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How do solar trackers with mirrors work?

How do solar trackers with mirrors work?

How do solar trackers with mirrors work?


Solar Trackers

All solar energy systems, photovoltaic (PV), solar thermovoltaic (STPV), or simply solar thermal (ST), look towards the sun for their energy. The energy intercepted depends on the area of the interceptor NORMAL to the sun’s rays. The solar collector must always face the sun’s rays for maximum energy acquisition. But the sun, when visible, continuously changes its azimuth (east to west) orientation during the day. It also changes its elevation during the year. Trackers are mechanisms which keep the collector pointed towards the sun. Ideally, a two-axis tracker is required, ie, in azimuth and elevation. However, cost optimization vs energy gain will often decide in favor of tracking only in the azimuth, where the changes are faster and more significant. The track of elevation changes is monthly or so manually. To learn more, click here:




Tracking- Manual or Automatic?

Theoretically, it is quite possible for solar trackers to track the sun’s orientation manually. In the old days sun-based operations were actually tracked manually. Today, manual tracking, at least in the fast-changing azimuth, is not thinkable (except in the under developed world) due to labor costs. Elevations adjustments can still be done manually after a month or so, and hence a single axis automatic tracker is quite feasible.

Use of Mirrors

Simple photovoltaic systems would employ the panel or panels facing the sun directly. But in many applications, e.g., in concentrators for concentrated solar power CSP), they use sets of mirrors to focus the energy to receiver, photovoltaic, thermal, or solar theromovoltaic.



Trackers with Mirrors

It’s necessary to continuously re-orient the mirrors to focus the solar energy on to the fixed receiver. Simple physical principles indicate that angular movement of such a tracker has to be exactly half of the solar angular movement. In view of the complexity, they often use a single-axis tracker to track the motion of the sun. They mount mirrors on parallel axes on a single platform and rotate synchronously about their axes. This will allow the use of a single pair of sensors for moving the mirrors. It’s important to place mirrors with respect to each other so they don’t shade each other. This arrangement gives a much lower wind loading than a single mirror of the same area. If two axis tracking is required the whole platform can be controlled around the other axis. A single, but much more powerful drive will be required for the other axis.

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