III-nitrides have emerged as a potential "next-generation" photovoltaic material and there has been increasing interest and progress in the development of InGaN based solar cells in the past few years. Tyndall have recently become involved in a European project as part of the ENIAC Joint Undertaking initiative to investigate the development of III-nitride photovoltaic junctions grown on Si substrates. This presentation will give an overview of the design, growth and characterization efforts associated with the project.