What is a solar tracker?

A solar tracker is a special device that directs a solar panel or module towards the sun. It can also direct Fresnel reflectors, lenses or mirrors. Collectively, these are called payload.  Another role of trackers is to minimize angle of incidence between photovoltaic panel and incoming sunlight. This happens for flat panel photovoltaic systems. The use of tracker increases amount of energy obtained from fixed amount of an installed power production capacity.

A study of trackers in 2009 predicted that they could be uses for at least 85 percent of commercial installations that exceed one megawatt. However,  up to 2 years ago, there has not been data to support the likelihood of such predictions coming into use.

Concentrated solar power (CSP) and concentrator photovoltaics (CPV)

CPV applications solarIn CSP and CPV applications, trackers are used for purpose of enabling optical components in CSP and CPV systems. Optics in the concentrated solar applications receive direct component of sunlight. They should therefore be oriented properly to collect energy.

All concentrator applications have tracking systems as these systems cannot produce energy unless they are pointed at the sun. For instance trackers with accuracies of ± 5 degrees have capacity to deliver more than 99.6% of energy delivered by direct beam and 100 percent of diffuse light.  For this reason, high accuracy tracking will not usually be used in non concentrating PV applications.

Benefit of trackers for fixed flat panel

SoitecCPV500Fixed flat panel may be set in that position to collect high proportion of the sunlight available at noon, there is significant power for collection in early hours of the morning and late in the afternoon.  If there is misalignment with fixed panel becomes too much to collect reasonable proportion of available. For instance, if the sun is just 10º above horizon, available energy will be approximately half of the energy levels at noon or even more depending on several factors. These include season, latitude and atmospheric conditions.

The primary advantage of having a tracking system is to collect energy from the sun for longest period of day and with highly accurate alignment as position of the sun shifts with seasons.  In addition, accurate tracking becomes more important as the level of concentration employed increases. The reason is that proportion of energy that is derived from, direct radiation will be higher and region where concentrated energy will be focused becomes smaller.

Non concentrating photovoltaic-PV- tracers

Photovoltaic panels will accept direct light from sky and diffuse it as well.  Panels on the standard photovoltaic trackers shall always gather available direct sunlight. Tracking functionality in standard trackers is responsible for minimizing angle of incidence between incoming light and photovoltaic panel. It increases amount of energy that is gathered from direct component of incoming sunlight.

The science behind standard PV trackers works with all the typical photovoltaic module technologies.