EP1170596-A2  EMERY K: "The rating of photovoltaic performance" IEEE TRANSACTIONS ON ELECTRON DEVICES IEEE USA, vol. 46, no. 10, October 1999 (1999-10), pages 1928-1931, XP002350133 ISSN: 0018-9383;  HEIDLER K ET AL COMMISSION OF THE EUROPEAN COMMUNITIES: "MEASUREMENT OF MULTI-JUNCTION SOLAR CELLS" 10TH. E.C. PHOTOVOLTAIC SOLAR ENERGY CONFERENCE. LISBON, PORTUGAL, APRIL 8 - 12, 1991, PROCEEDINGS OF THE INTERNATIONAL PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, DORDRECHT, KLUWER ACADEMIC PUBLISHERS, NL, vol. CONF. 10, 8 April 1991 (1991-04-08), pages 111-114, XP001135640 ISBN: 0-7923-1389-5;  GLATFELTER T ET AL: "A method for determining the conversion efficiency of multiple-cell photovoltaic devices" 4 May 1987 (1987-05-04), CONFERENCE RECORD OF THE NINETEENTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE - 1987 (CAT. NO.87CH2400-0) IEEE NEW YORK, NY, USA, PAGE(S) 1187 - 1193 , XP009055414 * abstract; figures 2-4 * * pages 1190-119, column 2 *US6876187-B2  Troy Glatfelter, et al., "A Method For Determining The Conversion Efficiency Of Multiple-Cell Photovoltaic Devices", IEEE, pp. 1187-1193 (1987).EP1170596-B1  EMERY K: "The rating of photovoltaic performance" IEEE TRANSACTIONS ON ELECTRON DEVICES IEEE USA, vol. 46, no. 10, October 1999 (1999-10), pages 1928-1931, XP002350133 ISSN: 0018-9383;  GLATFELTER T ET AL: "A method for determining the conversion efficiency of multiple-cell photovoltaic devices" 4 May 1987 (1987-05-04), CONFERENCE RECORD OF THE NINETEENTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE - 1987 (CAT. NO.87CH2400-0) IEEE NEW YORK, NY, USA, PAGE(S) 1187 - 1193 , XP009055414 * abstract; figures 2-4 * * pages 1190-119, column 2 *;  HEIDLER K ET AL COMMISSION OF THE EUROPEAN COMMUNITIES: "MEASUREMENT OF MULTI-JUNCTION SOLAR CELLS" 10TH. E.C. PHOTOVOLTAIC SOLAR ENERGY CONFERENCE. LISBON, PORTUGAL, APRIL 8 - 12, 1991, PROCEEDINGS OF THE INTERNATIONAL PHOTOVOLTAIC SOLAR ENERGY CONFERENCE, DORDRECHT, KLUWER ACADEMIC PUBLISHERS, NL, vol. CONF. 10, 8 April 1991 (1991-04-08), pages 111-114, XP001135640 ISBN: 0-7923-1389-5