A tracking array is a solar array that follows the path of the sun to maximize the solar radiation incident on the photovoltaic surface. The two most common orientations are:

 

One-axis where the array tracks the sun east to west – used mostly with flat-plate systems and occasionally with concentrator systems.

Two-axis tracking where the array points directly at the sun at all times – used primarily with PV concentrator systems.

 

Tracking arrays use both direct and diffuse sunlight. Two-axis tracking arrays capture the maximum possible daily energy. Typically, a single-axis tracker will give 15% to 25% more power per day than a fixed array, and dual-axis tracking will add about 5% to that. The exact gains will depend somewhat on latitude and season.

 

For more information, see solar tracker.