COMPARATIVE ANALYSIS OF THE DUST LOSSES IN PHOTOVOLTAIC MODULES WITH DIFFERENT COVER GLASSES

One cause of power losses in photovoltaic systems is the accumulated dirt on modules surface, mainly dust but also bird droppings. It is usual to include a loss factor for this cause about 3-4%. The large grid-connect photovoltaic plants include periodic modules cleaning to avoid these losses. In this paper we have quantified the losses caused by accumulated dirt on module surface. The use of textured glasses increases the performance of the modules due to the decrease of reflection losses. We have checked if these losses depend on the structure of the module surface and also if the rain cleans well enough the modules and in which conditions this cleaning happens. The obtained results show that losses due to accumulated dirt in modules can reach values about the 15% for period without rain. We have measure yearly average dirt values of losses about 6% that is greater than the values used in the sizing and design of grid-connected photovoltaic systems. We can conclude that textured glasses do not accumulate more dirt than the non-textured glasses and therefore the maintenance of photovoltaic system with textured glasses does not mean additional expenses.