PRINCETON, N.J. and SAN JOSE, Calif., Nov. 30, 2010 /PRNewswire/ -- NRG Solar, a subsidiary of NRG Energy, Inc. (NYSE: NRG) and SunPower Corp. (Nasdaq: SPWRA, SPWRB) today announced groundbreaking agreements to begin construction next year of the 250-megawatt (MW) California Valley Solar Ranch in Sa