Abstract: The invention relates to reflective means for use in solar energy utilizing apparatus and including reflective surfaces comprising two or more adjacent parallel troughs having inner surfaces with a reflective layer or coating, said troughs also having wall edge portions secured together to provide at least one inner wall and two outer walls, the cross-section of each trough being a portion of a parabola, said outer walls of end troughs following a longer portion of a parabola than the inner walls. Thus, the cross-sectional configuration of a twin trough arrangement resembles a letter "W".