[RE-wrenches] TL inverter with long DC Feeder

[William Miller]

Mike:

 

If I have just two strings of Solarworld SW275 modules per inverter, can I
use one input to the built-in combiner to feed in a combined string?  My
calculations indicate that I might be able to feed the two strings into one
25 amp KLKD fuse.  The Isc is 8.94.  times 1.25 = 11.715.  Times 2 = 22.35.

 

The manual says use of any fuse higher than 20 amps voids the warranty.
Could an exception be made if only one set of 25 amp fuses were installed?

 

William

 

 

PS:  I am not sure fuses are required in a combiner with just two strings.
The SW275 module can withstand 16 amp external feed (from the max fuse
rating).  A parallel module will output 8.94 times 1.56 or 13.95. This is
less than the 16 amps.  This used to be allowed in earlier versions of the
code,  I will have to look and see if it still is.

 

Wm

 

 

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

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of Michael Kelly
Sent: Monday, October 06, 2014 3:10 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] TL inverter with long DC Feeder

 

Hi William,

 

I wanted to let you know that currently, there is no bypass terminal to
allow for combining at the array in this series of inverters. We have gotten
a lot of feedback from customers that this is a required feature. Working
toward that, in the next few months, we will phase into production an update
that will include a bypass, but the existing stock does not have the
feature.

 

I wanted to let you know so you could plan appropriately.

 

Best,

Mike

 

Michael Kelly

 <http://www.solectria.com/> Solectria_Yaskawa_signature_logo

HQ: 360 Merrimack Street, Bldg 9, Fl 2, Entrance I, Lawrence, MA 01843 USA

O: +1 978-683-9700 x167 | F: +1 978-683-9702

mike.kelly at solectria.com | www.solectria.com <http://www.solectria.com/> 

 

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Thank you.

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of William Miller
Sent: Monday, October 6, 2014 14:40
To: RE-wrenches
Subject: [RE-wrenches] TL inverter with long DC Feeder

 

Wrenches:

 

We are getting up to speed on using transformer-less inverters.  I have
advocated long for the additional safety offered by these inverters but I am
realizing the trade-offs with the new technology:  The implementation gets
more complicated with the requirement for PV wire, OCPD and disconnecting
means for plus and minus and plus providing  Arc Flash rated equipment.

 

I am currently designing a system that will locate the PV about 400 feet
from the residence.  The system will utilize 2 Solectria 5200 watt inverters
at the residence.  I would like to provide disconnecting means for the 4
strings at the array, in case of any needed service or excavating.
Preferably I'd like the disconnecting means to be deployable by a lay person
(i.e. the gardener).

 

Finding an 8 pole, arc flash, 600 VDC rated disconnect is not easy.  I could
install an Outback 8 circuit combiner with 8 touch-safe fuse holders.  The
new combiners have had dead-fronts for a while now.  The gardener needs only
to have a Philips screw driver to open this cover.  Any better ideas out
there?

 

Thanks,

 

William

 

 

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

 

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