Sentence:  [Rural solar plant] schemes are of little help to industry or other heavy users of electricity. Nor is solar power yet as cheap as the grid. For all that, the rapid arrival of electric <WSD>light</WSD> to Indian villages is long overdue. When the national grid suffers its next huge outage, as it did in July 2012 when hundreds of millions were left in the dark, look for specks of <WSD>light</WSD> in the villages. 
Meaning of the word marked with <WSD> tags:  Visible electromagnetic radiation. The human eye can typically detect radiation (light) in the wavelength range of about 400 to 750 nanometers. Nearby shorter and longer wavelength ranges, although not visible, are commonly called ultraviolet and infrared light.