A novel method for determining bulk diffusion length in bifacial silicon solar cells

In contrast with the usual methods using Q(λ) with back illumination to determine the bulk diffusion length L in bifacial solar cells, the proposed method determines the actual parameters of the back doped layer and also an absolute, not differential L which is usually dependant on irradiance level. The experimental data needed are: Q(λ) measured at low irradiance, and I_sc, measured at high irradiance of known spectral distribution. The essence of the method is the determination at low irradiance of the recombination parameters of the base region and the back doped layer by comparison of calculated and experimental Q(λ) data and use of these parameters (except L) with L as a variable to calculate Q(λ) at high irradiance. The agreement of the measured I_sc and that calculated by integration of Q(λ) over the light spectrum yields the correct value of L