That's because asthe Earth moves around theSun, it is moving into a stationary field of dark matter - and for half the year it will be moving against the tide of dark matter - just like driving into the rain.
The Solbot, made by startup QBotix, stops at each array and extends a cylindrical arm to adjust the angle of the photovoltaic panels so they capture the most amount of sunas it moves across the sky and through the seasons.