The assembled cells were connected to a load resistor that was varied from 0 to 10 MQ through a current amplifier and the voltage V across and cur­rent I through it are measured as a function of RL (figure 2). The cells were pointed straight at the sun and were measured in Northridge, CA (visibil­ity: 10 miles, Latitude = 34N) at solar noon from Dec 2010 through April 2011. The sun’s altitude p was between 32.5 and 65.7, yielding an air mass of AM = 1/sinP ~ 1.7. The average solar flux was 770 W/m[1] [2] [3] [4] [5] [6] [7] [8] [9]. To minimize the effect of variability in solar conditions and cell assembly, devices were fabricated with large variations in carbon nanotube concentrations to high­light its effect on cell performance.

CNTs were created in batch operations, providing the ability to test various parameters and the resistances of electrodes used in experiments.