gen_ber_rating.RdStochastically generate a ber rating (kWh/m2/year) from a ber score. G ratings are exponentially distributed from 450kWh/m2/year with a default decay rate 0.01.
gen_ber_rating(ber_score, g_rate = 1/100)double
gen_ber_rating("B3")
#> B3
#> 142.1862