Question

1) If the lamp of 119.05 W is on for an average of 6 hours per day, and if peak sun hours average 6 hours per day,

• Determine the power output required for a PV array that would power the lamp, assuming 10% degradation of the PV array.

• Determine a general expression for PV array power as a function of lamp operating time, assuming full utilization of the PV output.

Answer 1

Energy requirement = 119.05 x 6 = 714.3 Wh(watt hour)

Assuming ratings for one PV Module.

open circuit voltage = 12 V

Short Circuit current = 2 A.

MPP (Maximum Power point voltage ) = 9

@ MPPV output current = 1 A.

Energy Output @ MPP @ 6 hours = 9 x 1 x 6 = 54 Wh.

Total no of Modules required = 714.3 Wh /54 Wh = 13.2 =13 Modules

Total power output required = 13 x 12 V x 2 A = 312 W.

Let Lamps operated for t hours ,then

Energy requirement = 119.05 x t = 119.5 t Wh(watt hour)

Assuming ratings for one PV Module.

open circuit voltage = 12 V

Short Circuit current = 2 A.

MPP (Maximum Power point voltage ) = 9

@ MPPV output current = 1 A.

Power Output @ MPP @ t hours = 9 x 1 x t = 9 t Wh.

Total no of Modules required = 119.5 t Wh /9 t Wh = 13.2 =13 Modules

Total power output required = 13 x 12 V x 2 A = 312 W.