The analysis, published by the Green Alliance, a UK think-tank, is supported by Christian Aid, Greenpeace, the Royal Society for the Protection of Birds and WWF.
It says low-carbon, decentralised energy can reach communities much faster than expanding existing, inefficient central grid systems - at less than half the operating costs of traditional diesel generators.
The study also shows how renewables can offer additional benefits, such as cutting air pollution and improved job creation.