"If we use the figure of 0.5% efficiency (Ayres and Scarlott)... we have consumed... 2,000,000 BTU/person/day of sunlight in producing the 10,000 BTU/person consumed. Solar energy then fills over 2/3 of the new energy pie."
January 1, 1970
https://en.wikiquote.org/wiki/Steve_Baer