Photovoltaic

Concentration Plants (GaAs and High efficiency Si)

Introduction to Technology

Concentrated PV plants use lenses or mirrors to concentrate sunlight on a PV cell. Since concentration greatly reduces the size of the solar cells needed, more expensive semiconductors like GaAs or high efficiency Si are used to maximize performance.

Low-concentration Plants

Low concentration PV plants often use mirrors to concentrate solar radiation onto a PV cell. Abengoa Solar often uses GaAs or high efficiency Si in their low concentration PV installations. The primary components of a low concentration PV installation are:

2-axis tracking heliostats: Heliostats that track the sun on 2 axes are the structure upon which mirrors and PV cells are supported. 2-axis tracking PV yields 35% to 48% more energy production than fixed PV systems.
Concentrators: Concentrators are used to direct solar radiation onto a PV cell. Often, these concentrators are mirrors manufactured with a silicone-covered metal. The orientation of mirrors on a concentrating PV module differ depending on their dimension, inclination angle, and module design.
Photovoltaic cells: : PV cells are what convert solar radiation into electricity. Low concentration PV cells are often made from single-crystalline silicon semiconductors. This technology has an efficiency of roughly 12%.
Inverter: Since the photovoltaic effect produces direct current (DC), an inverter must be used to change it to alternating current (AC).

Low concentration tracker, Sevilla PV

High-concentration Plants

High Concentration PV plants use optical technology and lenses to concentrate solar radiation up to 500 times. Since this greatly reduces the area of PV cells needed, more expensive and higher performance semiconductors like GaAs are often used.

Requirements

High concentration tracker, Sevilla PV

For high concentration PV plants to be feasible certain requirements must be met:

Favorable Weather: Economic feasibility and performance feasibility depends on the amount of radiation that falls onto the PV panels.
Topography: A flat surface eases the design and construction of a solar sytems.
Grid connectivity: In order to take advantage of the electricity produced by a solar system it must be able to easily connect to the electric grid.

Land Requirement for 1 MW Plants

The following table shows the total area needed to construct high concentration PV installations of 1 MW capacity. Accompanying the area (in acres) are the length and width (in meters).