*6.2.3. Parabolic dish (PD)*

The parabolic dish (PD) is one of the most important methods in solar power generation. It is a point-focus collector that tracks the Sun in two axes, concentrating solar energy onto a receiver. The receiver absorbs solar radiation, transforming it into thermal energy. The thermal energy can either be transported through piped to a central power-conversion system or it can be transformed into electricity [48]. Solar dish presents some advantages such as high efficiency, hardness against deflection and wind load, modularity, versatility, durability against moisture and temperature changes, long-term low maintenance operation, and long lifetime. There are some disadvantages such as conversion of heat into electricity is needed in the system to have moving parts, increasing maintenance and cost, and is necessary for a great supply of energy to the tracking solar system [52].

#### *6.2.4. Solar tower (ST)*

This is a technology composed of multiple mirrors called heliostats distributed on a field, ordered and oriented automatically using a solar tracking system to reflect the direct radiation to a receiver situated a great height. Usually, each heliostat has 50–150 m<sup>2</sup> of reflective surface transferring the thermal energy onto the receiver. The heat transportation system consists of pipelines, pumps, and valves, where the fluid flows in a closed circuit between receiver and storage tank. Some of the advantages of these are highly effective as much in the solar collection as in its transformation to electricity. Also, there is no necessity to flatten the field; therefore, this technology can be installed in a hill. One of the most important disadvantages is the higher cost of the solar tracking system compared with the same system installed in PTC because in ST, it is necessary to install in each heliostat one of these systems and in PTC, the tracking system can be installed by row [48, 53].
