[RE-wrenches] TL inverter with long DC Feeder

Tue Oct 7 17:36:06 PDT 2014

William,

Just to pile on here, if you're running 4 pairs of low-voltage dc for 
400' you may be better off just sticking the inverters right there at 
the array and making the long run as 240Vac. #2s on each inverter output 
(22A?) would work, keeping voltage drop to 1.3%. If you choose to 
combine inverter outputs right there at the array (you'd need ac 
disconnects there anyway) you'd have to run #3/0 for a 1.3% drop. Not 
sure whether that's more feasible for you.

DKC

On 2014/10/7 16:06, Isaac Opalinsky wrote:
>
> William,
>
> What is your string configuration?  The SMA TL inverters have a very 
> low operating voltage window, going down to 125 Vdc, but you still 
> have the issue of the disconnect.
>
> Have you looked at ABB’s (PowerOne) TL inverters: 
> http://www.abb.us/product/us/9AAC179447.aspx?country=US? They can be 
> programmed to operate down to 90 Vdc, and they give you the ability to 
> combine upstream and have the 2 MPPT’s operate as one, allowing you to 
> combine outside of the inverter and bring a single set of PV output 
> conductors to the inverter’s DC disconnect:
>
> *Isaac Opalinsky *| Technical Trainer | *SunPower Corporation*
>
> Desk 443-569-3476 | Cell 443-277-6286
>
> *From:*RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] 
> *On Behalf Of *William Miller
> *Sent:* Tuesday, October 07, 2014 12:01 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] TL inverter with long DC Feeder
>
> Friends:
>
> If only an SMA would work here. But DC volts too low. We are using 
> Solectria PVI5200TLS.
>
> We do not use PV wire. We transition to THWN-2 in conduit immediately.
>
> William
>
>
> Miller Solar
>
>
> On Oct 6, 2014, at 8:30 PM, Chris Mason <cometenergysystems at gmail.com 
> <mailto:cometenergysystems at gmail.com>> wrote:
>
>     I presumed SMA TL series.
>
>     On Mon, Oct 6, 2014 at 10:02 PM, Jerry Shafer
>     <jerrysgarage01 at gmail.com <mailto:jerrysgarage01 at gmail.com>> wrote:
>
>     As i read the thread you say TL which TL SMA, AE ect. They have
>     defferent dc input designs
>
>     On Oct 6, 2014 12:21 PM, "jay peltz" <jay at asis.com
>     <mailto:jay at asis.com>> wrote:
>
>     I do believe the outback and midnite combiners have a lock hole to
>     prevent exactly your concern.
>
>     unauthorized access.
>
>     jay
>
>     peltz power
>
>     On Oct 6, 2014, at 11:40 AM, William Miller wrote:
>
>
>
>     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
>
>     <image002.jpg>
>     Lic 773985
>     millersolar.com <http://www.millersolar.com/>
>     805-438-5600 <tel:805-438-5600>
>
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>
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