Here is a link to an article that talks about battery connected grid tie inverters that have dual AC outputs. One for selling power back to the PoCo and the other output to feed a subpanel.
One concern is correctly setting of the DC voltage setpoints because you have an integral battery charger in the inverter and the charge controller from the PV array.
http://www.backwoodshome.com/articles2/yago89.html
