Did you know that even if you have your own grid-connected solar PV system, if there is a power outage on the grid, your PV system will shut off? It's a safety measure, which ensures that the folks working on the lines, fixing the outage, won't be electrocuted by power coming from your PV system back onto the grid. This is a good reason to invest in battery storage as part of your PV generation design: no outages!
Here's another reason to consider including batteries in your PV design: it's highly likely that Arrowhead Electric, and possibly the PUC, will soon be able to offer members the option of interruptible service. Similar to a dual-fuel setup, an interruptible system would allow the utility to draw from your battery storage at peak usage times, when energy prices are high. Instead of buying expensive peak-usage energy from power generators, Arrowhead Electric or the PUC would instead buy it from you. In effect, you'd have the option to store excess power in your batteries so that you could sell it back to the grid during peak usage times, at a higher price than you'd get for it at other times.