Kind of makes sense to me that rooftop solar would be less viable financially than larger scale renewable schemes. A lot of work installing the small scale panels on a roof, getting all the household level electrics and household sized inverter installed etc. Compare to a large scale farm or covering a warehouse roof where economies of scale kick in.
Seems to me like the only way to make it economically attractive at the moment is with increased government subsidies, but I'd probably argue that would be a bit of a waste - same amount of money would have more impact subsidising large scale windfarms or large solar farms covering a car park or warehouse roof etc.
I guess the only advantage would be no need for extra transmission infrastructure for domestic installations (at least until you reach a point where the amount of noisy power generated by hones in the middle of a summer day starts to overwhelm the capacity of the local network to feed back into the grid and potentially causes interference problems). If it's too expensive or takes too long to get larger schemes hooked up the the DNO then that seems like the real problem that needs solving.