Flat high concentration devices

New concentrators achieving the theoretical maximum acceptance-angle-concentration product have appeared. Besides this, some of these concentrators are very compact (concentrator depth/aperture diameter smaller than 1/3). The feasibility of these concentrators for photovoltaic applications is studied. It is concluded that these concentrators may be useful for high concentration cells (irradiance for maximum efficiency greater than 800 suns) if these cells have a small size (diameter smaller than 5 mm). The concentrators may provide for this case an acceptance angle of /spl ap//spl plusmn/2.7 degrees with concentration factor around 1000/spl times/ and a concentrator depth 10 times the cell diameter. Instantaneous direct insolation and ambient temperature measurements of Madrid and a thermal model of the heat sink is used to calculate the annual electric energy output with which different concentration factors are compared. Concentration of 1000/spl times/ is close to the one giving the maximum annual electrical output.