A space solar concentrator based on deployable reflectors attached to a panel base is described. Each of the reflectors includes sides coated with reflective coating on surfaces facing away from the base. In one embodiment, the sides of the reflector have thicker portion to provide stiffness for deployment absent compressive force, and thinner portion to reduce weight and storage energy. In another embodiment, both reflective sides are unfolded when the reflectors are in stowed position. During deployment, a stop side will limit the deployment of both reflective sides and ensure the proper reflecting position. In addition, these embodiments reduce the storage energy.