A Study of the Antenna Effect of Photovoltaic Modules

We have investigated the reaction of photovoltaic cells to external electromagnetic fields in a frequency range of 10 Hz to 1 GHz. Outdoor recordings of received RF noise from the ambient were sampled for different solar cells and modules and compared with the reception of a simple whip antenna which represents a monopole for electromagnetic fields. Additionally in the laboratory well defined signals were generated and their reception was investigated depending on geometrical factors of the cells, such as orientation, size and distance. Two antenna models, namely dipole and patch configuration, are compared with the experimental findings. Simulations for the effect of modulated signals on solar cells were made as well. It was found that the gain in the investigated frequency range increases essentially linear with the cell area similar to patch antennas. A crystalline silicon cell of 100 cm2 has almost the same signal amplification as an 83 cm long whip antenna remaining coarsely constant over the whole frequency range. For narrow frequency bands however the signal attenuation or amplification is strongly modified by the dipole behavior caused by the front metal grid. Simulation shows that demodulation effects are biggest around the MPP, possibly affecting subsequent power conditioning units.