This idea has been around longer than the 1970s. In fact, Augustine Mouchot, a frenchman, made a portable solar cooker for Napoleon's troops in the French Foreign Legion in 1877. There is an even earlier use of the concept recorded, when in 1767, Horace de Saussure, (another Frenchman!), heated soup in an insulated box covered by layers of glass.
Conversation about: Solar cookers' Shine On at Sierra 2
This idea has been around longer than the 1970s. In fact, Augustine Mouchot, a frenchman, made a portable solar cooker for Napoleon's troops in the French Foreign Legion in 1877. There is an even earlier use of the concept recorded, when in 1767, Horace de Saussure, (another Frenchman!), heated soup in an insulated box covered by layers of glass.