1. Do the other costs scale with the number of panels? Because if the sites are 5 times the scale of the current ones I would imagine there are considerable scale based cost efficiencies, both within projects and across projects (through standardization and commoditization).
2. Vertically mounted bifacial PV already greatly smoothes the power production curve throughout the day, improving profitability. Lower cost panels make the downside of requiring more panels in such a setup almost non-existent. Additionally, they reduce maintenance/cleaning costs by being mounted vertically.
3. Battery/energy storage (which further improve profitability) costs are dropping and can drop further.
Also, please address the matter of using the overprovisioned power in summer. Possible projects are underground thermal storage ("Pit Thermal Energy Storage", only works in places where heating is required in winter), desalination, producing ammonia for fertilizer, and producing jet fuel.