Look at the schematic carefully, and you can just picture the proceedings. First you have the service in the room with the seats; then the casket would ceremoniously rise to the roof; whereupon a crane would lift it into the path of concentrated solar energy.
“A temperature of about 1,700° F. is required to provide incineration and a total of about 3,000,000 BTU’s is required to consume a corpse. Thus, at a supply rate of about 1,000,000 BTU/hour, cremation would take about three hours. A concave mirror-reflector bowl similar to the steam-producing Crosbyton hemisphere in Lubbock, Texas is considered a suitable collector. At 65 ft. diameter, a bowl of this type can produce approximately 1,000,000 BTU/Hr. under full sunshine conditions from mid-morning to mid-afternoon.”