A major problem for photovoltaics is the lack of a fast and accurate energy rating for new devices and modules. Currently, methods for predicting the energy yield for a given device are either too simplistic, especially with regard to emerging technologies, or long-measurement campaigns are required. This problem will be solved by developing an energy rating based on direct laboratory measurements and thus not be based on simplifications, reducing the time needed for realistic measurement campaigns from months to hours. At the heart of this method is a novel measurement apparatus, which will allow among other things the generation of variable irradiance spectra, closely matched to those experienced in real outdoor operation. A novel methodology will be developed to evaluate technologies currently at the development stage and an extensive validation of the approach will be carried out. Theoretical work will be undertaken to underpin the development of this new approach to energy rating of solar modules.