Light is a type of energy.
one energy can convert in another form of energy. so
yes light is main source of the energy. all plant make food by using energy from sun in form of light and convert H2O and CO2 in to glucose. all living organisms directly or indirectly depend on it.
Now we also use Solar penal and convert light energy in to electric energy
solar Light energy is one of the major source for space probe like Hubble space telescope etc.
