Quote:
Originally Posted by Xringer
It kinda looks like the Sunny Island goes between the Sunny Boy and the grid.
Or your gas generator.
Logically, it seems like the DC line (in blue) is a DC source for making AC to pass up
to the AC line (in red), to feed the loads and provide the AC (fake grid)
source to the GTIs on top (Red GTIs).
Also on the bottom is another PV array connected to a battery charger.
Price wise, it looks like a 5kW Island unit cost double a regular 5kW Sunny Boy.
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If your Grid tie inverter is large enough, all you need to add is the smaller 4k Sunny Island and batteries (and cables, disconnects). You do not need a separate array or charger for the batteries. This assumes 4K is enough to power your loads when it is cloudy and at night.
The Island includes a battery charger as part of the package (part of the reason it is more expensive). If the Boy is producing more power than is being used by the AC loads, the excess power is sent to the battery charger. If the loads exceed the capacity of the Boy, then the Island draws power from the batteries to make up the difference.
If the batteries get low and it's cloudy, then it is time to fire up the genny.
The nice thing about AC coupling is that everything occurs at a higher voltage and less amperage (less voltage drop). You can use smaller diameter cables and save a lot of money. Copper is not cheap around here.
You can add additional arrays later that may run at different voltages, different orientation, (or a wind driven generator). If they are connected to a Boy, they can be connected at the AC panel.