Solar power might be popular in Salem, Ore., but wind is the world’s fastest growing energy source, powering 10 million homes around the globe, according to a report issued yesterday by European, American, and Indian wind energy associations. Last year, wind turbine installations increased by 45 percent, or some 6,500 megawatts. Europe, long the leader in wind energy, accounted for most of that growth, at 4,500 MW; the U.S. came in second, increasing capacity by 1,700 MW, and India added about 240 MW. The bad news is that the U.S. wind energy sector could shrink next year, because wind-production tax credits that expired at the end of 2001 have yet to renewed. The credits played a key role in encouraging new wind power projects in the U.S. by making them more competitive with conventional energy.