Vijay Bhaskar of Mlinda says a big mistake in development has been to assume that,
once people are hooked up to electricity, businesses will automatically flourish.
People have to be taught how to make the most of power, he says.
"Bringing energy is the easy part. The hard part is finding productive ways to make use of it."
This understanding is spreading throughout rural parts of South Asia and Africa,
where mini-grids are increasingly seen as one of the most promising ways of connecting the 1.1bn people in the world who still lack access to electricity.
The World Bank says users of mini-grids may need microfinance and vocational training to make best use of it.
According to one British expert, "mini-grid operators are not sellers of kilowatt-hours; they are stimulators of rural development."
Jaideep Mukherjee, the boss of Smart Power India, an NGO supported by the Rockefeller Foundation,
says their job is to "demonstrate the benefits, train and then propagate".
Talk to Havil Bilung, a farmer in Narotoli, and the potential is clear.
He says that with help from Mlinda, increased access to electricity has allowed him to use irrigation pumps
to grow an extra harvest of pumpkin and okra in the pre-monsoon months, boosting his income.
More crops have cut the number of young men seeking itinerant employment in the cities during the dry season.
Women make mustard seed cooking oil, which sells in Kolkata.
An independent study for Mlinda found that GDP per person in eight villages with mini-grids rose by10.6% on average over the first 13 months,
compared with 4.6% in a group of similar villages without them.