alt Hacker Newsim a systems engineer and cost analyst who has put together some modeling myself as well. as a personal investment on your house, i agree. The economic value of solar seems to be best applied as neighborhood or block purchases, like as part of a co-op or hoa. they would need dedicated infrastructure like a communal parking lot with solar overhead, or running them on the property line borders with an easement underneath for servicing, using property fencing as main support (with upgraded fencing)
basically, the way it really makes sense (to me) is to integrate it as part of a micro-grid system, possibly with generator backups and everything to also keep the lights on in the entire neighborhood if the main grid goes down.
its a higher upfront cost on paper, but way less variables with the roof and you are grouping multiple peoples needs together so the gamble goes down on repairs. the poles for ground-mounting can be used for 40 - 60 years, so you would get multiple panels out of them
probably a bureaucratic nightmare though
This is also true of heating and cooling, and I've never understood why we (in the US) build relatively dense housing communities but don't implement things like this. Having a separate air conditioner for each home, especially in a condominium/townhouse complex, has never made sense to me as it's so inefficient compared to central heating/cooling.