How does a solar power plant work?

In the future, fossil fuel power plants - namely coal plants in the United States - will be replaced with clean, renewable sources of energy. Solar energy will play a major role in that future. Presently, solar power plants are gaining a foothold in utility-scale power generation.

Solar power plants can produce energy in two ways:

1. Solar thermal power plants - In this set-up, solar energy heats a transfer fluid, which is used to heat water. That water creates steam to spin a turbine that can then produce electricity.

2. Solar photovoltaic (PV) plants - PV plants utilize solar power panels to convert solar radiation directly into electricity.

Solar Thermal Power Plants

Solar thermal power plants also work in a few different ways. The most common type uses a parabolic trough design. In these plants, commonly known as concentrated solar power (CSP) plants, several rows of trough-shaped, parabolic mirrors are strategically designed to capture and concentrate the sun's rays onto a focal point, much like a child might use a magnifying glass to burn ants. That point is a black pipe running the length of the row of mirrors. Inside this pipe is a transfer fluid, which heats up to very hot temperatures, often upwards of 300 degrees Fahrenheit. The heated fluid is piped to a power generator, where its heat is used to boil water, creating steam and electricity.

Another version of a solar thermal power plant is a "power tower." Power towers take CSP technology in a new direction. Mirrors are situated to focus solar radiation onto a single focal point: a tall tower which houses a receiver that boils water to create steam. Mirrors are usually connected to a tracking system that allows them to follow the sun across the sky. Power towers have some key advantages, such as smaller footprints and relatively fast construction time.

Solar Photovoltaic Plants

Photovoltaic plants are very straightforward. Several solar power panels are installed to form an array. Typically, a handful of panels will be "strung" together in series on a single mounting system. Each set of panels collects solar energy, converts it directly into electricity, and sends that electricity through wiring to the electric grid. PV power plants are relatively rare because solar thermal power is currently much more efficient at producing electricity on a large scale.