[RE-wrenches] SI/SB MicroGrid - Recovery From Low Battery Shut Off

[Jeff Clearwater]

Hi Mark

Set up properly with the 3 protection thresholds  plus generator auto start you shouldn't need any DC PV input.  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 <maclewis1 at 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 <markf at 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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> 
> -- 
> 
> 
> 
> Mac Lewis
> 
> "Yo solo sé que no sé nada." -Sócrates
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