Spectrolab XTJ Prime cells are 30.7% efficient (and fall to 26.7% over 15 years), but I suspect they are on the order of $10-100/W as they are space rated and t

Spectrolab XTJ Prime cells are 30.7% efficient (and fall to 26.7% over 15 years), but I suspect they are on the order of $10-100/W as they are space rated and the minimum order quantity is not kind. The LCOE of them is amazing if you are building something in orbit, not so much for things on the ground or air.