Spirit won the tender working in partnership with the Carbon Trust. In the space of six weeks, we surveyed 90 properties, identified roofs appropriate for solar PV, carried out shading analysis where appropriate, and analysed the costs and returns of installing solar PV on each roof. The properties were then ranked for investment purposes taking into account FIT banding, high and medium tariffs, and taking into account considerations such as Energy Performance Certificates and structural assessment. The final report looked at financial returns over 20 years and over 40 years.