Alight bulb requires electrical energy to produce light, and solar-powered lights that use LED bulbs provide the most efficient and most hours of light at night. Given these facts, in order to operate at night, solar-powered LED lights require what among the following options:
- sun's heat
 - electrically
 - adding heat
 - focusing a lens
 - hydrogen and oxygen
 - kinetic energy
 - electrical energy
 - direct energy


 

       electrical energy  