[RE-wrenches] 208 3 phase Off Grid Inverter

[penobscotsolar at midmaine.com]

Hi Ray,
   This works very well with the SI's. We have an off grid, dual SI system
in the Bahamas which uses 5 Classics and 20 kW of PV, along with a 60
kW generator. It's been in for about 6 months and the client is very
pleased. Midnite makes a nice pre-wired panel (8' x4'), heavy, but in
off off grid it's nice to have as much pre-assembly as possible.

Daryl DeJoy
NABCEP Certified PPV installer
Penobscot Solar Design



> I had another related question to add to using the SMA SI inverters:
> Can't we still use regular charge controllers to charge the battery, and
> just use the SIs as inverters, and gen in charging only?
> I don't see justification for the extra cost of an AC coupled system
> here.  The array will be on the garage roof, with equipment below.  Only
> 50 ft run for the PV, so I was planning on using Midnite Classics.
>
> 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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