I'll let Robin weigh in here as well...
Brian, It used to be very clear on the older 5048 Sunny Island. They
wanted a 70 amp breaker connected to the input. They were assuming a
thermal breaker. 70 times .8 = 56. We use hydraulic/magnetic breakers.
They only go up to 60 amps and can be ran at full current continuously.
You cannot feed a 56 amp circuit with less than a 56 amp breaker, so 60
works just fine. The Sunny Island does shut down above 56 amps. SMA is
not counting on a breaker to keep from breaking the inverter. That would
never work. The breaker is there to protect the wiring, not the relay or
anything else in the inverter.
Thanks,
Robin
On 7/4/2014 11:30 AM, Brian Teitelbaum wrote:
Thanks for the clarification boB.
I would still however like to get confirmation from that the Sunny
Island does indeed protect itself from AC current over 56A. It says
nothing to this effect in the literature (at least that I can find),
and would seem to contradict the "Higher input currents must not be
connected to the Sunny Island" that it actually does say.
Steve, if you see this, could you please confirm the automated AC
current protection circuitry?
If we don't get a reply from Steve on this list, I'll contact him
directly and post his reply here, although it might be after the
Intersolar show next week.
Brian Teitelbaum
AEE Solar
*From:*RE-wrenches [mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of
*[email protected] <mailto:[email protected]>
*Sent:* Friday, July 04, 2014 11:11 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Sunny Island retrofit
The Sunny Island has circuitry to protect itself over 56 amps. I
think it shuts off.
The 60 amp circuit breaker is there to protect the wiring. Customers
complain when they cannot
get the full 56 amps from the system and 50 amps is the next nominal
current breaker below 60 A.
Thanks,
boB
On 7/3/2014 11:09 PM, Brian Teitelbaum wrote:
Yes it is. But since you have to install inverters based on the
manufacturer's requirements, SMA's instructions trump MidNite's,
IMHO.
Since MidNite and SMA worked jointly together to develop those
E-Panels, I can only assume that either it's an oversight on both
of their parts, or that SMA is being very conservative on the
switch rating in their installation manual and "Technical
Description", where that line I quoted is repeated. This wouldn't
surprise me, but if so SMA needs to issue a correction.
Maybe boB at MidNite or Steve from SMA will pipe in with some info...
Brian Teitelbaum
AEE Solar
*From:*RE-wrenches
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of
*Ray Walters
*Sent:* Thursday, July 03, 2014 10:18 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Sunny Island retrofit
A 60 amp continuously rated AC breaker is what is actually being
used in the UL listed E Panel from Midnite.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 7/3/2014 9:01 PM, Brian Teitelbaum wrote:
Mac,
Be careful with breaker sizing here. The transfer switch in
the SMA SI5048 is only rated for 56A at 120 VAC. From the SI
manual:
"The maximum input current allowed on the Sunny Island is 56
A. Higher input currents must not be connected to the Sunny
Island."
To protect that switch properly, you would need to use a 50A
breaker (unless you can find a 55A breaker that fits in your
AC panel). Since most common AC breakers are only rated for
80% duty, you would need to limit that 50A breaker to a
continuous 40A load. That's more than the max output current
of the Fronius 10.0-1, although it's debatable that the output
of a PV inverter is "continuous". It certainly could be in
some situations, especially with a tracker mount, although
even with a fixed array, you could see max rated output for at
least a couple of hours per day.
I agree with the suggestion of putting part of the PV array on
a 5kW Sunny Boy, or adding a second Sunny Island and using two
Sunny Boy 5000's. Using two Islands would eliminate the need
for a transformer, and allow for full array power during grid
outages.
Brian Teitelbaum
AEE Solar
*From:*RE-wrenches
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf
Of *Mac Lewis
*Sent:* Thursday, July 03, 2014 9:34 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Sunny Island retrofit
Hi Wrenches,
Jerry, I think you are correct, sma gear all around would be
best. This will be my recommendation but I am sensitive to
this substantial cost.
Dave, if I add the second Sunny Island, I don't think I will
be throttled back because the transfer relays are rated for
60A. This should pass the full current of the output of the
Fronius, which is 41.7A. My concern is more during backup
mode, if the Sunny Islands could "trick" the Fronius into
staying on line. I would add either load dump relay control
or an AC interrupt relay to knock the Fronius off-line if the
batteries were full, in addition to the frequency shift
control that the Sunny Island offers.
Thanks for the input, I'll shoot for all SMA gear.
Thanks
On Thu, Jul 3, 2014 at 9:23 AM, Dave Click
<[email protected] <mailto:[email protected]>> wrote:
Mac, that Island interconnects with a max 70A 1P breaker
(6.7kW continuous), so unless they have a constant critical
load draw or the Fronius is massively oversized, you probably
don't want to AC couple the Fronius. The 5048 is also able to
output a continuous 5000W only when it's cooler than 77F and
it derates above that (4500W at 95F, for example). I don't
believe its surge ratings apply to the AC2 output back into
the utility but they probably wouldn't be enough, anyway. I
think that whenever the Fronius output reached about 6000W,
the SI would shift its frequency to switch the Fronius off.
Cheapest may be along the lines of your first option-- not
sure what the PV stringing is like but maybe you could move a
string or two off the Fronius and put it onto a new Sunny Boy
with an autoformer. Since I imagine this system doesn't have
PV WIRE on the module leads or home runs, officially I'd
recommend a classic Sunny Boy. Then leave the Fronius as-is.
Unless of course the customer thought they were buying a
system with the full 10kW supplying critical loads when the
utility is down... then the original contractor is stuck with
buying the second SI they should have installed in the first
place.
DKC
On 2014/7/3, 10:46, Mac Lewis wrote:
Hello wrenches,
I wanted to run this scenario by the forum. I have spoken
with SMA about this, but want some other opinions.
We were recently contracted by a fellow solar company to
do some warranty work for them out of town on a Sunny
Island system that they had installed about 5 years ago.
It was VERY poorly implemented originally and was never
installed as SMA intended. In fact, during a small power
outage, the only loads that never came back on after the
utility was back on line were the loads in the critical
load panel. Oops.
Anyway, our job is to get it working properly for the
least amount of cost possible. They have a Fronius IG
Plus 10.0 fed into a 400A service panel. The Sunny Island
5048 AC Input also comes off of this panel and feeding a
120V only critical load panel. Please note that there is
no solar fed into the AC output side of the Sunny Island,
because there is not 120/240 available and thus there is
no possible way for this system to utilize the solar while
the grid is not present.
I see two options (but there may be more): pull out
Fronius, put in Sunny Boy inverters and an autoformer,
wire properly. Another option is to add second Sunny
Island and try to AC couple the Fronius with the two Sunny
Islands. The second option is less expensive overall, but
I'm hesitant to rely on AC coupling with the Fronius.
I'd appreciate any thoughts on this.
Thanks
Mac Lewis
"Yo solo sé que no sé nada." *-Sócrates*
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