Rapid shut down - what do I need?

[Trukinbear]

Okay, I've just been informed that I've got to have a rapid shut down system for my off-grid solar installation.

I've looked at the Birdhouse, it seems relatively straightforward, and the battery shutdown module to go in my OG E-panel, which already has the quick trip on the main breaker it appears... so Birdhouse + battery shutdown module + armored cat-5 cable between the two.

What about the PV side? My system doesn't have combiner boxes, and I really don't want them. I've got one set (+ -) coming into the E-panel for each Classic 250 (2) from the two PV arrays. I looked at the MNLSOB for array level shutdown, but it isn't clear that it works with the Birdhouse. Also, I'm a might confused with two versions (600V. 1000V), but then it says voltage has to be controlled to 80V within the array, and 30V leaving the array. Wait, 30V? How does a 30V PV system work with a MidNite Classic on a 48V system... I thought I needed a minimum of 81V to give the MPPT sufficient overhead? You'd think with a degree in English and experience as a technical proofreader that I'd understand this better.

What is with 600V and 1000V AND 80V and 30V? Are 80V and 30V AFTER the shutdown, or what?

Will two 600V MNLSOB, an MNLSOB-T1-AC, an MNBDM, and a Birdhouse (plus the armored cable) constitute a complete Rapid Shutdown System? Do I need anything else? System overview in the signature.

Thanks for your help.

[Trukinbear]

Ok, I see from the product description found at a retailer (but not in your brochure) that the MNLSOB doesn't work with charge controllers, only with grid-tied inverters (I'm guessing you really mean AC coupled string inverters?). I guess that explains the Current Transformer. 80V and 12A - what kind of string is that anyway? I'm looking at the MPPT pulling the voltage down to around 99V, and somewhere around 30A on each string... but then I thought we were talking DC all along. Say what you will but MidNite Solar's product line is confusing.

So. I need a combiner box even if I don't have anything to combine? :-(

Is that right?

[Trukinbear]

Yall make this harder than it needs to be. Let me see if I've got this right - the Shutoff boxes (according to rapidShutdown11x17_frontBack.pdf) ONLY works with TRANSFORMERLESS inverters? Geez, isn't there a way to make my system based around the SMA Sunny Island SI6048 comply with RSS requirements using MidNite Solar's stuff?

[Trukinbear]

NEC-2014 is what I need to meet.

I've got two 3x3 arrays on the roof that I need to shut off. I believe I understand the Birdhouse and battery disconnect module end.
Can someone point me in right product direction please?
The most economical solution would be appreciated as there isn't much left in me after all the stuff in my signature. :-)

Anybody?

[Trukinbear]

One of these?
MNSOB4X-4P-75A-PSB

[Kent0]

To shut down the PV array you could use the Tigo TS4-A-F with the Tigo transmitter - it is compatible with the Classic charge controller. Since it looks like you are shutting down the ac output of the system, an ac/dc adapter for the Tigo transmitter (as included with the transmitter kit) would also be shut down and the PV modules would all be disconnected (and in compliance with 2014 NEC 690.12).

By the way there is nothing in NEC 690.12 that requires the ac output of the inverter to be shut down. Your plan reviewer or inspector may have another code section in mind that allows that to be required, but if they are referring to 690.12, that claim is false and they don't know where the solar circuit ends.

[Trukinbear]

To shut down the PV array you could use the Tigo TS4-A-F with the Tigo transmitter - it is compatible with the Classic charge controller. Since it looks like you are shutting down the ac output of the system, an ac/dc adapter for the Tigo transmitter (as included with the transmitter kit) would also be shut down and the PV modules would all be disconnected (and in compliance with 2014 NEC 690.12).

Thanks, while what would amount to about the same amount of money as the MidNite Solar RSS systems I've seen, the thought of unmounting 18 panels on a roof about 6" wider all around than the array really makes this not doable - not unless I'm being threatened with condemnation or something. Those last panels were a b*tch to juggle around and get wired at about 50# each and taller than I am. And I am by myself...

Serously, MidNite Solar doesn't make RSS system components that work with a system based around their most popular charge controller? Color me confused.

[Trukinbear]

Bizarre! Do all of you guys just not have an RSS system, or none of you use the Classic charge controllers? Weird, probably another grand in MidNite solar equipment someone could sell me... I'm glad to see (I guess) that you don't need my business.

[boB]

We are working on RSS stuff and we do have an earlier system that works at a string level but that older system does not work so well on a modular (PV module) basis.

Also, the charge controller, whatever it is, in certain NEC jurisdictions has to discharge the input capacitor section of the CC within 30 seconds.

We are also working on a newer system that works on a modular basis for the newer  NEC version and states that have adopted the latest versions.  Some states are slow to adopt and enforce.  Some states have adopted a newer NEC but are not enforcing certain sections of that newer NEC version also.

BTW, as far as getting your business, this is a very difficult business to compete in and there is very little profit in these RSD/RSS products.  It all goes to the cheapest and lowest price the users can get away with.  There are very strict and difficult UL standards to comply with as well. 

Right now, TIGO is the only game in town and is suing companies to stay that way.  We will get there eventually but this stuff is not easy.  If it were, everybody would be doing it.

What year of NEC are you forced to work with ?  Maybe you don't need it (yet) ?

[Trukinbear]

Thanks for the response. Everything I've done/am doing is unpermitted thanks to an almost 4-year pissing match with the planning commission. The only way they can remove me from my long paid for and current with taxes property is to condemn me for safety reasons. A neighbor piped up and said I can expect a visit from the inspector now that my panels are visible (barely) from the street. I designed a building to mount them on with an idea that they wouldn't be visible from the street, and if they weren't on mounts (I forgot the 2" of the mounts) you wouldn't be able to see anything - as it is you can see the edge of the first row of panels. We're very rural and there is almost no solar in the county so I'm not sure the inspector will understand what he sees - I'd like for it to at least LOOK like I'm trying to comply. The counties website seems to mention NEC-2014 though what parts they're ga-ga for I don't know. I've met or exceeded every other building and electrical code so far... No idea what they're going to pull.

The Tigo is a non-starter for me - it took me 2-1/2 months working by myself to get the panels up there, and reversing the process (and renting another lift) will put me deep into our torrential rainy season. The reason I said I needed a rapid shut down system is the neighbor is volunteer fire and said they had been trained to look for a solar disconnect. Am I conflating two different things, a disconnect, and a rapid shutdown system?

What stops the MNSOB4X-4P-75A-PSB (+ birdhouse) from acting as an array level disconnect for my two arrays? I'm sure I'm missing something here.

[The Ugly One]

I am scratching my head to on this rss per module level. Now i have systems that are 30 panels with 3 classic 250's. 3 seperate systems, and i was planning on implimenting the birdhouse with battery disconnect and pv combiner with power supply boards. All of my pv systems are not mounted on roof tops. T hey are field/ground mounts. The idea that midnites rss cant be used or thebidea that if a conductor goes 1 ft outside of the  array that it needs to be safely disconnected. So what if my combiner disconnecting box sits within the footpring of the array. The whole concept of safety i understand. But not every solar system is sitting on top of the roof.

[Kent0]

The 2020 NEC has an exception to the RSS requirement for ground mounted (that includes pole-top mounts) arrays that don't enter a building or enter a building that only houses PV system equipment. Unfortunately PV circuits that enter other buildings are covered by the RSS requirements including the 1 foot in all directions and 30 volts in 30 seconds requirements. However, the purpose of the RSS requirement is to protect firefighters and once the PV array is shut down outside the building in question it seems logical that the exception should apply because the PV circuit no longer enters the building. Talk to your local inspector or authority having jurisdiction, your plan to use the bird house and the remote shutoff in the combiner at the PV array may be acceptable.

[The Ugly One]

I am going to have to reconsider where i am hanging the inverter a d equipment. It goes from the field to a storage shed thats like 8 ft x 20ft. The house electrical panel gets its energy from the generator that hooks into a panel that is also in that same shed. So i might just hang the equipment on the exterior of the building then to call it good.