About 1 to 2 years. Highly variable by technology.
There is a persistent myth that solar panels take more energy to fabricate than they produce in their lifetime. It is shown false with minimal effort (consider if the entire cost of a panel was energy. no labor, not capital equipment overhead, no raw materials… they still have payback periods shorter than their lifetimes).
I don't have a number, but the exotics that are used in space applications may never pay back their production energy. But it takes a lot of extension cords to reach geosynchronous orbit.
There is a persistent myth that solar panels take more energy to fabricate than they produce in their lifetime. It is shown false with minimal effort (consider if the entire cost of a panel was energy. no labor, not capital equipment overhead, no raw materials… they still have payback periods shorter than their lifetimes).