The proposed light setup was built using commercially
available materials and consists of an array of six halogen
(Tungsten filament) spot light bulbs (AC 50 W/120 V
Halogena, General Electric) perpendicularly illuminating the
sample testing surface . Each one of those bulbs can be
turned on and off independently, in this way the output
power in the form of irradiance could be regulated by
sequentially turning on each one of the light bulbs as well as
by a dimming component. A maximum input power of 300
W can be reached when all light bulbs are turned on; this is
equivalent to a maximum irradiance of 3500 W/m2 (3.5 SU).
A dimmer is incorporated into the circuit for further tuning of
the intensity of light. However, this configuration does not
accurately recreate the solar spectrum due to the mismatch
between the Tungsten lamps and the sun in the infrared (IR)
and the ultraviolet (UV) spectrums as depicted in Figure 1a
[16].