Architectural acceptance of façade integrated solar-thermal arrays requires novel solutions for the flat plate solar thermal collectors, in terms of shape, size, colour and functionality. The paper presents a novel concept of solar-thermal arrays with variable geometry, based on non-rectangular collectors; different shapes and sizes are analysed and their adaptability in developing arrays with various geometries is discussed. Two “unit” shapes are proposed (equilateral triangle and isosceles trapeze), based on which various geometries can be developed; the size range of the collectors is discussed, along with the tubes’ design for the inner circulation of the water based working fluid. Several examples of façade and roof integrated arrays are presented, outlining the versatility of the proposed solution