The paper presents an experimental study on the heat transfer and flow friction characteristics in a solar air heater channel fitted with delta-winglet type vortex generators (DWs). The experiments are conducted by varying the airflow rate for Reynolds number in the range of 5000 to 24000 in the test section with a uniform heat-flux applied on the upper channel wall. Firstly, the DW pairs are mounted only at the entrance of the lower wall of the test channel (called DW-E) to create multiple vortex flows at the entry. The effect of two transverse pitches (R-P = P-t/H = 1 and 2) at three attack angles (alpha = 30 degrees, 45 degrees and 60 degrees) of the DW-E with its relative height, b/H = 0.5 (half height of channel) is examined. Secondly, the 30 degrees DWs with three different relative heights (b/H = 0.3, 0.4 and 0.5) are placed on the upper wall only (absorber plate, called DW-A) of the test channel. The experimental result reveals that in the first case, the 60 degrees DW-E at R-P = 1 provides the highest heat transfer and friction factor while the 30 degrees DW-E at R-P = 1 performs overall better than the others. In the second case, the 30 degrees DW-A at b/H = 0.5 yields the highest heat transfer and friction factor but the best thermal performance is found at b/H = 0.4.