Desiccant type tapes for thin-film module edge sealing: types and applications
Desiccant type tape is a special adhesive tape which is commonly used as an edge sealant in solar PV modules.
Edge sealant in Solar PV
Edge sealants are used for thin film and crystalline silicon PV modules. It helps in delaying moisture ingress, which protects cells, connections, and conductive oxide coatings from corrosion and degradation. Edge sealants also strengthen the electrical isolation for PV modules. The many advances in sealing systems help PV manufacturers in finding ways to reduce costs and improve the protections of cells. Sealants have many forms which can be used, including liquid and tape forms.
Edge sealants are required to provide the following properties to the Solar PV modules:
- Very low MVTR (moisture vapor transmission rate)
- Reliable bonding throughout a range of temperatures and conditions
- Easy manufacturing process
- UV temperature degradation resistance
- Good adhesion properties.
Desiccant tape as an edge sealant
A desiccant is a type of hygroscopic substance which is used to induce or sustain desiccation (dryness state) in the vicinity of application and can be used industrially to control the level of water or moisture. Desiccant are used as dryer component in different systems and to prevent condensing of moisture and to protect goods in shipping containers against moisture damage. Desiccants come in various forms and have found widespread use in the food, pharmaceuticals, packing, electronics and many manufacturing industries.
For the Desiccant type tapes, the sealant layer includes a desiccant material which commonly has a concentration of less than 20% weight, this decreases the diffusion time and provides the sealant with moisture ingress resistance thereby extending the duration of the thin film photovoltaic panel which commonly needs more durability and moisture resistance than normal PV modules.
Advantages of using Desiccant type tape as an edge sealant
Integrated desiccant type tapes are typically used as an edge seal for thin film and crystalline silicon Photovoltaic modules. Using desiccant type tape delays moisture ingress, which helps to protect cells, transparent conductive oxide coatings and connections from degradation and corrosion. Using desiccant type tape also provides electrical isolation for PV modules which enables placing active cell area closer to the glass edge, thus making it a suitable choice for thin film PV modules.
The main advantages are good adhesion and insulation as it is Non-Conductive, durability and UV stability. On the other hand, mechanical and adhesion strength can be weaker than other alternatives.