Question

A typical Si-based PV cell will have a form factor, FF=0.7, and an open circuit voltage VOC=0.6 V and a short-circuit current density JSC=30 mA/cm2. What is the maximum real efficiency of this cell? Suppose now that by improving the manufacturing process, you are able to increase the carrier lifetime by a factor of 3. If nothing else is changed in the PV cell design? By how much will the efficiency improve? Hint: JSC is proportional to square root of the carrier life time. You need to carefully think how solar cell work how JSC and VOC will be effected by this change.

Answer 1

Given: Fill Factor (FF) = 6.7 open & circuit voltage = 0.6V (Voc) short circuit current density (Isc) = 30 mAlan² = 300 A/m2 Solution. mar. real efficiency Cy) = FF & Voc jsc where Io = solar irradiance onearth surface = 1000 W/m2 n = 0.7x 0.6x300 = 12.6% luo Shoot @ circuit density is proportional to square root of Corsier lifetime. rey Jose & Ter I . Jsc = ² (since corrier lifetime I Jsc (32e) is increased by a => Jsc = √3 Joc factor of 3) resultant efficiency a nd y = 0.78 0.6X300 x 3 1ooo 21.87