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@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 ---

