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: [email protected]
[mailto:[email protected]]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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