[RE-wrenches] Sunny Island sending power to the generator??

Fri Sep 19 10:57:49 PDT 2014

Hi:

The method by which inverters are able to control AC coupled power flow is 
the same as used throughout the grid.  The essence of it is based on a 
characteristic of rotating generating machines, (generators whether motor 
driven, hydro driven or other).  This characteristic is that generators 
slow down when they are overloaded and speed up when they are under 
loaded.

Here's a link to an interesting BBC video about grid management which 
shows this frequency effect on a GW grid scale.

http://www.bbc.co.uk/britainfromabove/stories/people/teatimebritain.shtml
This happens at small scale too and an inverter can be made to 
automatically lower its output power when the AC frequency increases. 
Victron and SMA were the first to use this to achieve AC controlled AC 
coupled charging and it will also work with generators, although due to 
the widely varying power/frequency characteristics of generators setting 
it up can be very challenging. 

I was not aware that there were older SI's which allowed a generator 
connect function, as although possible if things are set up appropriately, 
it will not work with every type of generator.  Perhaps they stopped 
allowing it due to setup frustrations.

Here's a very good paper from Victron Energy about the interaction of 
generators and inverters.  It has test results on efficiency, fuel 
consumption, output distortion, power/frequency characteristics, AC 
coupling, etc.

On our part at Schneider, the XW does not have this frequency controlled 
AC coupled function but the new XW+ does have it, although we will not 
support it for use with generators due to the wide variations in generator 
frequency/power behavior.  In the future things may change.

JARMO
_____________________________________________________________________________________ 

Jarmo Venalainen  |   Schneider Electric   |  Solar Business  |   CANADA | 
  Training & Development Specialist - Senior 
Phone: +604-422-2528  |   Fax: +604-420-1591  |   Mobile: +604-505-0291 
Email: jarmo.venalainen at schneider-electric.com  |   Site: www.SEsolar.com 
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From:
Jay Peltz <jay at asis.com>
To:
RE-wrenches <re-wrenches at lists.re-wrenches.org>, 
Date:
09/19/2014 06:35 AM
Subject:
Re: [RE-wrenches] Sunny Island sending power to the generator??
Sent by:
"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>

There is a setting in some older SI that allows for generator back feed, 
no idea why. It's not in the newest version that I can find (euro).
I had to fix a system ( not mine) and once that setting was fixed no more 
genny issues. 

But overall I believe this inverter has a totally different way it handles 
the generator vs other inverters, ( it has to) so
I'm not sure I agree with the email from Schneider. 

Jay
Peltz power

Sent from my iPhone

On Sep 19, 2014, at 6:11 AM, Tump <tump at swnl.net> wrote:

I too must agree with Kevin, SMA & SI is the kind! (although I have had a 
few fail) SMA IS the ONLY company that will expedite new inverter AND 
compensate monetarily, not just talk but they DO. Yeah its a bit&H when 
the installs are on islands cause their heavy but quality IS there, 
support IS there and their Tech support does acknowledge that the manual 
is complicated and there are places that exist in the manual that don't 
exist in the inverter but they are very patient, (uncomplaining, tolerant, 
resigned, stoical;calm, composed, even-tempered, imperturbable, 
unexcitable, accommodating,understanding, indulgent; informal unflappable, 
cool.)and the product is well worth the additional up front costs! ...... 
No I don't work for SMA! 
On Sep 18, 2014, at 7:45 PM, Kevin Pegg wrote:

Our firm has installed many Sunny Island hybrid gen cycle charge systems. 
In my experience they are hands down the most reliable inverter system out 
there for this application. Many sites that have been working perfectly 
with 100% uptime over several years. Most sites we visit once a year to 
check and there are no issues at all.

There are many small tricks on the install side to get to reliability like 
that. While the menus with the 8 characters and all manner of acronyms can 
be daunting, once it's configured there's generally no changes needed. 
Tying in the webbox option makes it a lot friendlier to program and 
monitor.

My direct experience does not match with the last paragraph comments. The 
only problematic installs we have worked on were installed by others and 
not installed well.

Kevin Pegg 
EA Energy Alternatives Ltd. 
37471 Hwy 16 E 
Telkwa, BC  V0J 2X2 
250-846-9888 
Http://www.EnergyAlternatives.ca
-----Original Message-----
From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org]On 
Behalf Of William Miller
Sent: September 17, 2014 10:23 PM
To: RE-wrenches
Subject: [RE-wrenches] Sunny Island sending power to the generator??

Colleagues:

I was invited to troubleshoot a Sunny Island system.  What I found is a 
Sunny Island mini-grid system behaving oddly.  The generator, when started 
with the SI, would run for a few minutes and then shut down.  Further 
investigation revealed that the SIs were indicating that the inverters 
were sending lots of power back to the generator, even with the Sunny Boy 
turned off. 

I don’t know if this was actually the case, nor can I grasp how this could 
happen.  The system was programmed as a PV/Gen only system.  Fortunately I 
reached an off-grid tech at SMA and we were able to resolve the issue.  I 
am not sure what we did but I suspect that simply rebooting the Sunny 
Islands was the cure.

I post this in case any of you experience this problem and could benefit 
from my experience.  Also, I want to understand this better.  Could it be 
true that the inverters could send power to the generator?  I know the 
circuitry is there to sell to AC2, which is how this system would work as 
a true grid-interactive system, but how did it get triggered?  Was it 
battery-selling to the generator?  I welcome any comments.

What I am starting to think is that the Sunny Island system, like any 
feature rich system, is complicated and has the potential to be less 
reliable than simpler systems.  On the plus side I could also think of 
these systems as job security for the knowledgeable technician.

Sincerely,

William

<image002.jpg>
Lic 773985
millersolar.com
805-438-5600

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