Silicone as edge sealant: application, advantages and disadvantages
Silicone is a polymer which is used as edge sealant in solar PV modules
Edge Sealant in Solar PV
Edge sealant is 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 helps PV manufacturers in finding ways to reduce costs and improve the protections of cells.
Edge sealants are required to provide the following:
- 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.
Silicone as Edge Sealant
Silicones (polysiloxanes) are polymers which include synthetic compounds made up of repeating units of siloxane. Silicone is typically resistant to heat and can be in liquid or rubber form. Silicones are used in various applications, mainly adhesives, sealants, medical applications, lubricants, and electrical and thermal insulation. In Solar panel manufacturing, silicone is used as an edge sealant.
Silicone is widely used as a sealant for a couple of reasons, mainly good mechanical properties, high adhesion properties, impact resistance and cheap cost.
Advantages and Disadvantages of Using Silicone as Edge Sealant
PV module manufacturers are increasingly researching methods to lower manufacturing prices and increase reliability and efficiency of components.
Silicone sealants can be used for frame sealing, bonding of Junction box, and ribbon sealing. Silicone sealants help maintain long-term reliability of PV system sealing and bonding and preventing PV modules from being affected by the external environment.
The main advantages are reliability, excellent gap-filling and fluidity, good thermal conductivity, good dielectric properties and flame retardancy, high elongation properties, strong adhesion and good resistance to environmental conditions. Also silicone adhesives and sealants can provide a reliable and strong bond in applications which need flexibility or resistance to extreme temperatures and moisture.
The main drawback is durability compared to other sealant materials and delamination that can happen with time.