parallel panels via their junction boxes

so to james,

yes, that is one choice.  if you plan on doubling your array, there is another choice.  switch to an mppt controller that can down convert voltages, (flexmax 60, others ...) and then you can leave each series string of up to 4 (maybe 5) modules on one overcurrent protection breaker.  if you took your current array of 3 kyo 40, and wired them in series instead, you would have that one string feed one 6a breaker in your combiner.  your pv disconnect would be 6a, however, the charge controller disconnect would be at minimum 20a, because by down converting voltage 3 to 1 ratio, your current would go up by that same ratio.

if you went this way, you would leave the combiner box, but have the ability to have your current 3 modules, or 4 modules (1 string of 4 in series), or you could double your array as proposed with 2 strings (in parallel each with ocpd in combiner) of three in series.

--

for mr. schmidt, it is important to remember that in a battery based system, it is not only other strings of modules that can be problematic in fault or component failure situations.  the battery bank has the capability of backfeeding, and the ocpd based on max series fuse size, protects the modules, as well as the system and potentially building from all the unpleasant (though less than likely) happenings.  whenever i reply to posts i do my best to highlight the "should" possibility rather than the "could" possibility.  thanks for your posts on this one



james
altE staff

http://www.nvenergy.com/renewablesenvironment/renewablegenerations/documents/Tab-2NABCEPStudyGuide.pdf
Page 20 paragraph 3.5.1
But this does not take into consideration the manufactures assessment of its own PV modules to withstand more than the series fuse rating printed on the module label. Engineers are always a bit conservative, at least on paper. If I were to try 2 - KC40T's in parallel on 1 - 6 amp fuse, I would insure that both the pos. and neg. leads from each to a j-box where they are spliced into one set of pos. and neg. were exactly the same length. Of course there is a good possibility that I might be voiding any expressed warranties offered by the manufacture.

More fun with Possibilities and Probabilities.
http://www.markvernon.com/friendshiponline/dotclear/index.php?post/2009/07/31/The-improbable-possibility-of-probabilities
http://hubpages.com/hub/The-Mental-Warrior
http://www.nonesoblind.org/blog/?p=3689