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:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *b...@midnitesolar.com *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:re-wrenches-boun...@lists.re-wrenches.org] *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:re-wrenches-boun...@lists.re-wrenches.org] *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 <davecl...@fsec.ucf.edu> 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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