Experimental energy yield in 1.5x and 2x PV concentrators with conventional modules

Low concentration devices along with standard (one sun) modules represent an attractive option to reduce the cost per kilowatt-hour in photovoltaic installations. This paper deals with the energy gains obtained over a year by two of such devices: a 2x V-trough concentrator and a 1.5x single flat mirror structure. The experiment was mounted on a two-axis tracking system located in Arguedas (northern Spain). Due to various optical and electrical phenomena, the energy gain is notably lower than the geometrical concentration. We have conducted a theoretical analysis of these phenomena and quantified the energy loss associated with each. Daily and monthly energy gains show an influence of daylight clearness index on energy output. In view of this effect, and taking into account a possible increase in degradation of the photovoltaic modules due to high working temperatures and hot-spots, the viability of these concentration devices is far from being clear. Copyright (C) 2007 John Wiley & Sons, Ltd.