My guess is the circuit adjusts for ambient light so the mechanism isn’t confused by bright moonlight or changing cloud cover.  Automatic if done by the microcontroller and a sensor, or manual via a control panel, and both could be available.

Might be a LED corrector as John suggests though my experience of electronics is that designers don’t think that far ahead.  Unfortunately!  (And if they do, it’s to part us from our hard-earned with a dose of planned obsolescence!)

Looks like an old-school binary weighted divider to me.  Old-fashioned in that modern designers are more likely use a DAC chip rather than separate resistors and op-amp, cos chips are cheaper and more reliable than components, especially potentiometers!  Shouldn’t be a problem – separate components will do the job and are much easier to work on.

Dave