There was already heavy investment in steam technology. Using the sun the boil water instead of coal or wood is much less resource intensive and completely eliminates external supply chains.
Did they have enough tech by that point to even begin to figure out mass manufacturing of solar cells to focus enough energy into water to make steam? Burning something that burns well is a much more intuitive and scalable process...
Also, mining the easy stocks (at that point) is a low tech affair too. Which was powered by... combustion of fuel and human labor.
We still can’t make solar panels with 100% efficiency, what hope did they have?
Good points. But lens building is a complex endeavour that requires tooling at the manufacturing level (especially computing power!) - no matter the choice of available material, yes? Doing it with high precision at a civilisation-powering scale seems like an impossible ask of a species that was still considering much of their Home planet to be “new” (Americas).