NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

ed NREL logo, June 15, 2009

Blue

Collector/Receiver Characterization

We use a variety of in-house techniques and tools to test the 

performance of systems, pinpoint areas of weakness, and help 

identify the most cost-effective design of CSP components. 

•	 Through Parabolic Trough Collector Testing, we can measure the optical performance of parabolic trough modules.

•	 At the Receiver Test Laboratory, we can measure heat loss

as a function of temperature to establish the thermal performance of receiver tubes in parabolic trough systems.

•	 The Receiver Infrared Imaging System uses a vehiclemounted infrared camera and global positioning system

that helps us identify which heat collection elements in an 

operating CSP parabolic trough plant are losing heat and

require maintenance.

•	 At the Concentrator Optical Measurements Laboratory,

we use VSHOT (Video Scanning Hartmann Optical Test)

and other state-of-the-art techniques to characterize 

the optical performance of point- and line-focus 

optical concentrators. 

•	 NREL’s High-Flux Solar Furnace consists of a tracking

heliostat and 25 hexagonal mirrors in parabolic configuration to concentrate sunlight to an intensity of up to 

≈ 30,000 suns. We use the furnace to test and evaluate CSP 

components, such as reflector and absorber materials and

receivers. The furnace is also used for investigating thermochemical hydrogen and advanced material processes. 

Advanced Reflector and Absorber Materials

Our researchers use NREL’s facilities and capabilities to

test new CSP optical materials—with industry partners—

to determine if the materials meet the optical requirements 

of CSP solar field components. Improvements in solar field

performance can significantly boost system-wide efficiency.

•	 Optical characterization involves measuring the reflectance and transmission of CSP mirrors, glazing, lenses, 

glass, and coatings. In material characterization, we study

the properties of materials, such as permeability, adhesion,

reflectivity, absorption, and more. 

•	 Accelerated exposure testing replicates the long-term effects of outdoor exposure in a short period of time. Thus,

we can assess the durability of CSP reflectors and absorbers in a timeframe that supports more rapid deployment of 

these advanced materials. 

•	 In our Thin Film Deposition Laboratory, we determine

characteristics and effectiveness of thin-film coating on

CSP mirrors and receivers. 

Concentrating solar power (CSP) is positioned to become a major source of renewable electricity generation in the United States.

Researchers in the Thermal Systems Group at the National Renewable Energy Laboratory (NREL) provide scientific, engineering,

and analytical expertise to help advance the state of the art in CSP. As part of NREL’s Electricity, Resources, and Building Systems

Integration Center, our R&D capabilities span the entire electricity system—from generation to transmission and distribution to

the end user—and offer assistance in four major areas of concentrating solar power and solar thermal technologies.

In the Thin Film

Deposition Laboratory,

we develop advanced

solar reflectors and

absorbers using

magnetron sputtering,

electron-beam evaporation, and ion-beamassisted deposition

equipment.

NREL’s VSHOT laser scanning system determines the accuracy of concentrator 

mirror structures and is used in both a laboratory setting and in the field. It 

has proven critical in the design of new reflector structures.

PIX 16740

PIX 16739

Concentrating Solar Power

Electricity, Resources, & Building Systems Integration
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401

303-275-3000 • www.nrel.gov 

Printed with a renewable-source ink on paper containing at least 

50% wastepaper, including 10% post consumer waste.

NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

NREL/FS-550-48658 • August 2010

Thermal Storage and Advanced 

Heat Transfer Fluids

We can measure and evaluate the 

properties of fluids that transfer and 

store heat in CSP systems and predict 

the overall performance of a thermalstorage system. 

•	 We use the Thermal Storage Materials Laboratory to evaluate the

thermal properties of storage materials and to characterize fluids 

for both heat transfer and storage.

•	 The Thermal Storage Process and

Components Laboratory, when

completed, will have the equipment and accessories to determine 

the overall performance of a 

complete thermal-storage system 

before it is tested at full scale.

•	 With Thermal Storage Heat Transfer and Fluid-Flow

Modeling, we use computer simulation software to model

the flow of thermal energy and fluid over time and to 

predict the performance of complex heat-transfer and

flow systems.

CSP Modeling and Analysis

We employ advanced modeling techniques and data 

collection methods to help determine the best locations

for CSP plants, based on solar irradiance, as well as

economic, social, and environmental factors. 

•	 We use models and analytical techniques to evaluate

the potential for large-scale deployment of CSP under 

various scenarios and to estimate the resulting 

impact in terms of energy delivery, jobs, and the

environment. Example include the Solar Advisor

Model (SAM), used to calculate the levelized cost

of CSP system designs; the Regional Energy

Deployment System (ReEDS), used to determine

energy and environmental impacts; and Job and

Economic Development Impact (JEDI), used to quantify

potential employment and financial outcomes.

•	 Our Resource Information and Forecasting group provides

us with the necessary solar data, including satellite imagery, to help stakeholders better understand the feasibility

of locating a CSP plant in a particular area.

Cold

Tank 

Superheater 

Steam

Generator 

Heat

Exchanger 

Preheater 

Reheater 

Expansion vessel 

Condenser 

Steam Turbine 

Collector Field 

Heat Transfer Fluid Thermal Energy Storage 

Hot

Tank 

Electricity, Resources, & Building Systems Integration Center

Helpful Websites

NREL Concentrating Power Research

www.nrel.gov/csp

TroughNet Parabolic Trough Solar Power Network

www.nrel.gov/csp/troughnet

This monthly energy flow diagram for a parabolic trough power plant 

shows the conversion of energy from incident sunlight (green) to net 

electricity delivered to the grid (white).

 Major components of a parabolic trough power plant are shown. 

 Heat transfer fluid from the collector field may generate electricity 

directly or be sent to thermal energy storage for later electricity generation.

Front page header images: Globe, iStock; Wind Turbine, iStock; Solar Trough, NREL/PIX 14381; Power 

Lines, iStock; Solar Radiation Monitor, Tom Stoffel/PIX 15554; RSF Building image, NREL/PIX 16250; 

Solar Panels on roof, iStock