What is a solar backsheet?
A backsheet is a backplane component of the solar panel which serves as mechanical, thermal and electrical support. It safeguards the solar cell matrix from external environmental stimuluses like dust, wind, hail, storm, etc. In other words, it acts as a first line of defense for solar module and hence must possess some of the important characteristics listed below.
Salient features of backsheet
Electrical insulation: A backsheet can come in direct contact with humans in the field and hence it must possess extremely high electrical insulation. The backsheets must be designed to withstand high leakage currents without significantly discharging it to its outer surfaces. Most obviously this function is performed by the heart of any backsheet, e.g. Polyester layer.
Weatherability: Apart from glass and frames, backsheet is the only component that comes in direct contact with the environmental stresses like wind, hail, UV, humidity and heat. Till date, the air side layer of the backsheet made up of fluoropolymer is considered to be superior in terms of resistance to extreme weather conditions. This is because of the very high chemical resistance of such material due to which longevity of PVF, PVDF or fluorocoatings is superior compared to other available options.
Hydrophobicity: Backsheets are designed to sustain in any harsh environments including extreme heat, humidity, cold, snow, mechanical or chemical loads and UV exposure. Though it is very difficult for a single type backsheet to sustain in all these conditions, fluoro materials have special advantage due to their inherent chemical structure. One of the most important parameters for any backsheet is its water vapor transmission rate, commonly known in PV industry as WVTR. Any type of backsheet one may opt for which offers WVTR as almost negligible, i.e as per standard practice < 2-3 gm/m2 day
Mechanical stability: A very high ultimate tensile strength of the PET based backsheets is one of the obvious reasons for industry to rely upon it. These backsheets can withstand the stress and strain conditions during manufacturing, handling, transportation and lamination. Moreover, these backsheets offer excellent adhesion with encapsulants, which is vital for overall stability of the solar module.
Available options in the market: Currently a variety of fluoro and non-fluoro backsheets are available in the market. Though most module manufacturers trust the performance of fluoro based versions, cheaper alternatives of non-fluoro backsheets are also serving well to the needs.
Laminated vs. coated backsheets
Traditionally, all laminated backsheets are being used and have proved their long-term properties in the field. However, as technology advances, industry has warmly welcomed fluorocoated backsheets due to its comparable mechanical properties and reliable outdoor performance. Coated backsheets keep the advantage of inherently superior chemical structure of Fluoro materials and offer light weight to the modules. In addition, such backsheets can be a game changer in a highly competitive market where quality and feasibility of GW scale is demanded.
Laminated or coated, whichever suits your need, contact Alishan Green Energy Pvt. Ltd. for superior quality and durable fluorocoated or laminated backsheets.