Working of CSP - Linear Fresnel Reflectors.

Continuing in our CSP series, we are going to understand how Linear Fresnel Reflectors work.

Before going to parabolic trough, let’s understand the principle of CSP.

The receiver receives heat from sun light. This heat is gathered in oil or other heat medium which further converts water into steam. This steam is used to run steam turbine which produces electricity.

As shown in the image, the reflectors which are flat are concentrated towards a pipe which is filled of oil (Heat conducting material). This pipe is a heat receiver. These reflectors track sun all the day so that they can concentrate maximum sun light towards the receiver.  This fluid heats up to 750 °F. The fluid then converts water into steam. This steam is used to run steam turbine to produce electricity.

This system is cheaper than photovoltaic cell. And it has low maintenance too!

Here are some images of this system.

Working of CSP - Dish Engine.

Continuing in our CSP series, let’s understand how dish antenna works.

Before going to parabolic trough, let’s understand the principle of CSP.

The receiver receives heat from sun light. This heat is gathered in oil or other heat medium which further converts water into steam. This steam is used to run steam turbine which produces electricity.

Source : solareis.anl.gov

The working of dish engine is slightly different from Parabolic Trough and Power Tower. Parabolic Trough and Power Tower used steam turbine to produce electricity whereas Dish Engine uses external combustion engine to produce electricity. The receiver situated at the focal point of the dish has external combustion engine. It has hydrogen or helium gas filled in piston cylinders. As concentrated sunlight falls on the receiver, it heats the gas in the tubes to very high temperatures, which causes hot gas to expand inside the piston cylinders. The expanding gas drives the pistons. The pistons turn a crankshaft, which drives an electric generator.

Here are some images of Dish Engine CSP. 

Working of CSP - Power Tower

Continuing in our CSP series, we are going to understand how power tower works.

Before going to parabolic trough, let’s understand the principle of CSP.

The receiver receives heat from sun light. This heat is gathered in oil or other heat medium which further converts water into steam. This steam is used to run steam turbine which produces electricity.

Source : solareis.anl.gov

As shown in the figure the reflectors which are known as heliostats reflects and focuses sun light to a tower. This tower is a heat receiver. These heliostats track sun all the day so that they can focus maximum sun light. There is a fluid in this tower such as molten salt. This fluid heats up to 565 °C. The fluid then converts water into steam. This steam is used to run steam turbine to produce electricity.

Molten salt can retain heat for long time. So it can be used to make steam when there is no sunlight or during night. That means this is advantage of CSP over photovoltaic cell which cannot produce electricity when there is no sunlight.

This system is cheaper than photovoltaic cell. And it has low maintenance too!

Here are some images of this system.

Working of CSP - Parabolic Trough

As concentrating solar power technology is developing day by day, here is an explanation how parabolic trough works.

Before going to parabolic trough, let’s understand the principle of CSP.

The receiver receives heat from sun light. This heat is gathered in oil or other heat medium which further converts water into steam. This steam is used to run steam turbine which produces electricity.

As you can see in the image the parabolic concentrator concentrates heat into the pipe which is filled with oil. These concentrators are made of mirrors. Concentrator tracks sun all the day so that they can get maximum solar energy. The oil in pipes heats up to 395°C. This oil converts water into steam. This steam is used to run steam turbine which will produce electricity.

This system is cheaper than conventional solar system which uses photovoltaic cell which is costly. This system has very less working parts so the maintenance cost is very low. 

Here are some images of parabolic trough. 

Desertec - Concentrating Solar Power From Deserts.

Our world is going to face energy crisis. Scientists are trying to find new eco-friendly and affordable energy sources. 70% of our electricity needs are being fulfilled by natural gas, petroleum, coal and nuclear power. But these energies are not renewable and are not eco-friendly too.

Desertec foundation is an organization which wants to generate renewable energy on nonprofit basis. They are focusing on solar energy which is raining in deserts! Deserts gets most amount of solar energy in the world. Deserts cover about 2,98,00,000 square kilometers of earth that means fifth part of earth is desert. If we combine 1 year energy of all the fossil fuels, then it would be equal to only 5.7 hours of solar energy in deserts. Energy in 1 square kilometer for 1 year in desert would be equal to 15,00,000 barrel of petroleum! World’s total energy needs can be fulfilled by utilizing only 1% area of deserts. Keeping this in mind, Desertec foundation is focusing on making energy from this.



They are using Concentrated Solar Power technology to generate electricity. This technology is cheaper than solar cell (photovoltaic cell) and has more efficiency too! This technology uses solar heat to run the steam turbine which ultimately converts it into electricity. Because of this, the technology is also known as Solar Thermal Energy. This technology has efficiency near to 30% which is almost double than photovoltaic cell (efficiency 15% - 20%).

The types of CSP (Concentrated Solar Power) are as under.

1. Parabolic Trough. 
2. Power Tower. 
3. Dish Engine. 
4. Linear Fresnel Reflectors.

All these types are different but they use same principle. Concentrating Solar Power (CSP) is electricity generated from mirrors to focus sunlight onto a receiver that captures the sun’s energy and converts it into heat. This heat can run a standard turbine generator or engine. These systems range from remote power systems which are as small as a few kilowatts and up to grid-connected power plants of 100’s of megawatts (MW). CSP systems work best in bright, sunny locations like the Southwest which has most deserts like areas. Because of the economies of scale and cost of operation and maintenance, CSP technology works best in large power plants.

Here are some images of CSP.

Parabolic Trough.

Power Tower.

Dish Engine.

Linear Fresnel Reflectors

Solar Paint

Energy crisis is a big issue in today’s era. Scientists are trying to find more and more alternate sources of energy. One of them is solar energy. Solar energy is most common and ubiquitous energy source. We get enough energy in 1 hour from sun to fulfill our energy need for one year!!

Currently, people are using solar panels to generate electricity from sunlight. But cost for installation of solar panel is high and its efficiency is near to 10% to 15%.

Researchers at the university of Notre Dame in US has developed a paint which can generate electricity from light when it is spreaded on a conductive surface. Indian origin professor Prashant Kamat is leader of this team. These researchers have called this paint as ‘Sun-believable Solar Paint’.

Power producing nano-sized particle made of titanium dioxide is used in this paint. These nano particles are called quantum dots. The paint is based on nano sized particles of titanium dioxide (quantum dots) coated with cadmium sulfide or cadmium selenide. These particles were mixed with water and alcohol to create a smooth paste.

“When the paste was brushed onto a transparent conducting material and exposed to light, it created electricity”: Prashant Kamat.

This paint doesn’t need any special equipment to apply on the surface it simply need a conventional paint brush.

This paint has light to energy conversion efficiency of 1% which is low compared to solar panels. But production cost of this paint is very low which makes it worth.

Researchers believe that small improvement in efficiency can make it commercially successful.

Transparent Solar Panels

As we all know that solar cells are used to convert sun light into electricity. It is generally made of silicon. But the researchers of MIT has invented solar cell which is transparent! Yes, it is transparent and still it can make electricity from sun light.

It is very thin and transparent and it can be applied to the widows of buildings, surface of buildings and in many more applications you could imagine. You would be more surprised to know that this can be available at very low cost than traditional solar panels.

Researcher Richard Lunt with a prototype.
Photo: Geoffrey Supran

It uses a photovoltaic cell based on organic molecules, which harnesses the energy of infrared light while allowing visible light to pass through. This way it generates power while being transparent.



The previous version of transparent solar cells failed because of their low efficiency and their low transparency. But the researcher at MIT(Massachusetts Institute of Technology), Richard Lunt said that this invention has relatively more efficiency and transparency than previous version of transparent solar cell.

However there are many difficulties to face for this invention to be commercially successful. The researchers are trying to make its lifetime upto minimum 25 years.

The efficiency of transparent solar cells is 20% of the traditional solar cells. But still it can be used where the traditional solar cells can’t be used. It can be used in huge sky scrapers where they have very large surface area. Thus it can generate a good amount of energy needed for sky scrapers.

The installation process of this is very easy as an average person can install it on his own. However for commercial success, the windows manufacturers are aiming to ensemble transparent solar cells into windows during manufacturing process.

Prototype of transparent solar cells can be seen on top of the banner at
150th anniversary of MIT.
Photo: Geoffrey Supran.