In central EU it would cost me about $7200 to have a decent (5kw) unit that would provide me with 630 watts 0-24h on average.
Using 630 watts 0-24h with $0.14/kWh costs $760 a year so that's over 9 years before reaching ROI.
So yeah, you might be able to get your hands on some super cheap solar panels+inverter+batteries but I'd much rather pay the $0.14 with a grin on my face and spend that $7k on more hardware.
In central EU you would be paying with EUR and in some EU countries the solar energy is sold at .14c/kWh. Oddly enough I was fairly ok with your argumentation specifically. I still suspect you should get in touch with real world when it comes to this but at least I admit you have given an elaborated answer!