Question

Explain clearly the difference between Concentration Solar Power (CSP) and Concentration Photovoltaics (CPV) and describe the advantages and disadvantages for both CSP and CPV.

Answer 1

ADVANTAGES OF CONCENTRATED SOLAR POWER

1. Uncomplicated Implementations and Operations

One of the remarkable benefits or advantages of concentrated solar power is that its corresponding power plant closely resembles most power plants based on steam turbines. Plants running on fossil fuels can technically be used for CSP systems. The operating cost of a CSP plant is comparatively lower than hydrocarbon-based and nuclear-based plants because of simpler operations and maintenance requirements. Depending on the location and the size of the entire plant, a CSP system is scalable up to more than 100 MW level.

2. Supplements Other Sources of Energy

Building a CSP plant can complement other sources of energy, thus promoting a more secure energy grid. Although this renewable energy source does not generate electricity enough to power large communities, adding it to the energy mix can address existing and future electricity requirements. CSP can also be used in effective and efficient oil recovery. Through so-called solar thermal enhanced oil recovery, the steam it produces is used to make heavy oil less viscous and easier to pump, thus extending the lives of fields with heavy oil and making them more economical.

3. Relatively Uninterrupted Source of Electricity

Round-the-clock generation of electricity is another remarkable advantage of concentrated solar power technology, especially when compared to photovoltaic solar panel and wind power technologies. Take note that photovoltaic solar panels and wind power are intermittent in nature. On the other hand, certain CSP plants can store energy in the form of molten salts. Hence, the electricity they generate is more sustainable, predictable, and reliable.

4. Converts Solar Energy into a Transportable Form Energy

Concentrated solar power has other uses beyond electricity generation. Several institutions are investigating and improving the application of CSP in thermal reaction technologies for solar fuel production. For example, a couple of studies have demonstrated the use of CSP to break apart water molecules to harness hydrogen without carbon emissions. The study of Elena Diaz et al. also demonstrated the use of CSP to decompose methane into hydrogen and carbon fuel cells. Promoting these processes further can make solar a transportable form of energy.

DISADVANTAGES OF CONCENTRATED SOLAR POWER

1. Dependent on Locations and Large Tracks of Lands

Similar to photovoltaic solar power and wind power, a fundamental limitation or disadvantage of concentrated solar power is that it requires using extensive land area that otherwise, could be used for commercial and residential development or agriculture. In addition, the study of M. Enjavi-Arsanji, K. Hibordi, and M. Yaghoubi noted that a CSP plant is economical only for locations with direct normal irradiation beyond 1800 kWh/m²/year such as sprawling open spaces and desert areas. This technology is not economical in populated areas and regions that receive less sunlight in a year.

2. Notable and Possible Negative Ecological Impacts

Another drawback of concentrated solar power is that it uses a lot of water either to drive steam turbines for electricity generation or to cool down thermochemical reactors. Although using sea water can be a conventional solution, this would imply building a CSP plant near the coastline that in turn, may not be suitable depending on the amount of solar radiation the specific area receives. There is also another issue concerning the impacts of CSPs on wildlife. Because it directs and redirects sunlight, it naturally attracts certain species such as insects that are preys of other species such as birds. The level of heat around the area can kill predators.

3. Costs Implications of Thermal Storage Materials

The study of Jun Wang et al. that several factors influence the costs of building and maintaining a CSP plant. The use of steam or thermal oil is not an attractive option for high-temperature thermal energy storage material because of its immediate cost and other costs associated with its temperature limitations and flammability. Molten salt is an alternative storage material but aside from drawback due to limited operating temperature range because it solidifies at low temperature and decomposes at high temperature, it promotes corrosion and deterioration, which in turn, requires the use of more expensive storage tank materials.

4. Possible Lack of Attention from Researchers and Investors

Different types of renewable and alternative sources of energy are competing against one another in terms of research attention and investment interest. Concentrated solar power is competing with photovoltaic solar power and wind power. Breakthroughs in photovoltaic technologies have increased the cost and energy efficiency of solar panels. Take note that CSP is also competing against more efficient sources of energy such as fission-based nuclear power. After all, CSP is not as energy dense as nuclear power and hydrocarbons. Further developments in the future might render CSP obsolete.

concentrating photovoltaics

One of the ways to increase the output from the photovoltaic systems is to supply concentrated light onto the PV cells. This can be done by using optical light collectors, such as lenses or mirrors. The PV systems that use concentrated light are called concentrating photovoltaics (CPV). The CPV collect light from a larger area and concentrate it to a smaller area solar cell.

Advantages and disadvantages of the CPV systems

Advantages	Disadvantages
Less PV material, hence less cost	With concentrated sunlight, formation of hot spots is possible
Increased efficiency	Tracking systems increase complexity
Higher productivity throughout the day due to tracking	CPV can properly function only under direct beam radiation

CPV Strengths	CPV Weaknesses
High efficiencies under direct normal irradiance	HCPV cannot utilize diffuse radiation. LCPV can only utilize a fraction of diffuse radiation.
Low cost per watt of manufacturing capital	Power output of MJ solar cells is more sensitive to shifts in radiation spectra caused by changing atmospheric conditions.
Low temperature coefficients	Tracking with sufficient accuracy and reliability is required.
No cooling water required for passively cooled systems	May require frequent cleaning to mitigate soiling losses, depending on the site
Additional use of waste heat possible for systems with active cooling possible (e.g.large mirror systems)	Limited market – can only be used in regions with high DNI, cannot be easily installed on rooftops
Modular – kW to GW scale	Strong cost decrease of competing technologies for electricity production
Increased and stable energy production throughout the day due to (two-axis) tracking	Bankability and perception issues
Low energy payback time	New generation technologies, without a history of production (thus increased risk)
Potential double use of land e.g. for agriculture, low environmental impact	Optical losses
High potential for cost reduction	Lack of technology standardization
Opportunities for local manufacturing	–
Smaller cell sizes could prevent large fluctuations in module price due to variations in semiconductor prices	–
Greater potential for efficiency increase in the future compared to single-junction flat plate systems could lead to greater improvements in land area use, BOS costs, and BOP costs	–

difference:

Photovoltaics transforms sunlight directly into electricity without any moving parts. You put up the panels, connect their plus and minus terminals, and you have a slow but steady flow of electricity, normally stored in batteries for later use to heat, light and run appliances. Solar panels generally cannot use heat (infrared wavelength) to generate electricity, so the heat resulting from the sun shining on solar panels has to be eliminated by cooling.

Concentrating solar power in contrast uses the sun’s heat, but not its visible light component.

In concentrating solar plants, the sun’s heat is focussed by concave mirrors on a heat exchanger normally located on a tower. Mirrors can also be formed as troughs with a heat exchanger pipe running along the focal point of each trough. The result is similar, we gain sufficient heat to boil water and make steam, which can then be used to drive turbine/generator combination

photovoltaics use semiconductors that convert certain wavelengths of light directly into electrical current, usually at around 15–22% efficiency, but sometimes in rare and expensive usages, triple-junction (3 layer) chips can convert more of the light spectrum and get ~40% efficiency (e.g., on satellites).

Concentrating solar power uses mirrors and/or lenses to focus ambient light at 10–400x intensity on to those very expensive ~40% efficient photovoltaic chips to attempt to get maximum power from a given amount of sunlight at a lesser cost…because lenses are cheaper than semiconductors.