There doesn't seem to be an absolute requirement tor aluminum in PV panels. It's light-for-strength, relatively weather resistant, easily machined (probably extrusion for this application). But it's not the only material. There's, for instance, glass fiber reinforced plastics and even concrete. (I helped a friend build a 40' wire-reinforced sailboat when I was a kid).

Then, there are places that produce aluminum with relatively low energy per ton. For example, New Zealand has a good bit of hydro on the west side of South Island (driven by oncoming westerlies running moisture laden air up a chain of mountains. The raw material is shipped from Australia, so not without carbon cost - and bauxite can be hazardous for shipping. Then the smelted aluminum is shipped from NZ, again not without carbon cost.