Concentrated solar power (CSP)

Many people are familiar with solar photovoltaic (PV) or solar hot water systems. But in sunny spaces across the world, another lesser-known technology exists as a different way to take advantage of the sun’s energy: concentrated solar power (CSP). In this article, we’ll describe how concentrated solar power technology works, and how the technology compares to the solar photovoltaic panels you might install on your property. 

What is concentrated solar power?

Have you ever tried using a mirror or magnifying glass to fry an egg on the pavement during a hot, sunny day? Concentrated solar power (also known as concentrating solar power or concentrating solar-thermal power) works in a similar way conceptually. CSP technology produces electricity by concentrating and harnessing solar thermal energy using mirrors. At a CSP installation, mirrors reflect the sun to a focal point. At this focal point is an absorber or receiver that collects and stores heat energy. Eventually, the heat is used to power an engine or turbine that is connected to an electricity generator.

CSP is used in utility-scale applications to help provide power to an electricity grid. Most of the world’s CSP solar power plants are currently in Spain, but the use of concentrated solar technology is increasing in other areas across the world. In 2018, the largest CSP plant to-date was being installed in Morocco – when finished, the plant will have a capacity of 580 megawatts (MW) and provide electricity to more than one million people.

Generally, concentrated solar power is not installed at a residential scale, and instead will almost always be installed over a large area as a utility-scale generating facility. For residential and commercial property owners, solar photovoltaic panels are the best way to harness the sun’s energy for use.

Concentrated solar power efficiency vs other renewable energy technologies

The solar-to-electricity efficiency of a CSP system depends on many factors, including the type of CSP system, the receiver, and the engine. Most CSP technologies will have an efficiency somewhere between 7 and 25 percent.

To compare this to the electricity conversion efficiencies of other renewable energy technologies, wind turbines can achieve up to 59 percent efficiency, and hydropower systems can have efficiencies of up to 90 percent. When it comes to solar photovoltaics, the conversion efficiencies of solar cells are in a similar range as CSP; most solar panels available on the market today have efficiencies between 14 and 23 percent.

Concentrated solar power vs. photovoltaic solar

Though CSP and PV have similar efficiencies, there are few notable differences between them when it comes to applications, costs, and storage capacity.

Application

Concentrated solar power systems require a significant amount of land with direct sunlight. Because of this, there are limited places to build these types of systems. CSP systems tend to be large, utility-scale projects, capable of providing a lot of electricity as a power source to the grid. They’re not used in residential applications, unlike solar PV.

PV is a lot more common because solar panels can be installed just about anywhere that the sun is shining. While utility-scale solar installations will require similar amounts of space that a CSP plant would, you can also install solar panels for your own personal use on your home in business without developing new, unused sunny land.

PV systems are also capable of generating electricity in more weather conditions than CSP. CSP technology requires direct solar radiation to operate. Because of this, the performance of a CSP system is more sensitive to cloudy weather, while PV systems will still generate electricity on cloudy days.

Storage

One major advantage that CSP has over PV is its storage capabilities. With CSP, the heat transfer fluid used to move the heat from the absorbers to the engine has high heating capacities, allowing this fluid to retain heat for a long period of time. Storing thermal energy with the use of thermal energy storage tanks is much easier than storing electricity. As a result, CSP is often dispatchable even when the sun isn’t shining.

Solar PV has a disadvantage when it comes to storage – while you can store solar electricity using solar battery technologies, it’s more difficult and expensive to do so at large power levels. This makes it a less feasible source of electricity to the grid come night time.