OK so I'm adding the SPD 115v to the output side of my classic charge controllers. Pic of my setup.
Wide Shot:
(http://i478.photobucket.com/albums/rr144/finalman123/2016-02-10%2009.51.13_zpsqdne9ptn.jpg)
Close up:
(http://i478.photobucket.com/albums/rr144/finalman123/2016-02-10%2009.36.50_zpshrga6uub.jpg)
I plan on having it in between the fuse holders (Blue and white) after I move them further apart. Or possibly either side of the fuse holders. What do you think would work best?
Now to stop a lightning induced surge from damaging the classics I assume the SPD wires must be shorter than the length of wire to the classic controllers. Is that correct?
Do you have SPDs on the combiner box, by or at the Array?
Generally speaking the battery will serve as a pretty good surge isolator. The input to the classic is more vulnerable, as is the inverter output /and/or AC input. The SPD acts by conduction overvoltage between the active leads and the ground (hence source) lead, so keeping them short, with miminal bends is wise.