Home solar is more valuable with an attached battery. Without it, most setups as sold will shutoff if your home loses grid power. A battery is not the only way to solve this but it's the best solution if you can afford it.
Spending tens of thousands of dollars on batteries that only last a few hours when grid-power is lost is not a luxury the typical person can afford. But solar panels that are cheaper (and provide revenue through net-metering) will revolutionize the energy industry.
The average homeowner uses 30 kW-hrs of electricity a day. So... what, three Power-Walls per day of backup energy for $10k + installation costs + inverter costs? With a power output of only 2kW? This is going to cost maybe 20k or 30k for a solution that gives you power for more than a day.
In contrast, a simple gasoline generator will get you 5kW of power (6kW peak) and run for as long as you have gasoline. This crazy solution costs like $600 from Home Depo... and has several decades of experience to prove its effectiveness.
http://www.homedepot.com/p/Powermate-5-000-Watt-Gasoline-Pow...
Generator + Solar Panels is still looking a hell of a lot more practical than Solar Panels + Battery. $50 of gasoline is going to run you ~25 gallons, enough to last 2+ days without any power. And if a crazy hurricane "Sandy" situation occurs again, you can always go out to the local gas station to grab more gasoline for day 8, day 9, or day 11 without power.
I mean, seriously? 10kWh per PowerWall is laughably small.
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I mean, when do you lose power for extended periods of time? Answer: when major hurricanes or snowstorms hit. That's what. It isn't like your Solar Panels will work while they're completely covered in snow. You'll need the generator if you actually want reliable off-grid energy anyway.
The true solution is the centralized utility providing energy storage for the masses. Again, large-scale infrastructure projects like the Bath County Pumped Storage Station and strong investments into a reliable local grid.
https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...
This plant provides dozens of Gigawatt-hours of energy storage for millions of Americans.
http://www.powersouth.com/mcintosh_power_plant/compressed_ai...
110 MWs of power for hundreds-of-thousands of homeowners.
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You tackle this energy problem by building a strong, reliable city, town, or neighborhood. At least if you want to tackle the energy problem of the 99% instead of the 1%. https://en.wikipedia.org/wiki/We_are_the_99%25
The solution is, build large-scale energy storage plants (CAES, Pumped Hydro), and then have local homeowners use the large-scale battery for storage and energy. IE: Net Metering.
During Sandy 80% of New Jersey gas stations were closed, so no you couldn't just run to the local gas station for a top off. Batteries + solar aren't going to power your whole house through Sandy but it will keep a minimal power level indefinitely so you can charge your phone, run your fridge, and perhaps have a night light to read by. Though I have to agree I don't see the point of giant batteries outside of a doomsday prepper strategy. It is much easier and cheaper to just draw power from the grid at night.