ADVANCEMENTS IN THE DEVELOPMENT OF 'ATAMO': A SOLAR MODULE ADAPTED FOR THE CLIMATE CONDITIONS OF THE ATACAMA DESERT IN CHILE-THE IMPACT OF SOILING AND ABRASION

摘要

Dust is currently one of the major problems of PV plants in Chile. In the present study we investigate the influence of abrasion and soiling on solar modules using different combinations of solar module materials and solar cells under simulated test conditions. Indoor and outdoor tests were performed at ISC Konstanz, Germany, and at the Solar Platform of the Atacama Desert (PSDA) in Yungay, Chile, respectively. We fabricated half-size and full-size cell modules employing different cell types, glass thickness, encapsulants, backsheets or glass-glass configurations. Modules were measured in the field for eight months. During exposure time, cleaning was performed every 60 days. Preliminary outdoor results indicate that ARC glass type exhibits higher Isc losses than standard (STD) glasses due to soiling, regardless of the combination of other materials used for the modules. Transparent backsheets (TBS) or glass on the rear side help to compensate the soiling losses due to increased internal reflection of light coming from the rear side of the module. In dirty condition, higher performance ratio (PR) was observed on half-size than on full-size cell modules under monofacial operation condition (the rear side covered: 97% compared to 94%). Under bifacial operation much higher but similar PRs for half- and full-size modules (both 107%) were reached. For the abrasion outdoor test, no damage was observed until now, even on vertical installed glasses which were installed perpendicular to the wind speed and close to the ground. For the indoor abrasion and soiling test, we adapted the standard testing conditions for sand (IEC and MIL-STD) using representative parameters such as temperature and humidity registered by 12 years of measurements and dust from eight PV plants located in the Atacama Desert. For the abrasion indoor test, the ARC layer on the glass was removed by all dust types after one minute of exposure and for 200-500 μm dust grain size. Increasing the exposure time, higher transmissivity (T), reflectivity (R) and Isc losses were detected until the abrasion effect almost reached saturation. When changing the tilt angle from 90° to 30° and reducing the grain size to 63-112 μm, lower losses were observed. Regarding the indoor test, a model was performed to predict the T and R losses according to the geographic place, glass type and sand density on the glass surface. The model predicts 3.5% higher T losses and 2.4% R losses for ARC compared to STD glasses with dust of less than 63 μm grain size, regardless of the location.