Abstract: The present invention refers to a covering system for building windows or facades. Particularly said covering system comprises at least a modular element, wherein said modular element comprises a multiplicity of photovoltaic modules (10), in particular DSSC photovoltaic modules, and each photovoltaic module (10) comprises at least a cell (1) and at least a substrate (2) made of rigid and transparent material, Said photovoltaic modules (10) are disposed sequentially and hinged to each other by hinging means (7), such that the same can be moved from a first closed position, wherein said photovoltaic modules (10) are mutually bellows folded, to a second opened position, wherein said photovoltaic modules (10) are substantially placed mutually side by side and substantially aligned, or vice versa.