This is how Porsche explains it:
"Due to its flat construction, the panoramic fixed glass roof blends harmoniously into the silhouette. Transverse bows were not required. This means the continuous area of the roof in the new Taycan measures one square metre, and as such provides an even more pleasant feeling of space and airiness. It is also possible to use a Porsche roof transport system.
For the first time in a Porsche, low-emissivity thermal insulation glass is used for the panoramic fixed glass roof. Several wafer-thin metal layers are applied to the insulating glass. As the thermal insulation glass allows short-wave radiation to pass through and reflects long-wave infra-red radiation, the vehicle interior will heat up more slowly in summer. This also means that the heat in the interior is retained longer in winter. In combination with the glass tint, it was therefore possible to dispense with a roller blind. An intermediate layer in the glass structure also provides acoustic insulation for the interior."
"Due to its flat construction, the panoramic fixed glass roof blends harmoniously into the silhouette. Transverse bows were not required. This means the continuous area of the roof in the new Taycan measures one square metre, and as such provides an even more pleasant feeling of space and airiness. It is also possible to use a Porsche roof transport system.
For the first time in a Porsche, low-emissivity thermal insulation glass is used for the panoramic fixed glass roof. Several wafer-thin metal layers are applied to the insulating glass. As the thermal insulation glass allows short-wave radiation to pass through and reflects long-wave infra-red radiation, the vehicle interior will heat up more slowly in summer. This also means that the heat in the interior is retained longer in winter. In combination with the glass tint, it was therefore possible to dispense with a roller blind. An intermediate layer in the glass structure also provides acoustic insulation for the interior."
