Rooftop photovoltaic is currently more expensive, less efficient, and surprisingly dangerous to install. Solar thermal designs actually benefit from being on rooftops.
As to dust, economies of scale make a huge difference. It’s rarely worth it, but using a farm truck to spray water across miles of panels is much more efficient than tens of thousands of homeowners doing the same.
It's also unattractive, which should matter to us.
Much of the distinctive beauty of traditional building in sunny areas comes from the roofs.
Solar tiling, which is still not a mature technology, doesn't add danger: we have to put something on a roof, and if installing solar tile takes extra time, it isn't by much. And it looks good.
Less efficient and more expensive? Sure. But as the meme would have it, it's free real estate. And since we're living through a grotesque failure of robustness on a civilizational scale, let me point out that it's more robust as well, particularly combined with on-site batteries.
Why do they count as unattractive? It seems that the "definition" of eyesore is wholey independent of aesthetics and entirely based upon if it is functional and new. Old windmills, steam engine trains, and canals are considered quaint, wind turbines, shipping canals and modern trains are considered "visual pollution". Modern art fixtures often deliberately defy all rules of structure and aesthetics and don't get tarred with this. I only have weird hypothesises as for why.
I'm dubious about rooftop solar in suburban/urban areas. I think the gain is mostly from tax write offs and arbitrage. Compare hand installing solar panels on a roof with mechanized installation of a large scale solar array.
Generation of power at the point of consumption is nothing to sneeze at. It’s also efficient use of space. Taxes can work as incentivizing tool instead of or in addition to generating revenue for the government which is precisely what’s going on here.
To be clear their not that dangerous, but we are still talking extra deaths and accidents. Mostly from increased amount of time people spend on residential roofs. Roofing is about 30 deaths per 100,000 full time workers which is about double the average rate for construction.
Currently instillation is the primary, but not only risk. You also get electrical accidents and in rare cases fires. Plus an increased tendency for people to go onto a roof to check them out and or clean them etc. And some extra roof maintenance due to leaks from improper installation etc.
Personally, I don’t think it’s a major deal at the individual level. However, I thik it should be considered in terms of public policy.
As to dust, economies of scale make a huge difference. It’s rarely worth it, but using a farm truck to spray water across miles of panels is much more efficient than tens of thousands of homeowners doing the same.