Even on a very good day for solar stocks (TAN +3.9%), the huge gains posted by SunPower (SPWR +23.3%) are eye-opening. No news has hit the wires to explain the move, but with 16.9% of the float shorted as of Jan. 31, short-covering could be playing a big role. Solar stocks had already rallied strongly on Monday and Tuesday thanks to growing optimism about an industry bottom. LDK +8.7%. DQ +12.6%. FSLR +7.6%. JASO +5.8%. ENPH +14.3%. WFR +5%. GTAT +5%.