Re: [RE-wrenches] Tell me what I'm missing on 690.12 B(2)? Where does it say "module-level???"

[Ray]

The Midnite SOB system is up and running.  We have one installed that 
has been working trouble free for about 8 months.


Ray Walters
Remote Solar
303 505-8760

On 4/27/19 12:07 PM, Mick Abraham wrote:

Scot Arey wrote:


"How did “module-level” shutdown get taken as gospel truth??

I’m thinking a Fronius Primo with its RSD Quattro device
mounted on an array rail meets current 2017 code."


Mick here: The issue is that if a Fronius type PV "string" is 
interrupted at the edge of the array, one still has open circuit 
voltage on the string that's much higher than the 80 volt limit. The 
MLPE "module level power electronics"--whether they're microinverters 
or DC optimizers--snub any sum of AC or DC voltage below 80 when 
they're in shutdown mode. Both of those solutions also optimize to the 
level of individual PV modules & they provide granular metering of the 
energy deliveries--but I assume those benefits are of little value to 
the project you're planning, Scot.



I don't know the availability status for Midnite's SOB "Shut Off Box", 
but this segments the PV string during shutdown & it gets the voltage 
below 80 without the expense of optimization & granular monitoring. 
There are still "electronics" behind each PV module because these 
shutoffs are triggered by radio but it's not MLPE in the usual sense & 
the cost is relatively low since all they're doing is opening 
contactors. I hope this reply is helpful.



The Wrench List is The Bomb!

Mick Abraham, Proprietor

www.abrahamsolar.com 

Landline: 970-731-4675
Cell phone or for text messaging: 970-946-6584
ᐧ

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Re: [RE-wrenches] Tell me what I'm missing on 690.12 B(2)? Where does it say "module-level???"

[Mick Abraham]

Scot Arey wrote:


> "How did “module-level” shutdown get taken as gospel truth??

I’m thinking a Fronius Primo with its RSD Quattro device mounted on an
> array rail meets current 2017 code."


Mick here: The issue is that if a Fronius type PV "string" is interrupted
at the edge of the array, one still has open circuit voltage on the string
that's much higher than the 80 volt limit. The MLPE "module level power
electronics"--whether they're microinverters or DC optimizers--snub any sum
of AC or DC voltage below 80 when they're in shutdown mode. Both of those
solutions also optimize to the level of individual PV modules & they
provide granular metering of the energy deliveries--but I assume those
benefits are of little value to the project you're planning, Scot.


I don't know the availability status for Midnite's SOB "Shut Off Box", but
this segments the PV string during shutdown & it gets the voltage below 80
without the expense of optimization & granular monitoring. There are still
"electronics" behind each PV module because these shutoffs are triggered by
radio but it's not MLPE in the usual sense & the cost is relatively low
since all they're doing is opening contactors. I hope this reply is
helpful.


The Wrench List is The Bomb!



Mick Abraham, Proprietor
www.abrahamsolar.com

Landline: 970-731-4675
Cell phone or for text messaging: 970-946-6584
ᐧ
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