I know you have already checked this but...

Do you have the bottom one in backwards???

PV panels are current generators, add a small series resistor
and re-run your test.

Aaron Lahman wrote:

>I don't have equipment to measure the current in low lighting (it's slightly
>less than 1mA, by inference) but I still get the effect if i switch the
>order of the two solar elements... it's always the one on top - providing
>the positive voltage - that has 2v across, and the one on the bottom
>having -0.5v.  They are set in a position where they receive approx. equal
>lighting at the same angle (side by side on a desk under a lamp a few feet
>up).
>
>>-----Original Message-----
>>From: pic microcontroller discussion list
>>[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of David VanHorn
>>
>>
>>Are they equally illuminated?
>>Try putting a load on the two panels separately, and checking them in
>>place. If one is putting out more current than the other, then you would
>>see as you describe.
>>
>>--
>>http://www.piclist.com hint: The list server can filter out subtopics
>>(like ads or off topics) for you. See http://www.piclist.com/#topics
>>
>>
>
>--
>http://www.piclist.com hint: The list server can filter out subtopics
>(like ads or off topics) for you. See http://www.piclist.com/#topics
>
>
>

--
  *
  |  __O    Thomas C. Sefranek  tcs@cmcorp.com
  |_-\<,_   Amateur Radio Operator: WA1RHP
  (*)/ (*)  Bicycle mobile on 145.41, 448.625 MHz

ARRL Instructor, Technical Specialist, VE Contact.
http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics