A review on barrier layers used in flexible stainless-steel based CIGS photovoltaic devices

Two primary engineering challenges are en route to fabricating high-performance flexible stainless-steel based Cu(In,Ga)(S,Se)_(2)solar cells;Growing absorbers without contamination from the substrate,and providing alkali dopants to the absorber.The former is chiefly addressed by introducing a barrier layer,and the latter by post-deposition treatment or including dopant-containing layers in the stack.Here we organize these solutions and different approaches in an accessible scheme.Additionally,reports on interaction between contamination and alkali elements are discussed,as is the impact of barrier layer properties on the interconnect technology.Lastly,we make recommendations to consolidate the multitude of sometimes inharmonious solutions.

Physics-based electrical modelling of CIGS thin-film photovoltaic modules for system-level energy yield simulations

Copper indium gallium selenide(CIGS)is a commercialized,high-efficiency thin-film photovoltaic(PV)technology.The state-of-theart energy yield models for this technology have a significant normalized root mean square error(nRMSE)on power estimation:De Soto model—26.7%;PVsyst model—12%.In this work,we propose a physics-based electrical model for CIGS technology which can be used for system-level energy yield simulations by people across the PV value chain.The model was developed by considering models of significant electrical current pathways from literature and adapting it for the system-level simulation.We improved it further by incorporating temperature and irradiance dependence of parameters through characterisation at various operating conditions.We also devised a module level,non-destructive characterization strategy based on readily available measurement equipment to obtain the model parameters.The model was validated using the measurements from multiple commercial modules and has a significantly lower power estimation nRMSE of 1.2%.