Non-Convex CHP workaround

Hello all,
I want to model a chp-unit with non-convex variable efficiencies. As I read, the implementation of a non-convex transformer with two outputs is not possible (yet).
Does anyone know a work around for that?
I’m trying to define to seperated transformers with each a non-convex output. But it seems, that the time to solve the problem, adding the non-convex feature for only one component, takes ages.
I’d be glad for any hint or help.
Kind regards!

Did you try the GenericCHP class?