Editing Parabolic trough (section)

== Design ==

[[File:Quadric Parabolic Cylinder.jpg|thumb|200px|left|A parabolic trough is shaped as a parabola in the x-y plane, but is linear in the z direction]]

A parabolic trough is made of a number of '''solar collector modules''' ('''SCM''') fixed together to move as one '''solar collector assembly''' ('''SCA'''). A SCM could have a length up to {{convert|15|m|ftin}} or more. About a dozen or more of SCM make each SCA up to {{convert|200|m|ftin}} length. Each SCA is an independently-tracking parabolic trough.<ref>{{cite web |url=https://www.gsenergy.eu/parabolic-trough/ |title= Parabolic Trough |publisher=www.gsenergy.eu |date=6 December 2017 }}</ref>

A SCM may be made as a single-piece parabolic mirror or assembled with a number of smaller mirrors in parallel rows. Smaller modular mirrors require smaller machines to build the mirror, reducing cost. Cost is also reduced in case of the need of replacing a damaged mirror. Such damage may occur due to being hit by an object during bad weather.

In addition, V-type troughs exist which are made from 2 mirrors and placed at an angle towards each other.<ref>{{cite journal|bibcode=1978PhDT.......157S|title=Analysis of flat mirror V-trough solar concentrator|first=B. C.|last=Son|date=1 January 1978|journal=Ph.D. Thesis|via=NASA ADS}}</ref>

In 2009, scientists at the [[National Renewable Energy Laboratory]] (NREL) and [[SkyFuel]] teamed to develop large curved sheets of metal that have the potential to be 30% less expensive than today's best collectors of [[concentrated solar power]] by replacing glass-based models with a [[silver]] polymer sheet that has the same performance as the heavy glass mirrors, but at a much lower cost and weight. It also is much easier to move and install. The glossy film uses several layers of polymers, with an inner layer of pure silver.<ref>{{cite web |url=http://www.energyboom.com/solar/award-winning-solar-reflectors-will-cut-production-costs |title=Award-Winning Solar Reflectors Will Cut Production Costs |author=Harry Tournemille |publisher=www.energyboom.com |access-date=2009-11-25 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303225053/http://www.energyboom.com/solar/award-winning-solar-reflectors-will-cut-production-costs |url-status=dead }}</ref>

As this renewable source of energy is inconsistent by nature, methods for energy storage have been studied, for instance, the single-tank ([[thermocline]]) storage technology for large-scale solar thermal power plants. The thermocline tank approach uses a mixture of silica sand and
quartzite rock to displace a significant portion of the volume in the tank. Then it is filled with the heat transfer fluid, typically a [[Molten salt|molten nitrate salt]].