Since he was a child, Santipada Gon Chaudhuri had sought ways to help India's rural poor, so when the electrical engineer was invited to visit a co-worker's home in the Himalayan village of Herma in the early 1980s, he saw his chance.
"I was appalled to see how local communities were living in darkness after sunset," remembered Chaudhuri, 71, who then worked for the government in the northeastern state of Tripura.
"Some used kerosene lamps, but even kerosene was not always easy to get. Since I had both the skill and position to try and provide power to them, it made me act," he said.