Actually its much more cost effective to use charge controllers than GT
inverters for the PV input. Just price out a 4 Kw GT inverter of your
choice compared to a Midnite Classic for instance. It's in the ball
park of 25 cents/ watt savings, and that's not chump change.
I only use AC coupling when the GT system is already in place, and we're
adding battery backup.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 6/6/2015 8:49 AM, Jeff Clearwater wrote:
Hi Mark
Seems a shame to spend the money on a charge control etc when SMA
has carefully provided a built in solution.
If you do decide to go that route you'll need to install a Shunt and
set up the DC Current Sense circuit so the inverter knows what other
current is flowing to and fro the batteries.
Best,
Jeff
Sent from my iPhone
On Jun 6, 2015, at 7:23 AM, Mac Lewis <maclew...@gmail.com
<mailto:maclew...@gmail.com>> wrote:
Hi Mark,
The Sunny Island has various battery protection modes and will
shutdown based on user programmable state of charge levels. Level 2
battery protection will start the Sunny Island every 2 hours in an
attempt to get charge into the batteries. You should set this level
up at times when energy input is likely. See page 113-114 here:
http://files.sma.de/dl/15216/SI4548-6048-US-BE-en-20.pdf If it
doesn't get any charging to the batteries for 10 minutes, it will
shut down and wait again.
This is an advantage of having at least some DC coupled solar input.
On Sat, Jun 6, 2015 at 7:39 AM, Mark Frye <ma...@berkeleysolar.com
<mailto:ma...@berkeleysolar.com>> wrote:
Hi Guys,
Just wondering about how a SI/SB microgrid works. If all the PV
is connected to SB inverters, what happens if the loads manage to
drain the batteries to their low voltage shutdown? Wouldn't the
SB stop providing the AC sync so then the SB wouldn't have
anything to sync to even if they had power available from the PV?
How is this handled? It seems to me you would always want to have
some amount of PV DC coupled.
Thanks,
Mark Frye
Berkeley Solar Electric Systems
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