I'm not sure to understand what you want to change.
If you want to change the power of the sun according to its position in the sky, you should just change how [font=courier new]sunPower[/font] is computed in the [font=courier new]render[/font] method of PhotoRenderer class.
[font=courier new]exportLightSources[/font] method is used to export the other light sources, but they are not supposed to vary, just maybe turned on and off.