I was recently told by SMA that in the event that
the inverters did connect to generator output,
and the load was less than the inverter output,
that the voltage would rise and the inverters
would fall off line. A year or so before I'd
been told by another SMA representative that
generator circuit boards had been fried by inverter backfeed.
It would be very good to get to the bottom of this one.
At 10:10 PM 3/1/2010, you wrote:
Hi folks:
(Eric, by 'directly to the utility grid' I do mean with a breaker)
Jason and Allen, I agree with what you are
saying, in theory, but in practice, it is not
always possible. I am installing a generator
in a couple of weeks for a customer with an
existing 9 KW array. The property's main
service is located at a separate building from
the house, loads, and solar. The main panel
feeds 200 Amps to the main residence and 200
Amps to a barn building (300 ft away) The barn
building has the array at it, and also the well
pump, which needs to be backed up by the
generator. This requires us to either dig a
300' trench or just leave the system in
auto. We will be utilizing a 200A Automatic
Transfer Switch, but we will not be able to
place the generator into Auto mode. The
customer understands the situation, and said
that he would leave the genny in 'manual' start
mode. I feed good about the situation, will
disable the auto-start system, and will provide competent labelling.
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037
From: Jason Szumlanski <ja...@fafcosolar.com>
To: re-wrenches@lists.re-wrenches.org
Sent: Mon, March 1, 2010 3:50:23 PM
Subject: Re: [RE-wrenches] Generators and Grid-tie Systems
This is déjà vu.
I would say that the only safe and "correct" way
is to connect the PV inverter output on the line
side of the transfer switch. If you are on the
generator side of the xfer switch, you are
asking for trouble. The only other choice would
be to use a contactor to ensure PV disconnection
when the grid is down - then you could tap the
PV on the load side of the transfer switch.
And to answer Eric's #1 question in the original
post, you may not need to resize/replace the
panel if you follow this approach. We go with a
line side tap in this scenario unless there is a
compelling reason to do otherwise.
Jason Szumlanski
Fafco Solar
<http://fafcosolar.com>http://fafcosolar.com
Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648
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