Curtain wall insulation system with improved insulation seam

A system for insulating a curtain wall structure connected to a building structure, the curtain wall structure having framing defined by at least first and second vertically disposed and parallel mullions separated by a mullion distance, the system comprising:

• a first curtain wall insulation panel having:
• a first face,
• a second face opposite the first face,
• a material thickness defined between the first face and the second face,
• a first end having a longitudinally extending indentation,
• a second end opposite the first end, and
• a first material length defined between the first end and the second end;
• and
• a second curtain wall insulation panel having:
• a first face,
• a second face opposite the first face,
• a material thickness defined between the first face and the second face,
• a first end having a longitudinally extending protrusion,
• a second end opposite the first end, and
• a second material length defined between the first end and the second end,
• wherein the first panel and the second panel are configured to be disposed within the framing such that the longitudinally extending protrusion of the second panel is at least partially disposed within the longitudinally extending indentation of the first panel.