Alternative energy is the only sector posting gains today, helped by a well-received trading statement from PV Crystalox Solar, the company that makes the silicon wafers used in solar power systems, as demand for its products improve.The company said shipment volumes for the first half of 2010 are expected to be in the range of 155-160 megawatts (mw), an upgrade on the guidance of 145-155mw given at the end of March and a significant improvement on the 139mw shipped in the second half of 2009.Mining stocks are among the worst-hit as developments in Europe once again raise fears over the state of the global economy. Germany has banned speculators from some bets against government bonds and banks. While the measure comes in response to debt problems in the eurozone, it stoked speculation that the European debt crisis will worsen. Copper prices fell sharply.Xstrata, Rio Tinto, Kazakhmys and Antofagasta are among the heaviest fallers in the sector.Top performing sectors so far todayAlternative Energy 6,068.35 +0.16%Bottom performing sectors so far todayAutomobiles & Parts 2,887.51 -8.18%Mining 19,929.97 -5.06%Industrial Metals & Mining 5,213.81 -4.91%Oil Equipment, Services & Distribution 16,788.00 -4.09%General Retailers 1,590.28 -3.92%