Well we'd need cheaper panels for that. Currently they last like what, 30 years and take 3 years to pay off the energy it took to make them? That gives them a roughly a 9x return on investment. You need at least 30-40x to maintain our civilization as-is. Crude oil provides about 100x return. Luckily offshore wind is almost over 30x.

Doesn't matter if you can cover all of the Sahara with panels and get near lossless transmission.

Economies of scale do apply.

They apply to some degree, but it still takes X amount of materials to make each panel, you don't magically get more because you're making a continent worth of them. Even if you magically reduce the overhead 50% somehow, that's still only 18x which is not even close. Plus the fixed cost of making a laughably absurd amount of superconductor, and the monumenal logistics of deploying and maintaining all of it likely puts the project into net negative for a decade or two.

Saharan dust will also cover those panels in like a day. Probably makes more sense to float them on some body of water instead, with automatic washing and cooling?