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Installation of thermal solar energy

Solar power plant
Thermoelectric

Solar Concentrators. Types And Operation

Solar concentrators. Types and operation

A solar concentrator is a system for concentrating solar energy. This concentrated solar power is used in thermal solar energy.

Its operation is based on the exploitation of the reflection of the sun rays in a large area through reflective surfaces. It is usually an arrangement of aligned mirrors. The goal is to concentrate them in a receiver of contained size.

In solar power plants, this thermal energy is used to generate steam. Steam drives steam turbines. In this way, the radiation is converted into mechanical energy by means of a heat engine. This heat engine can be a current generator and generate electricity.

The use of solar concentrators allows to reduce the consumption of fossil fuels. Therefore, it is a clean energy that does not incentivize climate change.

Compared to classic flat solar collectors, the following advantages are obtained:

  • High energy efficiency. Convection and radiation losses are directly proportional to the receiver area.

  • Economic. Construction costs move primarily on reflective surfaces and relative pointing devices.

As photovoltaic costs continue to plummet, many think it has a limited future in utility-scale electricity production.

Types of solar concentrators

There are two types of solar concentrators that allow to maximize the performance of the solar installation:

  • Cylindrical parabolic solar concentrators. These parabolic trough concentrators have a unique curvature. For this reason, they are called “2D” hubs. This system gets average temperatures between 200-300 degrees Celsius.

  • The paraboloid solar concentrators of revolution. These hubs have a double bend. For this reason, they are called “3D” hubs. These systems allow temperatures even higher than 3273 kelvin.

Tracking the sun

One of the difficulties of these systems is ensuring that solar radiation strikes parallel to the axis throughout the day.

Once a solar concentrator works, a tracking system for the apparent movement of the sun (guided by a control system) is needed. Commonly using dual axis.

In small solar concentrators, this monitoring of the sun can be guaranteed with a tracking system applied directly to the concentrator.

Deformations of the parabolic surface appear in large solar concentrators. These deformations affect performance of these energy systems. In these cases, one or more intermediate flat mirrors are used. They are called heliostats.

Applications of solar concentrators

The most common use is the generation of electricity. However, there are also other techniques to harness thermal energy directly.

1. Generation of electricity

Electricity generation is the most widely used application of solar concentrators. For this, it can be achieved in two ways:

  1. Generate steam and power steam turbines.

  2. Through a Stirling engine connected to an electric generator.

Sometimes this technique is also used to power photovoltaic solar cells. So they are photovoltaic solar energy installations.

2. Solar cookers

With small 3D hubs you can make solar cookers. The hub can be between 80 cm and 2 meters. A “stove” is placed in the focal area where the container with the contents to be prepared rests.

3. Industrial applications

Solar concentrators make it possible to take advantage of solar energy in multiple industrial applications, such as in the metallurgical industry.

Summary

Solar concentrators are alienated systems of mirrors. They concentrate all the solar radiation in a single point. This allows high temperatures to be obtained. This concentrated heat allows steam and electricity to be generated.

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Published: May 13, 2015
Last review: June 3, 2020