Identify racking system from 2012; worth reusing?

Update:

Current plan is to remove all panels and rails and reuse the existing posts, plus 4 more posts to support the 4th rail. So upper row: 4 panels, 2 rails, 4 posts per rail; lower row: 6 panels, 2 rails, 5 posts per row. The extra posts are properly overkill but are required by the AHJ's prescriptive structural standards for PV.

A couple questions about some of the practical aspects:

1) With Enphase IQ8As and their Q cable, and just two rows, is there any reason not to put the microinverters on adjacent rails? That is,
upper row microinverters on the lower rail of the row, and the lower row microinverters on the upper rail of the row. Would save some cable length and the need to skip a connector when jumping from one row to the next.

2) Is there some standard strategy to align the bottoms of the first row? E.g. adjustable l-brackets attached to the lower rail that could hold a 2x4 for the PV panels to butt against. Roof slope is 8/12.

3) With Ironridge XR and their UFOs and the given layout, seems like 3 of the fasteners will not admit close approach for fastening and will require reaching over the full panel width to tighten (45" reach). Any tips for doing this?

Thanks,
Wayne
 
wwhitney said:
1) With Enphase IQ8As and their Q cable, and just two rows, is there any reason not to put the microinverters on adjacent rails? That is,
upper row microinverters on the lower rail of the row, and the lower row microinverters on the upper rail of the row. Would save some cable length and the need to skip a connector when jumping from one row to the next.
Click to expand...

That is exactly the way I typically do it so the connectors reach when jumping rows.


2) Is there some standard strategy to align the bottoms of the first row? E.g. adjustable l-brackets attached to the lower rail that could hold a 2x4 for the PV panels to butt against. Roof slope is 8/12.
Click to expand...

I usually just run a string line. I always thought about taking the time to thoroughly secure a nice straight edge and just let the panels sit against back, but I have not tried it yet.
 
good plan

1. perfect, micro-inverters can go on any rail and spun around to face any way

2. eyeball the first panel when installing it. Then install the 2nd panel. The two together will be over 6' long and will give you a good idea where you are pointed uphill or downhill or level enough.
Loosen the UFOs on these first 2 panels, and adjust them a bit as needed.
....and then add the rest.

Gapping and "stepping" panels up/down an inch or so will never be apparent from ground level anyways. I spent too much time worrying about details that nobody can see.

3. Tall helper. Or ladder from ground.
 
One more followup question: with microinverters in a system with backup-capable ESS, to initiate RSD it is necessary to interrupt the inverter output circuit(s). Rather than have a breaker or switch outdoors to do this (single family dwelling), does it work to use a shunt-trip breaker with a remote outdoor switch as the initiator?

Perhaps I'm overthinking it, but it seems to me that there is one scenario where the behavior would differ between flipping the breaker itself off versus hitting a remote switch to trip a shunt trip breaker. Namely when the power is already out, which in this case would require the grid to be out and the ESS to be off (maybe out of charge, or maybe it has been shut-off). As long as the switch itself is latching (meaning the shunt trip would have to disconnect the coil when the breaker trips), then if the power were ever turned back on, the breaker would then trip. But it seems to me there would be a race condition between the shunt trip activating and the inverter output circuit reenergizing, and most likely there would be a "blip" of power on the inverter output circuit. Is that a problem that disqualifies using a shunt-trip breaker like this?

Cheers, Wayne
 
690.12(D) leaves open the possibility of a compliant shut trip setup for rapid shutdown if the setup uses a listed circuit breaker and listed "control switch." However the language in 690.12(C)(3) leaves something to be desired in terms of clarifying whether and how a simple shut trip device can be compliant. It requires the device that shunts the trip to be a "switch that plainly indicate whether it is in the "off" or "on" position." Not stated but perhaps implied is that the 'off' position means rapid shutdown is initiated, but this is the opposite of what you get if you connect most switches to the shut trip. Perhaps one could argue the point legalistically, but it's certainly not ideal to have a switch where the on and off indications are opposite what they'd be from the circuit breaker itself.

I've gotten away with using a normally closed plunger style e-stop switch in a similar but different application. You'd want a normally *open* switch if you went with that kind of option for a shunt trip. Finding such a switch that's plainly marked 'off' and 'on' may be difficult. Apparently it's accepted by at least some AHJs that a red pushbutton plainly indicates "off" and thus "rapid shutdown initiated" when depressed. Both from my experience and as I recently noticed on a recent Tesla system (Powerwall 3 I presume).
 
jaggedben said:
690.12(D) leaves open the possibility of a compliant shut trip setup for rapid shutdown if the setup uses a listed circuit breaker and listed "control switch."
Click to expand...
My reading of 690.12(D) is that "initiation devices such as listed disconnect switches, circuit breakers, or control switches" do not need to be listed for rapid shutdown. So the switch itself certainly doesn't need to be listed. Seems plausible that the shunt trip and the switch are together the "initiation device," so no special circuit breaker listing is required either. In so far as that when the manual operation of a circuit breaker is the initiation action, that circuit breaker is clearly the initiation device, and the in the shunt trip configuration, the circuit breaker is still performing the same function.

jaggedben said:
However the language in 690.12(C)(3) leaves something to be desired in terms of clarifying whether and how a simple shut trip device can be compliant. It requires the device that shunts the trip to be a "switch that plainly indicate whether it is in the "off" or "on" position." Not stated but perhaps implied is that the 'off' position means rapid shutdown is initiated, but this is the opposite of what you get if you connect most switches to the shut trip.
Click to expand...
Easy work around: use an unlabeled switch and add the appropriate labels; or use a labeled weatherproof switch cover over a regular switch which is "upside-down" so that the labels on the cover are opposite the switch itself.

Is the upshot that you don't see the corner case of the shutdown switch being set to "off" while all power is already off, and the resulting possibility of a brief power "blip" in the future as an obstacle at all? Too unlikely to worry about, and not likely to have any significant consequences anyway?

Cheers, Wayne
 
A related RSD question: when the premises has a grid connection, an MID, and a stand-alone capable BESS, killing either the grid or the BESS is not enough to cause the grid following microinverters to shutoff. But killing both of them would be.

So it is acceptable for the RSD initiation device to consist of two devices, the service disconnect and the ESS shutdown initiator? I.e. label them "Service Disconnect, PV RSD 1 of 2" and "ESS Shutdown, PV RSD 2 of 2".

Apparently only if you have more than one PV system, as 2020 NEC 690.12(C) says in part "For a single PV system, the rapid shutdown initiation shall occur by the operation of any single initiation device." With multiple PV systems, the corresponding requirement just says that activating all of the devices (up to 6) should cause all of the PV to shut down.

Cheers, Wayne
 
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