At 12:50 PM 6/7/2012, pickle vanagon wrote:
>We made some good progress on this project last night, but there something
>that is puzzling me about the foil.  In the bank of resistors on the back
>of the foil, the third one down is a diode which goes from ground to
>positive 12v.  What is the purpose of this kind of arrangement??

If it's a Zener (symbol would have little wings slanting up and down
from the ends of the line) it could be an overvoltage limiter.  Even
a plain diode (reverse biased of course) could be to suppress
ringing/spikes when the panel is shut down.  If it's forward biased
(arrow pointing toward ground) then you haven't traced it correctly.

VW had a tech note at some point about adding a diode when replacing
the panel voltage regulator, but I don't remember what precisely it
connected to.

Got a number on it?

Yours,
David