On the other hand, 100g/m² is too low for “simply unroll it on a roof”. A carpet so light will blow away in a storm, worst-case taking (part of) the roof with it (roofs often are fairly weak when pulled upwards or sidewards. That’s why solar panels on roofs sometimes are weighed down: it keeps the net force on the roof more or less downwards, even if the wind exerts an upwards force)

What would you use to attach these, and what would that weigh?

I see these end up on cars, sailing boats, etc, where I think weight and flexibility matter more, before ending up in high-volume applications.

On the plus side, the article doesn’t mention it, but I would guess recyclability for these would be higher because they don’t glue cells to glass.