Why not invest in women who have roots in the village and train them?

The United Nations estimates that around 1.5 billion people still live without electricity, and often the best and most immediate way to bring non-polluting electricity to remote regions is with solar energy.

Roy certainly believes so.

"The way to go about this is not a centralized grid system, which brings in power from hundreds of miles away," he says.

"It is to bring in basic light right down to the level of basic household wherein they take ownership and control over that technology."

Women are the focus for the solar power projects that the Barefoot College runs because men "were very untrainable," says Roy.