The key difference between windows and the solar panels, as designed, is the passive design of the solar panels. No need to close curtains on these panels, as w

The key difference between windows and the solar panels, as designed, is the passive design of the solar panels. No need to close curtains on these panels, as windows would require, for reduction of heat loss on winter nights. The black vanes are cooled, during the day, by induced air flow, such heated airflow going into the building (passively), and results in heating the building, without further action. The panels are designed to prevent winter-night cooling via the panels. Thus you're missing the passive intent heating intent of the design: windows fail as a passive heat source, because of the need to actively insulate them in some fashion in the winter night.