temperatures. It also has really good transmittance due to the absence of UV absorbers.
The PDMS has some problems, mainly high permeability and moisture breakthrough distance compared to other materials.
Alternatives to PDMS
Different materials are used as alternative to PDMS like EVA, PVB, TPU and Ionomer