RESUMEN
Several soiling mitigation solutions and cleaning techniques have been developed to maintain high efficiency of photovoltaic (PV) panels. First of its kind, the investigation of the adaptability of the cleaning systems to solar trackers has been performed. The majority of these systems are dedicated to fixed installations whereas only few systems that can be adapted to solar trackers are presented in the updated cleaning systems background. For this reason, this paper presents an innovative approach which consists of combining trackers with an integrated cleaning system that has been designed. Based on the conducted experimental study, a maximum of 7% in soiling losses has been found for the PV generator of 4 kWp equipped with a dual-axis tracker installed in Rabat-Morocco over almost 1 year. Consequently, a reduced cleaning prototype has been realized and tested to evaluate the energy recovery based on the performed cleaning. The automatic cleaning has presented a similar efficiency with the manual cleaning with a slight difference of 0.95 pp and an increase of energy of 11.5% in the arid region. Through the economic analysis carried out taking into account the gain in energy production, the automatic cleaning cost was 0.14 USD/kWh. It has been found that the cleaning technique based on the telescopic arm would be more effective if the tracker is installed in an arid region where soiling is higher than Rabat. In this case, the payback time of the cleaning solution is faster (8 to 9 years), hence its profitability.
Asunto(s)
Energía Solar , MarruecosRESUMEN
Soiling has a crucial importance regarding its impact mainly for countries that have high soiling levels, dust storms, water scarcity and a great solar energy potential as the case of Morocco. Soiling mitigation is therefore mostly required during spring, due to higher pollen concentration, and summer, due to the lack of heavy precipitation. In this work, systematic measurements of soiling ratio were made in Rabat, city of north-western Morocco, during almost 1 year. Soiling has been evaluated considering the effect of dual-axis tracking that was compared to photovoltaic (PV) on fixed structure. A soiling rate of about 0.22%/day has been found for static PV while only 0.1% was found for PV on tracker. An additional approach of cleaning has been proposed in this paper which aims to use dew water. Using glass samples that were exposed to real environmental conditions, similar to the exposure conditions of PV panels, the soiling ratio was determined. At sunrise time, the subsequent change of the glass sample, from the horizontal position at night into the position of 30° tilt angle during the day, is performed to promote dew flow by the force of gravity acting on the droplets of dew. It has been found that relying only on the change of tilt angle, the average soiling losses were only 3.8% compared with 11.8% for fixed PV. This approach can reduce soiling similarly to solar trackers.