Don't understand why they have to use the most expensive power. Even people in wealthy countries cannot afford living on solar, but the poor have to. I am quite sure there are more and better options.
[1] Along the lines of http://en.wikipedia.org/wiki/Rural_Electrification_Act
I think solar for the mountain population is very interesting. They don't have anything at all now, not like we're increasing their current energy bill. It's cleaner than most other options, and very low environmental impact for these typical rural communities.
Solar panels, while expensive to manufacture, can be put in a box, carried to the point of use, and left to function on-site indefinitely with nigh unto no maintenance.
Other options? Check out http://www.biolitestove.com - a very recent development of a wood-burning stove featuring a thermocouple electrical generator and very low emissions.
The systems in "developed" countries have been set up over time to make it "cheaper" to run on oil (for now, but this only going to get more expensive). And even then, you must constantly deal with the supply/demand and inflation issues when it comes to acquiring oil. That issue does not exist with acquiring solar energy. With PV's and CSP, one side of the equation takes care of itself (radiant energy from the sun).
Oil may be cheaper in terms of immediate dollar costs, but by using it you sell our future down the river.