Using 75 kWh per day to start. Living the SW USA you might get solar
insolation of 5 kWh per day in the winter.
For 10 percent efficient solar panels, thats 150 square meters of 100 watt
rated panels. Each panel being about 1 square meter.
150 panels times 400 dollars per panel is 60000 dollars. You'd need more for
cloudy days. Maybe $00,000 for panels alone.
Based on that, I'd guess around $50000 for the total system. That's for a
very good solar site.