I don't believe the claim that "solar photo-voltaic electricity is now less expensive than grid electricity" as bare fact. This all sounds *great*, but when I ran the numbers on a solar installation at my house, I was disappointed. I needed to lay out $23k capital cost, to generate slightly over $600 of electricity per year. Even with generous incentives, my break-even point on the installation was at around 11 years, assuming no other costs on my end. One possible cost that was not included was that of cleaning off the arrays, which would be about $150/year as a service (which really cuts into the net value of the $600/year electricity being generated). If I need to re-roof my house within the lifetime of the system, I had a several thousand dollar cost to de-install the panels, then re-install them.
The other challenge was that this installation was not sufficient to put me "off the grid," so I still needed to buy electricity in lean times (and to "sell" electricity in good times). However, the current rates structures and incentives in my area ignore the cost to the electric utility of maintaining the distribution grid. As the percentage of homeowners generating their own solar power increases, the cost of utility-generated electricity will need to increase as well, in order for the utilities to cover the cost of maintaining the grid (alternatively, people will have to pay a "grid connection fee" that will be substantial). Distributed power generation is a great idea, but too many folks are ignoring the cost of the utility system that still needs to be in place. This ignorance is sustainable at low self-generation adoption rates, but will become unattainable as adoption rates rise into a significant fraction of the utility's consumer base. Sort of like how some electric car owners are surprised when they are charged additional registration fees (over gasoline vehicles) because the existing road maintenance cost recovery is through gasoline taxes that electric vehicles are sidestepping.
I'm not slamming the idea of distributed generation, and I dearly want to have my own solar-photovoltaic generation capability, but the business case for the individual homeowner is still not in favor of it. A few more years, some additional efficiencies, and maybe we'll be there. A radical increase in storage capability would really help.