solar energy vs solar power

solar energy

noun
  • Energy in the form of electromagnetic radiation emitted from the Sun; especially that part of this energy that is converted into usable thermal or electrical energy by man. 

solar power

noun
  • The conversion of energy from sunlight into electricity, either directly using photovoltaics, indirectly using concentrated solar power, or a combination of the two. 

How often have the words solar energy and solar power occurred in a corpus of books? (source: Google Ngram Viewer )