When the Grid shuts off, the SI sends a signal to the SB's to go into what is 
called "Back-up Mode" (this is a parameter change in the SB).

When there are no loads and the Batt are full, the SI will ramp the Frequency 
up, thus forcing the power from the SB to drop down to close to zero watts, the 
SB never disconnects fully.
As soon as there is a load, the frequency drops, SB output raises and provides 
power to the protected loads.
The changing of the parameter in the SB, opens the window of the frequency to 
allow for this feature.

It will work with other brand inverters but, they would need to be in off-grid 
mode all the time (which is out of the standard UL settings). If not in 
off-grid mode, other inverters will go into the 5 minute waiting period before 
trying to reconnect, then if the Hz is not back within the UL range, it will 
wait another 5 min.

Thanks

SMA America, LLC
Steve Jefferson
Sr. Technical Service Specialist, Sunny Family
6020 West Oaks Blvd, Suite 300
Rocklin, CA 95765 - 3714
U.S.A.
Tel:  +1 916 625 0870
Fax: +1 916 624-2445
Service Line +1 877 697 6283 (Toll Free)
Email: steve.jeffer...@sma-america.com
www.SMA-America.com<http://www.sma-america.com/>

This email and any attachments thereto may contain SMA America, LLC 
confidential, privileged and private material for the sole use of the intended 
recipient. Any review, copying, or distribution of this email (or any 
attachments thereto) by others is strictly prohibited. If you are not the 
intended recipient, please contact the sender immediately and permanently 
delete the original and any copies of this email and any attachments thereto. 
Thank you.

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Glenn Burt
Sent: Monday, March 05, 2012 6:18 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Grid-Tied, PV by AC or DC

As I understand it, the SI to SB connection works slightly differently than 
described below, and this is borne out by my experience, and a lot of 
re-reading the SMA literature;

Grid goes away - SI shifts to a voltage source for the SB
SI communicates with SB and tells it to operate in off-grid mode, widening its 
voltage window outside of the UL 1741 usual values
Batteries full & no loads, SI shifts the frequency of its micro grid slightly 
and SB will eventually drop off line. This is why it also works with other 
manufacturers inverters because it does not rely on the SMA proprietary data 
comms to make this happen.
SI continues to monitor its loads and the grid and during the night it will 
shift the freq of its micro grid slightly in the opposite direction to 'make 
up' for the period it used this to remove the SB, allowing things like clocks 
that use the 60Hz of the grid to regain time.
SI detects return of grid - communicates with SB and returns it to normal UL 
1741 mode

Glenn Burt

From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Larry Brown
Sent: Sunday, March 04, 2012 11:13 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Grid-Tied, PV by AC or DC

Jay,

We have installed a number of AC Coupled systems using Sunny Boys and Sunny 
Islands.  One important consideration in this approach is to connect the 
inverters (Sunny Boys and Sunny Islands) together with a communication cable 
and Communication Cards and to upload new software into the Sunny Boys that let 
them know when the grid is down to operate in off grid mode. In this way when 
the grid is down the Sunny islands can limit the output of the Sunny Boys to 
meet the demand of the loads in the protected loads sub panel. Without the 
communication between the inverters, if the grid is down and the output of the 
Sunny Boys exceeds the demand of the loads in the protected load sub panel, 
then the Sunny Island will phase shift and the Sunny Boys will completely 
disconnect and then wait five minutes to try and connect again and will 
continue to do this until the output of the Sunny Boys does not exceed the 
demand of the loads.   So it is all or nothing without  communication between 
the inverters.  This would seem to hold true as well for Sunny Islands mixed 
with any other Grid Tied inverters that are not of the SMA family and can not 
effectively talk to each other.

Larry

Larry Brown
Sun Mountain
NABCEP Certified PV Installer


On Mar 4, 2012, at 10:25 AM, jay peltz wrote:

HI Darryl,

Is this a UL listed application for the Radian/Outback?

And in following this thread about AC coupled:
Given the higher efficiency of the batteryless inverter and fantastic MPP, vs 
the relatively high losses with the 600v xantrex or standard CC/inverter 
losses, I would use the AC couple technique.

Jay

peltz power


On Mar 3, 2012, at 8:06 AM, Darryl Thayer wrote:

A few years back I made some year long measurements on an outback GVFX and a 
sunny boy for net energy to the grid I got only a few percentages not 10%  I 
think one of the problems is the battery selection, these new batteries from 
Outback seem to have very low self discharge so very little energy should be 
expended to keep them charged.  I am trying to close on a system where the 
distance from the solar array to the house is far, so I am planning to AC 
couple to a Radian to the grid, and I have been sucessful with AC coupleing on 
GVFXs and Outback assures me it will workas well with theRradian.  This install 
is very sensitive to LOL (loss of load) and has the generator ready to go, but 
for the short outages that he has it is a hassel.  (he has worn out one 
generator all ready, it was a construction grade genny)

I am hoping if this system is a go to consider a Xantrex 600 volt charge 
controller, but it depends upon the customer
thanks for the patence
Darryl

From: Drake 
<drake.chamber...@redwoodalliance.org<mailto:drake.chamber...@redwoodalliance.org>>
To: RE-wrenches 
<re-wrenches@lists.re-wrenches.org<mailto:re-wrenches@lists.re-wrenches.org>>
Sent: Friday, March 2, 2012 9:31 AM
Subject: Re: [RE-wrenches] Grid-Tied, PV by AC or DC

I think the AC coupled approach would be the best.  For the 10KW system, a pair 
of Sunny Islands fed by Sunny Boys would make an efficient system.  Since there 
is no generator, the system should be fairly straight forward.

At 02:06 AM 3/2/2012, you wrote:

i think mark was asking more about ac coupling to get away from the horrible 
inefficiencies of battery based, grid-tied inverters.



as an experiment, i have been thinking about ac coupling one (or more) of my 
arrays on my outback system to gain 10% over having the gvfx do the selling.



stc to ptc usually costs about 20%, then losing another 10% in the inverter is 
a real performance hit. i advise customers about phantom loads and 
conservation, when actually the battery based inverter is itself the big lump 
under the carpet!



todd











On Thursday, March 1, 2012 7:07pm, "Maverick Brown [Maverick Solar]" 
<maver...@mavericksolar.com<mailto:maver...@mavericksolar.com>> said:

My two cents:
"battery-based inverter w/ PV on the DC side via charge controllers"
Simply replace the GT inverter with a Xantrex 600V Charge Controller plus the 
48V Grid Interactive Inverter of your choice and added battery bank, etc.
Until the market is saturated with unneeded GT Inverters, you will be ok. ;-)
Try your best to provide enough battery for at least 24 hours of outage at 50% 
DOD. You may have add a Sub-Panel or Manual Transfer Switch.
Thanks
Maverick
Maverick Brown
BSEET, NABCEP Certified Solar PV Installer ® # 091209-26
President & CEO
Maverick Solar Enterprises, Inc.
Billing:  PO BOX 1229, Dripping Springs, TX 78620
Office:       512-919-4493
Fax:           512-607-6398
Cell:          512-460-9825
Corporate: http://www.mavericksolarenterprises.com/
From: 
re-wrenches-boun...@lists.re-wrenches.org<mailto:re-wrenches-boun...@lists.re-wrenches.org>
 [ mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of 
toddc...@finestplanet.com<mailto:toddc...@finestplanet.com>
Sent: Thursday, March 01, 2012 5:46 PM
To: RE-wrenches
Cc: 'RE-wrenches'
Subject: Re: [RE-wrenches] Grid-Tied, PV by AC or DC

excellent question mark... and one which has been on my mind as well, being 
most of my work is bbgt.



todd







On Thursday, March 1, 2012 11:37am, "Mark Frye" 
<ma...@berkeleysolar.com<mailto:ma...@berkeleysolar.com>> said:

Folks,

I have a residential grid-tied customer in a net metered utility with a 
favorable TOU rate.

They could use about 10 kW of PV to offset 100% of their usage.

But, they also complain about regular power outages in their neigborhood. They 
don't want a generator.

With reliable AC coupling now available, do we yet know which is the more 
advantagous architecture; grid-tied, battery-based inverter w/ PV on the DC 
side via charge controllers, or grid-tied, battery-based inverter w/ PV AC 
coupled via grid-tied, utility-based inverter?

Your thoughts?

Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
www.berkeleysolar.com<http://www.berkeleysolar.com/>



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