[RE-wrenches] Grid-tie Sunny Island

Sun Apr 11 19:44:19 PDT 2010

Dave----this is exactly what the sunny island is capable of.....supply the
house panel from the sunny island output, and the main panel in the barn to
the input side, the house panel will run full time via the sunny islands,
install a MANUAL transfer switch for times when the sunny islands may need
to be turned off or removed for maintenance, I can't remember all the
parameters of the programable relays in the sunny island but more than
likely one of them is a warning, possibly to notify of no AC source.   also
you can pass power thru the relays in the sunny islands so no external relay
is required.    the beautiful thing about the sunny island/sunny boy set up
is you actually are able to get a full multi stage charge process on your
batteries during a power outage unlike most other AC coupled combinations
which are simply a charge or no charge, taper not included.
there are 2 programmable relays on each sunny island so in a dual inverter
system you still have other relays available for other things like battery
room fan control, or gen start.
we have a similar system to yours up and running using  4 sunny islands and
4 sunny boys, flawlessly so far......
good luck..
For technical help or advice for your system I strongly recommend talking to
Tucker in the service department over at SMA.......he knows the ac coupling
set up, and system commissioning steps really well and will be able to make
your job easy.....

-- 
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-592-3958 o

2010/4/11 Richard L Ratico <Richard.L.Ratico at valley.net>

> Hi Dave,
>
> Depending on the house loads, you might very well do without an additional
> (very
> expensive) auto transfer switch. The inverters, of course, already have
> one.
> Just leave the Sunny Islands connected 24/7.  The transfer from grid to
> battery
> is then milliseconds and flawless. The 56 amps continuous, and deep SI
> surge
> capacity will most likely, comfortably, handle the whole shebang. I've got
> a
> single SI5048 doing this now through a transformer. Works great.
>
> Put a manual transfer switch at the barn in the event there's ever a
> problem
> with the SI's. But, Iota makes a 100 Amp auto transfer switch, if you
> decide
> you've got to have one. It is attractively priced compared to anything else
> I
> could find. Beware, it may not be UL listed. I've got one, haven't used it
> yet.
> Let me know if you're interested :-)
>
> During a recent severe weather event, our customer's utility was down for 5
> days. Battery lasted 24 hours before shutting down the system to
> self-protect,
> as designed and programmed. We had to round up a generator in a hurry to
> "backup
> the backup". A previously installed a manual transfer switch, with the
> exterior
> generator inlet, made that relatively painless, but it was something we
> hoped
> would never be needed. As you know, you also need SMA communication boards
> and
> the SMA programming cable to get the Sunny Boy to work with the SI's when
> the
> grid is down.
>
> Regards,
> Dick Ratico
> Solarwind Electric
>
>
> I
>
> --- You wrote:
> We have a new (for us) application for grid connected net-metered PV with
> battery back-up as follows. The twist is that the entire load center in the
> house will be the "protected loads panel".
>
> -          5kW PV ground mount located 250 feet East of their barn.
>
> -          Will utilize AC Coupled SB5000US inverter to (2)Sunny Island
> 5048's for 120/240VAC back-up capability with 24.5kWh back-up battery bank.
> All inverters/batteries to be located in barn.
>
> -          Barn has 200A service from grid (PV system AC point of
> connection
> will be there), house is located 175 feet West of barn and has a 100A load
> center (sub panel from barn).
>
> -          Intention is to back up house as the protected loads panel fed
> by
> the Sunny Islands in case of grid failure.
>
> -          The Sunny Islands will be able to pass through up to 56 Amps at
> 240VAC.
>
> -          I want to supply the 100A house load center with up to 100A
> during normal operation with grid available. I am proposing to use an
> automatic contactor/transfer switch to feed the 100A house load center.
> Normally Closed contacts from grid power, N.O. contacts fed by Sunny
> Island.
> Therefore normal operation will be for grid to be connected directly to
> house 100A load center and under grid failure the transfer switch will
> connect the Sunny Islands to power the 100A house load center. Under grid
> failure condition we will have an LED signal light come on to warn the
> homeowners that they are on battery power.
>
> Questions for wrenches:
>
> 1)      Is that whole thing a viable idea?
>
> 2)      100 Amp automatic transfer switch recommendations?
>
> 3)      LED signal light recommendations?  Or is there another method to
> warn homeowner of grid down status?
>
>
>
> Thanks,
>
>
>
> Dave
>
>
>
> David Palumbo, NABCEP Certified PV Installer
> --- end of quote ---
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