Wedoany.com Report-Oct 31 , Researchers at the Universidad Politécnica de Madrid (UPM) have created a two-dimensional (2D) modeling tool for the deployment of large-scale bifacial PV plants using single-axis trackers over terrain of arbitrary orientation and slope.

The proposed model is intended to reduce yield losses caused by the fact that north-south aligned single-axis trackers are often deployed on uneven east-west slopes.

“This paper first outlines some relevant assumptions that standard PV software relies on to simplify the energy yield simulation and pinpoints the horizontal constraint, which does not necessarily require the ground to be horizontal, only that its cross-axis slope angle be zero,” the research group said. “The mathematical basis for modifications to overcome the horizontal constraint while preserving these assumptions is then described.”

The scientists used the Sisifo software, an open PV simulation tool developed by the UPM itself, and said it can overcome the horizontal constraint of conventional modeling solutions while still relying on 2D modeling and a single tracker representative row. Simple equations were also developed to monitor the trackers' motion control.

The proposed approach assumes that the axis length is infinite and the axis height above the ground is constant along its entire length. “This leads to relying on 2D modeling, which reduces the description of the geometry to a projection onto a plane normal to the tracker axes, that is, the cross-axis plane,” the academics explained. “On the other hand, it is assumed that the number of axes is infinite and that the axes are periodically arranged so that they all lie in the same plane, parallel to the ground and equidistantly spaced.”

Thanks to the software, the researchers analyzed a single-axis tracking bifacial PV plant over a ground that slopes only in the east-west direction, with each particular case being defined by the ground inclinations and the axis azimuth. They also simulated a benchmark PV plant deployed on a horizontal terrain with a south-oriented axis.

The analysis showed that PV plants in multifaceted terrains have to be addressed by considering that the terrains as composed of a set of flattened areas, each with a given azimuth and slope, with each area having to host a set of tracker axes with a given axis azimuth. The modeling was described in the study “Single-Axis Tracking and Bifacial Gain on Sloping Terrain,” published in Progress in Photovoltaics.