Trackers

Fig. 3.2 Sparse Tracking-Array. Many different types of solar technology use sparse arrays as their current practice. Here we see an example of an array used in a solar power plant and having a low area coverage---estimated at only 25%. Source: Getty Images.

Current Practice

In conventional HCPV solar power plants the solar panels are mounted on huge mechanical trackers, some larger than a city bus, in order to keep the solar panels oriented perpendicular to the incoming solar radiation. These trackers have to be spread apart from one another, over a much larger area than that utilized for solar collection, in order to ensure that they do not collide with, or shadow, one another, as well as for preserving maintenance access. Such spacing lowers the overall “area efficiency” of the solar power plant, i.e., the net amount of energy generated from the entire land footprint of the solar farm. This, combined with the excessive use of resources such as steel and concrete to build these large-scale mechanical trackers, makes traditional tracking CPV power plants less than ideal from both a dollar per Watt, and a Watt per unit area, perspective.

Most providers of solar energy have ignored the issue of area efficiency because desert land is currently considered cheap, plentiful, and they can still make a profit by spreading out the CPV panels on trackers. However, as we explained before, this is incredibly short sighted because the scale of the energy generation problem is so staggeringly large that if solar is to play a significant role in future power generation then huge land areas will need to be devoted to it. Nor will rooftop solar installations suffice to meet our energy needs because there is simply not enough roof area available. Thus, we foresee land as becoming the limiting resource to utility-scale solar energy, and area-efficient systems, such as XE-CPV, will minimize the land requirement. Furthermore, XE-CPV is superior to all other solar and non-solar renewable technologies in terms of area-efficiency too.