[RE-wrenches] 208 3 phase Off Grid Inverter

Tue Mar 25 21:51:29 PDT 2014

Hi Ray,

The Sunny Islands are capable of working with DC input if you include a
shunt on the battery side (see page 52 here
http://files.sma.de/dl/15216/SI4548_6048-US-TB_en-13w.pdf), and Midnite
will have a comm box that makes it look like an SMA device in the SMA
network.  I'm not sure if you still need this shunt if you include this in
your design.  This is supposed to be out any day now.

Sounds like a fun project.

On Tue, Mar 25, 2014 at 10:37 PM, Ray Walters <ray at solarray.com> wrote:

> Thanks Kevin;
>
> I follow what you are saying on the charge algorithm:  both the inverter
> and charge controller are very smart, but aren't talking to each other,
> which makes for a dysfunctional family with the batteries being the
> neglected kids.  In this case, I could see that a full on SMA solution
> would work nicely: Sunny boys AC coupled, SIs hooked up with the
> Multicluster box, etc.
> I yearn for those good, old days, when I could  build dream systems, while
> charging full retail.  Lately, I work twice as hard just to build systems
> that will still work on much tighter budgets.
> I'll hit up the folks at SMA, as I think that SIs will be in the mix in
> some fashion.
>
>
> R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
>
> On 3/25/2014 10:08 PM, Kevin Pegg wrote:
>
>> Hi Ray,
>>
>> Suggest you give the techs a call @ SMA and get some design assistance.
>> They are good.
>>
>> Sunny Islands can be used as regular inverter/charger units yes.
>>
>> >From my experience, we have done 1 string of 3 SI inverters (ie 18 kW @
>> 120/208) without the multicluster box. Anything larger than 1 string we
>> have always used the MC box. I believe it's required - or at least the
>> control board that handles communication between inverters is required. The
>> MC cabinet is very nicely done and makes inspectors very happy this is for
>> sure.
>>
>> As far as DC input from charge controller ie Classic yes this is also
>> possible. Screws up the inverter's very smart battery charge algorithm,
>> however. So there is a trade-off there. It will depend how much this site
>> is relying on diesel vs PV input.
>>
>> Kevin
>>
>> -----Original Message-----
>> From: re-wrenches-bounces at lists.re-wrenches.org
>> [mailto:re-wrenches-bounces at lists.re-wrenches.org]On Behalf Of Ray
>> Walters
>> Sent: March 25, 2014 4:37 PM
>> To: RE-wrenches
>> Subject: Re: [RE-wrenches] 208 3 phase Off Grid Inverter
>>
>>
>> OK everyone is steering me towards the Sunny Island.   I can probably
>> justify the inverter cost difference to the customer, then I found the
>> SMA Multicluster Box for the SI.  It seems like a glorified AC Combiner
>> and transfer switch box, but it retails for over $20K! Yikes.
>> Do we have to use that for a 3 phase install, or are there much lower
>> cost alternatives.  This is out of the country and does not need to be
>> NEC2014 compliant.  (maybe NEC 1956 compliant would be about in keeping
>> with the rest of the wiring.......)  This would be a budget buster for
>> sure.
>>
>> R.Ray Walters
>> CTO, Solarray, Inc
>> Nabcep Certified PV Installer,
>> Licensed Master Electrician
>> Solar Design Engineer
>> 303 505-8760
>>
>> On 3/25/2014 4:21 PM, Kevin Pegg wrote:
>>
>>> Hi Ray,
>>>
>>> I have several 3-phase off-grid inverter/battery/generator systems out
>>> there.
>>>
>>> - SMA Sunny Island is the best. Can scale to at least 180 kW, maybe
>>> more. Reliable & very solid. I have several sites going over 2 years
>>> without a single second of power outage.
>>> - Xantrex XW. It can work in a 3-ph config, but it's not as stable
>>> system. We have taken to preventatively rebooting the systems every 4
>>> months and that helps a lot - at least the outage can be planned and on our
>>> terms.
>>> - Outback has had so many power quality nightmares I won't go there
>>> anymore.
>>> - I believe Magnum has a 3-ph option but haven't installed one yet.
>>>
>>> SMA inverters are more expensive. And they work very well. They also
>>> have a very good battery charging algorithm and integral gen start control.
>>>
>>> Kevin
>>>
>>> -----Original Message-----
>>> From: re-wrenches-bounces at lists.re-wrenches.org
>>> [mailto:re-wrenches-bounces at lists.re-wrenches.org]On Behalf Of Ray
>>> Walters
>>> Sent: March 24, 2014 6:44 PM
>>> To: RE-wrenches
>>> Subject: [RE-wrenches] 208 3 phase Off Grid Inverter
>>>
>>>
>>> Hi All;
>>>
>>> I'm exploring options for an off grid project with an existing 30 Kw
>>> Kohler wired for 208 vac 3 phase.  The generator runs some 8 hp air
>>> compressors, so rewiring it is not an option.  We're primarily
>>> interested in reducing gen run time from the current situation: 14 hrs/
>>> day.
>>> So far, only the Outback VFX inverters seem capable of being wired in
>>> 208, 3 phase, but according to the manual they can only be stacked 1
>>> inverter per leg. This limits the system to only 3 inverters total, or
>>> 10.8 kW.  I would like expandability beyond this.
>>> 1) are there any other inverters available that I'm over looking?
>>> 2) Should I consider a transformer to convert from 208 vac/3phase to 240
>>> vac/ singe phase?
>>>
>>> We're not going to even try to run the compressors, just the other
>>> single phase loads, mostly 120 vac, but we have a couple of small air
>>> conditioners, that are currently running on 208 single phase.  I believe
>>> they would run fine on 240 vac, as they have a name plate rating at 230
>>> vac.
>>> 3) We may possibly run 2 separate 3 inverter stacks and only tie
>>> together at the battery, but otherwise they would not be connected. This
>>> seems inefficient, and would require some load balancing of the various
>>> inverters.
>>>
>>> All help and discussion is greatly appreciated as always,
>>>
>>>  _______________________________________________
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-- 

Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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