Lanzerstorfer

we are producer of east west tracker(1 axis) www.phlegon-solar.com and when i try to simulate a pv system, i just get a few percentage more kWh per kWp what does i make wrong?? orientation: field type: tracking, horizontal axis E-W and then from -45° to +45° our tracker stands morning 45° directly to east, midday 0° and afternoon 45° to west