Concentrating Solar Power Basics

Photo of several flat, octagonal panels arranged together to form a dish-shaped structure. The receiver is supported above the panels by an arm-like structure and glows as it is heated by concentrated sunlight. A technician sits below the dish, in the shade of the panels.

This solar concentrator has a fixed-focus faceted dish with a concentration of about 250 suns. This system can be used for large fields connected to the utility grid, hydrogen generation, or water pumping.
Credit: Science Applications International Corporation / PIX 13464

Concentrating solar power (CSP) offers a utility-scale, firm, dispatchable renewable energy option that can help meet our nation's demand for electricity. CSP plants produce power by first using mirrors to focus sunlight to heat a working fluid. Ultimately, this high-temperature fluid is used to spin a turbine or power an engine that drives a generator. And the final product is electricity.

Concentrating solar power systems can be classified by how they collect solar energy. The following pages discuss and illustrate the basic operation of each of the three main technologies of CSP systems, and they also provide information on thermal storage related to CSP technologies:

Aerial photo of a power tower system, showing numerous large, reflective mirrors in concentric circular rows. Tracking the sun, each mirror reflects onto the top of the tower at the center of the circle of mirrors. The receiver at the top of the tower is glowing.

Stretched-membrane heliostats with silvered polymer reflectors surround the Solar Two power tower in Daggett, California.
Credit: Sandia National Laboratories / PIX 00036

Smaller CSP systems can be located directly where the power is needed. Single dish/engine systems can produce 3 to 25 kilowatts of power and are well suited for such distributed applications. Larger, utility-scale CSP applications provide hundreds of megawatts of electricity for the power grid. Both linear concentrator and power tower systems can be easily integrated with thermal storage, helping to generate electricity during cloudy periods or at night. Alternatively, these systems can be combined with natural gas, and the resulting hybrid power plants can provide high-value, dispatchable power throughout the day.

These attributes—along with world-record solar-to-electric conversion efficiencies—make CSP an attractive renewable energy option in the southwestern United States and other sunbelts worldwide.