> $3 per watt, installed on your roof is typical these days
Which is why I was so fascinated by someone saying that you could get panels at 250USD/400W=0.625USD/W; I suppose it's possible that all the other stuff (electrician, mounting, inverters) is the difference, but a factor of 5? That feels like an chance to do something hacky and come out way ahead (like, say, DIYing a panel to run your computers, thus cutting out rewiring the house and needing an inverter).
Yes, a factor of 5 is fairly close. The prices of panels and inverters has dropped, while the price of labor and wiring has stayed constant or increased. The end result is the factor of 5 that you mention, and DIY systems are becoming more popular.
One of the factors in cheaper solar is that the panels have gotten bigger. Panels grew from 250w to 300, 350, and now to 400w and 450w. The 450w panels are 82 inches by 42 inches, so taller than the average person. Larger panels require less mounting and less labor, so even if they cost more they might be slightly cheaper to install.
I think that utility scale solar will eventually beat residential solar on price because of less labor per watt to install. I sometimes think about a solar system that could be set on top of a house in a few hours and would contain the inverters and interlocks and be wired into a single breaker in the house electrical panel. A truck operator/installer and electrician could do two installs a day and the labor price would be significantly less. We are so far from this currently, with site surveys, permitting processes, individual panels in custom configurations and so on that result in several days of work spread out over months. I don't know if it could ever happen, but it is fun to think about at times.
> I think that utility scale solar will eventually beat residential solar on price because of less labor per watt to install.
Utility scale solar beats residential solar by a huge margin already. New utility scale solar projects on the California grid are priced around $20/MWh [1] compared to feed in tariff rates of $0.08923/kWh = $89.23/MWh [2].
As a renter who can't have solar installed on my home I find it pretty objectionable that my electricity rates subsidise expensive toy systems of homeowners.
Which is why I was so fascinated by someone saying that you could get panels at 250USD/400W=0.625USD/W; I suppose it's possible that all the other stuff (electrician, mounting, inverters) is the difference, but a factor of 5? That feels like an chance to do something hacky and come out way ahead (like, say, DIYing a panel to run your computers, thus cutting out rewiring the house and needing an inverter).