The solar cell power output is loaded using a resistance
box (Cropico RM6-N decade box with 10 X resolution,
±1% accuracy) to allow adjustment of the load current.
The voltage across the load is measured with an A/D
convertor (NI USB-6008 with a resolution of 14.7 mV
and 12 bit output), and the output power density of each
solar cell is then calculated using Eq. (1).