Background Solar power output is expected to grow by at least 25% annually over the next 10 years. In order to further enhance the impact of photovoltaic (PV) electricity production, technology costs must be lowered to achieve ‘grid parity’. Two generations of PV technologies have been in mass production to date. These are: mono and polycrystalline silicon (1st generation PV with 86 % market share); and second generation thin films technologies (a-Si, CdTe, and copper indium gallium diselenide - CIGS). Thin film PV is expected to reach 20% market share by 2016. A recent study shows that CIGS thin film technologies have a lower carbon footprint than crystalline silicon PV. Objectives The project aims to demonstrate cost effective production processes for steel CIGS solar cells on a pilot scale. This will involve the preparation of an innovative steel frame combining roof and base components, that will lead to lower greenhouse gas emissions and eliminate the need for an aluminium support. The CIGS coating will be connected directly to the new steel frame and because the material has a high absorption coefficient, meaning it is highly able to absorb sunlight, a much thinner film is required than for other semiconductor materials. CIGS devices also offer benefits for ‘end-of-life’ recycling over other PV technologies. Expected results: The project expects to offer a number of benefits in terms of GHG emissions and materials reduction/recyclability:A 30 % reduction of the global warming potential with respect to a framed PV module installed on a metallic roof, representing 46 kg CO2 eq./m²;A 15%reduction of the carbon footprint and the primary energy use for manufacturing CIGS modules, thus leading to a savings of 15.8 kg CO2 eq./solar cell m². This will be achieved by reducing the energy required by 50% during the selenisation process, and by introducing energy efficient management of the solar cell installation;A 1.5 % increase of the kWh/kWp produced with respect to currently available BI-PV modules on steel roofs, mainly achieved by reducing the shadow effect on the steel profile and by optimising the PV module global design; A reduction of the amount of the rare toxic element cadmium by 20 to 25 g per m² of PV module (100% reduction in comparison with existing technologies); andThe achievement of an eco-designed BI-PV Roofing envelope, of which at least 85% (in weight) is recyclable. With a foreseen weight of the LIFE-PHOSTER envelope of 10 kg/m² a minimum 8.5 kg/m² of material can be recycled at the module’s end of life.