One of the primary benefits of solar energy is that it works most efficiently as a standalone or "non-distributive" system. Many countries in the 3rd world lack an energy infrastructure to move energy from its source of production to its point of consumption. Setting up a "local system" of solar panels where electricity can be produced and consumed in the same area precludes having to have a big, distributive network. Could it be that solar energy is not widely in place in 1st world countries because they possess such a network, which would become superfluous if homeowners generated their own electricity?
Another advantage is that electricity generation by solar panel is nearly pollution free, and the little pollution created is only when the panel is manufactured, not when it is in operation.
Environmentally friendly and economically friendly; good points for implementing solar energy in any country.