I was thinking plexiglass for a secondary backlight, like the 1948 Studebaker Starlight coupe. The shape would be more like the Rumpler Tropfenwagen than the Template.
At
EVTV Motor Verks Store: you can find a flexible 120watt/$245 panel:
EVTV Motor Verks Store: Flexible Solar Panel 120w, Solar, Boat and Golf, 120wsolarpanel
Those are make in China with American-made individual cells that are 3 watt/$8.95
EVTV Motor Verks Store: 1 Sunpower Cell, Solar, Boat and Golf, sunpower