It is instructive to get an overview of the expected effect of the
varied illumination intensity on the photovoltaic parameters of a solar
cell. The I(V) characteristics of solar cells can be described using the
basic diode equations and the equivalent circuits [12,20]. The circuit
consists mainly of a current source and a diode in the one-diode model
which assumes that the shunt resistance goes to infinity and the series
resistance is zero as in ideal solar cell [20]. This model however was
mainly implemented to describe the electrical behavior of p-n crystalline
silicon solar cells but has also been used in p-i-n thin-film solar
cells [12,21–24]. In TFSC with device-grade absorber layer, recombination
is ignored and hence the standard one-diode model is used to
describe the cell operation especially at standard AM1.5 illumination