It's cause you get better returns in centralized installations. For example, NREL estimates that centralized installations cost half as much as commercial roof

It's cause you get better returns in centralized installations. For example, NREL estimates that centralized installations cost half as much as commercial rooftop, and a third of residential (https://www.nrel.gov/solar/market-research-analysis/solar-installed-system-cost https://www.nrel.gov/solar/market-research-analysis/solar-in...) on a per-watt basis. Now normally, in a commercial or residential installation, as an owner you don't need to pay for cost of property. But as a utility (or government, or whatever), if you need to offer loans to get these installed, then those loans act a lot like property acquisition costs. There are definitely factors that can tip things in favour of such an approach (for example, if your land acquisition fees are particularly high for whatever reason, or you really really want a distributed grid), but I suspect that it's this fundamental aspect that keeps utilities from trying to push residential solar.