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Tracking Systems – These systems all track the sun—mechanically pointing the solar array more directly at the sun from sunup until sundown. By pointing the solar panels directly at the sun, a greater area of the panel is exposed to sunlight. And by having that greater area exposed to the sun, each solar panel produces more electricity. Therefore, tracking increases the electricity generated by solar panels.

There are three types of systems:

1. Fixed or Non-tracking – these systems are simply installed at a fixed angle and have no mechanical or moving parts. Our rooftop or remote systems are installed this way.
2. Single-Axis Tracking System – these systems have a single axis on which the solar array rotates. As you’ve seen from our APS Solar Partner® system at the beginning of the tour, this is the least complicated tracking. A fairly simple motor and control system turns the solar array from east to west each day. This keeps the array pointed in a close approximation to the sun.
3. Dual-Axis Tracking – this is the type of tracker we use for testing our individual solar panels. The large Martin-Marietta trackers that you see around APS STAR Centerۍ are all two-axis trackers. These computer-controlled trackers adjust the panel for seasonal and time of day changes, pointing the panels directly at the sun every day of the year.

Benefits of tracking - By adding single-axis tracking to a solar array, electrical output is increased by about 20 percent when compared to a non-tracking solar array. By moving to two-axis tracking, we increase the electrical output of an array by another 10 percent over a single-axis tracker and about 30 percent over a fixed array.

Detriments to tracking – tracking adds cost and mechanical fallibility. On small systems, like the rooftop systems, we’ve found that the added costs outweigh the benefits. On our larger commercial systems like the APS Solar Partner® power plants, the increased energy output more than offsets the added costs.

APS is currently experimenting with different types of tracking systems at APS STAR Center®:

Delta Tracker – This system is shaped to take advantage of the sun’s position as it gets lower in the winter. By tilting the tracking axis toward the south, the solar panels get a little more solar exposure in the winter and this will potentially increase its electrical output.

Linear Concentrator – This system, also tilted toward the south to increase its annual solar exposure, uses plastic lenses to focus the sun on a thin strip of PV material at the bottom of each trough. By concentrating the sun, as you’ll see later, this system requires less PV material to generate the same amount of electricity. Since the PV material is the most expensive part of a PV system, this will help reduce the cost. This is a brand new system and we are eagerly awaiting the results of this test to see how it performs.

Horizontal Tracker One – This is one of two systems using commercially available PV panels and a simple, reliable, straightforward horizontal tracking system to produce electricity.

Passive Trackers – These trackers follow the sun without having any motors to drive them. The trackers are carefully balanced and the tubes on the side of each tracker are filled with a gas. As the sun heats the gas on one side, the gas expands and flows into the other side of the tracker, This upsets the delicate balance and solar panels automatically tilt toward the sun. This is still being tested by APS.

Horizontal Tracker Two – This is the type of system that APS has chosen for its existing APS Solar Partnerۍ solar power plants. In our tests, this system proved to be effective, reliable and the lowest cost of all the systems tested.

Index of APS STAR Center® Virtual Tour
What's Happening at APS Star Center® Solar Panel Testing Array Rooftop Solar Installations Roof One Roof Two		Inverters Roof Three Tracking Systems APS Tilt Trackers Amonix Solar Arrays