[RE-wrenches] SMA $0 series DC disconnect

[billbrooks7 at sbcglobal.net]

William,

 

I’m not sure you meant to imply this, but carports and groundmounts do not need any RS equipment unless you were to bring the dc conductors into a building, which would not be smart.

 

The 2017 NEC allows connectors to be used as isolation devices for equipment as long as the circuit current is below 30 amps, which it always is on individual strings. I realize California will not be on the 2017 for 3 years, but it will make installations cheaper, not more expensive. 

 

Electronics are destined to become a bigger part of PV arrays in the future—and not just because of rapid shutdown requirements. It just makes sense in building applications for many reasons. The keys will be cost and reliability.

 

Bill.

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William Miller
Sent: Tuesday, December 13, 2016 5:39 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: [RE-wrenches] SMA $0 series DC disconnect

 

Friends:

 

I am taking a poll to see if any of you have noticed the change in the SMA 40 series DC disconnect as compared to earlier series inverters and how it may be affecting your installations.  The DC disconnect is no longer in the lower, connection box area, but in the electronics area.  This means it will not de-energize the DC connections.  Certain jurisdictions will not allow us to install this unit without an external disconnect.  The service manual addresses the subject. 

 

The Remote Shutdown Box unit may provide a means to de-energize PV sources, but in a webinar today SMA claims it does not meet code, possibly in regards to lock-out capability.  It actually looked viable to me, but that is not based on any research.

 

Soon all or most building mounted PV arrays will require Rapid Shutdown.  This will add hundreds of dollars to the cost of an install, but safety is safety.  What may sting is adding $400-500 of RS equipment to a carport or ground mount where it may not otherwise be required.

 

SMA has concurred that the issue bears further discussion and I should hear back from them soon.  In the meantime, I thought it might be useful to all parties to see how much impact this change in design is having to other installers.

 

Thanks in advance for any input.  I will report back on what I learn.

 

William Miller

 

 


Lic 773985
millersolar.com <http://www.millersolar.com/> 
805-438-5600

 

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