[RE-wrenches] Grid-tie Sunny Island

Thu Apr 15 08:25:40 PDT 2010

Regarding the DC disco issue, we have identified the 3-pole, 600Vdc rated,
200A Crouse-Hinds CH364R (
http://www.crouse-hinds.com/crousehinds/newproducts/relatedinfo/Solar%20Combiner%20Brochure%20110309.pdf)
as a replacement for the Square D version.  Its a little pricey but it looks
like the best available option these days.  We are also looking at the
SolarBOS disconnecting combiners - does anyone have any experience with
them?

Andrew Truitt
Standard Solar Inc.

On Wed, Apr 14, 2010 at 3:07 AM, Philip Boutelle <philboutelle at gmail.com>wrote:

> Kirpal and Wrenches,
>
> Can you describe your battery setup with the four Sunny Islands? SMA
> recommends using two parallel 1/0 conductors to each SI DC disconnect, for
> three reasons: wire fill limitations with the 1.5" knockouts they provide,
> ease of landing in the breaker, and because the 125A breaker is
> double-barreled and rated for 125A on each leg with the current flow not
> necessarily symmetric, so you need a rating of approx. 200A on the parallel
> conductors (I'm quoting Martin and Antonio at SMA here, this detail is not
> in the manual but what they recommended to me as best practice. The manual
> at one point lists "2 x 1AWG" for the DC connections, nothing further).
>
> With four SIs, that's eight positive and eight negative 1/0 conductors to
> be bussed from the battery bank, or at least to the SIs. I have a similar
> project coming up and am looking at a custom fuse/bus block from Deltec
> <http://www.deltecco.com/>to arrange/distribute those wires, but would
> love to hear other ideas and experiences on how to go from a single string
> of 48V batteries, through a fused DC disconnect, and then land in the 4 SIs.
>
>
> The fused DC disconnect is also an issue; with 20kW of rated continuous
> power at a worst-case of 41V (numbers from the spec sheets), that's 487A
> *1.25 = 610A. I could break that up into four parallel conductors, enabling
> me to use a 4-pole 200A disconnect w/ 175A fuses (space is an issue on the
> mechanical wall). But do I need to pass the DC conductors through two
> switches on the disconnect to maintain the DC rating on the switch? And if
> so, should I instead use a 4-pole 400A disco with 350A fuses and double
> pass-through on the two positive conductors connecting to the battery bank?
> Or.... ?
>
> Phil Boutelle
>
> Project Engineer
> NABCEP Certified Solar PV Installer TM
> Real Goods Solar, Inc.
>
> 831.477.0943 office
> 831.359.5268 mobile
>
> 831.477.0944 fax
> www.RealGoodsSolar.com <http://www.iesolar.com/>
>
>
>
> On Sun, Apr 11, 2010 at 7:44 PM, Kirpal Khalsa <solarworks at gmail.com>wrote:
>
>> 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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>>
>>
>>
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