[RE-wrenches] Radian vs SI - Shunt for SOC Control

[Tump]

the communication cable IS required, to switch the Sunny Boys
from grid tie to off-grid mode, in the event of a grid failure. 
This is true for the older SB U series, while one is able to move the rotary switch on the TL series of inverters. This grid/off grid setting is also able to be adjusted using the SMA service tool. This Off Grid mode set in the SB inverters can only be used when using a SI as now the SI is meeting the anti island mode for any grid tied system.
Com cable is used between the SI & the SB for the web box & sunny sensor box. 

On Jan 16, 2016, at 1:30 PM, Richard L Ratico wrote:

> All,
> 
> I've just updated the inverter firmware (to version 7.302) in an off-grid
> 120/240 Volt split phase Sunny Island, generator only system I installed in
> 2007. It's my understanding the Sunny Islands DO need an external shunt if if
> there are any DC loads or charging sources. I don't have any of those, other
> than battery vent fans, but installed a shunt anyway to work with a Trimetric.
> 
> Furthermore, In an off-grid install, the Sunny Islands control Sunny Boy
> inverters (which are pre-programmed for off-grid use) by frequency shifting
> alone, no separate communication cable is required. In a grid-tie, battery
> backup situation, the communication cable IS required, to switch the Sunny Boys
> from grid tie to off-grid mode, in the event of a grid failure. 
> 
> Dick Ratico
> Solarwind Electric
> 
> 
> --- You wrote:
> Hi Mark,
> 
> If all battery power flows in and out of Sunny Island(s) then it will keep
> track of SOC without a external shunt. I'm not sure how it does it but all
> the SOC dependent controls work fine in that scenario. The SOC algorithm
> calculation works much better than any other that I've used.
> On Jan 16, 2016 1:34 PM, "Mark Frye" <markf at berkeleysolar.com> wrote:
> 
>> Folks,
>> 
>> I know with both the Radian and the SI you can use an external shunt to
>> support the measurement of KWH and support various SOC controls.
>> 
>> But what happens if you don't use an external shunt?
>> 
>> I am pretty sure that the Radian does not have an internal shunt to
>> support SOC control.
>> 
>> What about with the SI? Does it implement it's SOC controls even without
>> an external shunt?
>> 
>> Thanks,
>> 
>> Mark Frye
>> Berkeley Solar Electric Systems
>> 
> --- end of quote ---
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