In this paper, the ac behaviour of crystalline silicon (c-Si) solar
cells fabricated in an industrial environment is studied using impedance
spectroscopy. The n+-p-p+ structure based cells have a p-n
junction (n+-p) and Al back surface field (BSF, with p-p+ structure)
at the rear side along with an antireflection layer on the front
besides front and back metal contacts. Impedance spectra are measured
at forward bias (Vb) condition (in dark) and at different illumination
(Pin) levels (at zero electrical bias). The noticeable
observation is the ‘‘negative capacitance” in the impedance data
in low frequency regime. To explain this, separate passive element
having inductive nature is added to the conventional equivalent
circuit having Voigt elements consisting of resistance and capacitance
(in parallel). The origin of low frequency inductance behaviour
is discussed in terms of ‘‘negative capacitance”.