[RE-wrenches] APS rapid shutdown

[Dave Tedeyan]

Hi All,

I am about to use the AP systems rapid shutdown units for the first time
(pairing with SMA inverters). I was reading through the manual and came
across a couple things that I am wondering if others have noticed issues
with:

1. The manual states that you need to keep the PV conductors from each
inverter (there are two in this system) separate, or else there may be
crosstalk. So this would imply that you need to have two separate DC
conduits from the roof to the inverters, rather than one. Has anyone
noticed if this is truly a concern?

2. The manual also states that there needs to be at least 20cm (or ~8")
from the RSD-S-PLC to another piece of equipment (other than the module it
is mounted on). I am attaching a diagram from the manual, but it sounds
like if you have three rows of modules, the RSD's need to be installed on
the top of the top row, the bottom of the bottom row, and you need an 8"
gap between the rows for the middle row. The diagram in the manual makes
this more clear than my words can. But has anyone not installed this large
gap and had issues, or did it still work just fine?

3. Lastly, I don't see a mention in the manual, but is there a string
length minimum? For some reason I thought with some of the older Tigo RSD
units you needed at least 5 or 6 in a string, or maybe I am thinking of
SolarEdge optimizers. I just want to make sure there is no minimum, since
another job coming up will have a string of 3 panels.

I appreciate your experience!
Cheers,
Dave

-- 

[image: Logo] <https://www.sungineersolar.com/>
Dave Tedeyan, P.E.
Owner | Sungineer Solar
p: he | him | his
a: 1653 Slaterville Rd. | Ithaca, NY 14850
w: www.sungineersolar.com <http://www.sungineersolar.com/>
c: (607) 270-0370
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