This paper presents a new type of PV structure called delta, Delta S(60). This was developed in order to achieve a constant irradiance daily profile similar to that obtained with a North-South horizontal axis tracker (1xh) since this constancy is essential for a number of PV applications, namely for PV irrigation systems. A comparison between these two structures and a tilt-fixed one oriented to the Equator, S(25), is presented. The results show a great performance of Delta S(60) for PV irrigation systems: to achieve the annual water volume pumped with a 1xh, the PV power needed for Delta S(60) is less than that needed for S(25). Furthermore, the values of a new parameter called the "constancy index" are as good as that obtained with a 1xh, with yearly mean values of more than 0.95.