My panels are 40.4v OC, rounded to the nearest volt that's 40 volts so I should be okay with using one RSD module like the outback per 2 panels since the limit is 80 volts that I see, where did you come up with 60 volts?
Faulty memory, perhaps. :) If you see 80, it's 80.
My 72-cell panels have an OC of about 47V, so the 60 vs 80 didn't matter - I needed a device per-panel.
The transmitter can just be powered off the inverter's mains connection so it's automatic, and the transmitter is fairly cheap ~$30 or so.
Probably go this route.
This is how the Tigo module works, too. Feed it such that a single switch kills the power to both the inverter and the injector, and you've met the rule.
Any thoughts on short circuiting and where it would be disallowed in NEC 2017? I can't find any mention on the internets of that idea. Seems like the easiest and in some ways simplest way to do it. Could be done with an inductor in series with the short circuiting switch so that the system voltage is brought down to 0v from 600v slow enough (microseconds instead of nano second) to not burn the switching device. Could even have a normally closed SSR do it so that it's automatic with the inverter's supply power.
So, let's move beyond the thought of whether I think it'll comply.
Where does the juice go when you connect the + and - side of your 400-600V string?
It turns your power leads into a big current sucking resistor - until it melts.
This isn't the 12V 300mw HF panel that keeps your car battery topped off between wheelin' trips.
My first array with used panels had some duds, and I was on the roof pulling and shuffling panels several times as I worked through the problems (likely PID degradation, possibly also water ingress on the backsheet from being stored face down and it raining when I was unstacking the panels and installing them, one or two a night it seemed - when I pulled them out and checked, several had significant voltage leakage to ground which the inverter didn't like).
I would usually disconnect the array in the dark, to reduce the voltage on the overall string at disconnect out of an abundance of caution.
You're talking about purposefully shorting a 400V/10A array. I don't think the results are the same as opening it. It's a lot more like dropping a box-end wrench over the battery terminals than you think..
I've been looking at scenarios where I return or sell the abb inverter (abb/fimer confirmed it doesn't have support for module level RSD) and switch to microinverters but I don't think that makes sense. The AP systems microinverters seem the most economical, but add up to $2000 and then the daisy chain AC cable is another $23 per microinverter. I'm still better off with the big ABB inverter I have.
NEC 2017 is a bit silly if you ask me. Aside from me, none of the firefighters on the depts. covering my area know enough about any of this to be comfortable chopping a hole in a panel for ventilation regardless of what stickers and buttons are around and are just going to steer clear of the panels anyway. NEC 2014 made a lot more sense, unless you're someone at NEC that has a BIL in the MLPE business.
I agree it's silly, and it was why I hurried up and got my first array installed under NEC2014. That, and I wanted to make sure I got grandfathered into the net-metering policy before they changed it.
A year later, I had to do NEC 2017 - just when I thought i had things figured out, they change the game.
I'm a ham radio operator. Micro-inverters sound nice, and maybe they're cost effective, but other hams have told me they generate a lot of RF noise that trashes HF radio operation - and you have 20-40 of them to check and try to choke off or correct or replace, all in close proximity, so finding the offender(s) is a PITA.
String inverters, however, are much better for that - and when they are not, they're easier to identify and rectify. One reason I went with SMA was a good report from other hams of minimal RF interference.
The other being the SPS option, which you can't get with any micro-inverter.
(Technically, the SPS doesn't work under NEC2017 because the inverter won't power up the RS devices, but I added the Tigo injector into the mix, and I can run that from a 12v battery to turn on the panels, so I can then use the SPS. My one NEC2014 install works fine with no difficulties. Our power outages are uncommon, but I can use the SPS to feed a UPS, to run the fan on the gas heater in the garage if I have to.. )
One other gotcha that hit me was (re)reading the specs on my panels, the UL fire rating required a certain distance of stand-of from the roof. A rail system is probably fine. My S5! mounts were too close so I built lift-blocks out of 4x2x.120 aluminum tubing.
![[486]](https://data.irate4x4.com/avatars/m/0/94.jpg?1700178133){kind=avatar}
