Abstract: A system for rapidly defocusing a solar concentrator has a plurality of variably curved reflectors carried on a frame for concentrating energy toward a target. The reflectors have an elastic reflective membrane secured to a hollow housing and are focused by an evacuation assembly which draws the membrane into the housing and into a concave configuration. The defocusing system comprises an inflation assembly which rapidly inflates the housing, moving the membrane out of the focused position to an unfocused position. The inflation assembly reacts to a control mechanism and comprises compressed air stored at about 100 psi.