UVM Campus Renewable Energy Feasibility Study Solar Photovoltaic
the picture above, the site is usually required to be filled in with crushed stone to ensure proper drainage. Requirements vary by site and local permitting authorities. 1.5
Solar Trackers Solar Trackers consist of tracking panels that move in one or more directions in order to maximize the
amount of time that they are directly facing the sun. Taking advantage of this direct sunlight maximizes the solar panels’ output. While fixed tilt panels are generally cheaper to install and maintain due to a lack of moving parts or a need for electricity to move the panels, tracking panels will produce more electricity per installed Watt because they are always optimizing their angle of incidence with the sun. There are several different varieties of solar trackers. Trackers are generally divided into categories based on how many axes they can move around. Uniaxial trackers pivot around one axis, and multiaxial trackers move around two or more axes. Increasing the tracker’s range of motion increases the cost, but the electrical output also grows. Like fixed ground-mount systems, uniaxial trackers can be arranged in rows. They will often be oriented east to west instead of south so they follow the sun as it moves across the sky. Multiaxial trackers often pivot around a central point or a tower such as the AllSun Tracker, manufactured by All Earth Renewables and further discussed in the next section. These trackers need to be installed farther apart compared to uniaxial or fixed-mount panels in order to minimize shading. However, their ability to always face directly into the sun significantly increases their output. 1.51
AllSun Tracker The AllSun Tracker, produced by All Earth Renewables 7 based in Williston, Vermont, is one of many
models of multiaxial solar trackers. There are two varieties of these trackers: the 20 series, (which has 20 solar panels (5kW)), and the 24 series, (which has 24 solar panels (6kW)). For large-scale or commercial production, the 24 series is the better design since it is slightly larger and has 20% more capacity. These trackers pivot around a single tower, which allows them to rotate 360° horizontally and 90° vertically, meaning they can be oriented at any angle tangent to the top half of a sphere. Also, these trackers are equipped with a GPS system to help them track the sun. When they are installed, the GPS delivers exact coordinates to a tracker to define its precise location. The tracker then calculates the exact angles it will need to be at to always directly face the sun. Using a hydraulic motor and actuator to move, they have a parasitic load of about 1% annually. Despite this loss,
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