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Question about wiring

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Posted by Tim Faust on March 30, 2008, 12:31 am
I'm trying to add to my small array of solar panels... I already have 4
equal panels (18VDC, approx 3-4 watts each in full sun) wired together
in parallel.  I would like to connect some smaller panels (approx 2VDC
each in full sun) that I grabbed off my old landscaping lights.  I plan
on wiring these in series to bring up the voltage with this set, and
then wire that series in parallel with my original panels.  Do I need to
match the voltage up exactly with my original panels in order for this
to work?  I'm already using a charge controller to charge two batteries
which are wired in parallel.


Posted by philo on March 30, 2008, 1:27 pm

Any panels wired in parallel must be of the same voltage.
(I doubt if a tiny voltage variance would matter)

Posted by Tim Faust on March 30, 2008, 5:04 pm
 philo wrote:

Does it matter if the panels are different types?  (My old ones are

Posted by David French on March 30, 2008, 8:06 pm


would like

off my

voltage with

need to

work?  I'm


I think they should all work just fine if you fit each panel/source with
a Schottky Diode to feed the charge controller.  Each panel 'should'
adjust its output to a point where the voltages match that required by
the battery/charger combination.

As long as the on-load voltage of a panel is higher than the load requires
to charge (plus about 0.5V for the diode), it will supply current to charge
the battery bank.


Posted by Tim Faust on March 30, 2008, 10:48 pm
 David French wrote:

Are Schottky Diodes necessary on every panel then?  Doesn't the charge
controller serve their purpose (or even have them in it) to prevent the
battery bank from discharging back to the panels?  I don't currently
have any on my existing panels and it seems to be working fine.


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