India unveiled the world's biggest solar farm earlier this year and has quadrupled its solar capacity in the last three years, bringing electricity to millions of off-grid households. But what are the innovations that could see solar replacing fossil fuels completely?

Rameshwarlal Choudhary, a 45-year old farmer, and his wife Dakha, 40, live with their two children in a small shack near the village of Solawata in India's Rajasthan.

Their home has thatched walls, a tin roof, and one side is completely open to the elements.