Record industrial demand for silver and resurging investor interest is diminishing a supply surplus, driving the metal used in everything from solar panels to batteries into its best start to a year in almost three decades. Manufacturers will use 15,415 metric tons, 2.5 percent more than in 2011 and reducing the glut by 41 percent to 3,297 tons, Barclays Capital estimates. Investors may buy 2,000 tons through exchange-traded products, after selling 1,300 tons last year, Morgan Stanley predicts. Prices will average $37.50 an ounce in the fourth quarter, 13 percent more than now, the median estimate in a Bloomberg survey of 13 analysts shows. The metal rallied 22 percent since closing at an 11-month low in December, entering a bull market on mounting confidence that another global recession will be avoided even as the World Bank and International Monetary Fund cut their growth forecasts. Prices had plunged 44 percent in eight months, making it the most volatile of any metal tracked b...