[RE-wrenches] Sunny Island Battery Disconnects

Brian Teitelbaum bteitelbaum at aeesolar.com
Fri Feb 7 18:28:18 PST 2014


William,

Are those the older Sunny Island 4.2 or 5kW units, or the newer 4.5 or 6kW units?

Is this single-phase or three phase?

The SMA BATFUSE would work, but it is not available in the US. It's not Code compliant nor UL Listed.

You could use the OutBack FW1000-DC, but you are going to have a little fun doing the DC cabling and conduit. The older Islands had dual 1/0 battery terminals. The newer ones have a single 3/0 terminal. Unfortunately, those sizes are hard to find in proper flexible battery/inverter cable, mostly because it doesn't sell in enough volume for distributors to carry. It also doesn't properly match available DC breaker sizes, like 4/0 and 2/0 cable does.

SMA worked directly with MidNite Solar to develop the MidNite E-Panel system for the Sunny Islands. It's what I would recommend using. For one thing, they have dealt with the DC cable and fusing size issues (and, no, you are not blind). You can run 2/0 (4.2 or 4.5kW units), or 4/0 (5 and 6kW units) to the E-Panels

However, I don't know offhand if they work with the older Islands. If you are dealing with the older units, you should contact them to confirm that they will fit.

If it's three-phase at 208 VAC, I also recommend that you use one of the MidNite three-phase Master units (MNE250SMA-3PH-Master) and two slaves. It has a three-phase bypass switch and color-coded bus bars for a full three-phase system. There isn't a whole lot in there that you won't likely use. The AC output on the bypass will just act as an AC main breaker. You can then run that to an external load center.

Now, the distance from the battery bank issue is new. These systems have been installed for a couple of decades now with up to 12 feet between the battery and the first disconnect, breaker, or fuse. Of course, that doesn't make it right, or compliant with the 2014 Code. The industry really needs to come up with a good solution here. The Wrenches thread over the last few days about placing fuses on or near batteries shows that an easy solution is not available (or not known), at least not for flooded batteries.

Brian Teitelbaum
AEE Solar

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of william at millersolar.com
Sent: Friday, February 07, 2014 5:29 PM
To: 'RE-wrenches'
Subject: [RE-wrenches] Sunny Island Battery Disconnects

Friends:

I am reworking an installation with 3 Sunny Island inverters.  The battery leads have no disconnecting means or OCP.  I have been looking for sensible hardware to provide this and I have found some options.  I am interested in any input on these or ideas I have not discovered.


1.       SMA BATFUSE.  I am having trouble deciding which one is right for a 3 SI install.

a.       The B.003 appears to have fuse positions for the positive and the negative leads.  I am fairly darn certain I don't want fuses in the negative leads of a negative bonded system, and although this is my first SI install, I am pretty sure this is negative bonded.  Am I missing something here?

b.      The B.001 has only positions for two fuses as far as I can see from the manual.

c.       So it looks like neither will work for me.  Does anyone have any experience and/or wisdom here?

2.       Midnite Solar E-panels:

a.       The regular panel has DC and AC components.  I want to control the AC elsewhere so I could order three slave units.  The Midnite unit mounts right under the inverter but I would prefer to have the OCP closer to the batteries.

3.       Outback:

a.       We could purchase an Outback FX1000 and install three breakers in it.

4.       Breaker Size:

a.       I have started to read the manual but I have yet to find out what size breaker fuse is recommended.  Have I just not found it yet?

b.      Also, I have not found a specification for battery cable size.  Am I blind?

Thanks in advance.  I really appreciate the help I receive here.  I try to give as well as receive.

William


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