Can be cost effective
>Smith says for most people the addition of a backup battery isn't a great value proposition.
>“By and large, most residential customers in cities and urban areas have a pretty robust connection,” he said.
That is not the issue, the problem is any power you produce is being sold to the power company and a crap rate, you then buy it back at a much higher rate.
At least with a battery you can use all of then power you generate so in effect you are getting full retail price for what you generate rather that the minuscule amount that the power company will pay.