COMPARISON OF PEAK-POWER MEASUREMENT UNDER NATURAL AMBIENT CONDITIONS IN COPENHAGEN (DK), DORTMUND (D) AND STELLENBOSCH (ZA)

摘要

Quality control of PV-modules includes measurement of peak-power P_(pk). Peak-power is defined as maximum power under standard test conditions (STC). As the peak-power can decrease due to degradation effects, a continuous quality control has to be realized on-site under natural ambient conditions. A measuring method is presented, which is implemented in a measuring-device, thus the measuring-result peak-power P_(pk) directly can be displayed. I-V-characteristics measured under ambient conditions can be corrected concerning temperature and irradiation according to IEC 60891. The description of the operating behaviour of solar cells by the effective solar cell characteristic allows explicit calculation of the parameters of the effective solar cell characteristic from the measured parameters Isc, V_(OC), I_(pmax), V_(pmax) with an accuracy of 1%. For the determination of the peak-power a new description of the irradiance is proposed. By analogy with the unit Lux (lx) of lighting technology it is proposed here to describe the spectral sensitivity of the photovoltaic solar cell by an effective irradiance with the new unit "Photovoltaic Lux" (phox). The method of the "effective solar cell characteristic" is presented as well as some significant results concerning P_(pk)-measurement under natural ambient conditions. A pv-module has been transported to measuring sites in South Africa, Germany and Denmark in order to compare the evaluated peak-powers of the same module under extremely different climatical conditions.