NYT: Until very recently, Hunan Province was known mainly for lip-searing spicy food, smoggy cities and destitute pig farmers. Mao was born in a village on the outskirts of Changsha, the provincial capital here in south-central China. Now, Changsha and two adjacent cities are emerging as a center of clean energy manufacturing. They are churning out solar panels for the American and European markets, developing new equipment to manufacture the panels and branching into turbines that …