A parabolic trough system is a type of concentrating solar power (CSP) system that collects direct normal solar radiation and converts it to thermal energy that runs a power block to generate electricity. The components of a parabolic trough system are the solar field, power block, and in some cases thermal energy storage system. The solar field collects heat from the sun and consists of parabolic, trough-shaped solar collector assemblies (SCAs) that focus direct normal solar radiation onto tubular heat collection elements (HCEs) or receivers. Each collector assembly consists of mirrors and a structure that supports the mirrors and heat collection elements, allows it to track the sun, and can withstand wind-induced forces. Each heat collection element consists of a metal tube with a solar radiation absorbing surface in a vacuum inside a coated glass tube.

Note. Many of the input variables in the parabolic trough model are interrelated and should be changed together. For example, the storage capacity, which is expressed in hours of thermal storage, should not be changed without changing the tank heat loss value, which depends on the size of the storage system. Some of these relationships are described in this documentation, but not all. If you have questions about parabolic trough input variables, please contact Solar Advisor Support at solar.advisor.support@nrel.gov.

A heat transfer fluid (HTF) transports heat from the solar field to the power block and other components of the system.  The power block is based on conventional power cycle technology, using a turbine to convert thermal energy from the solar field to electric energy. The parabolic trough systems may include a fossil-fuel backup system.

The concentrating solar power model in the current version of Solar Advisor is based on NREL's Excelergy software. For a more detailed description of the model, please download the CSP trough reference manual from the Solar Advisor website's support page: https://www.nrel.gov/analysis/sam/support.html.

To use the model, the technology option on the Technology and Market window should be Concentrating Solar Power, Parabolic Trough System.

For an example of parabolic trough systems, open the sample template Sample Parabolic Systems: On the File menu, click Open Sample Template and select the template from the list. The template contains three cases. The first case represents a 100 MW baseline system with a medium temperature heat-transfer fluid and an indirect 2-tank thermal energy storage system. The second case represents a similar 100 MW system with dry cooling. The third case shows how to optimize the solar field thermal energy storage system size to minimize the system levelized cost of energy, and is described in Solar Multiple Optimization.

The parabolic trough input pages for this option described in this section are: