Abstract: In a concentrating solar collector, a plurality of pivotally-mounted, elongated, side-adjacent parabolic reflectors are inclined toward the sun by a tracking device to focus incident sunlight on a plurality of parallel, spaced-apart, blackened stripes on a lengthwise extending water pipe absorber, whose outer surface is otherwise of low thermal emittance. Because the absorber has a relatively small area of high emittance, namely the combined area of the striped segments, it radiates less heat than if it were totally blackened. The temperature of the absorber at the stripes is not substantially greater than at the shiny areas between, due to the high thermal conductivity of the absorber pipe and the moderating effect of the water within it. Thus, the absorber has a lower emittance of thermal radiation than a totally blackened absorber, without a corresponding decrease in absorptance of sunlight.