This shows the photovoltaic efficiency of millimeter square InP single band gap nanowire solar cells as a function of time measured within the FP7 financed AMON-RA project. About four million InP NWs contribute to the signal. The line is a guideline for the eye. This figure gives an overview of the development of NWPV within AMON-RA. A comparison with the record efficiency development of other types of solar cells can be made using this plot by NREL: http://www.nrel.gov/ncpv/images/efficiency_chart.jpg. This image relates to a paper that appeared in Jan. 17, 2013, issue of Science Express, published by AAAS. The paper, by Jesper Wallentin at Lund University in Lund, Sweden, and colleagues was titled, "InP Nanowire Array Solar Cells Achieving 13.8% Efficiency by Exceeding the Ray Optics Limit."