SMA rapid shutdown not code compliant after JAN 1st?

Zee

Senior Member
Am I interpreting NEC 2017 correctly in that the SMA RSS solution [Box (flat white box at array on roof) and Controller (red button switch) ]
will no longer be Code compliant next year?

I don't understand 690.12 (B) (2) (3). Does this mean it can in fact be used?
 

pv_n00b

Senior Member
RSS systems that just provide string isolation at the array boundary will not comply with 690.12(B)(2)(2), that includes the SMA contactor system and many others. NEC 690.12(B)(2)(3) is intended for BIPV modules with no metal parts other than the conductors. If the modules have metal frames or metal mounting systems then it will not comply with 690.12(B)(2)(3).
 

jaggedben

Senior Member
If all your work is in California then you have until Jan 1st 2020. But yes, then it will change. This is why SMA partnered with Tigo, I think.
 

Zee

Senior Member
pv noob: I see, 690.12(B)(2)(3) means BIPV when they mention "no exposed conductive parts".
:thumbsup: thx

well, that's the last Sunny Boy I install.

Seems like this would be a big loss (the whole US market) for them?
 

Zee

Senior Member
If all your work is in California then you have until Jan 1st 2020. But yes, then it will change. This is why SMA partnered with Tigo, I think.
CA has until 2020?
I thought this.....
"The requirement of 690.12 (B) (2) shall become effective January 1st 2019."
....meant that it applied sooner than usual.

Oh, i see, this is actually a delay of two years (for areas that adopt the 2017 cycle in 2017) rather than a moving up of the deadline (if you adopt it later, like 2020)?
 

Zee

Senior Member
Regarding TIGO and SMA. Interesting.
Never used it!
Is this a future or existing deal?
Has anyone installed such a system?

Does TIGO obviate the need for the SMA RSS?

Can you still use the SPS feature of the SMA inverter?

Seems like it would be more expensive than Solaredge or Enphase. Significantly?
 

jaggedben

Senior Member
Regarding TIGO and SMA. Interesting.
Never used it!
Is this a future or existing deal?
Existing.

Has anyone installed such a system?
I installed a Tigo system a few years back with another inverter. Didn't end up doing it twice.


Does TIGO obviate the need for the SMA RSS?
I believe so. It may depend on exactly which type of optimizers you install.

Can you still use the SPS feature of the SMA inverter?
Again, I think it depends on the exact models of optimizers. Somewhere I saw a chart.

Seems like it would be more expensive than Solaredge or Enphase. Significantly?
Maybe 25% more on the inverter/optimizer category. YMMV.
 

ggunn

PE (Electrical), NABCEP certified
I believe so. It may depend on exactly which type of optimizers you install.
Optimizers? I'm pretty sure that the basic Tigo is just a module add-on switch that opens when it doesn't see the dead man signal on the DC conductors. SMA is going to build the signal transmitters into the inverters, so that's all you need for now. Pretty soon many (most? all?) module manufacturers will put the switches in the junction boxes so then it will be back to business as usual.
 

Carultch

Senior Member
Optimizers? I'm pretty sure that the basic Tigo is just a module add-on switch that opens when it doesn't see the dead man signal on the DC conductors. SMA is going to build the signal transmitters into the inverters, so that's all you need for now. Pretty soon many (most? all?) module manufacturers will put the switches in the junction boxes so then it will be back to business as usual.
Tigo has a series of module-level power electronics (MLPE) devices, based on how complex you want their functionality to be.

F for Fire Safety is the basic rapid shutdown part, relying on a power-line carrier signal to communicate the "stay-on" ("heartbeat") signal.
S for Safety is also a rapid shutdown part, but uses radio signals to communicate instead of power line carrier. It also has module-level monitoring.
O is for Optimization, which is like the S-units, but will also perform module-level optimization. It can be mixed with S-units in the same string, where only selective optimization may be needed (such as local shading).
L is for Long Strings, which is like the O-units, but also allows strings in excess length of the standard sizing calculation. It is only available built-in to the module, rather than as an add-on for the installer to mount/connect.
 

pv_n00b

Senior Member
Here's what I see happening with 690.12(B)(2)(2). Inverter manufacturers are going to team up with MLPE manufacturers to provide controllable switches at each module controlled using the SunSpec communication protocol. The Tigo system is ready to go, inverter manufacturers just need to implement SunSpec. SolarEdge and micro-inverters are ready to go today. This is a low cost and low effort move for the manufacturers since most of it is ready to go.

At some point, UL 3741 will be released and then 690.12(B)(2)(1) will be available. I have no idea how viable an alternative that will be though. It might be that doing (2) ends up being easier and cheaper than (1).

Right now manufacturers who might be interested in creating a 690.12(B)(2)(2) compliant solution are waiting to see if the UL standard makes everything else useless and a waste of their money. Why design and build something if the UL Standard makes in useless? In a way having the UL Standard in the wings has been a problem for getting solutions on the shelf.
 

romex jockey

Senior Member
I'm splitting a job with my solar counterpart , which we hope to have passed pre 1-1-19

The RSD specifics juxtaposed to PV make/model confuse me in 690.....

I had thought....possibly in error, that the whole RSD was for FF's venting roofs ?? So i'm confused as to how this impending change compliments that....:?~RJ~
 

jaggedben

Senior Member
I'm splitting a job with my solar counterpart , which we hope to have passed pre 1-1-19

The RSD specifics juxtaposed to PV make/model confuse me in 690.....

I had thought....possibly in error, that the whole RSD was for FF's venting roofs ?? So i'm confused as to how this impending change compliments that....:?~RJ~
I don't think it has much to do with venting roofs, at least not in the typical case. The issue with traditional string inverters with no module level power electronics (MLPE) is that you have up to 600V DC running totally uncontrolled from the array to the inverter on the ground. As long as the sun is shining, nothing is shutting that off. And so it's just a danger to FFs that you have live conductors in the building that don't and won't go dead when they cut utility power.

I used to work in some AHJs that required a DC disconnect on the roof so that these DC wires could be shut down by a firefighter on the roof, and only the array itself would be still live. Technically this solution complies with the 2014 rapid shutdown requirements, since those requirements didn't call for the rapid shutdown switch to be readily accessible. But as micro-inverters and optimizers and other MLPE have taken over market share in residential solar, the code making panel has seen fit to essentially require MLPE since it essentially allows the FFs to ignore the solar as a safety issue apart from shutting down utility power like they've always done.

My only criticism is that it will probably take decades before most of the systems FFs encounter are 2017 RSS compliant, as well as the FFs being well trained enough to understand exactly what the labeling and placarding means.
 
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