Grid connected has best operating characteristics. Use as much self generated as ya can, some times back fill from grid, sometimes sell back.

Cost to install and get turn key depends on buy or lease and kinda oddly like a car. Lease is like no money down but they own the hardware for the first 20 yrs. Less out of pocket but less margin because it's split. Still a long term option. I like cut a good deal, buy it, take 30% tax credit except retired, no income to use it until a few years from now. More out of pocket, much faster pay back and larger long term gain. Roof condition before install should be looked at. Probably pretty easy to pop the racks off for a re shingle but why do it if ya don't have to.

Overall prices have gone down as availability has gone up and technology improved. Monitor / control yer install and connections thru yer app. Boom market for installers, Obama policies helped, local governments are insane. A few years back some sun belt state yanked all incentives / grid buy back mins - totally killed solar as viable and a company or three. Eventually over turned in the courts, check yer local scenario. That was extreme but conditions are subject to change.