Photovoltaic system assessment considering temperature and overcast conditions: Light load efficiency enhancement technique

• The assessment of a light load enhancement technique (LLET) is presented in this paper.
• The technique is aimed at improving the efficiency of photovoltaic inverters.
• Efficiency improvement in PV inverters is crucial when a light load operation regimes occur frequently.
• A set of ten sites in the Gulf of Mexico shore were selected for the assessment.
• Four different PV technologies are also assessed with the light load enhancement technique.

Currently, there is an ongoing trend to promote photovoltaic systems as they are a sustainable option for power generation. However, the efficiency conversion of solar energy into electric energy can diminish due to adverse environmental conditions and the performance of power processing circuits. Several approaches have been proposed to mitigate the negative effects of high temperatures and light load operation on power converters. Nonetheless, in areas with hot climates and overcast conditions, the efficiency consequences must be specifically evaluated. In this paper, the assessment of an approach to enhance the converter efficiency at low power levels is presented. The approach employs hybrid-switches within a transformerless converter topology, in such a way that, under light-load operational conditions, soft-switching is achieved. The technique is evaluated for ten specific sites from which there is ample meteorological data available. Results indicate that a 1.35 percent increase in overall efficiency can be obtained with the proposed approach, with an annual surplus energy of 7220 W h for a 1 kW system.